U.S. patent application number 09/822179 was filed with the patent office on 2002-01-31 for image recording method and apparatus and image reproducing method and apparatus.
Invention is credited to Kihara, Nobuhiro, Shirakura, Akira.
Application Number | 20020012136 09/822179 |
Document ID | / |
Family ID | 27302765 |
Filed Date | 2002-01-31 |
United States Patent
Application |
20020012136 |
Kind Code |
A1 |
Kihara, Nobuhiro ; et
al. |
January 31, 2002 |
Image recording method and apparatus and image reproducing method
and apparatus
Abstract
An image recording method and apparatus for recording an image
on a holographic stereogram in such a manner as to generate an
optimum reproduced image, and an image reproducing method and
apparatus capable of generating an optimum reproduced image from
the holographic stereogram. A parallax image string is recorded as
a series of strip- or dot-shaped hologram elements by having an
object light beam and a reference light beam fall on one and the
other surfaces of a recording medium for hologram 130. On the
reference light incident side, a light inlet block 52 is arranged
for having contact with the recording medium for hologram 130 so
that no significant change in the refractive index will be produced
on an interface with the recording medium for hologram 130. The
reference light beam is illuminated via this light inlet block 52
on the recording medium for hologram.
Inventors: |
Kihara, Nobuhiro; (Kanagawa,
JP) ; Shirakura, Akira; (Kanagawa, JP) |
Correspondence
Address: |
Ronald P. Kananen
RADER, FISHMAN & GRAUER, PLLC
Suite 501
1233 20th Street, N.W.
Washington
DC
20036
US
|
Family ID: |
27302765 |
Appl. No.: |
09/822179 |
Filed: |
April 2, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09822179 |
Apr 2, 2001 |
|
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08874665 |
Jun 13, 1997 |
|
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|
6236475 |
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Current U.S.
Class: |
359/30 |
Current CPC
Class: |
G03H 1/04 20130101; G03H
1/0486 20130101; G03H 2223/25 20130101; G03H 1/0408 20130101; G03H
2001/2695 20130101; G03H 1/268 20130101; G03H 2223/12 20130101;
G03H 2001/2685 20130101; G03H 1/22 20130101 |
Class at
Publication: |
359/30 |
International
Class: |
G03H 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 21, 1996 |
JP |
P08-162139 |
Jun 28, 1996 |
JP |
P08-170020 |
Mar 28, 1997 |
JP |
P09-078611 |
Claims
What is claimed is:
1. An image recording method for sequentially recording images
corresponding to image data of a parallax image string as strip- or
dot-shaped hologram elements by causing an object light beam to
fall on one of the surfaces of a recording medium for hologram and
by causing a reference light beam to fall on the opposite surface
thereof, characterized in that an optical component is contacted
with at least one surface of the recording medium for hologram and
a liquid is interposed between said recording medium for hologram
and said optical component.
2. The image recording method as claimed in claim 1 characterized
in that said liquid is continuously supplied to a space between
said recording medium for hologram and said optical component.
3. The image recording method as claimed in claim 1 characterized
in that the optical component contacted with the recording medium
for hologram via said liquid is a set of a one-dimensional
diffusion plate and a louver film arranged on the object light beam
incident side.
4. The image recording method as claimed in claim 1 characterized
in that the optical component contacted with the recording medium
for hologram via said liquid is a light inlet block arranged on the
reference light inlet side and in that each image corresponding to
the image data of the parallax image string is recorded by the
edge-lit system.
5. The image recording method as claimed in claim 4 characterized
in that an index matching liquid for index matching between said
recording medium for hologram and the light inlet block is used as
said liquid.
6. An image recording method for sequentially recording images
corresponding to image data of a parallax image string as strip- or
dot-shaped hologram elements by causing an object light beam to
fall on one of the surfaces of a recording medium for hologram and
by causing a reference light beam to fall on the opposite surface
thereof, comprising: an optical component contacted with at least
one of the surfaces of the recording medium for hologram; and
liquid supplying means for supplying a liquid to a space between
said recording medium for hologram and the optical component.
7. The image recording apparatus as claimed in claim 6
characterized in that said liquid supplying means continuously
supplies the liquid.
8. The image recording apparatus as claimed in claim 6
characterized in that the optical component contacted with said
recording medium for hologram via said liquid is a set of a
one-dimensional diffusion plate and a louver film arranged on the
object light beam incident side.
9. The image recording apparatus as claimed in claim 6
characterized in that the optical component contacted with said
recording medium for hologram via said liquid is a light inlet
block arranged on the reference light inlet side and in that each
image corresponding to the image data of the parallax image string
is recorded by the edge-lit system.
10. The image recording apparatus as claimed in claim 9
characterized in that an index matching liquid for index matching
between said recording medium for hologram and the light inlet
block is used as said liquid.
11. An image recording method characterized in that an object light
beam is caused to fall on one of the surfaces of a recording medium
for hologram, the opposite surface of which is optically contacted
with a light inlet block, and a reference light beam is caused to
fall on an end of said light inlet block for fabricating a
holographic stereogram of the edge-lit system.
12. An image recording apparatus comprising: a light inlet block
optically contacted with at least one surface of a recording medium
for hologram; characterized in that an object light beam is caused
to fall on one of the surfaces of the recording medium for hologram
and a reference light beam is caused to fall on the opposite
surface via a light inlet block for fabricating a holographic
stereogram of an edge-lit system.
13. The image recording apparatus as claimed in claim 12
characterized in that an optical element capable of transmitting
the reference light beam and interrupting the object light beam is
arranged between said light inlet block and the recording medium
for hologram.
14. The image recording apparatus as claimed in claim 12
characterized in that said light inlet block includes a light
absorbing member, and in that said light absorbing member plays the
role of preventing the object light beam and the reference light
beam falling on the light inlet block and reaching the recording
medium for hologram from subsequently undergoing unneeded
reflection in the light inlet block.
15. The image recording apparatus as claimed in claim 12
characterized in that a film-shaped medium is used as said
recording medium for hologram and in that an image is recorded in a
state in which the recording medium for hologram is directly
contacted with said light inlet block.
16. The image recording apparatus as claimed in claim 12
characterized in that said light inlet block is substantially
columnar-shaped and is adapted for rotating with movement of said
recording medium for hologram.
17. The image recording apparatus as claimed in claim 16
characterized in that said light inlet block is adapted for being
rotated with the recording medium for hologram being kept in
contact with the light inlet block.
18. The image recording apparatus as claimed in claim 16
characterized in that said light inlet block has an internal hollow
portion in which is arranged a light absorbing member and in that
said light absorbing member plays the role of preventing the object
light beam and the reference light beam falling on the light inlet
block and reaching the recording medium for hologram from
subsequently undergoing unneeded reflection in the light inlet
block.
19. The image recording apparatus as claimed in claim 12 further
comprising: thrusting means for thrusting said light inlet block to
said recording medium for hologram.
20. The image recording apparatus as claimed in claim 12
characterized in that a recording medium for hologram having a
cover sheet for protecting a photosensitive portion is used as said
recording medium for hologram and in that cover sheet removing
means is provided for peeling off the cover sheet from the
recording medium for hologram before said recording medium for
hologram is contacted with said light inlet block.
21. The image recording apparatus as claimed in claim 12 further
comprising: cleaning means for removing contamination from said
light inlet block.
22. The image recording apparatus as claimed in claim 12 further
comprising: a one-dimensional diffusion plate on the object light
beam inlet side in the vicinity of said recording medium for
hologram.
23. An image reproducing method for reproducing a three-dimensional
image recorded on a holographic stereogram of an edge-lit system by
causing an object light beam and a reference light beam to fall on
one and the other surfaces of a recording medium, respectively,
characterized by arranging a holographic stereogram on a surface of
said light inlet block towards a viewer, illuminating a reproducing
illuminating light beam on the holographic stereogram via said
light inlet block, and reproducing the three-dimensional image by
light diffracted when the reproducing illuminating light beam is
transmitted through said holographic stereogram.
24. An image reproducing apparatus for reproducing a
three-dimensional image recorded on a holographic stereogram of an
edge-lit system by causing an object light beam and a reference
light beam to fall on one and the other surfaces of a recording
medium, respectively, comprising: a light inlet block having a
holographic stereogram on its surface towards a viewer; and a light
source for illuminating a reproducing illuminating light beam via
said light inlet bock on said holographic stereogram; the
reproducing illuminating light beam from said light source being
diffracted at the time of transmission through said holographic
stereogram for reproducing the three-dimensional image.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to an image recording method and
apparatus for recording a stereographic image on a holographic
stereogram and an image reproducing method and apparatus for
reproducing a stereographic image from the holographic
stereogram.
[0003] 2. Description of the Related Art
[0004] A holographic stereogram is produced by sequentially
recording a large number of images, obtained on sequentially
shooting an object from different viewing points, as original
images, as strip- or dot-shaped hologram elements, on a sole
recording medium.
[0005] For example, in a holographic stereogram having the parallax
information only in the transverse direction, plural original
images 301a to 301e, obtained on sequentially imaging an object 300
from plural viewing points in the transverse direction, are
sequentially exposed to light and recorded on a recording medium
for hologram 302 as strip-shaped hologram elements.
[0006] With the present holographic stereogram, since the picture
information obtained on sequentially imaging an object from plural
viewing points in the horizontal direction is sequentially recorded
in the transverse direction as strip-shaped hologram elements, the
two-dimensional pictures as viewed by left and right eyes of a
viewer if the holographic stereogram is viewed by the viewer with
both eyes. This the observer feels the parallax so that a
three-dimensional image is reproduced.
[0007] However, with the conventional holographic stereogram, an
optimum reproduced picture cannot be produced. Specifically, with
the conventional holographic stereogram, a reproduced image is
unclear, dark and poor in contrast, while the reproduced image has
a narrow angle of visibility.
[0008] For enabling an optimum picture to be produced from a
holographic stereogram,. it is necessary to completely fix a
recording medium for hologram during light exposure of the recoding
image to prevent minute vibrations even of the order of the light
wavelength. During production of the holographic stereogram, the
recording medium for hologram is moved little by little for
sequentially recording an extremely large number of hologram
elements. For providing a practically useful picture recording
device used for producing a holographic stereogram, the recording
medium for hologram needs to be transferred quickly during
fabrication of the holographic stereogram. Therefore, means for
holding and transferring the recording medium for hologram needs to
be such a device in which not only the recording medium for
hologram can be transferred quickly, but also no vibrations of the
recording medium for hologram are allowed after completion and
halting of the recording medium for hologram.
[0009] For example, if the recording medium for hologram is
transferred using an ordinary electrically driven sliding stage,
the time of the order of 2 seconds is required until the vibrations
of the recording medium for hologram are attenuated, after transfer
of the recording medium for hologram, to the extent that the
hologram elements can be formed. Therefore, if the recording medium
for hologram is transferred each time the hologram element is
formed using the electrically driven stage, an extremely long time
is consumed until completion of a sole holographic stereogram.
[0010] The present inventors have conducted searches into holding
and transfer means capable of suppressing the vibrations of the
recording medium for hologram more quickly. Thus it has been found
that, by loading an elongated recording medium for hologram between
two parallel rolls, holding the recording medium for hologram by a
torsion coil spring for producing a pre-set tensile force and by
causing an object light to fall on the recording medium for
hologram placed between the two parallel rolls, the vibrations of
the recording medium for hologram can be suppressed more promptly.
By employing this method, the time until attenuation of the
vibrations after transfer of the recording medium for hologram has
been reduced to less than one fourth that when the electrically
driven sliding stage is used. However, if this method is employed,
the vibrations cannot be suppressed completely. Thus, it has been
desired to develop a method and apparatus capable of further
suppressing vibrations of the recording medium for hologram.
[0011] In a usual hologram, an illuminating light source for
reproducing a three-dimensional picture and a hologram are
spatially separated from each other. Thus, in a usual hologram, a
broad spacing is required for reproduction. On the other hand, for
reproduction under an optimum condition, the relative positions of
the hologram and the illuminating light source need to be set under
a pre-set condition. This applies for a holographic stereogram made
up of plural hologram elements.
[0012] If the illuminating light source and the hologram are
unified with each other, the spacing for illumination becomes
unnecessary to make it possible to reduce the size of the
apparatus. Moreover, since the relative positions of the hologram
and the illuminating light become always constant, reproduction can
be performed at all times under optimum conditions. As a hologram
for realizing this, there is known an edge-lit system hologram in
which recording and/or reproduction is carried out with a recording
medium bonded to a transparent light-inlet block.
[0013] With such edge-lit system hologram, the optical system for
reproduction can be reduced in size and reproduction can be
performed at all times under optimum conditions by unifying the
light source for the reproducing illuminating light and a light
inlet block. Also, since the angle of incidence of the reproducing
illuminating light is increased with the edge-lit type hologram, an
image is not reproduced by the light incident from outside the
light inlet block. Thus the edge lit type hologram is in use in a
field in which it is not desirable for an image to be reproduced
with, for example, the sunlight, such as in a head-up display
device.
[0014] For producing a transmission type hologram in which a
three-dimensional image is reproduced by the light transmitted
through the recording medium, a recording medium for hologram 311
is bonded to a surface 310a of a light inlet block 310 formed of a
glass plate or a synthetic resin plate of a suitable thickness, as
shown in Fig.2. At this time, the recording medium for hologram 311
is bonded via an index matching liquid 312 to the light inlet block
310. An object light beam 314 from an object 313 is illuminated
from an other surface 310b of the light inlet block 310 towards the
recording medium for hologram 311, while a reference light beam 315
is illuminated from an end face 310c of the light inlet block 310
towards the recording medium for hologram 311. This completes a
transmission type edge-lit hologram.
[0015] For reproducing the thus produced transmission type edge-lit
hologram, the hologram 321 is bonded on an end face 320a of the
light inlet block 320 via an index matching liquid 322 and a
reproducing illuminating light beam 323 is illuminated from the end
face 320b of the light inlet block 320 towards the hologram 321.
The light transmitted through the hologram 321 is diffracted at
this time by the hologram 321. A reproduced image 325 is generated
by a diffracted light beam 324 so as to be viewed by a viewer
326.
[0016] For producing a reflection type hologram in which a
three-dimensional image is reproduced by the light reflected by the
recording medium, by the edge-lit system, a recording medium 332 is
bonded via an index matching liquid 331 on one surface 330a of a
light inlet block 330, as in the case of producing a transmission
type edge-lit hologram, as shown in FIG. 4. For the reflection type
hologram, an object light beam 334 from an object 333 is
illuminated from the side of bonding the recording medium 332
towards the recording medium 332, while a reference light beam 335
is illuminated from an end face 330b of the light inlet block 330.
This completes the edge-lit reflection type hologram.
[0017] For reproducing the edge-lit reflection type hologram, thus
produced, usually a hologram 341 is bonded via an index matching
liquid 342 to a surface 340a of a light inlet block 340, as shown
in FIG. 5, and a reproducing illuminating light beam 343 is
illuminated towards the hologram 341 from an end face 340b of the
light inlet block 340. The light reflected at this time by the
hologram 341 is diffracted by the hologram 341. A reproduced image
is generated by this diffracted light 344 so as to be viewed by a
viewer 346.
[0018] If such edge-lit system is applied to a holographic
stereogram, and an image is generated as if there were an object
behind the light inlet block, the reproduced image is difficult to
view and lowered in stereographic feeling to detract from the
display effect. It is therefore desirable that an image can be
reproduced so that an object will be as close to the view as
possible. However, with the edge-lit system holographic stereogram,
an image is reproduced as if the object as viewed by the viewer
were at back of the light inlet block, as shown in FIG. 5.
[0019] For producing the image as though the object were as close
to the viewer as possible, a transmission type edge-lit system
holographic stereogram is preferably employed. However, if the
stereogram is recorded by the transmission type hologram, both the
object light beam and the reference light beam need to be incident
on one side of the recording medium for hologram. This lowers the
degree of freedom in arranging the optical system to raise
difficulties in constituting an optimum optical system.
[0020] Moreover, if desired to assure a broad angle of visibility
angle in the up-and-down direction in reproducing a holographic
stereogram, a one-dimensional diffusion plate for diffusing the
object light beam in a one-dimensional in-plane direction is
desirably provided in the vicinity of the recording medium for
hologram on the object light beam incident side. However, with the
transmission type recording n which a light incident block needs to
be arranged towards the object light beam incident side, it becomes
impossible to array this one-dimensional diffusion plate.
Consequently, it has hitherto not been practiced to produce the
edge-lit system holographic stereogram as a transmission type
stereogram.
SUMMARY OF THE INVENTION
[0021] It is therefore an object of the present invention to
provide an image recording method and apparatus in which an image
is recorded on a holographic stereogram so as to produce a better
reproduced image.
[0022] It is another object of the present invention to provide an
image reproducing method and apparatus which renders it possible
produce a better reproduced image from the holographic
stereogram.
[0023] In a first image recording method for sequentially recording
images corresponding to image data of a parallax image string as
strip- or dot-shaped hologram elements, by causing an object light
beam to fall on one of the surfaces of a recording medium for
hologram and by causing a reference light beam to fall on the
opposite surface thereof, according to the present invention, an
optical component is contacted with at least one surface of the
recording medium for hologram, and a liquid is interposed between
the recording medium for hologram and the optical component.
[0024] If a liquid is interposed between the recording medium for
hologram and the optical component, the optical component can be
tightly contacted with the recording medium for hologram without
producing a void therebetween, so that vibrations of the recording
medium for hologram during image recording can be suppressed
sufficiently.
[0025] It may be contemplated to have the recording medium for
hologram and the optical component arranged in a liquid for having
the liquid interposed between the recording medium for hologram and
the optical component. Herein, however, the recording medium for
hologram and the optical component are arranged in air and the
liquid is held by surface tension between the recording medium for
hologram and the optical component.
[0026] For maintaining the liquid charged at all times in the space
between the recording medium for hologram and the optical
component, it is preferred that the liquid be continuously supplied
to the space between the recording medium for hologram and the
optical component.
[0027] The optical component contacted with the recording medium
for hologram via liquid is preferably a set of a one-dimensional
diffusion plate and a louver film arranged on the object light
incident side. For example, the optical component, comprised of the
set of the one-dimensional diffusion plate and the louver film, is
thrust, during recording on the recording medium for hologram,
against the recording medium for hologram placed under pre-set
tensile tension. The one-dimensional diffusion plate performs the
role of slightly diffusing the object light during recording in a
one-dimensional direction for maintaining a broad angle of
visibility in the up-and-down direction for scattering noise
components ascribable to, for example, the optical system. On the
other hand, the louver film prevents the reference light from being
reflected by, for example, the above-mentioned one-dimensional
diffusion plate to be re-incident on the recording medium for
hologram after passing through the recording medium for
hologram.
[0028] The hologram of the edge-lit system has many merits, as
described above. Thus the edge-lit system may be applied to the
above-mentioned first image recording method. In such case, the
images corresponding to respective image data of the parallax image
series are sequentially recorded as hologram elements by the
edge-lit system.
[0029] In the edge-lit system, a recording medium for hologram is
bonded to a transparent light inlet block, which then causes the
reference light beam or the illuminating light beam to fall at an
acute angle on the surface of the recording medium for hologram for
recording or reproduction. If the edge-lit system is applied to the
holographic stereogram, the illuminating light source can be
integrated to the holographic stereogram, thus eliminating the
necessity for providing an illuminating space. Morever, since the
relative position between the holographic stereogram and the
illuminating light source becomes perpetually constant,
reproduction can be done perpetually under optimum conditions.
[0030] For recording by the edge-lit system, the light inlet block
can be contacted with the recording medium for hologram from the
object light incident side or from the reference light incident
side. However, even in case of recording by the edge-lit system,
the one-dimensional diffusion plate and the louver film are
preferably arranged in a contact area with the recording medium for
hologram. In this case, the one-dimensional diffusion plate and the
louver film are arranged on the object light inlet side, while the
light inlet block is arranged on the reference light incident side
of the recording medium for hologram. The light inlet block and the
recording medium for hologram are contacted with each other via a
liquid. If, in the following description, it is necessary to
clarify the fact that the light inlet block is arranged on the
reference light incident side, the light inlet block is termed a
reference light inlet block. If the reference light inlet block s
contacted with the recording medium for hologram, the liquid
interposed therebetween is preferably an index matching liquid
responsible for index matching between the recording medium for
hologram and the reference light inlet block.
[0031] If, during recording by the edge-lit system, the refractive
index is changed drastically between the recording medium for
hologram and the light inlet block, the reference light beam,
incident at an acute angle on the surface of the recording medium
for hologram, is reflected by total reflection on an interface
between the light inlet block and the recording medium for
hologram, or surface irregularities of the image recording layer of
the recording medium for hologram are presented as non-uniformities
like wood grains in the recorded image. For overcoming these
difficulties, light exposure may be carried out in a liquid capable
of achieving index matching between the recording medium for
hologram and the reference light inlet block. However, if the light
exposure is carried out in a liquid, the image recording device
becomes complex in structure and larger in size, while being in
need for frequent maintenance, thus making it difficult to automate
the fabrication of the holographic stereogram.
[0032] Conversely, should the index matching liquid be interposed
only between the recording medium for hologram and the reference
light inlet block, the reference light inlet block can be contacted
completely intimately with the recording medium for hologram, while
there is no risk of complicating the structure or increasing the
size of the image recording device. In addition, since there is no
necessity of transferring the reference light inlet block in a
direction towards and away from the recording medium for hologram
each time the recording medium for hologram is transferred, thus
even simplifying the structure of the image recording device.
[0033] For enabling index matching between the recording medium for
hologram and the reference light inlet block by the index matching
liquid, it is necessary to set a condition in which no total
reflection occurs on an interface between the reference light inlet
block and the index matching liquid, as well as on an interface
between the index matching liquid and the recording medium for
hologram, and in which the intensity reflectance (s-component) on
each interface is reduced.
[0034] If the liquid interposed between the reference light inlet
block and the recording medium reference light inlet block and the
recording medium for hologram meets the above condition, the
reference light passed through the reference light inlet block and
the recording medium to fall on the recording medium for hologram
can be prevented to occur total reflection, while non-uniformities
may be prevented from being produced in the image, thus improving
the image quality of the fabricated holographic stereogram.
[0035] For implementing the above-described first image recording
method, the following first image recording apparatus is used.
[0036] The first image recording apparatus for sequentially
recording images corresponding to image data of a parallax image
series as strip- or dot-shaped hologram elements by causing an
object light beam to fall on one of the surfaces of a recording
medium for hologram and by causing a reference light beam to fall
on the opposite surface thereof, according to the present
invention, includes an optical component contacted with at least
one of the surfaces of the recording medium for hologram, and
liquid supplying means for supplying a liquid to a space between
the recording medium for hologram and the optical component.
[0037] Since the first image recording apparatus includes liquid
supplying means, the liquid can be interposed between the recording
medium for hologram and the optical component, and hence the
optical component can be tightly contacted with the recording
medium for hologram without voids in-between to suppress vibrations
of the recording medium for hologram sufficiently.
[0038] The liquid supplying means is preferably capable of
continuously supplying the liquid to a space between the recording
medium for hologram and the optical component. Although any known
means for supplying the liquid to the space between two members can
be used as such liquid supplying means, a foamed member, such as
sponge, impregnated with a liquid, is preferred. That is, by
arranging a foamed member, such as a liquid-impregnated sponge, may
be placed in the vicinity of the interface between the recording
medium for hologram and the optical component for continuously
supplying the liquid to a space between the recording medium for
hologram and the optical component.
[0039] In the above-described image recording apparatus, the
optical component contacted with the recording medium for hologram
via the liquid may be a set of the one-dimensional diffusion plate
and the louver film on the object light incident side.
Alternatively, the optical component may be a reference light inlet
block on the reference light incident side if recording is done by
the edge-lit system. if the recording is by the edge-lit system,
the index matching liquid may be used as the liquid interposed
between the recording medium for hologram and the reference light
inlet block, as explained previously.
[0040] For raising the light exploitation efficiency for reducing
image non-uniformities, a smaller interface passed through by the
reference light is desirable. Thus, if the edge-lit system is used,
the recording medium for hologram and the reference light inlet
block may be directly intimately contacted with each other, that is
without interposition of a liquid. Above all, if the recording
medium for hologram used is relatively soft and adhesive, such as
photopolymer, the recording medium for hologram and the reference
light inlet block can be contacted relatively easily with each
other. In such case, since the reference light inlet block and the
recording medium for hologram can be intimately contacted with each
other, without voids in-between, oscillations of the recording
medium for hologram can be suppressed sufficiently.
[0041] In light of the above, a second image recording method
includes causing an object light beam to fall on one of the
surfaces of a recording medium for hologram, the opposite surface
of which is optically contacted with a light inlet block, and
causing a reference light beam to fall on an end of the light inlet
block for fabricating a holographic stereogram of the edge-lit
system.
[0042] A second image recording apparatus includes a light inlet
block optically contacted with at least one surface of a recording
medium for hologram and is designed so that, for fabricating a
holographic stereogram of an edge-lit system, an object light beam
is caused to fall on one of the surfaces of the recording medium
for hologram and a reference light beam is caused to fall on the
opposite surface via a light inlet block.
[0043] Preferably, the light inlet block includes a light absorbing
member operating for preventing the object light and the reference
light incident on the light inlet block and reaching the recording
medium for hologram from undergoing needless reflection within the
light inlet block.
[0044] In the second image recording apparatus, a film-shaped
medium is used as the above-mentioned recording medium for
hologram. Although the index matching liquid may be interposed
between the recording medium for hologram and the reference light
inlet block, as described above, image recording may also be
performed with the recording medium for hologram being kept in
direct contact with the light inlet block.
[0045] Also, in the second image recording apparatus, the light
inlet block is substantially cylindrical in shape and is designed
to rotate with movement of the recording medium for hologram.
Preferably, the light inlet block is designed to rotate with the
recording medium for hologram being kept in direct contact with the
light inlet block. Also preferably, the light inlet block has an
internal hollow portion within which is arranged a light absorbing
member designed for preventing the object light and the reference
light incident on the light inlet block and reaching the recording
medium for hologram from undergoing needless reflection in the
light inlet block.
[0046] Preferably, the second image recording apparatus includes
thrusting means for thrusting the light inlet block against the
recording medium for hologram.
[0047] In the second image recording apparatus, a recording medium
for hologram having a cover sheet for protecting a photosensitive
portion may be used as the recording medium for hologram.
Preferably, cover sheet removal means for peeling off the cover
sheet from the recording medium for hologram is preferably provided
before contacting the recording medium for hologram with the light
inlet block.
[0048] Preferably, the second image recording apparatus includes
cleaning means for removing contamination of the light inlet block.
Also preferably, the second image recording apparatus includes a
one-dimensional diffusion plate on the object light incident side
in the vicinity of the recording medium for hologram.
[0049] An image reproducing method for reproducing a
three-dimensional image recorded on a holographic stereogram of an
edge-lit system by causing an object light beam and a reference
light beam to fall on one and the other surfaces of a recording
medium, respectively, according to the present invention, includes
arranging a holographic stereogram on a surface of the light inlet
block towards a viewer, illuminating a reproducing illuminating
light beam on the holographic stereogram via the light inlet block,
and reproducing the three-dimensional image by light diffracted
when the reproducing illuminating light beam is transmitted through
the holographic stereogram.
[0050] With the above image producing method, a holographic
stereogram of the edge-lit system, recorded with the reflection
type stylized optical system having high flexibility of layout, is
reproduced with the transmission type hologram in which the
holographic stereogram transmits the reproducing illuminating light
beam. In this manner, a reproduced three-dimensional image appears
as if the object were closer to the viewer, instead of being
backwardly of the holographic stereogram.
[0051] An image reproducing apparatus for reproducing a
three-dimensional image recorded on a holographic stereogram of an
edge-lit system by causing an object light beam and a reference
light beam to fall on one and the other surfaces of a recording
medium, respectively, according to the present invention, includes
a light inlet block having a holographic stereogram on its surface
towards a viewer and a light source for illuminating a reproducing
illuminating light beam via the light inlet bock on the holographic
stereogram. The reproducing illuminating light beam from the light
source is diffracted at the time of transmission through the
holographic stereogram for reproducing the three-dimensional
image.
[0052] With the above image producing apparatus, a holographic
stereogram of the edge-lit system, recorded with the reflection
type stylized optical system having high flexibility of layout, is
reproduced with the transmission type hologram in which the
holographic stereogram transmits the reproducing illuminating light
beam. In this manner, a reproduced three-dimensional image appears
as if the object were closer to the viewer, instead of being at
back of the holographic stereogram.
BRIEF DESCRIPTION OF THE DRAWINGS
[0053] FIG. 1 is a schematic view showing a method for producing a
holographic stereogram.
[0054] FIG. 2 is a schematic view showing a method for producing a
transmission type edge-lit hologram.
[0055] FIG. 3 is a schematic view showing the reproducing method
for reproducing a transmission type edge-lit hologram with a
transmission type hologram.
[0056] FIG. 4 is a schematic view showing a method for producing a
reflection type edge-lit hologram.
[0057] FIG. 5 is a schematic view showing the reproducing method
for reproducing a reflection type edge-lit hologram with a
reflection type hologram.
[0058] FIG. 6 is a schematic view showing an illustrative structure
of a holographic stereogram printer system.
[0059] FIGS. 7A and 7B are schematic views showing an example of an
optical system of a holographic stereogram printer system.
[0060] FIG. 8 is a cross-sectional view showing an example of a
recording medium for hologram.
[0061] FIGS. 9A, 9B and 9C are schematic views showing a
photosensitive process of a light polymerization type
photopolymer.
[0062] FIG. 10 is a schematic view showing an illustrative
structure of the vicinity of a printer head.
[0063] FIG. 11 is a schematic view showing an illustrative
structure of the vicinity of the printer head in case of recording
by an edge-lit system.
[0064] FIG. 12 is a schematic view showing a reproducing method of
a holographic system with a reflection type hologram.
[0065] FIG. 13 is a schematic view showing a reproducing method of
a holographic system with a transmission type hologram.
[0066] FIG. 14 illustrates an incident path of the reference light
beam for finding a condition of refractive index of a liquid.
[0067] FIG. 15 shows the relation between the refractive index of a
liquid and the intensity reflectance for
.theta..sub.g=75.degree..
[0068] FIG. 16 shows the relation between the refractive index of a
liquid and the intensity reflectance for
.theta..sub.g=78.degree..
[0069] FIG. 17 shows the relation between the refractive index of a
liquid and the intensity reflectance for
.theta..sub.g=45.degree..
[0070] FIG. 18 is a schematic relation showing an illustrative
structure of a holographic stereogram printer system.
[0071] FIGS. 19A and 19B are schematic views showing an example of
an optical system of a holographic stereogram printer device.
[0072] FIG. 20 is a schematic view showing the manner of total
reflection of a reference light beam on an interface of a recording
medium for hologram.
[0073] FIG. 21 is a schematic view showing the manner of preventing
the reference light beam from re-entering a recording medium for
hologram by a louver film.
[0074] FIG. 22 is a schematic view showing an illustrative
structure of the vicinity of a printer head of a holographic
stereogram printer device of the type in which a recording medium
for hologram is intimately contacted with a light inlet block.
[0075] FIG. 23 is a schematic view showing another illustrative
structure of the vicinity of a printer head of a holographic
stereogram printer device of the type in which a recording medium
for hologram is intimately contacted with a light inlet block.
[0076] FIG. 24 is a schematic view showing an illustrative
structure of the vicinity of a printer head of a holographic
stereogram printer device of the type in which a liquid is
interposed between the recording medium for hologram and the light
inlet block.
[0077] FIG. 25 is a schematic view showing a reproducing method of
a holographic stereogram by a reflection type.
[0078] FIG. 26 is a schematic view showing a reproducing method of
a holographic stereogram by a transmission type.
[0079] FIG. 27 is a cross-sectional view showing an instance in
which a louver film is inserted between a light inlet block and a
recording medium for hologram.
[0080] FIG. 28 is a cross-sectional view showing another instance
in which a louver film is inserted between a light inlet block and
a recording medium for hologram.
[0081] FIG. 29 is a schematic view showing an illustrative
structure of a stereographic stereogram producing system.
[0082] FIGS. 30A and 30B are schematic views showing an
illustrative optical system of a holographic stereogram printer
device.
[0083] FIG. 31 is a cross-sectional view showing an illustrative
recording medium for hologram.
[0084] FIGS. 32A, 32B and 32C are schematic views showing a
photosensitive process of a photopolymerization type
photopolymer.
[0085] FIG. 33 is a schematic view showing an illustrative
structure of an illustrative structure of a recording medium feed
mechanism.
[0086] FIG. 34 is a schematic view showing the method for a
holographic stereogram with a reflection type hologram.
[0087] FIG. 35 is a schematic view showing the method for a
holographic stereogram with a transmission type hologram.
[0088] FIG. 36 is a schematic view showing an illustrative
structure of an image reproducing apparatus embodying the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0089] Referring to the drawings, preferred embodiments a first
image recording method and an image recording device of the present
invention will be explained in detail.
[0090] 1. First age Recording Method and Image Recording Device
[0091] A first embodiment of an image recording method and image
recording device according to the present invention will be
hereinafter explained.
[0092] 1-1 Schematics of an Image Recording Device
[0093] The schematics of a holographic stereogram printer system of
a first image recording device embodying the present invention will
be explained.
[0094] FIG. 6 shows a structure of this holographic stereogram
printer system 10. The holographic stereogram printer system 10 is
made up of a data processor 11, a control computer 12 and a
holographic stereogram printer device 13.
[0095] The data processor 11 generates a parallax image series
based on image data D1 for plural image data D2 of an rendering
image (image resulting from rendering). The image data D1,
outputted by a parallax image string imaging device 14, is obtained
by imaging an object from plural viewing points in the transverse
direction, such as by simultaneously imaging by a multi-eye camera
or by continuous imaging with a moving camera, while the image data
D2 of a rendering image, outputted by a computer 15, are formed by
sequentially according the parallax in the transverse direction.
The data processor 11 then performs pre-set image processing for
hologram on each image data D3 of the parallax image string for
transiently recording the processed image data D3 on a recording
medium 16, such as a memory or a hard disc.
[0096] During the subsequent light exposure operation, the data
processor 11 sequentially reads out the image data D4 of the
parallax image string recorded on the recording medium 16 and sends
out the read-out image data D5 sequentially to the control computer
12.
[0097] During the light exposure, the control computer 12 controls
the driving of a shutter 17 of the holographic stereogram printer
device 13, a liquid crystal display device (LCD) 18 and a printer
head, as later explained, based on the image data D5 of the
parallax image string sent from the data processor 11.
[0098] The holographic stereogram printer device 13 has a structure
as shown in FIGS. 7A and 7B in which parts or components similar to
those of FIG. 6 are depicted by the same reference numerals as
those used in FIG. 6. The holographic stereogram printer device 13
is configured for driving the LCD 18 based on the image data D5
supplied from the control computer 12 for sequentially recording
the images corresponding to the image data D5 as hologram elements
on a recording medium for hologram 19 for producing a holographic
stereogram.
[0099] Specifically, the LCD 18 is driven based on one of image
data of image data D5 supplied for the control computer 12 for
displaying an image corresponding to the image data D5 on the LCD
18, while the control signal S1 is sent from the control computer
12 to the shutter 17 for opening it for causing a laser light beam
L1 outgoing from a laser light source 20 via shutter 17, half
mirror 21 and mirror 22 to a spatial filter 23.
[0100] The laser light beam L1 is enlarged by the spatial filter 23
and a collimator 24 and transmitted through the LCD 18 so as to be
converted into a projected light beam corresponding to the image
displayed on the LCD 18. The projecting light is incident on the
collimator lens 26 via condenser lens 25 so as to be thereby
converged in the transverse direction by the collimator lens 26 to
fall on the recording medium for hologram 19 held by a printer head
27.
[0101] The laser light beam Li reflected by the half mirror 21 is
incident at an incident position on the recording medium for
hologram 19 via a cylindrical lens 28, a collimator lens 29 and a
mirror 30 in this order as a beam at a pre-set angle from the back
side of the recording medium for hologram 19 as a reference
light.
[0102] The light path length for the reference light beam is
selected to be equal to the light path length of the laser light
beam L1 transmitted through the half mirror 21 and incident via
mirror 22 on the recording medium for hologram 19. This laser light
beam L1 is referred to herein as an object light beam.
[0103] Thus, with the present holographic stereogram printer device
13, this object light beam (projecting light beam) can be caused to
interfere with the reference light beam on a recording surface of
the recording medium for hologram 19 whereby the image displayed on
the LCD 18 can be recorded as strip-shaped interference fringes on
the recording medium for hologram 19.
[0104] Moreover, with the present holographic stereogram printer
device 13, when later the recording of the image comes to a close,
the shutter 17 is driven by the control computer 12 to interrupt
the laser light beam L1 outgoing from the laser light source 20, as
the same time as the LCD 18 ceases to be driven. In addition, the
printer head 27 is driven under control by the control computer 12
to feed the recording medium for hologram 19 by a length equal to
the transverse width of a sole hologram element.
[0105] The LCD 18 is then driven under control by the control
computer 12 for displaying an image corresponding to the next
following portions of the image data D5. The shutter 17 then is
opened under control by the control computer 12 for recording the
image displayed on the LCD 18 in a strip shape on the recording
medium for hologram 19. The above sequence of operations is
repeated in succession.
[0106] Thus, with the holographic stereogram printer device 13, the
images corresponding to the image data of the supplied parallax
image string can be sequentially recorded in a strip-like pattern
on the recording medium for hologram 19 to produce a desired
holographic stereogram.
[0107] The recording medium for hologram 19, used in the present
holographic stereogram printer system, is now explained.
[0108] The recording medium for hologram 19 is a so-called film
coating type recording medium in which a photopolymer layer 19b
formed of a photopolymerizable photopolymer is formed on a
tape-shaped film base material 19a and a cover sheet 19c is
deposited on the photopolymer layer 19b, as shown in FIG. 8. In the
present embodiment, a photopolymer layer of `OMNI-DEX`, with a
refractive index before light exposure of 1.487, manufactured by DU
PONT Inc. as a photopolymer layer 19b as a photosensitive portion
to a thickness of approximately 20 .mu.m.
[0109] In the initial state of the photopolymerizable photopolymer,
a monomer M is uniformly dispersed in a matrix polymer, as shown in
FIG. 9A. If a light beam L2 of the power of, for example, 10 to 400
mJ/cm.sup.2 is illuminated, the monomer M is polymerized in a
light-exposed portion, as shown in FIG. 9B. With progress in
polymerization, the monomer M is migrated from ambient portions to
cause local variation in the concentration in the monomer M to
produce refractive index modulation. The polymerization of the
monomer M then comes to a close by illuminating the UV light or the
visible light L3 with the power on the order of 1000 mJ/cm.sup.2 as
shown in FIG. 9C. Since the photopolymerizable photopolymer has its
refractive index varied with the incident light beam, the
interference fringes, brought about by interference between the
reference light beam and the object light beam, can be recorded as
changes in the refractive index.
[0110] The recording medium for hologram 19, employing the
photopolymerizable photopolymer, need not be processed with
particular development operations after light exposure. Thus the
holographic stereogram printer device 13 employing the recording
medium for hologram 19 having its photosensitive portion formed of
a photopolymerizable photopolymer can be simplified in
structure.
[0111] Meanwhile, the first image recording device according to the
present invention sequentially records images corresponding to
image data of a parallax image string sequentially as strip- or
dot-shaped hologram elements by having the object light beam and
the reference light beam fall on one and the other surfaces of the
recording medium for hologram, respectively. The first image
recording device according to the present invention includes an
optical component contacted with at least one surface of the
recording medium for hologram and liquid supplying means for
supplying the liquid to a space between the recording medium for
hologram and the optical component.
[0112] Thus, with the above-described holographic stereogram
printer system 10, the main point of the present invention resides
in a portion of the holographic stereogram printer device 13,
especially a portion thereof in the vicinity of the printer head
27. Therefore, an illustrative structure of the vicinity of the
printer head 27 is explained in detail hereinbelow by way of
illustrating an embodiment of the first image recording device
according to the present invention.
[0113] Since the image recording method according to the present
invention is characterized in that, during recording on the
recording medium for hologram, an optical component is contacted
with at least one surface of the recording medium for hologram, and
in that a liquid is interposed between the recording medium for
hologram and the optical component, an embodiment of the method of
the present invention is explained in connection with the
explanation of the operation of the vicinity of the printer head
27.
[0114] 1-2 First Embodiment
[0115] With the image recording device according to the present
invention, optical components made up of the one-dimensional
diffusion plate and the louver film are contacted via a liquid with
the object light incident side of the recording medium for hologram
19. The image recording method according to the present invention
produces a holographic stereogram using the above-described image
recording device.
[0116] For explaining the image recording device according to the
present invention, the structure of the vicinity of the printer
head 27 of the holographic printer device 13 in the above-described
holographic stereogram printer system 10 is explained in detail. In
the present embodiment, the printer head 27 is constructed as a
printer head 27-1, as shown in FIG. 10.
[0117] The printer head 27-1 has a mechanism for holding and
transporting the recording medium for hologram 19.
[0118] Specifically, the printer head 27-1 is configured for
rotatably holding a roll 41 with a pre-set torque within a film
cartridge 40 loaded in position and for holding the recording
medium for hologram 19 drawn out from the film cartridge 40 between
the intermittent feed rolls 42 and 43 for thereby positioning the
recording medium for hologram 19 between the roll 41 and the
intermittent feed roll 42 in a vertical position relative to the
object light (laser light beam L1).
[0119] The roll 41 and the intermittent feed roll 42 are biased by
a torsion coil spring, not shown, in a direction away from each
other, whereby a pre-set tensile force is applied on the recording
medium for hologram 19 loaded so as to lie across the roll 41 and
the intermittent feed roll 42.
[0120] Between the roll 41 and the intermittent feed roll 42 is
arranged an optical component 46, as a rigid member made up of a
one-dimensional diffusion plate 44 and a louver film 45, unified
together in a bent state, in meeting with the point of incidence of
the object light beam. The optical component 46 is held for
movement in a direction towards and away from the recording medium
for hologram 19, as indicate by arrow b by an optical component
driving mechanism, not shown.
[0121] Before starting the light exposure operation, the optical
component driving mechanism drives the optical component 46 based
on a control signal S2 supplied from the control computer 12 for
displacing the optical component 46 in a direction towards the
recording medium for hologram 19 for pressing the bent distal end
of the optical component 46 against the point of incidence of the
object light beam on the recording medium for hologram 19 loaded
between the roll 41 and the intermittent feed roll 42.
[0122] Thus, with the holographic stereogram printer device 13, the
optical component 46 operates for suppressing micro-sized
vibrations of the recording medium for hologram 19 between the roll
41 and the intermittent feed roll 42, whereby a bright holographic
stereogram, that is a holographic stereogram with a higher
diffraction efficiency, is produced.
[0123] The distal end of the optical component 46 contacted with
the recording medium for hologram 19 is curved in a crown shape for
protruding both end portions and a center portion thereof, whereby
the distal end of the optical component 46 is contacted uniformly
with both width-wise ends and with the center portion of the
recording medium for hologram 19 for reliably uniformly suppressing
micro-sized vibrations of the recording medium for hologram 19
between the roll 41 and the intermittent feed roll 42 along the
direction of width of the recording medium for hologram 19.
[0124] In the present embodiment, a sponge 51 impregnated with a
liquid is arranged as liquid supplying means upstream of the
optical component 46 so as to be in contact with both the optical
component 46 and with the recording medium for hologram 19. The
liquid supplied from the sponge 51 is supplied to a cover sheet 19c
sheathing the photopolymer layer 19b so that it is not directly
contacted with the photopolymer layer 19b.
[0125] Meanwhile, the sponge 51 is narrower in width than the
recording medium for hologram 19 for preventing the liquid from
flowing round the back side of the recording medium for hologram
19. The liquid used for impregnating the sponge 51 is o-xylene.
[0126] By arranging the sponge 51, it becomes possible to supply
the liquid to a spacing between the recording medium for hologram
19 and optical component 46 at all times and to have the liquid
interposed in the spacing. Since this enables the optical component
46 and the recording medium for hologram 19 to be contacted
intimately with each other without void in-between, vibrations of
the recording medium for hologram 19 can be suppressed
sufficiently.
[0127] Moreover, if the liquid is interposed between the recording
medium for hologram 19 and the optical component 46, the recording
medium for hologram 19 can be fed intermittently without the
necessity of moving the optical component 46 in an opposite
direction. This renders it possible to omit the above-mentioned
optical component driving mechanism to simplify the structure of
the image recording device.
[0128] For having the liquid interposed between the recording
medium for hologram 19 and the optical component 46, it is also
possible to arrange the recording medium for hologram 19 and the
optical component 46 in a liquid. However, since the recording
medium for hologram 19 and the optical component 46 are both
arranged in air, and the liquid is held by surface tension, it
becomes possible to simplify the image recording device in
structure, while facilitating the maintenance.
[0129] On the other hand, the intermittent feed roll 42 is
configured for being rotated in a direction indicated by arrow c
based on the force of rotation outputted by a stepping motor, not
shown. The stepping motor is configured for rotating the
intermittent feed roll 42 a pre-set angle, based on the control
signal S2 supplied from the control computer 12, each time the
light exposure for one image comes to a close. This feeds the
recording medium for hologram 19 by one hologram element.
[0130] Downstream of the intermittent feed roll 42 in the travel
passage of the recording medium for hologram 19 is arranged a UV
lamp 47 for extending along the travel passage whereby a UV light
beam L3 of a pre-set power for terminating the diffusion of the
monomer M can be illuminated with a pre-set power to the
light-exposed portion of the recording medium for hologram 19
forwarded by the intermittent feed roll 42.
[0131] Downstream of the UV lamp 47 in the travel passage of the
recording medium for hologram 19 are arranged a rotatably fulcrumed
heat roll 48, a pair of feed-out rolls 49A, 49B and a cutter 50, in
this order. The feed-out rolls 49A, 49B are arranged for holding
the recording medium for hologram 19 in a state of being placed in
tight contact by 180.degree. around the outer periphery of the heat
roll 48.
[0132] The heat roll 48 is provided with internal heating means,
not shown, for maintaining the peripheral surface of the roll at
approximately 120.degree. C.
[0133] This setting is based on an experiment by which it has been
found that, by having an as-exposed photopolymerizable photopolymer
(OMNI-DEX) sandwiched between a heating plate
temperature-controlled for maintaining a constant temperature of
120.degree. C. and a glass plate pressed from above by a spring
pressure and by heating the resulting assembly for five minutes,
the refractive index modulation of the same order of magnitude as
that obtained in case the assembly is atmosphere-heated at
120.degree. C. for two hours is achieved.
[0134] For this reason, the outer diameter of the heat roll 48 is
selected so that the time since the recording medium for hologram
19 starts to be contacted with the outer peripheral surface of the
heat roll 48 until it is detached therefrom is substantially equal
to the time required for the recorded image to become fixed for
thereby assuring positive fixation of the image recorded on the
recording medium for hologram 19.
[0135] The driving mechanism for the feed-out rolls 49A, 49B,
referred to hereinafter as a feed-out roll driving mechanism, is
configured for rotating the feed-out rolls 49A, 49B in synchronism
with the intermittent feed roll 42 based on the control signal S2
outputted by the control computer 12. This enables the recording
medium for hologram 19 to be kept tightly contacted with the
peripheral surface of the heat roll 48 without becoming slacked
between the intermittent feed roll 42 and the feed-out rolls 49A,
49B.
[0136] A driving mechanism for the cutter 50 (cutter driving
mechanism) , not shown, drives the cutter 50 after a desired image
is recorded on the hologram recording medium 19 based on the
control signal S2 supplied from the control computer 12 and entire
areas of the hologram recording medium 19 having the image recorded
therein are subsequently discharged to outside for severing the
discharged portion from the remaining portion of the hologram
recording medium 19. This enables the image-baring portion of the
hologram recording medium 19 to be discharged to outside as a sole
holographic stereogram.
[0137] For explaining the image recording method embodying the
present invention, the operation of the holographic stereogram
printer device 13 inclusive of the printer head 27-1 is explained
in detail.
[0138] For producing a holographic stereogram, using the
above-described holographic stereogram printer device 13, the
hologram recording medium 19 configured as shown in FIG. 8 is
coiled around the roll 41 and the resulting assembly is housed
within the film cartridge 40.
[0139] The hologram recording medium 19 is then loaded between the
roll 41 and the intermittent feed roll 42 and the optical component
46 is set so that its curved distal end will be pressed against the
recording medium for hologram 19 with a pre-set pressure. The
sponge 51 as liquid supplying means is sufficiently impregnated
with a liquid.
[0140] Before actually recording the image on the recording medium
for hologram 19, the control signal S2 is issued from the control
computer 12 to the stepping motor of the printer head 27-1 and to
the feed-out roll mechanism for driving the stepping motor and the
feed-out roll mechanism for feeding the recording medium for
hologram 19 a distance necessary for establishing the contact
between the recording medium for hologram 19 and the optical
component 46.
[0141] Since the liquid is supplied to the recording medium for
hologram 19 at a position at which the recording medium for
hologram 19 starts to be contacted with the recording medium for
hologram 19 and the optical component 46 is contacted with the
recording medium for hologram 19 already holding the liquid, the
liquid can be interposed between the recording medium for hologram
19 and the optical component 46.
[0142] The control computer 12 then sends the image data D5
corresponding to the respective images of the parallax image string
to the LCD 18 for driving the LCD 18 for displaying an image
corresponding to the image data D5.
[0143] The control computer 12 also sends out the control signal S1
to the shutter 17 for opening it in order to have the laser light
L1 emitted by the laser light source 20 fall on the recording
medium for hologram 19 via LCD 18. The laser light beam L1,
outgoing from the laser light source 20, is passed through the
shutter 27, half mirror 22, spatial filter 23 and the collimator
lens 24, as explained previously, so as to fall on the recording
medium for hologram 19 as object light (projecting light). One-half
of the laser light beam L1 radiated from the laser light source 20
to fall on the half-mirror 21 via shutter 17 is reflected to fall
as reference light beam on the back side of the recording medium
for hologram 19 via cylindrical lens 28, collimator lens 29 and
mirror 30.
[0144] By having the object light beam interfere with the reference
light beam on the recording medium for hologram 19 so as to be used
for light exposure, an image displayed on the LCD 18 is recorded in
a strip shape as interference fringes on the recording medium for
hologram 19.
[0145] When the recording of this image comes to a close, the
shutter 17 is closed under control by the control computer 12 to
interrupt the laser light beam L1 radiated from the laser light
source 20 to stop the driving of the LCD 18. By sending out the
control signal S2 from the control computer 12 to the stepping
motor of the printer head 27-1 and to the feed-out roll driving
mechanism for driving these two components, the recording medium
for hologram 19 is fed by one hologram element. For intermittent
feeding of the recording medium for hologram 19, there is no
necessity of spacing the optical component 46 away from the
recording medium for hologram 19.
[0146] By repeating the operations of displaying an image
corresponding to the image data D5 on the LCD 18, opening the
shutter 17 for having the object light beam interfere with the
reference light beam on the recording medium for hologram 19 for
light exposure and feeding the recording medium for hologram 19 by
the stepping motor and the feed-out roll driving mechanism by one
hologram element, the image data D5 corresponding to the respective
images on the parallax image string supplied from the data
processor 11 are sequentially recorded in a strip-like form on the
recording medium for hologram 19.
[0147] Downstream of the portion of the printer head 27-1 where the
recording medium for hologram 19 is exposed to the object light and
the reference light, the entire surface of the intermittently fed
recording medium for hologram 19 is illuminated by the light beam
L3 from the UV lamp 47. This completes polymerization of the
monomer M in the exposed portion of the photopolymer layer 19b of
the recording medium for hologram 19, as shown in FIGS. 9A, 9B and
9C.
[0148] Downstream of the UV lamp 47, the recording medium for
hologram 19 is heated by the heat toll 48. This increases the
refractive index modulation factor of the photopolymer layer 19b
for fixing the recorded image.
[0149] Downstream of the heat roll 48, the cutter driving mechanism
is driven based on the control signal S2 supplied from the control
computer 12 so that the completed holographic stereogram is cut to
a desired size by the cutter 50 so as to be discharged to
outside.
[0150] By continuously supplying the liquid to a space between the
recording medium for hologram 19 and the optical component 46 for
having the liquid interposed therebetween at all times, for
recording a desired image on the recording medium for hologram 19,
the optical component 46 and the recording medium for hologram 19
can be tightly contacted with each other without producing an
intervening space thus sufficiently suppressing vibrations of the
recording medium for hologram 19.
[0151] By having the liquid interposed between the recording medium
for hologram 19 and the optical component 46, as described above,
the recording medium for hologram 19 can be intermittently fed
without the necessity of moving the optical component 46 in the
opposite direction.
[0152] Moreover, the recording medium for hologram 19 and the
optical component 46 are arrayed in air and the liquid is held
under surface tension, thus facilitating the maintenance.
[0153] 1-3 Second Embodiment
[0154] In the image recording device of the instant embodiment, in
which recording is performed by the edge-lit system, an optical
component comprised of a reference light inlet block is contacted
via liquid with a reference light incident side of the recording
medium for hologram 19. With the image recording method embodying
the present invention, a holographic stereogram is produced using
the above-described image recording device.
[0155] In carrying out the recording by the edge-lit system, the
structure of the holographic stereogram printer system is as
explained by referring to FIG. 6, while that of the holographic
stereogram printer device is also as explained by referring to
FIGS. 7A and 7B except that the angle of incidence of the reference
light, for example, is changed from the arrangement shown in FIG.
6.
[0156] For illustrating the image recording method embodying the
present invention, the structure of the vicinity of the printer
head 27 in the holographic stereogram printer device 13 is
explained in detail. In the present embodiment, the printer head 27
is constructed as a printer head 27-2 shown in FIG. 11.
[0157] With the printer head 27-2, similarly to the printer head
27-1 shown in FIG. 10, the recording medium for hologram 19 is
loaded thereon. The parts and components common to those of the
printer head 27-1 shown in FIG. 10 are indicated by the same
numerals and the corresponding description is omitted for avoiding
redundancy.
[0158] In the printer head 27-2, the optical component 46 made up
of the one-dimensional diffusion plate 44 is arranged at a spacing
from the recording medium for hologram 19. That is, the present
one-dimensional diffusion plate 44, while having the same optical
function as that of the printer head 27-1 shown in FIG. 10, has no
function of retaining the recording medium for hologram 19.
[0159] Meanwhile, with the printer head 27-2, the reference light
beam, incident on the recording medium for hologram 19 via a
reference light inlet block 52 as later explained, is totally
reflected on an interface with air without reaching the
one-dimensional diffusion plate 44. Thus, with the present printer
head 27-2, there is no necessity of providing a louver film between
the recording medium for hologram 19 and the one-dimensional
diffusion plate 44.
[0160] Also, with the present printer head 27-2, the reference
light inlet block 52 formed of transparent glass is arranged in
register with the point of incidence of the reference light so as
to be in contact with the recording medium for hologram 19. In
carrying out the recording by the edge-lit system, the reference
light beam falls on an end of the reference light inlet block 52 in
order to fall at an acute angle on the surface of the recording
medium for hologram 19. The reference light inlet block 52 herein
is formed of glass BK7 having a refractive index of 1.51.
[0161] In the present printer head 27-2, interference fringes are
formed on the recording medium for hologram 19 by the object light
beam incident substantially at a right angle on the surface of the
recording medium for hologram 19 and the reference light beam
incident substantially at an acute angle on the surface of the
recording medium for hologram 19.
[0162] Moreover, since the reference light inlet block 52 is
provided in contact with the recording medium for hologram 19,
micro-sized vibrations of the recording medium for hologram 19
between the roll 41 and the intermittent feed roll 42 can be
suppressed for forming a bright holographic stereogram, that is a
holographic stereogram having a high diffraction efficiency.
[0163] Also, with the present embodiment, a liquid-impregnated
sponge 53 is arranged as liquid supply means upstream of the
above-mentioned reference light inlet block 52 so as to be in
contact with both the reference light inlet block 52 and the
recording medium for hologram 19. Meanwhile, the sponge 53 is
narrower in width than the recording medium for hologram 19 for
preventing the liquid from flowing round the back side of the
recording medium for hologram 19.
[0164] The liquid with which to impregnate the sponge 53 herein is
o-xylene having a refractive index enabling index matching of the
recording medium for hologram 19 with the reference light inlet
block 52. The conditions for the refractive index enabling index
matching will be explained later.
[0165] By arranging the sponge 53, it becomes possible to supply
the liquid continuously to a space between the recording medium for
hologram 19 and the reference light inlet block 52 in order to have
the liquid interposed at all times between the recording medium for
hologram 19 and the reference light inlet block 52. Since this
achieves tight contact free of voids between the recording medium
for hologram 19 and the reference light inlet block 52,
oscillations of the recording medium for hologram 19 can be
suppressed sufficiently.
[0166] Since the recording medium for hologram 19 and the reference
light inlet block 52 realizes index matching, there is no risk that
the reference light passed through the reference light inlet block
52 and incident on the recording medium for hologram 19 be totally
reflected within the interior of the reference light inlet block
52. Thus it becomes possible to fabricate a holographic stereogram
of superior image quality.
[0167] Moreover, if the liquid is interposed between the recording
medium for hologram 19 and the reference light inlet block 52 the
recording medium for hologram 19 can be fed intermittently without
the necessity of moving the reference light inlet block 52 in an
opposite direction. This renders it possible to omit the
above-mentioned optical component driving mechanism for displacing
the reference light inlet block towards or away from the recording
medium for hologram 19 to simplify the structure of the image
recording device.
[0168] Moreover, if the liquid is interposed between the recording
medium for hologram 19 and the reference light inlet block 52, as
described above, the recording medium for hologram 19 and the
reference light inlet block 52 may be immersed in a liquid.
However, the recording medium for hologram 19 and the optical
component 46 are arrayed in air and the liquid is held under
surface tension, thus simplifying the structure of the image
recording device and facilitating the maintenance.
[0169] In the present printer head 27-2, since the structure
downstream of the intermittent feed roll 42 is similar to that of
the printer head 27-1 shown in FIG. 10, the corresponding
description is omitted for simplicity.
[0170] For explaining the image recording method embodying the
present invention, the operation of the holographic stereogram
printer device 13 inclusive of the printer head 27 is explained in
detail.
[0171] For producing a holographic stereogram, using the
above-described holographic stereogram printer device 13, the
hologram recording medium 19 configured as shown in FIG. 8 is
coiled around the roll 41 and the resulting assembly is housed
within the film cartridge 40.
[0172] The hologram recording medium 19 is then loaded between the
roll 41 and the intermittent feed roll 42 and the reference light
inlet block 52 will be contacted with the recording medium for
hologram 19. The sponge 53 as liquid supplying means is
sufficiently impregnated with a liquid.
[0173] Before actually recording the image on the recording medium
for hologram 19, the control signal S2 is issued from the control
computer 12 to the stepping motor of the printer head 27-2 and to
the feed-out roll mechanism for driving the stepping motor and the
feed-out roll mechanism for feeding the recording medium for
hologram 19 a distance corresponding to the contact between the
recording medium for hologram 19 and the reference light inlet
block 52.
[0174] Since the liquid is supplied to the recording medium for
hologram 19 at a position at which the recording medium for
hologram 19 starts to be contacted with the reference light inlet
block 52 and the recording medium for hologram 19 is contacted with
the recording medium for hologram 19 already holding the liquid,
the liquid can be interposed between the recording medium for
hologram 19 and the reference light inlet block 52.
[0175] The control computer 12 then sends the image data D5
corresponding to the respective images of the parallax image string
for driving the LCD 18 for displaying an image corresponding to the
image data D5.
[0176] The control computer 12 also sends out the control signal S1
to the shutter 17 for opening it in order to have the laser light
L1 emitted by the laser light source 20 fall on the recording
medium for hologram 19 via LCD 18. The laser light beam Li,
outgoing from the laser light source 20, is passed through the
shutter 17, half mirror 21, spatial filter 23 and the collimator
lens 24, as explained previously, to fall on the recording medium
for hologram 19 as object light (projecting light). One-half of the
laser light beam LI radiated from the laser light source 20 to fall
on the half-mirror 21 via shutter 17 is reflected to fall as
reference light beam on the back side of the recording medium for
hologram 19 via cylindrical lens 28, collimator lens 29 and mirror
30.
[0177] By having the object lightbeam interfere with the reference
light beam on the recording medium for hologram 19 so as to be used
for light exposure, an image displayed on the LCD 18 is recorded in
a strip-shape as interference fringes on the recording medium for
hologram 19.
[0178] When the recording of this image comes to a close, the
shutter 17 is closed under control by the control computer 12 to
interrupt the laser light beam Li radiated from the laser light
source 20 to stop the driving of the LCD 18. By sending out the
control signal S2 from the control computer 12 to the stepping
motor of the printer head 27-2 and to the feed-out roll driving
mechanism for driving the two components, the recording medium for
hologram 19 is fed by one hologram element. For intermittent
feeding of the recording medium for hologram 19, there is no
necessity of spacing the reference light inlet block 52 away from
the recording medium for hologram 19.
[0179] By repeating the operations of displaying an image
corresponding to the image data D5 on the LCD 18, opening the
shutter 17 for having the object light beam interfere with the
reference light beam on the recording medium for hologram 19 for
light exposure and feeding the recording medium for hologram 19 by
the stepping motor and the feed-out roll driving mechanism by one
hologram element, the image data D5 corresponding to the respective
images of the parallax image string supplied from the data
processor 11 are sequentially recorded in a strip-like form on the
recording medium for hologram 19.
[0180] Downstream of the portion of the printer head 27-2 where the
recording medium for hologram 19 is exposed to the object light and
the reference light, the entire surface of the intermittently fed
recording medium for hologram 19 is illuminated by the light beam
L3 from the UV lamp 47. This completes polymerization of the
monomer M in the exposed portion of the photopolymer layer 19b of
the recording medium for hologram 19, as shown in FIGS. 9A, 9B and
9C.
[0181] Downstream of the UV lamp 47, the recording medium for
hologram 19 is heated by the heat toll 48. This increases the
refractive index modulation factor of the photopolymer layer 19b
for fixing the recorded image.
[0182] Downstream of the heat roll 48, the cutter driving mechanism
is driven based on the control signal S2 supplied from the control
computer 12 so that the completed holographic stereogram is cut to
a desired size by the cutter 50 so as to be discharged to
outside.
[0183] By continuously supplying the liquid to a space between the
recording medium for hologram 19 and the reference light inlet
block 52 for having the liquid interposed therebetween at all
times, for recording a desired image on the recording medium for
hologram 19, the reference light inlet block 52 and the recording
medium for hologram 19 can be tightly contacted with each other
without producing an intervening space thus sufficiently
suppressing vibrations of the recording medium for hologram 19.
[0184] Moreover, since the liquid supplied to the space between the
recording medium for hologram 19 and the reference light inlet
block 52 realizes index matching, the reference light beam passed
through the reference light inlet block 52 so as to fall on the
recording medium for hologram 19 is not totally reflected within
the reference light inlet block 52, thus achieving a holographic
stereogram of superior image quality.
[0185] By having the liquid interposed between the recording medium
for hologram 19 and the optical component 46, as described above,
the recording medium for hologram 19 can be intermittently fed
without the necessity of moving the reference light inlet block 52
in the opposite direction.
[0186] Moreover, the recording medium for hologram 19 and the
optical component 46 are arrayed in air and the liquid is held
under surface tension, thus facilitating the maintenance.
[0187] Meanwhile, if, in carrying out reproduction by the edge-lit
system, an illuminating light inlet block having optical properties
similar to those of the reference light inlet block 52 is contacted
with the holographic stereogram, and the illuminating light beam is
incident on this illuminating light inlet block at the same angle
as the angle of incidence of the reference light to the surface of
the recording medium for hologram 19, the illuminating light is
diffracted by interference fringes formed on the recording medium
for hologram 19, thus producing the diffracted light similar to the
object light for producing a reproduced image.
[0188] Thus, for fabricating a transmission type holographic
stereogram by the edge-lit system, the reference light beam needs
to fall from the object light incident side on the recording medium
for hologram. Thus the reference light inlet block is arrayed
between the cylindrical lens for collecting the object light and
the recording medium for hologram. However, because of spatial
constraints, it is extremely difficult to arrange the reference
light inlet block between the cylindrical lens and the recording
medium for hologram.
[0189] On the other hand, with a holographic stereogram printer
device 13 having the printer head 27-2, as shown in FIG. 11, since
the holographic stereogram of the edge-lit system is fabricated as
a reflection type hologram, it is sufficient if the object light is
caused to fall on one of the surfaces of the recording medium for
hologram 19 and if the reference light is caused to fall on the its
opposite surface. Thus it suffices if the cylindrical lens 20 for
condensing the object light is arranged on one side of the
recording medium for hologram 19 and the reference light inlet
block 52 is arranged on the other side thereof in order to
construct the optical system with ease in a manner free from
spatial limitations.
[0190] Meanwhile, the holographic stereogram fabricated as the
reflection type hologram reproduces the three-dimensional image by
the reflection type hologram. For reproducing the three-dimensional
image as the reflection type hologram, a holographic stereogram 62
is bonded to an illuminating light inlet block 61 via liquid 60
and, under this condition, a reproducing illuminating light beam 63
is caused to fall from an end 61a of the illuminating light inlet
block 61 towards the holographic stereogram 62. The holographic
stereogram 62 is bonded to a surface 61b of the illuminating light
inlet block 61 remote from a viewer 64.
[0191] In this case, a reproduced image 66 generated by a
diffracted light beam 65 diffracted from the holographic stereogram
62 by the reflection mode is observed by the viewer 64. Thus, when
a three-dimensional image is reproduced, a reproduced image 66
appears as if the object were behind the illuminating light inlet
block 61 as viewed by the viewer 64.
[0192] It is also possible for the holographic stereogram,
fabricated as the reflection type hologram as described above, to
reproduce a three-dimensional image as a transmission type
hologram.
[0193] That is, with a holographic stereogram 72 bonded via a
liquid 70 to an illuminating light inlet block 71, a reproducing
illuminating light beam 73 is caused to fall at an end 71a of the
illuminating light inlet block 71 towards the holographic
stereogram 72. It is noted that the holographic stereogram 72 is
bonded to a surface 71c of the reproducing light inlet block 71
closer to a viewer 74.
[0194] At this time, a reproduced image 76 generated by a
diffracted light beam 75 diffracted from the holographic stereogram
72 with the transmission mode is viewed by the viewer 74. Thus, if
a three-dimensional image is reproduced, a reproduced image 76
appears as if it were located closer to the viewer than if a
three-dimensional image is reproduced with the reproducing method
shown in FIG. 12. Thus, by reproducing the three-dimensional image
shown in FIG. 13, the stereoscopic feeling can be emphasized thus
realizing a higher display effect.
[0195] Meanwhile, the shape of the illuminating light inlet block
71 need not be parallelepipedic and may be optionally selected on
the condition that the angle of incidence of the illuminating
reproducing light 73 with respect to the holographic stereogram 72
is coincident with that of the reference light beam incident on the
recording medium for hologram 19.
[0196] In the present embodiment, the wavelength of the laser light
used for fabricating the holographic stereogram is approximately
532 nm, while the angle the reference light makes with the object
light is approximately 75.degree.. The film thickness of a
photosensitive portion of the recording medium for hologram 19 is
approximately 20 .mu.m, with its refractive index being
approximately 1.5. Therefore, the allowance of selection of the
wavelength of the holographic stereogram is approximately 50 nm.
Thus, for reproducing the holographic stereogram, an LED emitting a
light beam having a center wavelength of approximately 525 nm and
the wavelength width of approximately 50 nm is desirable as the
light source of the reproducing illuminating light 73. Since the
LED has an extremely high light emitting efficiency, it becomes
possible to obtain the driving power of the image reproducing
device from, for example, a battery, thereby enabling the size and
the cost of the device to be lowered.
[0197] For reproducing a holographic stereogram as the reflection
type, a reproduced image can be usually obtained even if the white
light is used as the reproducing illumination because the
stereogram has higher wavelength selectivity. Conversely, for
regenerating a holographic stereogram as the reflection type, it
becomes difficult to reproduce the holographic stereogram with the
white light because the wavelength selectivity becomes weaker than
if the holographic stereogram is reproduced as the reflection type.
Therefore, if a holographic stereogram is reproduced as the
transmission type, a light source with a higher color purity is
preferably used as a reproducing light source. Specifically, if a
LED emitting the light of high color purity is used as a
reproducing light source, it becomes possible to obtain a clear
reproduced image. The LED also has merits that it s closer in
nature to a pont light source and hence is effective to prevent
blurring of the reproduced image due to spreading of the light
source, and that it scarcely generates heat.
[0198] However, the light source for the reproducing illuminating
light is not limited to LEDs. If a light source capable of emitting
the light of high color purity, such as a semiconductor laser, a
reproduced image can be produced in similar manner. The light
raised in color purity by a wavelength selective filter or a narrow
band reflection mirror may also be used as the reproducing
illuminating light.
[0199] L-4 Condition for Liquid Interposed between Recording Medium
for Hologram and Optical Component
[0200] In the above-described first and second embodiments, the
optical component 46 made up of a set of the one-dimensional
diffusion plate 44 and the louver film 45 is contacted with the
recording medium for hologram 19 via liquid and the reference light
inlet block 52 is contacted with the recording medium for hologram
19 via liquid, respectively. The conditions for the liquid
interposed between the reference light inlet block 52 and the
recording medium for hologram 19 are hereinafter explained.
[0201] First, the conditions for a liquid interposed between the
reference light inlet block 52 and the recording medium for
hologram 19 in case of recording by the edge-lit system are
explained.
[0202] During recording by the edge-lit system, the reference light
beam falls at an acute angle on the surface of the recording medium
for hologram 19. Thus it is a frequent occurrence that this
reference light beam be totally reflected on an interface between
the reference light inlet block 52 and the recording medium for
hologram 19 or surface irregularities on the surface of the
recording photopolymer layer 19b of the recording medium for
hologram 19 be presented on the image as stripes looking like
wooden grains. It s therefore required of the liquid interposed
between the recording medium for hologram 19 and the reference
light inlet block 52 to achieve index matching between the
recording medium for hologram 19 and the reference light inlet
block 52. That is, the above conditions need to be selected so that
no total reflection occurs on the interface between the reference
light inlet block 52 and the recording medium for hologram 19 and
so that the intensity reflectance (s-components) on each interface
is reduced.
[0203] Referring to FIG. 14, if a reference light beam 55 falls on
an end 52a of the reference light inlet block 52 having a
refractive index n.sub.g and is transmitted through a liquid 56
having a refractive index n.sub.m to reach the recording medium for
hologram 19, the following equation (1):
n.sub.g sin .theta..sub.g=nm sin .theta..sub.m=n.sub.p sin
.theta..sub.p (1)
[0204] where .theta..sub.g, .theta..sub.m and .theta..sub.p are
angles of the light beam on the respective interfaces. The
conditions under which no total reflection occurs on the respective
interfaces are given by the following equations (2) and (3)
n.sub.m>n.sub.g sin .theta..sub.g (2)
n.sub.p>n.sub.m sin .theta..sub.m(=n.sub.g sin .theta..sub.g)
(3)
[0205] Meanwhile, if the photopolymer layer 19b of the recording
medium for hologram 19 having the refractive index of 1.487, as
described above, is used, n.sub.P=1.487 is substituted into
equation (3) to give n.sub.g by the following equation (4):
n.sub.g<1.487/sin .theta..sub.g (4)
[0206] If .theta..sub.g=75.degree. or .theta..sub.g=78.degree.,
n.sub.g is given by the following equations (5) and (6):
.theta..sub.g<1.539 for .theta..sub.g=75.degree. (5)
.theta..sub.g<1.520 for .theta..sub.g=78.degree. (6)
[0207] Among materials satisfying the above equations (5) and (6)
is the glass BK7 having the refractive index of 1.51. If the glass
BK7 is used as this reference light inlet block 52, then n.sub.m
can be found by substituting n.sub.m=1.51 in the above equation
(2).
[0208] Therefore, if .theta..sub.g=75.degree. or
.theta..sub.g=78.degree., n.sub.m is found by the following
equations(7) and (8):
n.sub.m>1.458 for .theta..sub.g=75.degree. (7)
n.sub.m>1.477 for .theta..sub.g=78.degree. (8)
[0209] That is, for preventing total reflection of the reference
light beam 55 on the interface between the reference light inlet
block 52 and the recording medium for hologram 19, it suffices to
use a liquid having the refractive index nm satisfying the above
equations (7) and (8) as the liquid 56 interposed between the
reference light inlet block 52 and the recording medium for
hologram 19.
[0210] However, for fabricating the holographic stereogram, it is
necessary not only to satisfy the above conditions but also to
reduce the intensity reflectance (s-component) on each interface
because stronger reflectance on the interface leads to increased
light loss and to formation of excess hologram by the reflected
light to lower the diffraction efficiency. The conditions for
preventing the above-mentioned total reflection applies only for a
case in which each interface is planar. With the actual recording
medium for hologram 19, the surface of the photopolymer layer 19
presents inundations to a more or less extent, such that, even if
the above conditions are met, total reflection occurs locally to
produce uneven portions in the form of wooden grains.
[0211] The intensity reflectance (s-components) Rs.sub.(g-m) on the
interface between the light inlet block 52 and the liquid 56 and
the intensity reflectance (s-components) Rs.sub.(m-p) on the
interface between the liquid 56 and the recording medium for
hologram 19 are represented by the following equations (9) and
(10):
Rs.sub.(g-m)=sin.sup.2(.theta..sub.g-.theta..sub.m)/sin.sup.2(.theta..sub.-
g+.theta..sub.m) (9)
Rs.sub.(m-p)=sin.sup.2(.theta..sub.m-.theta..sub.p)/sin.sup.2(.theta..sub.-
m+.theta..sub.p) (10)
[0212] Since both Rs.sub.(g-m) and Rs.sub.(m-p) as close to zero as
possible are desired, the value obtained by the following equation
(11):
(1-Rs.sub.(g-m)).times.(1-Rs.sub.(m-p)) (11)
[0213] is desirably as close to unity as possible.
[0214] The values of Rs.sub.(g-m), Rs.sub.(m-p) and
(1-Rs.sub.(g-m)).times.(1-Rs.sub.(g-m)) for n.sub.p=1.487,
n.sub.g=1.51, .theta..sub.g=75.degree. or .theta..sub.g=78.degree.
and for various values of n.sub.m have been found by simulation.
The results of the simulation are shown in FIGS. 15 and 16.
[0215] The range for which the value of
(1-Rs.sub.(g-m)).times.(1-Rs.sub.(- m-p)) becomes 0.9 or larger has
been found. The following equations (12), (13) were obtained:
1.475<n.sub.m<1.549 for .theta..sub.g=75.degree. (12)
1.486<n.sub.m<1.514 for .theta..sub.g=78.degree. (13)
[0216] It may be said that, for preventing total reflection on the
respective interfaces and for sufficiently reducing the intensity
reflectance for satisfying the condition for prevention of total
reflection given by the above equations (7) and (8), it suffices to
have the liquid 56 with the refractive index nm satisfying the
above equations (12) and (13) interposed between the reference
light let block 52 and the recording medium for hologram 19.
[0217] Among the liquids 56 satisfying these conditions, there are,
for example, ethyl benzene, o-xylene, tetrachloroethylene, toluene,
pyridine, pyrrole and mesitylene.
[0218] An instance in which there is no necessity for the reference
light beam 55 to fall at an acute angle on the surface of the
recording medium for hologram 19 is explained.
[0219] In order to prevent total reflection on the interface
between the reference light inlet block 52 and the liquid 56 and on
the interface between the liquid 56 and the recording medium for
hologram 19, for n.sub.p=1.487 and .theta..sub.g=45.degree.,
n.sub.g is given by the following equation (14):
n.sub.g>2.103 (14)
[0220] from the above equation (4).
[0221] If n.sub.m=1.51 and n.sub.g=1.51 and
.theta..sub.g=45.degree. are substituted in the above equation (2),
n.sub.m is given by the following equation (15):
n.sub.m>1.068 (15)
[0222] For finding the condition for suppressing the intensity
reflectance to a smaller value, the values of Rs.sub.(g-m) and
Rs.sub.(m-p) for various values of n.sub.m with n.sub.p=1.487,
n.sub.g=1.51 and .theta..sub.g45.degree. were found by simulation.
The results are shown in FIG. 17.
[0223] The range of n.sub.m for which the value of
(1-Rs.sub.(g-m)).times.- (1-Rs.sub.(m-p)) is 0.9 or larger was
found. The range was found to have an extremely large width as
given by the following equation (18):
1.26<n.sub.m<1.97 (16)
[0224] If the value of (1-Rs.sub.(g-m)).times.(1-Rs.sub.(m-p)) is
set to 0.98 or larger, the range of n.sub.m was found to have a
broad width as indicated by the equation (17):
1.38<n.sub.m<1.67. (17)
[0225] Since the above equation (17) satisfies the above equation
(15) which is the condition for preventing total reflection, it
becomes possible to prevent total reflection occurring on the
interfaces to suppress the intensity reflectance to a sufficiently
small value if a liquid having the refractive index n.sub.m in
meeting with the equation (17) is used as the liquid 56 interposed
between the reference light let block 52 and the recording medium
for hologram 19.
[0226] If the reference light beam 55 is not incident at an acute
angle on the surface of the recording medium for hologram 19, total
reflection inherently is less liable to occur, while the intensity
reflectance is also small, so that the condition required of the
liquid 56 interposed between the reference light let block 52 and
the recording medium for hologram 19 become extremely moderate.
Therefore, most of known organic solvents become usable as the
liquid 56 satisfying the conditions for the refractive index
56.
[0227] In the foregoing, it is assumed that the reference light let
block 52 is contacted via liquid 56 with the recording medium for
hologram 19, as shown in FIG. 14, even in cases wherein the
reference light beam 55 need not fall at an acute angle to the
surface of the recording medium for hologram 19. However, in the
first embodiment, since it is not only the reference light let
block 52 but also the optical component 46, made up of the
one-dimensional diffusion plate 44 and the louver film 45, that are
contacted via liquid 56 with the recording medium for hologram 19,
there is produced certain deviation in the range of n.sub.m due to
the difference in refractive index between the reference light
inlet block 52 and the optical component 46.
[0228] Also, the refractive index of the photopolymer layer 19b is
adopted as the refractive index n.sub.p of the recording medium for
hologram 19. However, in the recording medium for hologram 19,
actually in use, the photopolymer layer 19b is sandwiched between
the film base 19a and the cover sheet 19c, without the photopolymer
layer 19b being in contact with the liquid 56. If the refractive
index of the film base 19a or the cover sheet 19c is not equal to
that of the photopolymer layer 19b or of the liquid 56, there is
produced certain deviation in the above range of n.sub.m.
[0229] 1-5 Modification
[0230] Although the first embodiment of the image recording method
and apparatus according to the present invention has been described
above, the present invention is not limited to these particular
embodiments. For example, although sponges 51 or 53 have been used
as liquid supplying means, liquid supplying means may be of any
suitable structure if it can supply liquid to a space between the
recording medium for hologram 19 and the optical component 46 or
the reference light inlet block 52. The liquid supplying means may
be designed as a coater employing a die coater or a coater
employing a roll for applying a liquid to the recording medium for
hologram 19.
[0231] In the second embodiment, since the reference light inlet
block 52 is contacted with the recording medium for hologram 19,
the optical component 46 made up of the one-dimensional diffusion
plate 44 and the louver film 45 is arranged at a spacing from the
recording medium for hologram 19, both the reference light inlet
block 52 and the optical component 46 may be contacted via liquid
with the recording medium for hologram 19.
[0232] In the above-described embodiments, the present invention is
applied to fabrication of a holographic stereogram having the
parallax information only in the transverse direction. The present
invention is, however, not limited to these embodiments, but may
also be applied to fabrication of a holographic stereogram having
the parallax information only in the longitudinal direction or to a
holographic stereogram having the parallax information in both the
transverse direction and the longitudinal direction.
[0233] In addition, although the above embodiments are directed to
fabrication of a monochromatic holographic stereogram, the present
invention may similarly be applied to fabrication of a colored
holographic stereogram. For producing of the colored holographic
stereogram, three light beams corresponding to the three prime
colors of light may be used as the recording light. For reproducing
a colored holographic stereogram recorded using three light beams
corresponding to the three prime colors of light, three light
sources are provided in an image reproducing device for emitting
three prime colors of light so that light beams from the light
sources will be illuminated simultaneously on the holographic
stereogram as reproducing illuminating light beams. However, if
such plural light sources are used, the optical system needs to be
constructed so that light beams from the light sources will be
parallel to one another. For reproducing the white holographic
stereogram, light sources with high color purity are preferably
used as the light sources because reproduction with the
transmission type hologram suffers from weak wavelength
selectivity. This renders it possible to reproduce the colored
holographic stereogram clearly even with the transmission type.
[0234] In addition, the direction of incidence of the reference
light beam, number or types of lenses or the combination thereof
may be suitably modified from je above-described arrangement.
[0235] 2. Second Image Recording Method and Apparatus
[0236] The schematics of a holographic stereogram printer system
100, as an embodiment of the second image recording device
according to the present invention, is hereinafter explained.
[0237] 2-1 Schematics of Image Recording Device
[0238] The schematics of the holographic stereogram printer system,
as an embodiment of the second image recording device according to
the present invention, are hereinafter explained.
[0239] FIG. 18 shows a structure of the holographic stereogram
printer system 100 made up of a data processor 101, a control
computer 102 and a holographic stereogram printer device 103.
[0240] The data processor 101 generates a parallax image string,
based on image data D11 or plural images of image data D12 for
plural rendering images, performs pre-set image processing for
hologram on image data D13 of the parallax image string to produce
image data for hologram D14 and transiently records the image data
for hologram D14 on a recording medium 114, such as a hard disc.
The image data D11 of plural images are obtained on imaging an
object from plural viewing points in the transverse direction, such
as on simultaneous imaging by a multi-eye camera or on continuous
imaging by a moving camera, while the image data D12 is produced on
sequentially according the parallax in the transverse direction and
is outputted by the image data generating computer 112.
[0241] During the subsequent light exposure operation, the data
processor 101 sequentially reads out the image data D14 of the
parallax image string recorded on the recording medium 114 to send
the read-out image data D15 sequentially to the control computer
102.
[0242] During light exposure, the control computer 102
driving-controls the shutter 132, LCD 141 and the printer head, as
later explained, of the holographic stereogram printer device 103,
based on the image data D15 of the parallax image string supplied
from the data processor 101.
[0243] The holographic stereogram printer device 103 has the
structure shown in FIGS. 19A, 19B in which corresponding parts to
those shown in FIG. 18 are denoted by the same reference numerals.
Specifically, the holographic stereogram printer device 103 drives
the LCD 141 based on the image data D15 supplied from the
above-described control computer 102 for sequentially recording
respective images corresponding to the image data D15 as
strip-shaped hologram elements on a recording medium for hologram
130 for fabricating the holographic stereogram. The recording
medium for hologram 130 used may be similar to that explained above
in connection with the first image recording method and device.
[0244] With the present holographic stereogram printer device 103,
the LCD 141 is driven based on one of the image data D15 supplied
from the control computer 102 for displaying an image corresponding
to the image data D15 on the LCD 141. In addition, a control signal
S11 is sent from the control computer 102 to the shutter 132 for
opening the shutter 132 for causing a laser light beam L11 radiated
from the laser light source 131 to fall via shutter 132, half
mirror 133 and mirror 138 on a spatial filter 139.
[0245] This laser light beam L11 is enlarged in width by a spatial
filter 139 so as to be then collimated by a collimator lens 140.
The collimated light beam is transmitted through a LCD 141 so as to
be converted into projecting light corresponding to an image
displayed on the LCD 141. The projecting light is then incident on
a cylindrical lens 143 so as to be thereby converged in the
transverse direction. The converged light beam is then incident on
the recording medium for hologram 130 held by a printer head
150.
[0246] At a position directly before incidence of the object light
and out of contact with the recording medium for hologram 130 is
arranged a one-dimensional diffusion plate 144 exhibiting diffusion
characteristics only in the longitudinal direction. This
one-dimensional diffusion plate 144 has the function of securing
the angle of visibility in an up-and-down direction when the
holographic stereogram is reproduced for viewing.
[0247] The laser light beam 111, reflected by the half-mirror 133,
is transmitted through a cylindrical lens 134, a collimator lens
135 and a mirror 136 in this order so as to fall at a pre-set angle
on the reverse surface of the recording medium for hologram 130. In
this case, if the angle of incidence of the reference light beam is
increased, surface reflection on the surface of the recording
medium for hologram 130 is increased. Thus, a light inlet block 137
is used and the reference light beam is allowed to fall at an end
of the block 137. The light path length of the reference light beam
is selected to be substantially equal to that of a laser light beam
L11 transmitted through the half mirror 133 and the mirror 138 to
fall on the recording medium for hologram 130. This laser light
beam L11 is referred to herein as an object light beam.
[0248] With the holographic stereogram printer device 103, this
object light beam can be caused to interfere with the reference
light beam on a recording surface of the recording medium for
hologram 130 so that the image displayed on the LCD141 can be
recorded as strip-shaped interference fringes on the recording
medium for hologram 130.
[0249] With the holographic stereogram printer device 103, the
shutter 132 is driven, after the end of recording the image, under
control by the control computer 102, for interrupting the laser
light L11 radiated by the laser light source 131. The LCD 141 then
ceases to be driven and the printer head 150 is driven, under
control by the control computer 102, for feeding the recording
medium for hologram 130 by a length equal to the width of a sole
hologram element.
[0250] The LCD 141 is further driven, under control by the control
computer 102, for displaying an image corresponding to the next
following image data D15. The shutter 132 is then opened, under
control by the control computer 102, for recording an image
displayed on the LCD 141 on the recording medium for hologram 130.
The similar operations are then sequentially carried out in
succession.
[0251] Thus, in the present holographic stereogram printer device
103, the images of the respective image data of the supplied
parallax image string can be sequentially recorded in the form of
strips on the recording medium for hologram 130, thus producing a
desired holographic stereogram.
[0252] For recording an image on the recording medium for hologram
130, two holograms, namely a hologram reproducible as the
reflection type and a hologram reproducible as the transmission
type, are produced simultaneously. This mechanism is explained by
referring to FIG. 20. For simplicity of explanation, it is assumed
that the refractive index of the light inlet block 137 is equal to
that of the recording medium for hologram 130.
[0253] Referring to FIG. 20A, a light beam L11A, incident via light
inlet block 137 as reference light beam on the recording medium for
hologram 130, proceeds straightly within the recording medium for
hologram 130 so as to be reflected by total reflection on an
interface 130a with air. A light beam L11B returned after total
reflection is also used as a reference light beam. The result is
that the recording medium for hologram is illuminated by two
reference light beams of different proceeding directions.
Therefore, if an illuminating light beam corresponding to the light
beam L11A prior to total reflection is used as the reproducing
illuminating light beam for the holographic stereogram, fabricated
as described above, the recorded image can be reproduced as the
reflection type whereas, if the illuminating light corresponding to
the lightbeam L11B subsequent to total reflection is used as an
illuminating light beam, the recorded image can be reproduced as
the transmission type.
[0254] Meanwhile, it depends on the refractive index of the
recording medium for hologram 130 and on the angle of incidence of
the reference light beam whether or not the reference light beam
undergoes total reflection on the interface 130a between the
recording medium for hologram 130 and air. Thus, in the present
embodiment, the refractive index of the recording medium for
hologram 130 and the angle of incidence of the reference light beam
are set in such a manner that the reference light beam undergoes
total reflection.
[0255] Conversely, if, when the reference light beam is not
reflected by total reflection on the interface 130a between the
recording medium for hologram 130 and air, that is when the
reference light beam is transmitted through the recording medium
for hologram 130, the reference light beam is transmitted through
the recording medium for hologram 130 falls on the one-dimensional
diffusion plate 144 arranged on the object light incident side for
the purpose of diffusing the object light beam, the reference light
beam is reflected by the one-dimensional diffusion plate 144 so as
to be again incident on the recording medium for hologram 130. Thus
the light beam reflected by the one-dimensional diffusion plate 144
so as to be re-incident on the recording medium for hologram 130
represents a noisy component in image recording.
[0256] Thus, if the reference light beam is not reflected by total
reflection on the interface 130a between the recording medium for
hologram 130 and air, a louver film 145 needs to be arranged
between the one-dimensional diffusion plate 144 and the recording
medium for hologram 130 for preventing such re-incidence, as shown
in FIG. 21. Thus it becomes possible to prevent the reference light
beam from being reflected by the one-dimensional diffusion plate
144 to be re-incident on the recording medium for hologram 130.
[0257] However, since such louver film 145 is arranged in the light
path of the object light beam, the object light beam tends to be
thereby disturbed to detract from image uniformity or brightness.
Conversely, if the reference light beam is reflected by total
reflection on the interface 130a between the recording medium for
hologram 130 and air, the reference light beam is not transmitted
through the recording medium for hologram 130, so that the louver
film 145 may be eliminated. Moreover, the optical system may be
correspondingly simplified in structure.
[0258] For improving sharpness of the recorded image, the
one-dimensional diffusion plate 144 is preferably arranged at a
position as close to the recording medium for hologram 130 as
possible. However, a void is provided between the recording medium
for hologram 130 and the one-dimensional diffusion plate 144 for
permitting total reflection of the reference light beam on the
interface 130a between the recording medium for hologram 130 and
air. That is, total reflection of the reference light is allowed to
occur on the interface 130a between the recording medium for
hologram 130 and air which is interposed between the
one-dimensional diffusion plate 144 and recording medium for
hologram 130.
[0259] Meanwhile, a material having the refractive index satisfying
the condition of total reflection of the reference light on the
interface to the recording medium for hologram 130 may be
interposed, in place of air, between the one-dimensional diffusion
plate 144 and the recording medium for hologram 130. That is, the
recording medium for hologram 130, a spacer having a refractive
index satisfying the condition for total reflection of the
reference light beam and the one-dimensional diffusion plate 144
may be arranged in superposition.
[0260] Meanwhile, the second image recording device according to
the present invention sequentially records images corresponding to
image data of the parallax image string as strip- or dot-shaped
hologram elements by causing the object light and the reference
light to fall on one and the other surfaces of the recording medium
for hologram 130. To this end, the second image recording device
includes an optical component contacted with the reference light
incident surface of the recording medium for hologram.
[0261] Thus, in the above-described holographic stereogram printer
system 100, the feature of the present invention resides in the
structure of the holographic stereogram printer device 103, in
particular the vicinity of the printer head 150. Thus, an
illustrative structure of the vicinity of the printer head 150 is
now explained in detail by way of illustrating an embodiment of the
image recording device of the present invention.
[0262] 2-2 First Embodiment
[0263] The image recording device of the present embodiment is
configured so that the optical component is contacted in a
void-free fashion on the reference light inlet side of the
recording medium for hologram 130. The image recording device of
the instant embodiment fabricates a holographic stereogram using
the above-described image recording device.
[0264] For illustrating the image recording device of the instant
embodiment, the structure of the vicinity of the printer head 150
of the holographic stereogram printer device 103 of the
above-described holographic stereogram printer system 100 is
explained in detail. In the present embodiment, the printer head
150 is configured as a printer head 150-1 as shown in FIG. 22.
[0265] The printer head 150-1 is configured for holding and
transporting the recording medium for hologram 130.
[0266] That is, the printer head 150-1 is configured for rotatably
fulcruming a roll 152 in a film cartridge 151 loaded in position
with a pre-set torque and for holding the recording medium for
hologram 130 drawn out from the film cartridge 151 between a first
intermittent feed roll 153A and a second intermittent feed roll
153B.
[0267] Between the roll 152 and the intermittent feed rolls 153A
and 153B, a light inlet block 137A formed of a transparent rigid
material, such as glass, is arranged in contact with the recording
medium for hologram 130 on the object light inlet side on the
opposite surface to the object light incident side. The light inlet
block 137A is columnar-shaped and is held by a holding mechanism,
not shown, for rotation about the shaft as center.
[0268] The recording medium for hologram 130 is adapted for being
contacted with the light inlet block 137A between the roll 152 and
the intermittent fed rolls 153A, 153B. The object light beam is
adapted to fall at a right angle on the recording medium for
hologram 130 in an area thereof in contact with the light inlet
block 137A.
[0269] The recording medium for hologram 130 enclosed within the
film cartridge 151 has a cover sheet for protecting the
photosensitive portion. That is, the recording medium for hologram
130 is of a sandwiched structure in which the photopolymer layer as
the photosensitive portion is sandwiched in an initial state
between the base film material and the cover film and is coiled
about the roll 152 within the film cartridge 151. In the printer
head 150-1, the cover sheet 130a is peeled from the recording
medium for hologram 130 so as to be taken up on another roll 154
before the recording medium for hologram 130 led out from the film
cartridge 151 is contacted with the light inlet block 137A, as
shown in FIG. 22. The recording medium for hologram 130, from which
the cover sheet 130a has been peeled off, is led out towards the
light inlet block 137A, so that the object light incident side and
the reference light incident side prove to be a base film material
and the photopolymer layer, respectively.
[0270] If the recording medium for hologram 130 devoid of the cover
sheet is used it is unnecessary to peel the cover sheet off in
order to take up the cover sheet on another roll. That is, the
recording medium for hologram 130 having the photopolymer layer
formed on the base film material may directly be routed to the
light inlet block 137A without peeling the cover film from the
recording medium for hologram 130. Meanwhile, the printer head
150-2 shown in FIG. 23 is similar to the printer head 150-1 shown
in FIG. 22 except the slight difference in the structure of the
film cartridge 151.
[0271] The light inlet block 137A light inlet block 137A is used
for routing the reference light to the recording medium for
hologram 130. The reference light is incident on ne end face of the
light inlet block 137A. This light inlet block is supported by a
first thrusting roll 155A and a second thrusting roll 155B arranged
on the object light incident side and by a third thrusting roll
155C arranged on the reference light incident side. The first
thrusting roll 115A and the second thrusting roll 115B are fixed
while the third thrusting roll 155C is movable in the fore-and-aft
direction as indicated by arrow d in FIG. 22. The recording medium
for hologram 130 is passed through a space between the first
thrusting roll 155A and the light inlet block 130 and into a space
between the second thrusting roll 155B and the light inlet block
130. In this state, the third thrusting roll 155C is moved as
indicated by arrow d in FIG. 22 and exerts a pressure against the
light inlet block 137A in a direction of thrusting the light inlet
block 137A against the first thrusting roll 155A and the second
thrusting roll 155B. In this manner, the recording medium for
hologram 130 and the light inlet block 137A are supported with the
recording medium for hologram 130 being pressed against the light
inlet block 137A.
[0272] That is, the recording medium for hologram 130 is led out of
the film cartridge 151 so that the object light inlet side proves
to be the base film material and the reference light inlet side,
that is the side of the light inlet block 137A, proves to be the
photopolymer layer. The recording medium for hologram 130 is kept
in a state in which the photopolymer layer is contacted tightly
with the light inlet block 137A so that there is left no gap
between the photopolymer layer and the light inlet block 137A.
[0273] With the printer head 150-1, having the light inlet block
137A, the light inlet block 137A is a rigid member, and is
positioned by a bearing, not shown, micro-sized vibrations of the
light-exposed portions of the recording medium for hologram 130 can
be suppressed extremely efficiently. This produces a holographic
stereogram of increased brightness, that is of high diffraction
efficiency.
[0274] The printer head 150-1 is provided with a cleaning member
156 in a portion of the light inlet block 137A not in contact with
the recording medium for hologram 130. The function of this
cleaning member 156 is to remove dust and dirt affixed to the
lateral side of the rotating light inlet block 137A. To this end,
the cleaning member 156 is formed by s plate member of, for
example, urethane rubber, or s soft cloth, and is supported in
contact with the lateral side of the light inlet block 137A.
[0275] When the recording medium for hologram 130 is peeled off
from the light inlet block 137A, as when the dust and dirt in air
has become affixed to the light inlet block 137A or recording of
the hologram elements has come to a close, part of the recording
medium for hologram 130 is occasionally left on the light inlet
block 137A. The cleaning member 156 removes part of the recording
medium for hologram 130 left on the light inlet block 137A or dust
and dirt in air out of the light inlet block 137A. Thus, the light
inlet block 137A is completely cleaned before coming into contact
with the recording medium for hologram 130. That is, with the
present printer head 150-1, the light inlet block 137A and the
recording medium for hologram 130 are brought into tight contact
with each other after cleaning of the light inlet block 137A.
[0276] The cleaning member 156 is built into the film cartridge 151
so that, when the film cartridge 151 is built into the printer head
150-1, the cleaning member 156 is contacted with the lateral side
of the light inlet block 137A. Thus, when exchanging the film
cartridge 151 having enclosed therein the recording medium for
hologram 130, the cleaning member 156 can be exchanged
simultaneously to facilitate maintenance.
[0277] The first and second intermittent feed rolls 153A, 153B are
configured for being rotated in a direction shown by arrow e under
the force of rotation outputted by a stepping motor, not shown.
This stepping motor sequentially rotates the intermittent feed
rolls 153A, 153B a pre-set angle, under control by a control signal
S12 furnished from the control computer 102 each time light
exposure for one image comes to a close. Thus the recording medium
for hologram 130 is fed by one hologram element each time light
exposure for one image comes to a close.
[0278] Downstream of the intermittent feed rolls 153A, 153B in the
travel passage of the recording medium for hologram 130 is arranged
a UV lamp 157 for extending along the travel passage whereby a UV
light beam L13 of a pre-set power for terminating the diffusion of
the monomer M is illuminated on the light-exposed portion of the
recording medium for hologram 130 forwarded by the intermittent
feed rolls 153A, 153B.
[0279] Downstream of the UV lamp 157 in the travel passage of the
recording medium for hologram 130 are arranged a rotatably
fulcrumed heat roll 158, a pair of feed-out rolls 159A, 159B and a
cutter 160, in this order. The feed-out rolls 159A, 159B are
arranged for holding the recording medium for hologram 130 in a
state of being tightly placed 180.degree. around the outer
periphery of the heat roll 158.
[0280] The heat roll 158 is provided with internal heating means,
not shown, for maintaining the peripheral surface of the roll at
approximately 120.degree. C. This setting is based on an experiment
by which it has been found that, by having as-exposed
photopolymerizable photopolymer (OMNI-DEX) sandwiched between a
heating plate temperature-controlled for maintaining a constant
temperature of 120.degree. and a glass plate pressed from above by
a spring pressure and by heating the resulting assembly for five
minutes, the refractive index modulation of the same order of
magnitude as that obtained in case the assembly is
atmosphere-heated at 120.degree. C. for two hours can be
achieved.
[0281] The outer diameter of the heat roll 158 is selected so that
the time since the recording medium for hologram 130 starts to be
abutted against the outer peripheral surface of the heat roll 158
until it is detached therefrom is substantially equal to the time
required for the recorded image to become fixed for thereby
assuring positive fixation of the image recorded on the recording
medium for hologram 130 passed through the heat roll 158.
[0282] The driving mechanism for the feed-out rolls 49A, 49B,
referred to hereinafter as a feed-out roll driving mechanism, is
configured for rotating the feed-out rolls 153A, 153B in
synchronism with the intermittent feed rolls 153A, 153B based on
the control signal S12 outputted by the control computer 102 during
intermittent feed of the recording medium for hologram 130. This
enables the recording medium for hologram 130 to be kept tightly
contacted with the peripheral surface of the heat roll without
becoming slacked between the intermittent feed rolls 153A and 153B
and the feed-out rolls 159A, 159B.
[0283] A driving mechanism for the cutter 160 (cutter driving
mechanism) , not shown, drives the cutter 160, after a desired
image is recorded on the hologram recording medium 130 based on the
control signal S12 supplied from the control computer 102 and
entire areas of the hologram recording medium 130 having the image
recorded therein are subsequently discharged to outside, for
severing the discharged portion from the remaining portion of the
hologram recording medium 130. This enables the image-bearing
portion of the hologram recording medium 130 to be discharged to
outside as a sole holographic stereogram.
[0284] For explaining the image recording method embodying the
present invention, the operation of the holographic stereogram
printer device 103 inclusive of the printer head 150-1 is explained
in detail.
[0285] For producing a holographic stereogram, using the
above-described holographic stereogram printer device 13, the
hologram recording medium 130 is coiled around the roll 152 and the
resulting assembly is housed within the film cartridge 151.
[0286] The cover film 130a is peeled off from the hologram
recording medium 130. The cover film 130a, thus peeled off, is
taken up on the roll 154. The portion of the hologram recording
medium 130, from which the cover film 130a has been peeled off,
that is which has the photopolymer layer formed on a base film
thereof, is loaded up to the intermittent feed rolls 155A, 155B in
a state in which the recording medium 130 is thrust by the first
and second rolls 155A, 155B in a gap-free manner against the light
inlet block 137A.
[0287] The control computer 102 then sends the image data D15
corresponding to the respective images of the parallax image string
for driving the LCD 141 for displaying an image corresponding to
the image data D15. The control computer 102 also sends out the
control signal S11 to the shutter 132 for opening it in order to
cause the laser light L11 emitted by the laser light source 131 to
fall on the recording medium for hologram 130 via LCD 141. The
laser light beam L11, outgoing from the laser light source 131, is
passed through the shutter 132, half mirror 133, mirror 138,
spatial filter 139 and the collimator lens 140, as explained
previously, to fall on the recording medium for hologram 130 as
object light (projecting light). One-half of the laser light beam
L11 radiated from the laser light source 131 to fall on the
half-mirror 133 via shutter 132 is reflected by the half mirror 133
to fall as reference light beam on the back side of the recording
medium for hologram 130 via cylindrical lens 134, collimator lens
135 and mirror 136.
[0288] By having the object light beam interfere with the reference
light beam on the recording medium for hologram 130 so as to be
used for light exposure, an image displayed on the LCD 141 is
recorded in a strip-shape as interference fringes on the recording
medium for hologram 130.
[0289] When the recording of this image comes to a close, the
shutter 132 is closed under control by the control computer 102 to
interrupt the laser light beam L11 radiated from the laser light
source 131 to stop the driving of the LCD 141. By sending out the
control signal S12 from the control computer 102 to the stepping
motor of the printer head 150-1 and to the feed-out roll driving
mechanism for driving these two components, the recording medium
for hologram 130 is fed by one hologram element.
[0290] The recording medium for hologram 130 is fed without
displacing the light inlet block 137A from the recording medium for
hologram 130, with the recording medium for hologram 130 being kept
in tight contact with the light inlet block 137A. The light inlet
block 137A, while not having its own driving mechanism, can be
rotated freely. Thus, if the recording medium for hologram 130 is
fed without being displaced away from the light inlet block 137A,
the latter is also rotated with movement of the recording medium
for hologram 130. That is, with the present printer head 150-1, the
light inlet block 137A can be rotated while the recording medium
for hologram 130 and the light inlet block 137A are kept in contact
with each other.
[0291] By repeating the operations of displaying an image
corresponding to the image data D15 on the LCD 141, opening the
shutter 132 for having the object light beam interfere with the
reference light beam on the recording medium for hologram 130 for
light exposure and feeding the recording medium for hologram 130 by
the stepping motor and the feed-out roll driving mechanism a
distance corresponding to one hologram element, the image data D15
corresponding to the respective images on the parallax image string
supplied from the data processor 101 are sequentially recorded in a
strip-like form on the recording medium for hologram 130.
[0292] Downstream of the portion of the printer head 150-1 where
the recording medium for hologram 130 is exposed to the object
light and the reference light, the entire surface of the
intermittently fed recording medium for hologram 130 is illuminated
by the UV light beam L13 from the UV lamp 157. This completes
polymerization of the monomer M in the exposed portion of the
photopolymer layer 19b of the recording medium for hologram
130.
[0293] Downstream of the UV lamp 157, the recording medium for
hologram 130 is heated by the heat toll 48. This increases the
refractive index modulation degree of the photopolymer layer for
fixing the recorded image. Downstream of the heat roll 158, the
cutter driving mechanism is driven based on the control signal S12
supplied from the control computer 102 so that the completed
holographic stereogram is cut to a desired size by the cutter 160
so as to be discharged to outside.
[0294] For recording a desired image on the recording medium for
hologram 130, the recording medium for hologram 130 is contacted
with the light inlet block 137A at the same time as the air is
expelled continuously by the thrusting rolls 155A, 155B for
eliminating voids between the recording medium for hologram 130 and
the light inlet block 137A, for enabling the reference light beam
to fall at an acute angle without interposition of, for example, an
index matching liquid. Meanwhile, the light inlet block 137A is a
rigid member and has its relative position rigidly fixed with
respect to, for example, a casing. Thus, the vibrations of the
recording medium for hologram 130, held in tight contact with the
light inlet block 137A, can be suppressed sufficiently.
[0295] Meanwhile, it depends on characteristics of the recording
medium for hologram 130, in particular its hardness or thickness,
whether or not the recording medium for hologram 130 can be tightly
contacted with the light inlet block 137A without voids. However,
since the photopolymer, as a material for the recording medium for
hologram 130, usually exhibits moderate pliability, the recording
medium for hologram 130 can be brought easily into tight contact
with the light inlet block 137A without voids. If `OMNI-DEX`
manufactured by DU PONT Inc. is used as a material for a
photopolymer layer for the recording medium for hologram 130 and
its film thickness is set to approximately 20 .mu.m, the recording
medium for hologram 130 could be bonded tightly with the light
inlet block 137A without voids.
[0296] 2-3 Second Embodiment
[0297] The image recording device of the present embodiment
performs edge-lit recording via an index matching liquid and is
configured so that a light inlet block is contacted via liquid with
the reference light incident side of the recording medium for
hologram 130. The image recording method of the present embodiment
fabricates a holographic stereogram using the above image recording
device.
[0298] Meanwhile, in performing edge-lit recording via an index
matching liquid, the structure of the holographic stereogram
printer system is as explained with reference to FIG. 18, while the
structure of the holographic stereogram printer device is as
explained with reference to FIGS. 19A and 19B except for the
partially modified light inlet block.
[0299] For illustrating an image recording device of the instant
embodiment, the structure of the vicinity of the printer head 150
of the holographic stereogram printer device 103 is explained in
detail. In the instant embodiment, the printer head 150 is
constructed as a printer head 150-3 shown in FIG. 24.
[0300] The printer head 150-3 is designed to load the recording
medium for hologram 130 in the same manner as the printer head
150-2 shown in FIG. 23. The parts or components similar to those of
the printer head 150-1 or 150-2 are denoted by common numerals and
are not described for avoiding redundancy.
[0301] With the printer head 150-3, the one-dimensional diffusion
plate 144 is arranged at a position spaced away from the recording
medium for hologram 130. Also, with the printer head 150-3, a light
inlet block 137B, formed of transparent glass, is arranged in
register with the reference light incident position in contact with
the recording medium for hologram 130. In carrying out recording by
the edge-lit system, the reference light beam is caused to fall at
an edge portion of the light inlet block 137B so as to fall at an
acute angle on the surface of the recording medium for hologram
130. For the light inlet block 137B, glass BK7 having the
refractive index of 1.51 was used.
[0302] Thus, on the recording medium for hologram 130, interference
fringes are formed by the object light incident at a right angle on
the surface of the recording medium for hologram 130 and the
reference light incident thereon at an acute angle.
[0303] Since the light inlet block 137B is arranged in contact with
the recording medium for hologram 130, micro-sized vibrations of
the recording medium for hologram 130 between the film cartridge
and the intermittent feed rolls 153A, 153B can be suppressed for
producing a holographic stereogram of higher brightness, that is of
higher diffraction efficiency.
[0304] In the present embodiment, a sponge 161 impregnated with a
liquid is arranged as liquid supplying means upstream of the light
inlet block 137B so as to be in contact with both the light inlet
block 137B and with the recording medium for hologram 130. The
sponge 51 is narrower in width than the recording medium for
hologram 130 for preventing the liquid from flowing round the back
side of the recording medium for hologram 130.
[0305] The liquid used for impregnating the sponge 51 is o-xylene
having the refractive index enabling index matching between the
recording medium for hologram 130 and the light inlet block 137B.
The conditions for the liquid interposed between the light inlet
block 137B and the recording medium for hologram 130 are the same
as those explained in connection with the first embodiment of the
image recording method and device.
[0306] By arranging the sponge 161, it becomes possible to supply
the liquid to a spacing between the recording medium for hologram
130 and the light inlet block 137B at all times in order to have
the liquid interposed therein. Since this enables the light inlet
block 137B and the recording medium for hologram 130 to be
contacted intimately with each other without voids, vibrations of
the recording medium for hologram 130 can be suppressed
sufficiently.
[0307] Moreover, since the liquid supplied to the space between the
recording medium for hologram 130 and the light inlet block 137B
performs index matching, the reference light transmitted through
the light inlet block 137B so as to fall on the recording medium
for hologram 130 is not reflected by total reflection within the
light inlet block 137B. The result is the holographic stereogram of
superior image quality.
[0308] Moreover, if the liquid is interposed between the recording
medium for hologram 130 and the light inlet block 137B, the
recording medium for hologram 130 can be fed intermittently without
the necessity of moving the light inlet block 137B in an opposite
direction. This renders it possible to omit a driving mechanism for
moving the light inlet block 137B towards and away from the
recording medium for hologram 130 to simplify the structure of the
image recording device.
[0309] For having the liquid interposed between the recording
medium for hologram 130 and the light inlet block 137B, it is also
possible to arrange the recording medium for hologram 130 and the
light inlet block 137B in a liquid. However, in the instant
embodiment, since the recording medium for hologram 130 and the
light inlet block 137B are both arranged in air and the liquid is
held by surface tension, it becomes possible to simplify the image
recording device in structure, while facilitating the
maintenance.
[0310] In the printer head 150-3, since the structure downstream of
the intermittent feed rolls 153A, 153B is similar to that of the
printer head 150-1 shown in FIG. 22 and the printer head 150-2
shown in FIG. 23, the corresponding description is omitted for
avoiding redundancy.
[0311] For illustrating the picture recording method according to
the present embodiment, the operation of the holographic stereogram
printer device having the above-mentioned printer head 150-3 is
explained in detail.
[0312] For producing a holographic stereogram, using the
above-described holographic stereogram printer device 103, the
hologram recording medium 130 is coiled around the roll 152 and the
resulting assembly is housed within the film cartridge 151. The
hologram recording medium 130 is then loaded between the film
cartridge 151 and the intermittent feed rolls 153A, 153B and the
light inlet block 137B is set in contact with the recording medium
for hologram 130. The sponge 161 as liquid supplying means is
sufficiently impregnated with a liquid.
[0313] Before actually recording the image on the recording medium
for hologram 130, the control signal S12 is issued from the control
computer 102 to the stepping motor of the printer head 150-3 and to
the feed-out roll mechanism for driving the stepping motor and the
feed-out roll mechanism for feeding the recording medium for
hologram 130 a distance for establishing the contact between the
recording medium for hologram 130 and the light inlet block
137B.
[0314] Since the liquid is supplied from the sponge 161 to the
recording medium for hologram 130 at a position at which the
recording medium for hologram 130 starts to be contacted with the
light inlet block 137B and the light inlet block 137B is contacted
with the recording medium for hologram 130 already holding the
liquid, the liquid can be interposed between the recording medium
for hologram 130 and the light inlet block 137B.
[0315] The control computer 102 then sends the image data D15
corresponding to the respective images of the parallax image a
string for driving the LCD 141 for displaying an image
corresponding to the image data D15.
[0316] The control computer 102 also sends out the control signal
S12 to the shutter 132 for opening it in order to cause the laser
light L11 emitted by the laser light source 131 to fall on the
recording medium for hologram 130 via LCD 141. The laser light beam
L11, outgoing from the laser light source 131, is passed through
the shutter 132, half mirror 133, mirror 138, spatial filter 139
and the collimator lens 140, as explained previously, to fall on
the recording medium for hologram 130 as object light (projecting
light). One-half of the laser light beam L11 radiated from the
laser light source 131 to fall on the half-mirror 13 via shutter
132 is reflected to fall as reference light beam on the back side
of the recording medium for hologram 130 via cylindrical lens 134,
collimator lens 135 and mirror 136.
[0317] By having the object light beam interfere with the reference
light beam on the recording medium for hologram 130 so as to be
used for light exposure, an image displayed on the LCD 141 is
recorded in a strip-shape as interference fringes on the recording
medium for hologram 130.
[0318] When the recording of this image comes to a close, the
shutter 132 is closed under control by the control computer 102 to
interrupt the laser light beam L11 radiated from the laser light
source 131 to stop the driving of the LCD 141.
[0319] By sending out the control signal S12 from the control
computer 102 to the stepping motor of the printer head 150-3 and to
the feed-out roll driving mechanism for driving the two components,
the recording medium for hologram 130 is fed by one hologram
element. For intermittent feeding of the recording medium for
hologram 130, there is no necessity of spacing the optical
component 137B away from the recording medium for hologram 130.
[0320] By repeating the operations of displaying an image
corresponding to the image data D15 on the LCD 141, opening the
shutter 132 for having the object light beam interfere with the
reference light beam on the recording medium for hologram 130 for
light exposure and feeding the recording medium for hologram 130 by
the stepping motor and the feed-out roll driving mechanism by one
hologram element, the image data D15 corresponding to the
respective images on the parallax image string supplied from the
data processor 11 are sequentially recorded in a strip-like form on
the recording medium for hologram 130.
[0321] Downstream of the portion of the printer head 150-3 where
the recording medium for hologram 130 is exposed to the object
light and the reference light, the entire surface of the
intermittently fed recording medium for hologram 130 is illuminated
by the light beam L13 from the UV lamp 157. This completes
polymerization of the monomer M in the exposed portion of the
photopolymer layer of the recording medium for hologram 130.
[0322] Downstream of the UV lamp 157, the recording medium for
hologram 130 is heated by the heat toll 158. This increases the
refractive index modulation degree of the photopolymer layer for
fixing the recorded image.
[0323] Downstream of the heat roll 48, the cutter driving mechanism
is driven based on the control signal S12 supplied from the control
computer 102 so that the completed holographic stereogram is cut to
a desired size by the cutter 50 so as to be discharged to
outside.
[0324] By continuously supplying the liquid to a space between the
recording medium for hologram 130 and the light inlet block 137B
for having the liquid interposed therebetween at all times, for
recording a desired image on the recording medium for hologram 130,
the light inlet block 137B and the recording medium for hologram
130 can be tightly contacted with each other without producing an
intervening space thus sufficiently suppressing vibrations of the
recording medium for hologram 19.
[0325] Also, since the liquid supplied to the space between the
recording medium for hologram 130 and the light inlet block 137B
performs index matching, the reference light beam transmitted
through the light inlet block 137B to fall on the recording medium
for hologram 130 is not reflected by total reflection within the
light inlet block 137B thus producing a holographic stereogram of
superior image quality.
[0326] By having the liquid interposed between the recording medium
for hologram 130 and the light inlet block 137B, as described
above, the recording medium for hologram 130 can be intermittently
fed without the necessity of moving the light inlet block 137B in
the opposite direction.
[0327] Moreover, since the recording medium for hologram 130 and
the light inlet block 137B are both arranged in air and the liquid
is held by surface tension, it becomes possible to simplify the
image recording device in structure, while facilitating the
maintenance.
[0328] For carrying out reproduction by the edge-lit system, an
illuminating light inlet block having optical properties similar to
those of the light inlet block 137B is contacted with the
holographic stereogram and an illuminating light beam is caused to
fall on the illuminating light inlet block at the same angle as the
angle of incidence of the reference light beam to the surface of
the recording medium for hologram 130, the illuminating light beam
is diffracted by the interference fringes formed on the recording
medium for hologram 130 to produce a diffracted light beam similar
to that produced by the object light beam thus producing a
reproduced image.
[0329] Thus, for fabricating the transmission type holographic
stereogram by the edge-lit system, it is necessary to have the
reference light beam fall on the recording medium for hologram via
a reference light inlet block from the object light incident side.
To this end, the reference light inlet block is arranged between
the cylindrical lens configured for converging the object light and
the recording medium for hologram. However, because of spatial
limitations, it is extremely difficult to arrange the reference
light inlet block between the cylindrical lens and the recording
medium for hologram. Moreover, the one-dimensional diffusion plate
cannot be inserted in position with ease.
[0330] Conversely, with the holographic stereogram printer device
103 having the printer head 150-3 as shown in FIG. 24, the
holographic stereogram of the edge-lit system is fabricated with
the reflection type, so that it suffices if the object light and
the reference light are caused to fall on one and the opposite
surfaces of the recording medium for hologram 130, respectively.
Thus, with the present embodiment, it suffices if the cylindrical
lens 143 for converging the object light and the one-dimensional
diffusion plate 144 are arranged on one surface of the recording
medium for hologram 130 and the reference light inlet block 137B is
arranged on the opposite surface thereof to enable the optical
system to be constructed easily without spatial limitations.
[0331] As a matter of fact, it is possible with the holographic
stereogram, fabricated as the reflection type, to reproduce a
three-dimensional image as the reflection type. That is, a
holographic stereogram 172 is bonded via a liquid 170 on an
illuminating light inlet block 171 and a reproducing illuminating
light beam 173 is caused to fall from an end 171a of the
illuminating light inlet block 171 towards the holographic
stereogram 172. The holographic stereogram 172 is bonded to a
surface 171b of the illuminating light inlet block 171 remote from
a viewer 174.
[0332] In this case, a reproduced image 176 generated by a
diffracted light beam 175 diffracted from the holographic
stereogram 172 by the reflection mode is observed by the viewer
174. Thus, when a three-dimensional image is reproduced, a
reproduced image 176 appears as if the object were behind the
illuminating light inlet block 171 as viewed by the viewer 174.
[0333] It is also possible for the holographic stereogram
fabricated as the reflection type as described above, to reproduce
a three-dimensional image as a transmission type.
[0334] That is, with a holographic stereogram 182 bonded via a
liquid 180 to an illuminating light inlet block 181, a reproducing
illuminating light beam 183 is caused to fall at an end 181a of the
illuminating light inlet block 181 towards the holographic
stereogram 182. It is noted that the holographic stereogram 182 is
bonded to a surface 181c of the reproducing light inlet block 181
closer to a viewer 184.
[0335] At this time, a reproduced image 186 generated by a
diffracted light beam 185 diffracted from the holographic
stereogram 182 with the transmission mode is viewed by the viewer
184. Thus, if a three-dimensional image is reproduced, a reproduced
image 186 appears as if it were located closer to the viewer than
with the reproducing method shown in FIG. 25. Thus, by reproducing
the three-dimensional image shown in FIG. 26, the stereoscopic
feeling can be emphasized for improving the display effect.
[0336] Meanwhile, the shape of the illuminating light inlet blocks
171, 181 need not be parallelepipedic and may be optionally
selected on the condition that the angle of incidence of the
illuminating reproducing light beams 173, 183 with respect to the
holographic stereograms 172, 182 is coincident with that of the
reference light beam incident on the recording medium for hologram
130 during recording.
[0337] In the present embodiment, the wavelength of the laser light
used for fabricating the holographic stereogram is approximately
523 nm, while the angle e the reference light makes with the object
light is approximately 75.degree.. The film thickness of a
photosensitive portion of the recording medium for hologram 130 is
approximately 20 .mu.m, with its refractive index being
approximately 1.5. Therefore, the allowance of selection of the
wavelength of the holographic stereogram is approximately 50 nm.
Thus, for reproducing the holographic stereogram, an LED emitting a
light beam having a center wavelength of approximately 525 nm and
the wavelength width of approximately 50 nm is desirable as the
light source of the reproducing illuminating light beams 173, 183.
Thus it becomes possible to obtain the driving power of the image
reproducing device from, for example, a battery, thereby enabling
the size and the cost of the device to be lowered.
[0338] For reproducing a holographic stereogram as the reflection
type, a reproduced image can be usually obtained, even if the white
light is used as the reproducing illumination, due to higher
wavelength selectivity. Conversely, for regenerating a holographic
stereogram as the transmission type, it becomes difficult to
reproduce the holographic stereogram with the white light because
the wavelength selectivity becomes weaker than if the holographic
stereogram is reproduced as the reflection type. Therefore, if a
holographic stereogram is reproduced as the transmission type, a
light source with a higher color purity is preferably used as a
reproducing light source. Specifically, if a LED emitting the light
of high color purity is used as a reproducing light source, it
becomes possible to compensate for weak wavelength selectivity in
order to obtain a clear reproduced image. The LED also has merits
that it is closer in nature to a point light source, and hence is
effective to prevent the reproduced image from becoming blurred due
to spreading of the light source, and that it scarcely generates
heat.
[0339] However, the light source for the reproducing illuminating
light is not limited to LEDs. If a light source capable of emitting
the light of high color purity such as a semiconductor laser is
used, a reproduced image can be produced in similar manner. The
light raised in color purity by a wavelength selective filter or a
narrow band reflection mirror may also be used as the reproducing
illuminating light.
[0340] 2-4 Modification
[0341] Although the second embodiment of the image recording method
and apparatus according to the present invention has been described
above, the present invention is not limited to these particular
embodiments. For example, although sponge 161 is used as liquid
supplying means, liquid supplying means may be of any suitable
structure may be used if it can supply liquid to a space between
the recording medium for hologram 130 and the light inlet block
137B. The liquid supplying means may be designed as a die coater or
a coater employing a roll for applying a liquid to the recording
medium for hologram 130.
[0342] In the above-described embodiments, the present invention is
applied to fabrication of a holographic stereogram having the
parallax information only in the transverse direction. The present
invention is, however, not limited to these embodiments, but may
also be applied to fabrication of a holographic stereogram having
the parallax information only in the longitudinal direction or to a
holographic stereogram having the parallax information in both the
transverse direction and the longitudinal direction.
[0343] In addition, although the above embodiments are directed to
fabrication of a monochromatic holographic stereogram, the present
invention may similarly be applied to fabrication of a colored
holographic stereogram. For producing the colored holographic
stereogram, three light beams corresponding to the three prime
colors of light may be used as the recording light. For reproducing
a colored holographic stereogram recorded with use of three light
beams corresponding to the three prime colors of light, three light
sources are provided in an image reproducing device for emitting
three prime colors of light so that light beams from the light
sources will be illuminated simultaneously on the holographic
stereogram as reproducing illuminating light beams. For reproducing
the white holographic stereogram, light sources with high color
purity are preferably used as the light sources because
reproduction with the transmission type suffers from weak
wavelength selectivity. This renders it possible to reproduce the
colored holographic stereogram clearly even as the transmission
type.
[0344] The structure of the light inlet block also is not limited
to that shown in the previous embodiments. For example, the object
light beam converged and incident on a recording medium for
hologram is likely to be transmitted through the recording medium
for hologram to be incident on a light inlet block, with the
incident light being partially reflected on an opposite lateral
surface of the light inlet block to return to the light inlet
block. If this occurs, unneeded interference fringes tend to be
formed in the light exposed portion to lower the contrast of the
reproduced image. Also, if an unexposed portion of the recording
medium for hologram is illuminated by light, the unexposed portion
is likely to be sensitized before light exposure to render it
impossible to effect regular recording. Thus it is possible to form
the light inlet block as a cylinder in the hollow inner portion of
which is arranged a light absorbing member. The light absorbing
member is arranged at a position of not obstructing inlet of the
reference light. This eliminates unneeded reflection in the
interior of the light inlet block.
[0345] It is desirable that air, for example, be not present in a
space between the light inlet block and the light absorbing member.
Also, the refractive index is desirably close to that of the light
absorbing member. Specifically, a black adhesive tape having an
adhesive the refractive index of which is close to that of the
light absorbing member may be used. Alternatively, clay or a black
liquid may be enclosed in a hollow portion of the light inlet
block.
[0346] The same holds if a square prismatic light inlet block is
used in place of the cylindrical block. That is, a black adhesive
tape, for example, may be arranged at a position around the light
inlet block not obstructing introduction of the reference light
beam for preventing unneeded reflection in the light inlet block
for improving the image quality.
[0347] In an image recording device, a louver film 193 may be
arranged between a light inlet block 191 and a recording medium for
hologram 192, as shown in FIGS. 27 or 28. FIG. 27 shows an instance
of a prismatic light inlet block 191, while FIG. 28 shows an
instance of a cylindrical or columnar light inlet block 191.
[0348] The louver film 193 is made up of a large number of louvers,
at a pre-set interval from each other, as physical blinds, having
an angle of the order of the reference light incident angle
relative to its surface, and has characteristics of not passing the
light entering the surface at a right angle.
[0349] If such louver film 193 is arranged optically between the
light inlet block 191 and the recording medium for hologram 192,
without interposition of air or the like, the light radiated
through the light inlet block 191 at an acute angle to the
recording medium for hologram 192 is transmitted through the louver
film 193 to reach the recording medium for hologram 192, while the
object light incident at a right angle on the surface of the louver
film 193 is absorbed by the louver film 193 after passing through
the recording medium for hologram 192 and hence cannot reach the
light inlet block 191. This eliminates unneeded reflection to
improve the image quality.
[0350] In addition, the direction of incidence of the reference
light or the number, type or combination of lenses in the
holographic stereogram printer device is not limited to those of
the previous embodiments and may comprise various
modifications.
[0351] 3. Image Reproducing Method and Device
[0352] Illustrative embodiments of the image reproducing method and
apparatus according to the present invention will be hereinafter
explained.
[0353] 3-1 Holographic Stereogram Producing System
[0354] First, an illustrative structure of a system for producing a
holographic stereogram in which an image is reproduced using an
image reproducing method and an image reproducing device according
to the present invention is explained. The present embodiment is
directed to a holographic stereogram in which plural strip-shaped
hologram elements are recorded on a recording medium for generating
the parallax information in the transverse direction. However, the
present invention is applicable to a holographic stereogram in
which plural dot-shaped hologram elements are recorded on a sole
recording medium for generating the parallax information in both
the transverse and longitudinal directions.
[0355] The present holographic stereogram producing system is a
system in which a recording medium for hologram, having recorded
thereon interference fringes by the object light and the reference
light to prove to be a holographic stereogram, or a so-called
one-step holographic stereogram, is fabricated by an edge-lit
system. The system includes a data processor 201 for processing
image data to be recorded, a control computer 202 for controlling
the entire system and a holographic stereogram printer device 203,
as shown in FIG. 29.
[0356] The data processor 201 generates a parallax image string D23
based on plural image data D21 including the parallax information
furnished by a parallax image string imaging device 213 having a
multi-eye camera and a moving camera and plural image data D22
including the parallax information generated by an image data
generating computer 214.
[0357] The plural image data D21, inclusive of the parallax
information furnished by a parallax image string imaging device
213, are image data of plural images obtained on imaging an object
from plural viewing points in the transverse direction by
simultaneously imaging by a multi-eye camera or by continuous
imaging by a moving camera.
[0358] The plural image data D22, inclusive of the parallax
information generated by the image data generating computer 214,
are image data, such as plural CAD (computer aided design) images
or CG (computer graphics) images, produced on sequentially
according the parallax in the transverse direction.
[0359] The data processor 201 performs pre-set image processing for
holographic stereogram by an image processing computer on the
parallax image string D23 and records the processed image data D24
on a storage device 212, such as a memory or a hard disc.
[0360] When recording an image on the recording medium for
hologram, the data processor 201 sequentially reads out data on the
image basis for sending the image data D25 to the control computer
202.
[0361] The control computer 202 drives the holographic stereogram
printer device 203 for sequentially recording images corresponding
to the image data D25 furnished from the data processor 201 on a
recording medium for hologram 230 set in the holographic stereogram
printer device 203 as strip-like hologram elements.
[0362] At this time, the control computer 202 controls a shutter
232, a display device 241 and a recording medium feed mechanism
provided on the holographic stereogram printer device 203. That is,
the control computer 202 sends out a control signal S21 to the
shutter 232 for controlling the opening/closure of the shutter 232,
while furnishing the image data D25 to the display device 241 for
causing the display device 241 to display an image corresponding to
the image data D25 and for sending out a control signal S22 to the
recording medium feed mechanism for controlling the feed operation
of the recording medium for hologram 230 by the recording medium
feed mechanism.
[0363] By referring to FIGS. 30A and 30B, the holographic
stereogram printer device 203 will be explained in detail. FIG. 30A
and FIG. 30B view the entire optical system of the holographic
stereogram printer device 203 from above, and the portion of the
optical system of the holographic stereogram printer device 203
associated with the object light, from a lateral side,
respectively.
[0364] The holographic stereogram printer device 203 includes a
laser light source 231 for radiating a laser light beam of a
pre-set wavelength, and a shutter 232 and a half-mirror 233
arranged on the optical axis of the laser light beam L21 from the
laser light source 231, as shown in FIG. 30A. In the instant
embodiment, a laser light source emitting a laser light beam with a
wavelength of approximately 532 nm is used as laser light source
231.
[0365] The shutter 232 is controlled by the control computer 202
and is closed or opened when the recording medium for hologram 230
is not exposed to light or is exposed to light, respectively. The
half-mirror 233 has the function of separating the laser light beam
L22 transmitted through the shutter 232 into a reference light beam
and an object light beam, with the light beam L23 reflected by the
half-mirror 233 and the laser light beam L24 transmitted through
the half-mirror 233 proving to be the reference and object light
beams, respectively.
[0366] On the optical axis of the light beam L23 reflected by the
half-mirror 233 are arranged, as an optical system for the
reference light, a cylindrical lens 234, a collimator lens 235 for
collimating the reference light beam and a total reflection mirror
236 for reflecting the collimated light beam from the collimator
lens 235.
[0367] The light reflected by the half-mirror 233 is first diffused
by the cylindrical lens 234 and collimated by the collimator lens
235. The collimated light is then reflected by the total reflection
mirror 236 so as to fall on the recording medium for hologram 230.
The recording medium for hologram 230 is arranged in contact with a
light inlet block 237 of transparent glass, via a matching liquid,
for recording hologram elements by the edge-lit system. The
reference light falls on the recording medium for hologram 230 from
the side of the light inlet block 237.
[0368] That is, the reference light enters the inside of the light
inlet block 237 from the end 237a of the light inlet block 237 so
as to fall with a large angle of incidence on the recording medium
for hologram 230 arranged for contacting the light inlet block 237
via matching liquid. In the present embodiment, the wavelength of
the laser light used for fabricating the holographic stereogram is
approximately 523 nm, while the angle .theta. the reference light
makes with the object light is approximately 75.degree..
[0369] On the optical axis of the light beam L24 transmitted
through the half-mirror 233 are arranged, as an optical system for
the object light, a total reflection mirror 238 for reflecting the
transmitted light from the half mirror 233, a spatial filter 239
combined from a convex lens and a pinhole, a collimator lens 240
for collimating the object light, a display device 241 for
displaying an image of an object, a diffusion plate 242 for
diffusing the light transmitted through the display device 241 and
a cylindrical lens 243 for converging the object light on the
recording medium for hologram 230, in this order, as shown in FIGS.
30A and 30B. In addition, a mask 244 having a strip-shaped opening
is arranged directly ahead of the recording medium for hologram
230.
[0370] The light beam L24 transmitted through the half-mirror 233
is reflected by the total reflection mirror 238 and turned into a
diffused light from a point light source by the spatial filter 239.
The diffused light is then turned by the collimator lens 240 into
collimated light which then falls on the display device 241. The
display device 241 is a transmission type image display device
formed by, for example, a liquid crystal display, and is configured
for displaying an image corresponding to image data D25 sent from
the control computer 220 under control by the control computer 202.
The light transmitted through the display device 241 is modulated
in accordance with the image displayed on the display device 241.
The modulated light is diffused by the diffusion plate 242 to fall
on the cylindrical lens 243. The diffusion plate 242 slightly
diffuses the transmitted light from the display device 241 for
contributing to improving the image quality of the produced
holographic stereogram.
[0371] The light transmitted through the display device 241 is
converged by the cylindrical lens 243 in the transverse direction.
Of the converged light, the light transmitted through the
strip-shaped opening of the mask 242 falls as object light on the
recording medium for hologram 230. The object light falls on the
recording medium for hologram 230 from the side thereof devoid of
the light inlet block 237 so that its optical axis will be
perpendicular to the surface of the recording medium for hologram
230.
[0372] In the above optical system, the light path length of the
reference light reflected by the half-mirror 233 so as to fall via
light inlet block 237 on the recording medium for hologram 230 is
selected to be substantially equal to that of the object light
transmitted through the half-mirror 233 to fall via display device
241 on the recording medium for hologram 230. This enhances
interference characteristics between the reference light and the
object light to enable the production of a holographic stereogram
which gives a clearer reproduced image.
[0373] In the above-described holographic stereogram printer device
203, it is desirable to provide a mechanism for dripping an index
matching liquid to a space between the light inlet block 237 and
the recording medium for hologram 230 for index matching for the
recording medium for hologram 230. Thus, in the present embodiment,
a sponge impregnated with the index matching liquid is arranged in
the vicinity of the contact portion between the light inlet block
237 and the recording medium for hologram 230. Thus, each time the
recording medium for hologram 230 is fed, the index matching liquid
is supplied from the sponge to the space between the light inlet
block 237 and the recording medium for hologram 230 for index
matching between the light inlet block 237 and the recording medium
for hologram 230.
[0374] For fabricating the transmission type holographic
stereogram, both the object light and the reference light are
caused to fall on one surface of the recording medium for hologram
230. Thus, for fabricating the transmission type holographic
stereogram by the edge-lit system, it is necessary for the
reference light to fall via light inlet block on the recording
medium for hologram 230 from the object light incident side. Thus
the light inlet block is arranged in a space between the object
light converging cylindrical lens and the recording medium for
hologram. However, because of spatial limitations, it is extremely
difficult to arrange the light inlet block between the cylindrical
lens and the recording medium for hologram.
[0375] Conversely, with the holographic stereogram printer device
203 in which the holographic stereogram of the edge-lit system is
fabricated as the reflection type, it suffices if the object light
and the reference light are caused to fall on one and the opposite
surface of the recording medium for hologram 230, respectively.
Therefore, with the present embodiment, it suffices if the
cylindrical lens 243 for converging the object light is arranged on
one of the surfaces of the recording medium for hologram 230 and
the light inlet block 237 is arranged on the opposite surface
thereof to enable the optical system to be constructed easily
without spatial constraints The holographic stereogram printer
device 203 has a recording medium feed mechanism 250 for
intermittently feeding the recording medium for hologram 230 by one
hologram element responsive to a control signal from the control
computer 202. This recording medium feed mechanism 250 is designed
to feed the recording medium for hologram 230 intermittently under
control by the control computer 202, as will be explained
subsequently. For fabricating the holographic stereogram by the
holographic stereogram printer device 203, images corresponding to
image data of the parallax image string sequentially recorded, as
strip-shaped hologram elements, on the recording medium for
hologram 230 set under a pre-determined condition on the recording
medium feed mechanism 250.
[0376] Referring to FIGS. 31 and 32A to 32C, the recording medium
for hologram 230 used in the above-described holographic stereogram
fabricating system is explained in detail.
[0377] The recording medium for hologram 230 is a so-called film
coating type recording medium in which a photopolymer layer 230b
formed of a photopolymerizable photopolymer is formed on a
tape-shaped film base material 230a and a cover sheet 230c is
deposited on the photopolymer layer 230b, as shown in FIG. 31. In
the present embodiment, a photopolymer layer of `OMNI-DEX`,
manufactured by DU PONT Inc. is formed as a photopolymer layer 19b
as a photosensitive portion to a thickness of approximately 20
.mu.m.
[0378] In the initial state of the photopolymerizable photopolymer,
a monomer M is uniformly dispersed in a matrix polymer, as shown in
FIG. 32A. If a light beam LA of the power of, for example, 10 to
400 mJ/cm.sup.2 is illuminated, the monomer M is polymerized in a
light-exposed portion. With progress in polymerization, the monomer
M is migrated from ambient portions to cause local variation in the
concentration in the monomer M to produce refractive index
modulation. The polymerization of the monomer M then comes to a
close by illuminating the UV light or the visible light LB with the
power on the order of 1000 mJ/cm.sup.2 as shown in FIG. 32C. Since
the photopolymerizable photopolymer has its refractive index
changed with the incident light beam, the interference fringes,
brought about by interference between the reference light beam and
the object light beam, can be recorded as changes in the refractive
index.
[0379] The recording medium for hologram 230, employing the
photopolymerizable photopolymer, need not be processed with
particular development operations after light exposure. Thus the
holographic stereogram printer device 203 employing the recording
medium for hologram 230 having its photosensitive portion formed of
a photopolymerizable photopolymer can be simplified in
structure.
[0380] The recording medium feed mechanism 250 will be explained in
detail by referring to FIG. 33. For.33 is an enlarged view showing
a portion of the recording medium feed mechanism 250 of the
holographic stereogram printer device 203.
[0381] Referring to FIG. 33, the recording medium feed mechanism
250 has a roll 251 and an intermittent feed roll 252. The recording
medium for hologram 230 is housed within the film cartridge 253 in
the state of being coiled around the roll 251. The recording medium
feed mechanism 250 rotatably fulcrums the roll 251 in the film
cartridge 253 loaded in position with a re-set torque and holds the
recording medium for hologram 230 pulled out of the film cartridge
253 by the roll 251 and the intermittent feed roll 252. The
recording medium feed mechanism 250 holds the recording medium for
hologram 230 so that the surface of the recording medium for
hologram 230 will be substantially at right angles to the object
light between the roll 251 and the intermittent feed roll 252. The
roll 251 and the intermittent feed roll 252 are biased by a torsion
spring in a direction away from each other for applying a pre-set
tension on the recording medium for hologram 230 loaded for
extending between the roll 251 and the intermittent feed roll
252.
[0382] The intermittent feed roll 252 of the recording medium feed
mechanism 250 is connected to a stepping motor, not shown, and is
adapted for being rotated in a direction indicated by arrow f in
FIG. 33 under the force of rotation of the stepping motor. Based on
the control signal S22 supplied form the control computer 202, the
stepping motor sequentially rotates the intermittent feed roll 252
a pre-set angle corresponding to a hologram element each time the
light exposure for one image is terminated. This causes the
recording medium for hologram 230 to be fed one hologram element
each time an image is exposed.
[0383] Downstream of the intermittent feed roll 252 in the travel
path of the recording medium for hologram 230 is arranged a UV lamp
254 along the travel path. This UV lamp 254 has the function of
competing the polymerization of the monomer M of the recording
medium for hologram 230 exposed to light and is adapted for
radiating UV light of a pre-set power on the recording medium for
hologram 230 fed by the intermittent feed roll 252.
[0384] Downstream of the TJV lamp 254 in the travel path of the
recording medium for hologram 230 are sequentially arranged a
rotatably fulcrumed heat roll 255, a pair of feed-out rolls 256,
257 and a cutter 258.
[0385] The feed-out rolls 256, 257 are adapted for feeding the
recording medium for hologram 230 so that the cover sheet side of
the recording medium for hologram 230 will be placed over
180.degree. in tight contact with the periphery of the heat roll
255. Based on the control signal S22 supplied form the control
computer 202, this stepping motor sequentially rotates the feed-out
rolls 256, 257 in synchronism with the rotation of the intermittent
feed roll 252 by a pre-set angle corresponding to one hologram
element each time the light exposure for one image is terminated.
This enables the recording medium for hologram 230 to be kept
tightly contacted with the peripheral surface of the heat roll 255
without becoming slacked between the intermittent feed roll 252 and
the feed-out rolls 256, 257.
[0386] The heat roll 255 has internal heating means, such as
heaters, whereby the peripheral surface of the heat roll 255 is
maintained at a temperature of the order of 120.degree. C. This
heat roll 255 heats the photopolymer layer 230b of the recording
medium for hologram 230 fed thereto via cover sheet 230c for
increasing the refractive index modulation factor of the
photopolymer layer 230b for fixing the recording image on the
recording medium for hologram 230. The outer diameter of the heat
roll 255 is selected so that the time since the recording medium
for hologram 230 starts to be contacted with the outer peripheral
surface of the heat roll 255 until it is detached therefrom is
substantially equal to the time required for fixing the recorded
image.
[0387] The cutter 258 includes a cutter driving mechanism, not
shown, and drives this cuter driving mechanism for severing the
recording medium for hologram 230 fed thereto. Based on the control
signal S22, supplied from the control computer 202, the cutter
driving mechanism drives the cutter 258 when all image-bearing
portions of the recording medium for hologram 230 are discharged
outwardly from the cutter 258 after the images corresponding to the
image data of the parallax image string have been recorded on the
recording medium for hologram 230. This severs the image data
bearing portions from the remaining portions so as to be discharged
to outside as a sole holographic stereogram.
[0388] The operation for fabricating a holographic stereogram by
the above-described holographic stereogram producing system
hereinafter explained.
[0389] For fabricating a holographic stereogram, the control
computer 202 drives the display device 241 based on image data D25
supplied thereto from the data processor 201 for displaying an
image on the display device 241. The control computer 202 then
sends out the control signal S21 to the shutter 232 for opening the
shutter 232 for a pre-set time for exposing the recording medium
for hologram 230 to light. Of the laser light beam L22 radiated at
this time from the laser light source 231 so as to be transmitted
through the shutter 232, the light beam 123 reflected by the mirror
233 falls at this time as a reference light beam on the recording
medium for hologram 230 via light inlet block 237. The light beam
L24 transmitted through the half-mirror 233 proves to be a
projecting light having an image displayed on the display device
241 projected therein. This projecting light is incident as an
object light beam on the recording medium for hologram 230. This
records an image displayed on the display device 241 as a
strip-shaped hologram element on the recording medium for hologram
230.
[0390] When an image has been recorded on the recording medium for
hologram 230, the control computer 202 sends out the control signal
S22 to the stepping motor connected to the intermittent feed roll
252 and to the stepping motor connected to the feed-out rolls 256,
257 for driving these rolls for feeding the recording medium for
hologram 230 by one hologram element.
[0391] Based on the next image data D25 supplied from the data
processor 201, the control computer 202 drives the display device
241 for displaying the next image thereon. The above sequence of
operations is then repeated for sequentially recording the images
corresponding to the image data D25 from the data processor 201 as
strip-shaped hologram elements on the recording medium for hologram
230. Since the recording medium for hologram 230 is fed by one
hologram element from one image to another, the hologram elements
are arrayed in succession in the transverse direction. Thus, plural
images inclusive of the parallax information in the transverse
direction are recorded on the recording medium for hologram 230 for
producing a holographic stereogram having the parallax in the
transverse direction.
[0392] The recording medium for hologram 230, having the hologram
elements recorded thereon as described above, is illuminated by UV
light from the UV lamp 254. This completes polymerization of the
monomer M. The recording medium for hologram 230 then is heated by
the heat roll 255 for fixing the recorded image.
[0393] When the entire image-bearing portion of the recording
medium for hologram 230 has been sent out, the control computer 202
sends the control signal S22 to the cutter driving mechanism for
driving it so that the image bearing portion of the recording
medium for hologram 230 is severed by the cutter 258 so as to be
discharged to outside as a sole holographic stereogram.
[0394] The above-described process competes the reflection type
holographic stereogram of the edge-lit system having the parallax
in the transverse direction.
[0395] 3-2 Reproduction of Holographic Stereogram
[0396] The reproduction of the holographic stereogram, fabricated
as described above, is hereinafter explained.
[0397] For reproducing a three-dimensional image from the
holographic stereogram as the reflection type, fabricated as
described above, a holographic stereogram 262 is bonded to a light
inlet block 261 via an index matching liquid 260, as shown in FIG.
34, and a reproducing illuminating light beam 263 is caused to fall
from the end 261a of the light inlet block 261 to the holographic
stereogram 262. The holographic stereogram 262 is bonded to a
surface 261b of the light inlet block 261 remote from the viewer
264. At this time, a reproduced image 266 generated by a light beam
265 diffracted with the reflection mode from the holographic
stereogram 262 is viewed by the viewer 264. However, when a
three-dimensional image is reproduced with the reflection mode in
this manner, a reproduced image 266 is reproduced as if the object
were behind the illuminating light inlet block 261 as viewed by the
viewer 264.
[0398] With the present invention, the three-dimensional image from
the reflection type holographic stereogram of the edge-lit system,
fabricated as described above, is reproduced as the transmission
type. That is, with the reproducing method according to the present
invention, after a holographic stereogram 272 is bonded via index
matching liquid 270 on the light inlet block 271, a reproducing
illuminating light beam 273 is caused to fall at an end 271a of the
light inlet block 271 towards the holographic stereogram 272. The
holographic stereogram 272 is bonded to the surface 271a of the
light inlet block 271 closer to a viewer 274.
[0399] At this time, a reproduced image 276, generated by the
diffracted light beam 275 diffracted with the transmission mode
from the holographic stereogram 272, is viewed by the viewer 274.
If a three-dimensional image is reproduced in this manner, the
reproduced image 276 appears as though the object were closer to
the viewer than with the reproducing method explained with
reference to FIG. 34. Thus, by reproducing the three-dimensional
image as shown in FIG. 35, the stereoscopic feeling can be
emphasized for improving the display effect.
[0400] Referring to FIG. 36, an illustrative structure of an image
reproducing device by the transmission type is hereinafter
explained.
[0401] The image reproducing device is of the edge-lit system and
includes a light inlet block 281 on which is bonded a holographic
stereogram 280 and a light source 283 for illuminating a
reproducing illuminating light beam from an end face 281a of the
light inlet block 281. The holographic stereogram 280 of an object
is a holographic stereogram of the edge lit system on which the
three-dimensional image information is recorded by causing the
object light and the reference light to fall on one and the other
of the surfaces of the recording medium for hologram,
respectively.
[0402] The light inlet block 281 is used for introducing the
reproducing illuminating light beam 282 into the holographic
stereogram 280 and is a parallelepipedic block of transparent glass
similar to that used for recording. The holographic stereogram 280
to be reproduced is bonded to the light inlet block 281 via an
index matching liquid. It is noted that the holographic stereogram
280 is bonded to a surface 281b of the light inlet block 281 closer
to a viewer 284.
[0403] Meanwhile, the shape of the illuminating light inlet block
281 need not be parallelepipedic and may be optionally selected on
the condition that the angle of incidence of the illuminating
reproducing light beam 282 will be incident at a pre-set angle on
the holographic stereogram 280. That is, the light inlet block 281
may be of any suitable shape if, during recording, the angle of
incidence of the reference light on the recording medium for
hologram during recording is set so as to coincide with that of the
reproducing illuminating light 282 for the holographic stereogram
280.
[0404] On the other hand, the light source 283 is an LED arranged
for illuminating the reproducing illuminating light beam 282 on the
holographic stereogram 280. Since the LED used as the light source
283 has extremely high light emitting efficiency, a battery, for
example, may be used for a practically sufficient time interval.
Thus the driving power source of the image reproducing device may
be furnished from the battery or the like for reducing the size and
cost of the device.
[0405] In the above-described image reproducing device, the light
source 283 of the reproducing illuminating light beam 282 may be
integrated with the light inlet block 281 for simplifying and
reducing the size of the optical system. Morever, by integrating
the light source 283 of the illuminating light beam 282 with the
light inlet block 281, the angle of incidence of the reproducing
illuminating light beam 282 to the holographic stereogram 280 may
be perpetually set to an optimum value for producing a high-quality
reproduced image 285.
[0406] In the present embodiment, the wavelength of the laser light
used for fabricating the holographic stereogram is approximately
523 nm, while the angle .theta. the reference light makes with the
object light is approximately 75.degree.. The film thickness of a
photosensitive portion of the recording medium for hologram 230 is
approximately 20 .mu.m, with its refractive index being
approximately 1.5. Therefore, the allowance of selection of the
wavelength of the holographic stereogram is approximately 50 nm.
Thus, in the above image reproducing device, a LED emitting the
light with the wavelength of approximately 525 nm and the
wavelength width of approximately 50 nm is optimum.
[0407] For reproducing a three-dimensional image from the
holographic stereogram 280 by the above image reproducing device,
the holographic stereogram 280 is bonded to the light inlet block
281 via index matching liquid. At this time, the holographic
stereogram 280 is arranged on the side of a viewer 284. The
illuminating light beam 282 is illuminated from the light source
283 via light inlet bock 281 to the holographic stereogram 280. A
reproduced image 285 is generated by a light beam 286 diffracted
when the illuminating light beam 282 is transmitted through the
holographic stereogram 280. This reproduced image 285 is formed as
if the object were at a position closer to the viewer to give an
extremely stereoscopic image.
[0408] For reproducing a holographic stereogram by the reflection
type, a reproduced image can be usually obtained even if the white
light is used as the reproducing illumination due to higher
wavelength selectivity. Conversely, for regenerating a holographic
stereogram by the transmission type, it becomes difficult to
reproduce the holographic stereogram with the white light because
the wavelength selectivity becomes weaker than if the holographic
stereogram is reproduced as the reflection type. Therefore, if a
holographic stereogram is reproduced as the transmission type, a
light source with a higher color purity is preferably used as a
reproducing light source. Specifically, if a LED emitting the light
of high color purity is used as a reproducing light source, it
becomes possible to compensate for weak wavelength selectivity in
order to obtain a clear reproduced image. The LED also has merits
that it is closer in nature to a point light source and hence is
effective to prevent blurring of the reproduced image 285 due to
spreading of the light source, while scarcely generating heat,
However, the light source 283 for the reproducing illuminating
light 282 is not limited to LEDs. If a light source capable of
emitting the light of high color purity such as a semiconductor
laser is used, a reproduced image 285 can be produced in similar
manner. The light raised in color purity by a wavelength selective
filter or a narrow band reflection mirror may also be used as the
reproducing illuminating light 282.
[0409] In addition, although the above embodiments are directed to
fabrication of a monochromatic holographic stereogram, the present
invention may similarly be applied to fabrication of a colored
holographic stereogram. For producing the colored holographic
stereogram, three light beams corresponding to the three prime
colors of light may be used as the recording light. For reproducing
a colored holographic stereogram recorded using three light beams
corresponding to the three prime colors of light, three light
sources are provided in an image reproducing device for emitting
three prime colors of light so that light beams from the light
sources will be illuminated simultaneously on the holographic
stereogram as reproducing illuminating light beams. For reproducing
the white holographic stereogram, light sources with high color
purity are preferably used as the light sources because
reproduction as the transmission type suffers from weak wavelength
selectivity. This renders it possible to reproduce the colored
holographic stereogram clearly even as the transmission type.
[0410] It is seen from above that, with the first image recording
method and device according to the present invention, vibrations
can be suppressed sufficiently during recording on the recording
medium for hologram. This enables accurate recording for improving
the diffraction efficiency during reproduction. That is, with the
first image recording method and device according to the present
invention, a holographic stereogram producing a bright clear
reproduced image may be produced. Moreover, the queuing time until
attenuation of the vibrations after transfer of the recording
medium for hologram may be significantly reduced thus enabling
reduction in the process time in fabricating a holographic
stereogram by transferring the recording medium for hologram each
time a hologram element is recorded. Moreover, the queuing time
which elapses after transfer of the recording medium for hologram
until attenuation of the oscillations can be significantly reduced
thus significantly reducing the queuing time in fabrication of the
holographic stereogram by transferring the recording medium for
hologram each time a hologram element is recorded. Also, by using,
as a liquid interposed between the recording medium for hologram
and the optical component, an index matching liquid having an
optimized refractive index, recording by the edge-lit system can be
carried out in a state in which total reflection of the reference
light in the light inlet block is prohibited and the intensity
reflectance is suppressed, thus assuring fabrication of the
edge-lit holographic stereogram having improved image quality.
[0411] With the second image recording method and device according
to the present invention, an edge-lit holographic stereogram that
can be reproduced as the transmission type can be fabricated
easily. Moreover, oscillations during recording on the recording
medium for hologram can be suppressed sufficiently. This enables
correct recording and improves the diffraction efficiency during
reproduction. That is, in the second image recording method and
device according to the present invention, an edge-lit holographic
stereogram which gives a clear and bright reproduced image can be
produced. In addition, the queuing time which elapses since the end
of transfer of the recording medium for hologram until attenuation
of oscillations again can be reduced significantly, thus
significantly shortening the processing time in fabricating the
holographic stereogram by transferring the recording medium for
hologram each time a hologram element is recorded.
[0412] With the image recording method and apparatus according to
the present invention, since the edge-lit holographic stereogram
recorded as the reflection type having high degree of freedom of
the optical system is reproduced as the transmission type, the
reproduced image appears as if it were situated close to the
viewer. Thus, with the image recording method and device according
to the present invention, an extremely stereoscopic image with
excellent display effect can be reproduced. That is, in the image
recording method and device according to the present invention, a
three-dimensional image which appears as if it were situated close
to the viewer can be reproduced from en edge-lit holographic
stereogram recorded using an optical system having a high degree of
freedom and that may be fabricates easily.
[0413] Thus, the present invention provides an image recording
method and device for recording an image on a holographic
stereogram in such a manner as to generate an optimum reproduced
image, and an image reproducing method and device for generating an
optimum reproduced image from the holographic stereogram.
* * * * *