U.S. patent application number 09/973247 was filed with the patent office on 2002-06-27 for method and apparatus for direct image pick-up of granular speck pattern generated by reflecting light of laser beam.
Invention is credited to Konno, Hiroyuki.
Application Number | 20020080264 09/973247 |
Document ID | / |
Family ID | 18670091 |
Filed Date | 2002-06-27 |
United States Patent
Application |
20020080264 |
Kind Code |
A1 |
Konno, Hiroyuki |
June 27, 2002 |
Method and apparatus for direct image pick-up of granular speck
pattern generated by reflecting light of laser beam
Abstract
A method and apparatus allowing said direct image pick-up using
a commercially available digital or a video camera by depriving the
camera of its image forming lens. According to a second aspect, the
method and apparatus allows said direct image pick-up in a well
lighted environment like an ordinary office by providing in front
of the CCD element of the camera a shielding tube adapted to shield
extraneous light rays.
Inventors: |
Konno, Hiroyuki;
(Odawara-shi, JP) |
Correspondence
Address: |
HIROYUKI KONNO
695 Kenmoor, S.E.
Post Office Box 2567
Grand Rapids
MI
49501
US
|
Family ID: |
18670091 |
Appl. No.: |
09/973247 |
Filed: |
October 9, 2001 |
Current U.S.
Class: |
348/370 |
Current CPC
Class: |
G01D 5/347 20130101;
G01D 5/3473 20130101; H04N 5/2256 20130101; G01B 11/00 20130101;
G01D 5/34715 20130101; H04N 5/335 20130101 |
Class at
Publication: |
348/370 |
International
Class: |
H04N 005/222 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 26, 2000 |
JP |
2000-166833 |
Claims
What is claimed is:
1. A method for direct image pick-up of a particular granular speck
pattern generated by reflecting light of a laser beam depending on
a degree of roughness of the surface of an object to be inspected,
said method comprising the steps of: irradiating said object to be
inspected with the laser beam; directly picking up said granular
speck pattern in a relatively well lighted environment using a
lensless video camera having a CCD (Charge Coupled Device) element
incorporated in said video camera; and providing a shielding tube
coupled to said camera to shield extraneous light rays.
2. Apparatus for direct image pick-up of a particular granular
speck pattern generated by reflecting light of a laser beam
depending on a degree of roughness of the laser beam irradiated
surface of an object to be inspected, said apparatus comprising: a
lensless video camera having a CCD element incorporated in said
video camera; and a shielding tube coupled to said camera for
shielding extraneous light rays.
3. A method for direct image pick-up of a particular granular speck
pattern generated by the transmitted light of a laser beam
diffusively reflecting depending on a degree of roughness of the
laser beam irradiated onto the surface of an object to be inspected
or shapes of fine ingredients constituting said object to be
inspected, said method comprising the steps of: irradiating said
object to be inspected with the laser beam; directly picking up
said granular speck pattern in a relatively well lighted
environment using a lensless video camera having a CCD element
incorporated in said video camera; and a shielding tube coupled to
said camera to shield extraneous light rays.
4. Apparatus for direct image pick-up of a particular granular
speck pattern generated by transmitted light of laser beam
diffusively reflecting depending on a degree of roughness of the
laser beam irradiated surface of an object to be inspected or on
shapes of fine ingredients constituting said object to be
inspected, said apparatus comprising: a commercially available
video camera having a CCD image detector and deprived of its image
forming lens; and a shielding tube coupled to said camera to shield
extraneous light rays from striking the CCD of said camera.
5. Apparatus for direct image pick-up of a particular granular
speck pattern comprising: a laser for directing a laser beam onto
the surface of an object to be inspected; a digital camera having a
CCD element incorporated in said camera; and a shielding tube
coupled to said camera for shielding extraneous light rays.
6. A method for direct image pick-up of a particular granular speck
pattern generated by the transmitted light of a laser beam
diffusively reflecting depending on a degree of roughness of the
laser beam irradiated onto the surface of an object to be inspected
or shapes of fine ingredients constituting said object to be
inspected, said method comprising the steps of: irradiating said
object to be inspected with a laser beam; directly picking up said
granular speck pattern in a relatively well lighted environment
using a lensless digital camera having a CCD element incorporated
in said camera; and a shielding tube coupled to said camera to
shield extraneous light rays.
7. Apparatus for direct image pick-up of a particular granular
speck pattern generated by transmitted light of laser beam
diffusively reflecting depending on a degree of roughness of the
laser beam irradiated surface of an object to be inspected or on
shapes of fine ingredients constituting said object to be
inspected, said apparatus comprising: a lensless video camera
having a CCD image detector for receiving light directly onto said
CCD; and a shielding tube coupled to said camera to shield
extraneous light rays from striking the CCD of said camera.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method and an apparatus
for direct image pick-up of a granular speck pattern generated by
reflecting and/or transmitted light of a laser with which an
opaque, translucent or transparent object to be inspected is
irradiated.
[0003] The present invention is based on the fact that the
reflected and/or transmitted light in such granular speck pattern
is generated as the object to be inspected is irradiated with a
laser beam. This phenomenon will be discussed with respect to the
case of the reflected light in the granular speck pattern. The
granular speak pattern appears over an entire reflection surface to
be inspected as it is irradiated with a monochromatic laser beam of
high directivity, luminance and linearity. The granular speck
pattern has the maximum within an angle of reflection at an
incidence spot of said laser beam and gradually decreases toward
the peripheral edge. In the case of the transmitted light also,
such granular speck pattern appears over the entire transmission
surface.
[0004] This granular speck pattern depends on the degree of
roughness on the surface of the object to be inspected or shapes of
fine ingredients forming the object to be inspected. The granular
speck pattern as the object to be inspected moves and the same
pattern is reproduced so far as no change occurs in the spot on the
object to be inspected at which said object is irradiated with the
laser beam, the wavelength of the laser beam and the beam diameter.
The granular specks have their sizes reduced or magnified depending
on a particular pattern of the object to be inspected at the
particular laser irradiated spot thereon and the granular specks
have their sizes magnified or reduced as the diameter of the laser
beam is reduced or enlarged as the object to be inspected moves
back or forth.
[0005] The granular speck pattern is generated depending on a
roughness of the surface of the object to be inspected. This
granular speck pattern can be picked up not only when the object is
made of metal, rubber, wood etc., but also when the object is a
mirror surface finished IC wafer or glass having a high
transparency, both of which present the highest smoothness.
[0006] In this manner, the granular speck pattern may be picked up
as an index to observe changes of various conditions, for example,
a quantity of movement, displacement, deformation, coagulation,
melting or progress of rust in a non-contact fashion without demand
for any specified index or mark.
[0007] 2. Description of the Related Art
[0008] Usually a darkroom has been used as the measurement
environment to pick up the granular speck pattern and reflecting
light or transmitted light of the laser beam has been projected on
a screen made of frosted glass. A pattern projected on the screen
has then been indirectly picked up by a digital or video
camera.
[0009] So-called cross correlation method is also well known in
which the object is irradiated with laser beam oriented vertically
to the object and there are provided a pair of unidimensional
sensors at an angle of 4520 about the normal line, respectively,
and a difference between photoelectric outputs of these
unidimensional sensors is used to measure a distortion. However,
direct observation of such distortion in the form of an image is
impossible and any effective measurement is impossible for this
method for the object moving back and forth.
[0010] Said indirect image pick-up method has usually been carried
out in a darkroom According to said cross correlation method, the
variation in light intensity has been directly converted to the
corresponding variation in voltage and therefore it has been
impossible to visually recognize the image picked up. In addition,
this cross correlation method is not effective at all for the
object moving back and forth since the irradiation laser beam
cannot be focussed into a single spot.
SUMMARY OF THE INVENTION
[0011] The present invention aims to eliminate the above described
restrictions as well as many requirements imposed on the prior art
due to the designing technique as well as the measuring
environment. To meet this, the present invention aims to simplify
respective means in the method and apparatus for measurement, on
one hand, and to alleviate restrictions imposed on the object to be
inspected, on the other hand.
[0012] The object set forth above is achieved, according to a first
aspect of the present invention, by method and apparatus for
allowing said direct image pick-up using the commercially available
digital or video camera by depriving the camera of its image
forming lens.
[0013] The object set forth above is achieved, according to a
second aspect of the present invention, by method and apparatus
allowing said direct image pick-up in a well lighted environment
like an ordinary office merely by providing in front of the CCD
element, a shielding tube (e.g., the shielding tube having a
circular cross section) adapted to shield extraneous light rays
such as illuminating right coming from indoor luminaries or
sunlight coming through windows.
[0014] Operation
[0015] The present invention generally comprises five features.
[0016] A first feature is to irradiate an object to be inspected
with laser beam.
[0017] A second feature is to pick-up a granular speck pattern in a
direct manner.
[0018] A third element is to carry out the image pick-up in a well
lighted environment like an ordinary office.
[0019] A fourth feature is to quantitatively correlate movement,
shift, deformation, coagulating rate or melting rate of the object
or progress of rusting on the object with movement of the picked-up
granular speck pattern and thereby to use this quantitative
correlation for a specific machine or apparatus.
[0020] A fifth feature is to quantitatively calculate movement,
shift or deformation of the picked-up granular speck pattern on the
basis of a pixel interval of the CCD element or to compare the
immediately previous image of picked-up granular speck pattern with
the immediately subsequent image of picked-up granular speck
pattern to calculate a coagulating rate, a melting rate or progress
of rusting so that the result of calculation may be displayed
depending on the particular purpose of every machine or
apparatus.
[0021] These features will be summarized in combination with one
another. The object to be inspected is irradiated with the laser
beam to generate the granular speck pattern depending on a degree
of roughness of said object to be inspected or shapes of fine
ingredients constituting said object to be inspected. In this way,
the image of the granular speck pattern, depending on movement,
shift or deformation, is continuously picked up. A center of
gravity of a speck selected as a reference point in the granular
speck pattern is tracked in a time series fashion so that a
quantity of movement is real-time calculated on the basis of the
pixel interval or the memory address real time displayed.
[0022] If a quantity of the object to be inspected is relative
large, immediately before said center of gravity of the selected
granular speck as the reference point departs from the view field
of the CCD element, a center of gravity of another granular speck
still lying within said view field may be selected as a new
reference point. Such renewal of the reference point may be
repeated to achieve a continuous measurement.
[0023] As for the back and forth movement of the object to be
inspected, the granular speck pattern has its entire area
proportionally reduced as the object to be inspected gets nearer to
the CCD element while the granular speck pattern has its entire
area proportionally enlarged. On the basis of this area ratio, a
quantity of the back and forth movement of the object to be
inspected is calculated and displayed.
[0024] A quantity of the back and forth may be also calculated by
selecting two granular specks from the granular speck pattern and
by determining a variation in a distance in straight line between
respective centers of gravity of these two granular specks.
[0025] The coagulating rate, melting rate or progress of rusting
can be determined by comparing the immediately previous image with
immediately subsequent image of the continuously picked-up granular
speck patterns on the basis of a degree of coincidence between
these two images.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a diagram illustrating a method for direct image
pick-up of a granular speck pattern generated by laser beam
reflected on an opaque object to be inspected; and
[0027] FIG. 2 is a diagram similar to FIG. 1 but illustrating a
granular speck pattern generated by laser beam reflected on a
transparent or translucent object to be inspected.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] Before a preferred embodiment of this invention is described
in reference with FIGS. 1 and 2 of the accompanying drawings,
details of an object to be inspected and of respective components'
types as well as functions will be described.
[0029] Respective reference numerals designate elements as
following: 1 object to be inspected; 1a blood; 2 laser projector; 3
laser beam; 4 laser beam irradiated spot; 5 image pick-up device; 6
CCD element; 7 shielding tube adapted to shield extraneous light
around granular speck pattern; 8 view field of CCD element; 9
granular pattern generated by reflected light; 9a pattern generated
by transmitted light; 10 frosted glass on which transmitted light
is projected within darkroom according to conventional method for
indirect image pick-up; 10a frosted glass on which transmitted
light is projected within a darkroom according to conventional
methods for indirect image pick-up; 11 granular speck pattern
generated by reflected light; 11a granular speck pattern generated
by transmitted light; 12 monitoring device for display of picked-up
granular speck pattern; 13 video signal brancher for picked-up
video signal in granular speck pattern imaged granular speck
pattern; 14 A/D (Analog/Digital) converter adapted to digitalize
video signals in the form of analog signal before input to
computer; 15 processing unit adapted to, depending on particular
purpose of application, calculate quantity of movement, deformation
or displacement of granular specks or granular speck pattern and
thereby to calculate coagulating or melting rate on the basis of
coinciding degree between immediately previous image and
immediately subsequent image; 16 display device adapted to display
various quantities or rates calculated by processing unit in the
form of numerical value or graphic chart; and 17 a slide glass used
for process based on transmitted light.
[0030] FIG. 1 is a diagram illustrating method and apparatus
according to claims 1 and 2, respectively, for direct image pick-up
of a granular speck pattern generated by laser beam reflected on an
opaque object to be measure.
[0031] An object 1 to be inspected is irradiated with laser beam 3
from a laser projector 2. In the case of a sheet copper as an
example of the object 1, a granular speck pattern 11 is generated
on the entire surface of the object 1 as said object 1 is
irradiated at a target spot 4 thereon with the laser beam 3. It
should be understood that such granular speck pattern 11 cannot be
visually recognized directly.
[0032] When the measurement is carried out in a darkroom, the
granular speck pattern 11 is projected on a frosted glass plate 10
placed on an optical path as seen in FIG. 1. Conventionally, the
granular speck pattern 11 projected in this manner has been picked
up using a digital or other video camera.
[0033] According to the present invention, an image pick-up device
5 corresponding to said digital or video camera deprived of its
image forming lens (i.e., the lens is removed to define a lensless
video camera) is incorporated with a CCD element 6. Said image
pick-up device 5 is provided on its front side, i.e., in front of
said CCD element 6, with a shielding tube 7 serving to shield any
extraneous light due to an indoor illuminating light. The shielding
tube 7 is slightly larger than the CCD element 6, more
specifically, has a length of several centimeters and a circular or
square cross section. This arrangement enables the granular speck
pattern 11 to be directly picked up. A scope (i.e., area) of the
image picked up by the CCD element 6 is defined by a view field
8.
[0034] A video signal based on the picked-up image is branched in
two by a video signal brancher 13, one of which is input to a
monitor device 12 which then displays a particular image of the
granular speck pattern 11 given by said one of the branched
signals.
[0035] The other of said branched video signals is input to an A/D
converter 14 in the form of an analog signal and converted by said
A/D converter 14 to the corresponding digital signal to be input to
a processing unit 15. The unit 15 carries out a desired processing
and a result of this processing is input to a display device 16
which displays said result in the form of a numerical value or
graphic chart.
[0036] More specifically, the granular speck pattern 11 moves in
parallel to the object to be measure as said object 1 moves. In
view of this, the quantity of movement is calculated on the basis
of a pixel interval in the CCD element 6 and not only quantity but
also a speed as well as a direction of movement are displayed.
[0037] As for coating or adhesive, each pair of immediately
previous and immediate subsequent images in continuously picked-up
granular speck patterns are successively compared to each other to
calculate a coinciding degree so that drying rate or hardening rate
obtained on the basis of said coinciding degree may be displayed.
After coating has been dried or adhesive has been hardened, the
picked-up image remains identical with the coinciding degree of
100%.
[0038] In the case of thermally meltable solder, the picked-up
image remains constant with a coinciding percentage of 100% before
heated, and the coinciding percentage gradually decreases down to
0% as the solder begins to be heated until the solder is
liquidized. This is also true for progress of rusting.
[0039] An average area of the granular speck pattern 11 and an area
of the individual granular speck 9 are proportionally enlarged as
the object to be inspected recedes from the image pick-up device 5
and proportionally reduced as said object gets nearer to said image
pick-up device 5. Such phenomenon may be utilized to determine a
distance from the image pick-up device 5 to the object to be
inspected.
[0040] FIG. 2 is a diagram illustrating a method for direct pick-up
of the granular speck pattern generated by transmitted light of the
laser beam when the object to be inspected using a shielded direct
view CCD is transparent or translucent.
[0041] An object 1 to be inspected is irradiated with laser beam 3
from a laser projector 2. It is assumed here that blood 1a is the
object to be inspected and has been dropped on slide glass 17.
Irradiation of the object 1a at the spot 4 with the laser beam 3
causes a granular speck pattern 11 and a granular speck pattern 11a
to be generated by reflected light and transmitted light,
respectively, of the laser beam 3 on entire surface of the object
11a. It should be understood that these granular speck patterns 11,
11a cannot be visually recognized by an operator.
[0042] When the measurement is carried out in a darkroom, the
granular speck pattern 11 and the granular speck pattern 11a are
projected on frosted glass plates 10, 10a, respectively, as seen in
FIG. 2. Conventionally, the granular speck patterns 11, 11a
projected in this manner have been picked up.
[0043] According to the present invention, an image pick-up device
5 corresponding to said digital or video camera deprived of its
image forming lens includes a CCD element 6. Said image pick-up
device 5 is provided on its front side, i.e., in front of said CCD
element 6, with a shielding tube 7 serving to shield any extraneous
light due to an indoor illuminating light. The shielding tube 7 is
slightly larger than the CCD element 6, more specifically, has a
length of several centimeters and a circular or square cross
section. This arrangement enables the granular speck pattern 11 to
be directly picked up. A scope of the image picked up by the CCD
element 6 is defined by a view field 8.
[0044] A video signal based on the picked-up image is branched in
two by a video signal brancher 13, one of which is input to a
monitor device 12 which then displays a particular image of the
granular speck pattern 11 given by said one of the branched
signals.
[0045] The other of said branched video signals is input to an A/D
converter 14 in the form of an analog signal and converted by said
A/D converter 14 to the corresponding digital signal to be input to
a processing unit 15. The unit 15 carries out a desired processing
and a result of this processing is input to a display device 16
which displays said result in the form of a numerical value or
graphic chart.
[0046] When the method according to the invention relies upon the
transmitted light of laser beam, the granular speck pattern 11
generated by the reflecting light of laser beam presents the same
nature as that of the granular speck pattern 11 obtained when the
method relies upon the reflecting light of laser beam as
illustrated by FIG. 1.
[0047] For the blood sample 1a to be inspected by the method
relying on the transmitted light, the laser beam is diffusively
reflected on erythrocytes to generate the granular speck pattern
11a since the beam from the laser beam projector 2 has a wavelength
in the order of 700 nm. In other words, this granular speck pattern
11a is based on movement of the erythrocytes in the blood
sample.
[0048] The granular speck pattern 11 generated by the reflecting
light depends on a surface condition of the blood sample 1a while
the granular speck pattern 11a generated by the transmitted light
depends on an interior condition of the blood sample 1a.
[0049] To determine, for example, a blood coagulation time, the
surface of the blood sample dropped on the slide glass 17 is
irradiated with the laser beam 3 to obtain the granular speck
pattern 11 generated by the reflecting light and the granular speck
pattern 11a generated by the transmitted light.
[0050] The granular speck pattern 11a generated by the transmitted
light is remarkably unstable at the beginning but gradually
stabilized as the blood coagulation progresses until the pattern
11a is completely stabilized, suggesting completion of the blood
coagulation. In this way, the blood coagulation time can be
determined in non-contact fashion. Similarly, hardening or drying
of translucent adhesive or coating can be observed.
[0051] Effect of the Invention
[0052] As will be apparent from the foregoing description, the
method according to the invention enables the granular speck
pattern to be directly detected using a digital or other video
camera deprived of its image forming lens. By providing a shielding
tube adapted to shield any extraneous light in front of the CCD
element incorporated therein with the direct image pick-up can be
easily achieved even in a well lighted environment like an ordinary
office. In this manner, movement, deformation, shift of the object
to be inspected as well as coagulation, melting or progress of
rusting in the object such as a sample of adhesive, metal or blood
can be easily and quantitatively determined.
* * * * *