U.S. patent application number 12/381311 was filed with the patent office on 2009-12-03 for method for providing color images from a monochromatic electro-optical device using two optical channels and systems, apparatuses and devices related thereto.
This patent application is currently assigned to Tenebraex Corporation. Invention is credited to Peter W. J. Jones, Dennis W. Purcell.
Application Number | 20090296247 12/381311 |
Document ID | / |
Family ID | 34994332 |
Filed Date | 2009-12-03 |
United States Patent
Application |
20090296247 |
Kind Code |
A1 |
Jones; Peter W. J. ; et
al. |
December 3, 2009 |
Method for providing color images from a monochromatic
electro-optical device using two optical channels and systems,
apparatuses and devices related thereto
Abstract
An apparatus and methods for converting a monochrome night
vision or other electro-optical device into one that provides a
sensation of full color, including from red to blue with white and
black. The method provides color images from an electro-optical
device in which the image data from the electro-optical device
contains brightness information of an area being viewed by the
device without separate color information. Such a method includes
operably coupling an optical channel system to the electro-optical
device and configuring the optical channel system and arranging the
optical channel system with respect to the electro-optical device
so two color informational channels are provided to the viewer,
whereby the two informational channels formed by said configuring
and arranging of the optical channel system are such that the
viewer sees a color image. Such methods and apparatuses of the
present invention provides a sensation of full color image,
including from red to blue with white and black, to the viewer.
Inventors: |
Jones; Peter W. J.;
(Belmont, MA) ; Purcell; Dennis W.; (Medford,
MA) |
Correspondence
Address: |
EDWARDS ANGELL PALMER & DODGE LLP
P.O. BOX 55874
BOSTON
MA
02205
US
|
Assignee: |
Tenebraex Corporation
Boston
MA
|
Family ID: |
34994332 |
Appl. No.: |
12/381311 |
Filed: |
March 10, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11084389 |
Mar 17, 2005 |
7507964 |
|
|
12381311 |
|
|
|
|
60553835 |
Mar 17, 2004 |
|
|
|
Current U.S.
Class: |
359/887 ;
359/890 |
Current CPC
Class: |
G02B 23/12 20130101;
H04N 9/43 20130101 |
Class at
Publication: |
359/887 ;
359/890 |
International
Class: |
G02B 5/22 20060101
G02B005/22 |
Claims
1. An electro-optical viewing device, comprising: a light filtering
system including a first light filter sub-system positioned at a
light-input end of the device and a output sub-system distinct from
the first light filter sub-system and positioned at a light-output
end of the device, wherein each of the first filter sub-system and
the output sub-system are configured and arranged so as to form two
light channels each light channel having a transmission
characteristic defining the boundaries of the light channel with
respect to wavelength; wherein the first filter sub-system is
configured and arranged so the characteristics for the two light
channels cross each other at a predetermined point, where a
wavelength at which the characteristics for the two light channels
cross each other lies in the range of from about 580 nm to about
620 nm; wherein the device has a substantially monochromatic output
in the absence of the filtering system; and wherein the two light
channels provides a sensation of a full color output to a
viewer.
2. (canceled)
3. The device of claim 2, wherein the characteristics for the two
light channels of the first filter sub-system cross each other at a
predetermined point with respect to a cut-off for each respective
characteristic.
4. The device of claim 3, wherein the characteristics for the two
light channels each have a sloping edge that approaches the cut-off
for each respective characteristic and wherein the characteristics
of the two light channels cross at a predetermined point along the
sloping edge of the respective light channel.
5. The device of claim 1 wherein the output sub-system comprises a
second filter sub-system.
6. The device of claim 1 wherein the output subs-system comprises a
display device.
7. The device of claim 1, wherein each of the first filtering
sub-system and the output sub-system are configured and arranged so
as to filter light into respective light channels using one of
absorption, reflection or filtering techniques.
8. The device of claim 3, wherein the characteristics for the two
light channels of the first filtering sub-system cross each other
at one of about a .ltoreq.50% or a 10% cut-off point for each
respective characteristic.
9. The device of claim 1, wherein the wavelength at which the
characteristics for the two light channels cross each other lies in
the range of from about 580 nm to about 600 nm.
10. The device of claim 1, wherein the characteristics for the two
light channels cross each other at a wavelength of about 600
nm.
11. The device of claim 1, wherein one of the first light filtering
sub-system and output sub-system further includes two filters so as
to form the two channels, where the two filters are one of
electrically operated filter or filters that are oscillated or
rotated.
12. The device of claim 11, wherein the wavelength at which the
characteristics for the two light channels cross is selected from
the group consisting of (a) in the range of from about 580 nm to
600 nm, or (b) about 600 nm.
13. The device of claim 1, wherein the first light filtering
sub-system further includes two filters that are being oscillated
or rotated, and wherein excluding portions of the characteristics
that are overlapping, one of the filters is a long-wave pass filter
and the other of the filters is a short-wave pass filter.
14. The device of claim 1, wherein the device comprises a night
vision device.
15. (canceled)
16. The device of claim 11, wherein the first and second filter
sub-systems are each rotated at a speed whereby successive
switching between each of the plurality of filters comprising each
filer sub-system occurs faster than about 15 times per second.
17. A night vision system comprising: an electro-optical viewing
device; a light filtering system including a first light filter
sub-system positioned at a light-input end of the device and an
output sub-system that is distinct from the first light filter
sub-system and is positioned at a light-output end of the device,
wherein each of the first filter sub-system and the output second
filter sub-system are configured and arranged so as to include two
light channels each light channel having a characteristic defining
the boundaries of the light channel; wherein the first filter
sub-system is configured and arranged so the characteristics for
the two light channels cross each other at a predetermined point:
wherein the electro-optical viewing device has a substantially
monochromatic output; and wherein the two light channels provides a
sensation of a full color output to a viewer.
18. The night vision system of claim 17, wherein a wavelength at
which the characteristics for the two light channels cross is
selected from the group consisting of (a) in the range of from
about 580 nm to about 620 nm, (b) in the range of from about 590 nm
to 610 nm, or (c) about 600 nm.
19. The night vision system of claim 18, wherein the
characteristics for the two light channels cross each other at a
point that is at one of about a .ltoreq.50% or 10% cut-off point
for each respective characteristic of the two light channels.
20. A method for providing color images from an electro-optical
device in which the image data from the electro-optical device
contains brightness information of an area being viewed by the
device without separate color information, said method for
providing color images, comprising the steps of: operably coupling
an optical channel system to the electro-optical device;
configuring the optical channel system and arranging the optical
channel system with respect to the electro-optical device so two
color informational channels are provided to the viewer, wherein a
boundary is set between the two color informational channels, where
the boundary is in a predetermined range of values of wavelengths
of radiation, whereby the two informational channels formed by said
configuring and arranging of the optical channel system are such
that the viewer sees a color image; and wherein the boundary is set
so as to satisfy the following relationship:
580.gtoreq..lamda..sub.b.gtoreq.620 nm where .lamda..sub.b is the
wavelength of the radiation corresponding to the boundary between
the two color informational channels.
21-36. (canceled)
Description
[0001] This application is a continuation of co-pending U.S.
application Ser. No. 11/084,389, filed Mar. 17, 2005, issuing on
Mar. 24, 2009 as U.S. Pat. No. 7,507,964; which application claims
the benefit of U.S. Provisional Application Serial No. 60/553,835
filed Mar. 17, 2004, the teachings of all of which are incorporated
herein by reference.
FIELD OF INVENTION
[0002] The present invention relates generally to techniques and
apparatus for converting a monochromatic night vision device or
other electro-optical device to produce a full-color output, more
particularly techniques and apparatuses that utilize a filtering
system embodying two optical channels with the monochromatic night
vision device or other electro-optical device to produce a
full-color output.
BACKGROUND OF THE INVENTION
[0003] The vast majority of night vision devices have a
monochromatic output. They typically work by using a lens to focus
light from a scene onto the front of a sensor or image intensifier
tube. The image is amplified and finally output on a phosphor
display screen. While night vision (NV) is itself a great
enhancement of normal human vision, it is sometimes desirable to
have a NV device with full color output, for example to better
differentiate an object one is searching for from its background
environment.
[0004] At present, most typical methods of achieving a full-color
NV device have been by the use of an especially sensitive and
highly amplified CCD device (television camera). Alternatively,
three separate image intensifier tubes are used that are selected
or filtered so as to be sensitive to the red, green and blue
portions of the spectrum. The outputs of these three tubes are then
fused by the use of partially silvered prisms or mirrors or by
integrating them in an interlaced red, green and blue (RGB)
television-type display tube.
[0005] Among the disadvantages of these techniques are higher power
usage, added weight, increased optical complexity compared to a
simple image intensifier NV device, and susceptibility to being
knocked out of alignment. In addition, CCD devices are not
effective image intensifiers and thus limit the light amplification
possible. Also many night vision devices are designed so as to be
mounted on the user's head, a position where excess weight can be a
problem. In addition, there is a vast installed base of
monochromatic NV systems. Also, such techniques generally try and
recreate the full color image by filtering light into three (3)
optical channels (i.e., red, green and blue light).
[0006] There is described in International Application No.
PCT/US01/05866 and U.S. Pat. No. 6,614,606, which are owned by the
assignee of the present invention and whose teachings are
incorporated herein by reference, methods of converting
monochromatic night vision or other electro-optical viewing devices
to portray a full-color image. The techniques and/or methods
described therein yield night vision devices or other
electro-optical viewing devices that convert a monochromatic image
so as to portray a full-color image and that avoid prior art
shortcomings of higher power usage and increased optical
complexity. The described methods or techniques, while advancing
the art as to conversion of such monochromatic images to full color
images, do not describe all particular techniques for designing
filter systems or sub-systems for such use.
[0007] It thus would be desirable to provide two optical channel
filtering systems or sub-systems that can provide color output from
monochromatic-output electro-optical systems as well as devices;
apparatuses and methods that embody such filtering systems. It
would be particularly desirable to provide such filtering systems
or sub-systems as well as related apparatuses, devices and methods,
that would be adaptable to use any of a number of types of filters
or filtering arrangements to provide the color output from the
monochromatic output of electro-optical systems using a two channel
filtering technique. It also would be highly desirable to provide a
simple and low-cost technique whereby an apparatus; device or
system embodying a monochromatic-output NV system is capable of
providing a full-color output.
SUMMARY OF THE INVENTION
[0008] The present invention relates generally to techniques and
apparatus for converting a monochromatic night vision device or
other electro-optical device to produce a full-color output, more
particularly techniques and apparatuses that utilize a filtering
system embodying two optical channels with the monochromatic night
vision device or other electro-optical device to produce a
full-color output. The two optical channels are established so that
a boundary is set between the two optical channels, where the
boundary is set so as to satisfy the following relationship
580.ltoreq..lamda..sub.b.ltoreq.620 nm, where .lamda..sub.b is the
wavelength of the radiation corresponding to the boundary between
the two color informational channels. In more specific embodiments,
the boundary is set so as to satisfy one of the following
relationships 580.ltoreq..lamda..sub.b.ltoreq.600 nm,
590.ltoreq..lamda..sub.b.ltoreq.610 nm or .lamda..sub.b about 600
nm (.+-.2 nm).
[0009] The present invention features apparatus, devices, systems
and methods for converting a monochrome night vision or other
electro-optical device into one that provides a sensation of full
color, including from red to blue with white and black using two
optical channels. Preferred methods of the present invention
provide such color images from an electro-optical device in which
the image data from the electro-optical device contains brightness
information of an area being viewed by the device without separate
color information. Such methods includes operably coupling an
optical channel system to the electro-optical device and
configuring the optical channel system and arranging the optical
channel system with respect to the electro-optical device so two
color informational channels are provided to the viewer, whereby
the two informational channels formed by said configuring and
arranging of the optical channel system are such that the viewer
sees a color image.
[0010] In further embodiments, such configuring includes
configuring the optical channel system so that a boundary is set
between the two color informational channels, where the boundary is
in a predetermined range of values of wavelengths of radiation. In
yet further embodiments, each color informational channel is
characterizable by a transmission characteristic having a cutoff
point, and said configuring includes configuring the optical
channel system so the boundary between the two color informational
channels corresponds to one of a 50% cut-off point for each
respective transmission characteristic, to less than a 50% cut-off
point for each respective transmission characteristic or to a 10%
cut-off point for each respective transmission characteristic.
[0011] In yet further embodiments, the boundary is set so as to
satisfy the one of the following relationships
580.ltoreq..lamda..sub.b.ltoreq.620 nm,
580.ltoreq..lamda..sub.b.ltoreq.600 nm or
590.ltoreq..lamda..sub.b.ltoreq.610 nm, where .lamda..sub.b is the
wavelength of the radiation corresponding to the boundary between
the two color informational channels. In more specific embodiments,
the boundary is set so .lamda..sub.b is about 600 nm (one of .+-.2
nm or .+-.6 nm).
[0012] In further embodiments the boundary is set so as to satisfy
the following relationships; .lamda..sub.b>580 nm, where
.lamda..sub.b is the wavelength of the radiation corresponding to
the boundary between the two color informational channels. In yet
further embodiments the boundary is set so as to satisfy the
following relationships; .lamda..sub.b>590 nm, where
.lamda..sub.b is the wavelength of the radiation corresponding to
the boundary between the two color informational channels. Also,
the boundary is further set so as to satisfy one of
.lamda..sub.b.ltoreq.620 nm, .lamda..sub.b.ltoreq.610 nm or
.lamda..sub.b.ltoreq.600 nm.
[0013] In further embodiments, said configuring includes
configuring the optical channel system so that the boundary set
between the two color informational channels is such that one of
the two informational channels includes wavelengths of radiation
that are generally characterized as being longer than wavelengths
of radiation of the other of the two informational channels and
correspondingly such that said other of the two informational
channels includes wavelengths of radiation that are generally
characterized as being shorter than wavelengths of radiation of
said one of the two informational channels. Such an optical channel
system is further configurable so as to set the boundary between
the two optical channels as herein described.
[0014] In yet further embodiments, such configuring and arranging
further includes configuring the optical channel system so as to
include a first filtering sub-system and arranging the first
filtering sub-system so as to be disposed between light coming from
the area being viewed and an input end of the electro-optical
device and wherein said configuring further includes configuring
the first filtering sub-system so light being received at the input
end of the electro-optical device is in two first color
informational channels. In more particular embodiments, said
configuring further includes configuring the first filtering
sub-system so that a boundary is set between the two first color
informational channels, where the boundary is in a predetermined
range of values of wavelengths of radiation. The first filtering
sub-system is further configurable so as to set the boundary
between the two optical channels as herein described.
[0015] In further embodiments, such configuring and arranging
further includes configuring the optical channel system so as to
include an output system which is preferably a second filtering
sub-system and arranging the second filtering sub-system so as to
be operably coupled to an output end of the electro-optical device
and so as to be viewable by an observer, and wherein said
configuring further includes configuring the second filtering
sub-system so light in two second color informational channels is
presented to the observer. In particular embodiments, the
wavelengths of light in the two second color informational channels
are within the boundaries defining the two first color
informational channels.
[0016] In yet further embodiments, such said configuring includes
configuring the first filtering sub-system so that the boundary set
between the two first color informational channels is such that one
of the two first color informational channels includes wavelengths
of radiation that are generally characterized as being longer than
wavelengths of radiation of the other of the two first color
informational channels and correspondingly such that said other of
the two first color informational channels includes wavelengths of
radiation that are generally characterized as being shorter than
wavelengths of radiation of said one of the two first color
informational channels. Also, such configuring further includes
configuring the second filtering sub-system so that the two second
color informational channels are such that one of the two second
color informational channels includes wavelengths of radiation that
are generally characterized as being longer than wavelengths of
radiation of the other of the two second color informational
channels and correspondingly such that said other of the two second
color informational channels includes wavelengths of radiation that
are generally characterized as being shorter than wavelengths of
radiation of said one of the two second color informational
channels.
[0017] Additionally, in another preferred embodiment, rather than
directly filtering the output of the electro-optical device as
described, the output can be transmitted to a display device in the
absence of filtering whereby the output of the display (e.g., the
wavelengths of light emitted by the display, or the light from the
phosphors that comprise the display) correspond to the result
produced by the above described filtered output. Thus, as referred
to herein, and unless otherwise indicated, the second output system
can comprise an output of a display device and such a display
device can constitute a "second light filter sub-system" that can
be positioned at a light-output end of an electro-optical viewing
device.
[0018] In more particular embodiments, the second filtering
sub-system or other output system is configured such that light
from said second filtering sub-system in said one of the second
color informational channels is in a narrower range than a light
range of said one of the first color informational channel, and the
light from said second filtering sub-system in said another of the
second color informational channels is in a narrower range than a
light range of said another of the first color informational
channel. More particularly, the second filtering sub-system is
configured such that light from said second filtering sub-system in
said one of the second color informational channels is light
predominantly in the range of between about 580 nm and 595 nm, and
light exiting from said second filtering sub-system in said another
of the second color informational channels is light predominantly
in the range of between about 530 nm and 555 nm.
[0019] In yet further embodiments, methods of the present invention
include adding an amount of noise in each of the two color
informational channels, where the noise being added is one of
random or gaussian.
[0020] Preferred apparatus of the invention comprise an
electro-optical viewing device, particularly a mono-chromatic night
vision device, and a light filtering system comprising two or more
light filter subsystem each light filter sub-system, at least one
at an input end of the night vision device and another light
filtering sub-system at an output end of the night vision device.
Each of the light filtering sub-systems is configured and arranged
so as to filter light into two optical channels. The light
filtering system of the present invention thus arranged with
respect to the night vision device can provide to a viewer a
sensation of full color image, including from red to blue with
white and black.
[0021] In particular embodiments, each of the light filtering
sub-systems is composed and/or configured so as to form two light
channels, each channel having a defining characteristic (e.g.,
light transmission characteristic). As to the light filtering
sub-system, the defining characteristics of the two light channels
are established such that a cutoff point characterizing the first
light channel and a cutoff point characterizing the second light
channel lies within a predetermined range of wavelengths or
frequencies. Because most filtering sub-system characteristics
comprise sloped regions in the region of the characteristic curve
that approached the cutoff points, the light filtering sub-system
disposed at the input end of the night vision device is configured
and arranged so the characteristic curve defining each of the light
filtering sub-systems are set so that they cross each other at a
point in a predetermined range of wavelengths or frequencies,
whereby a region is defined by an overlapping portion of each
characteristic.
[0022] In further embodiments, such an electro-optical viewing
device includes a light filtering system including a first light
filter sub-system positioned at a light-input end of the device and
a second light filter sub-system positioned at a light-output end
of the device. The first light filter sub-system is configured and
arranged so as the light is filtered into two light channels, each
light channel having a characteristic defining the boundaries of
the light channel. Also, the first filter sub-system is configured
and arranged so the characteristic for the two light channels cross
each other at a predetermined point that lies in a range of
predetermined values.
[0023] The second light filter subsystem is configured and arranged
so as the light is filtered into two light channels, each light
channel having a characteristic defining the boundaries of the
light channel. More particularly, one of the light channels of the
second light filter sub-system is generally characterized as
including light whose wavelengths are generally longer that the
light that lies within the boundaries of the second light channel.
In an embodiment of the present invention, the first and second
light filter sub-systems are established so that the
characteristics that define each of the light channels do not
overlap. In another embodiment of the present invention, the first
and second light filter sub-systems are established so that the
characteristics that define each of the light channels do overlap.
In a more particular embodiment, the second filter sub-system is
configured and arranged so the characteristic for the two light
channels cross each other at a predetermined point that lies in a
range of predetermined values. In more specific embodiments, the
predetermined point is essentially the same as that where the light
channels of the first filter sub-system cross.
[0024] In more particularly embodiments, and where each of the
characteristics defining the first light filter sub-system includes
a region sloping towards a cut-off of the respective light channel,
the light channels are established such that the characteristics
for the light channel cross each other at or about the same point
with respect to the cut-off. In an exemplary embodiment, the
characteristics cross each other at about a point corresponding to
one of the 50% cut-off point for the respective characteristic, to
less than a 50% cut-off point for each respective transmission
characteristic or to a 10% cut-off point for each respective
transmission characteristic.
[0025] Each of the first filtering sub-system and the second
filtering sub-system are configured and arranged so as to filter
light into the respective light channels using one of absorption,
reflection or filtering techniques.
[0026] In more specific embodiments, the first filter sub-systems
is composed, configured and/or arranged so the characteristics for
the adjacent light channels cross each other at a point that lies
in the range of from about 580 nm to about 620, more particularly
in the range of from about 590 nm to about 610 nm and more
specifically at a wavelength of about 600 nm.
[0027] In further specific embodiments, each of the first and
second light filter sub-systems further include one of one or more
electrically operated filter or one or more filters that are
oscillated or rotated. It is within the scope of the present
invention for the first light filter sub-system to comprise one
type of filter and the second light filter sub-system to comprise
another type of filter.
[0028] In yet further specific embodiments, excluding portions of
the characteristics that are overlapping, the two light channels
are characterized as including light having different wavelengths.
In the case where one or both of the first and second light
filtering sub-systems further include a plurality of filters that
are being oscillated or rotated, and excluding portions of the
characteristics that are overlapping, one of the filters is
generally characterized as a long-wave pass filter and the other of
the filters is characterized as a short-wave pass filter. Also,
when one or both of the first and second light filtering
sub-systems further includes a plurality of filters that are being
oscillated or rotated, and excluding portions of the
characteristics that are overlapping, one of the filters passes
light have a wavelength longer than the wavelength of light at the
predetermined point and the other filter passes light have a
wavelength shorter than the wavelength of light at the
predetermined point.
[0029] In yet further specific embodiments, the filters comprising
the first and second light filter sub-systems are arranged and
operated so that the general light characteristic of the filter
(e.g., long wavelength light filter) of the first light filter
sub-system disposed at the input end of the night vision device is
the same as that for the filter of the second light filter
sub-system correspondingly disposed at the output end. In other
words, when a filter of the first light filter sub-system that is
generally characterized as being a long wavelength filter is
disposed in front of the light input end, a filter of the second
light filter sub-system that is generally characterized as a long
wavelength filter would be disposed an the light output end of the
night vision device.
[0030] It should be recognized that the characterization of long
and short wavelength filters is established based on the
characteristics of the filters making up the first filter
sub-system and correspondingly the filters making up the second
filter sub-system. As such, it should be recognized that although
the general characteristic of the filters (e.g., long or short
wavelength) are the considered as being the same, the
characteristic curves for each of the corresponding filters need
not be the same and the wavelength cutoffs for the corresponding
filters need not be the same. Also, as discussed above, it is
recognized that a display device can function as and constitute a
second light filter sub-system that can be positioned at a
light-output end of an electro-optical viewing device.
[0031] In yet another specific embodiment, the filters comprising
the first and second light filter sub-systems are arranged and
operated so that the general light characteristic of the filter
(e.g., long wavelength light filter) of the first light filter
sub-system disposed at the input end of the night vision device is
different from that for the filter of the second light filter
sub-system correspondingly disposed at the output end. In other
words, when a filter of the first light filter sub-system that is
generally characterized as being a long wavelength filter is
disposed in front of the light input end and a filter of the second
light filter sub-system that is generally characterized as a short
wavelength filter would be disposed an the light output end of the
night vision device.
[0032] The device can comprises a night vision device or a device
that has a substantially monochromatic output in the absence of the
filtering system including but not limited to thermal
electro-optical devices. For the present invention, the term
monochromatic shall be understood to be the case where the whole
image is being described by lighter and darker regions and while
the image may appear as a single color, this shall be understood to
mean that the output is not necessarily limited to a single
wavelength.
[0033] In yet further specific embodiments, when one or both of the
first and second light filtering sub-systems further includes a
plurality of filters that are being rotated, the first and second
filter sub-systems are rotated at a speed whereby successive
switching between each of the plurality of filters comprising each
filer sub-system occurs faster than about 15 times per second.
[0034] Also featured is a light vision system including an
electro-optical device and a light filtering system as hereinabove
described.
[0035] Other aspects and embodiments of the invention are discussed
below.
BRIEF DESCRIPTION OF THE DRAWING
[0036] For a fuller understanding of the nature and desired objects
of the present invention, reference is made to the following
detailed description taken in conjunction with the accompanying
drawing figures wherein like reference character denote
corresponding parts throughout the several views and wherein:
[0037] FIG. 1 is a schematic view of a color night vision device
broadly illustrating the filtering system of the present
invention;
[0038] FIG. 2 is a schematic view of another color night vision
device according to the present invention;
[0039] FIGS. 3A, B are views of filter wheels according to the
present invention that illustrate exemplary embodiments for such
filter wheels;
[0040] FIG. 4 is a schematic view of another device according to
the present invention;
[0041] FIG. 5A is a graph illustrating the light transmission
characteristic of the first filtering sub-system according to the
present invention;
[0042] FIG. 5B is a graph illustrating the light transmission
characteristic of the second filtering sub-system according to the
present invention;
[0043] FIGS. 6A, B are graphs more particularly illustrating the
transmission characteristic of reflective type of filters;
[0044] FIG. 7A is a schematic view of another color night vision
according to the present invention;
[0045] FIG. 7B is a schematic view of another embodiment of the
device of FIG. 7A; and
[0046] FIG. 7C is a schematic view of another color night vision
device according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0047] The present invention features apparatus, devices, systems
and methods for converting a monochrome night vision device or
other electro-optical device, such as thermal night vision device
into one that provides a sensation of full color, including from
red to blue with white and black using two optical channels. Such
electro-optical devices are generally characterized as providing
image data from the electro-optical device that contains brightness
information of an area being viewed by the device without separate
color information. For example, a typical night vision device
amplifies the available light from the area being viewed and the
output of such a device provides a monochromatic display of the
area being viewed.
[0048] Such methods of the present invention includes operably
coupling an optical channel system or a light filtering system to
the electro-optical device. The optical channel system or the light
filtering system is configured and arranging with respect to the
electro-optical device so two color informational channels are
provided to the viewer. In this way, the brightness information for
or the light from the area being viewed is effectively separated
into the two color informational channels, whereby the two
informational channels being formed are such that the viewer sees a
color image. More particularly such methods of the present
invention provides a sensation of full color to the viewer,
including from red to blue with white, black and gray from the two
color informational channels.
[0049] In particular embodiments, the viewing or objective lens
side of the two-channel optical channel system views the scene
through a filtering system that includes two filters or filtering
mechanisms as herein described. These filters or filtering
mechanisms divide the color information into two channels, such
that one channel passes light with wavelengths that are generally
shorter than a certain value and such that the other channel passes
light of wavelengths that are generally longer than a certain
value. The two channels of color information are then passed
through the electro-optical device that amplifies or otherwise
passes an image that contains only brightness information.
[0050] At the output end of the electro-optical device these two
color informational channels are presented to the viewer. In
preferred embodiments, the two channels being presented use two
different colors, one for each channel. As herein described such
output can be presented sequentially (e.g., by presenting light for
one of the two channels and then presenting light for the other of
the two channels). Alternatively, the output can be presented in an
interleaved manner such as by using one color of phosphors in a
color CRT display to render the grayscale information from the
electro-optical device for one of the two channels and a second
color of phosphors to render the grayscale information from the
electro-optical device for the other of the two channels. In more
particular embodiments, the colors of the two channels from the
output end are selected so as to generally correspond to the
wavelength range of the filters or filtering mechanism at the input
end of the electro-optical device. For example, a shorter
wavelength color would be used to render the light or grayscale
information of the light passing through the filter or filtering
mechanism passing short wavelength radiation to the input end of
the electro-optical device and a longer wavelength color would be
used to render the light or grayscale information of the light
passing through the filter or filtering mechanism passing long
wavelength radiation to the input end. These shall not be construed
as limiting as it is within the scope of the present invention to
reverse this arrangement, such as for example, when a thermal
electro-optical device is being utilized to image an area.
[0051] That is, the output side of the device can present at least
two channels of information of a viewer with two different
wavelength bands of light. Thus, in one aspect, when the first
information channel is presenting color information derived from
shorter wavelength light, the output side of the device can present
its information using shorter wavelength light. In another aspect,
when the first information channel is presenting color information
derived from longer wavelength light, the output side of the device
can presents its information using the longer wavelength of
light.
[0052] The multiple channels of information presented to a viewer
through the output side of a device of the invention suitably may
have a variety of specific configurations. For instance, in one
configuration, the device output may comprise a shorter wavelength
channel that provides light having a wavelength of 544 nm.+-.5 nm
and a longer wavelength channel that provides light having a
wavelength of 622 nm.+-.5 nm. In another configuration, the device
output may comprise a shorter wavelength channel that provides
light having a wavelength of 544 nm.+-.5 nm and a longer wavelength
channel that provides light having a wavelength of 670 nm.+-.5 nm.
In yet another configuration, the device output may comprise a
shorter wavelength channel that provides light having a wavelength
of 544 nm.+-.5 nm and of 588 nm.+-.5 nm and a longer wavelength
channel that provides light having a wavelength of 622 nm.+-.5 nm
of 670 nm.+-.5 nm.
[0053] In further embodiments, the provided optical channel system
is configured and arranged so that a boundary is set between the
two color informational channels, where the boundary is in a
predetermined range of values of wavelengths of radiation. In
further embodiments, particularly suited for use with any of a
number of conventional night vision devices, the boundary is set so
as to satisfy the one of the following relationships
580.ltoreq..lamda..sub.b.ltoreq.620 nm, or
590.ltoreq..lamda..sub.b.ltoreq.610 nm, where .lamda..sub.b is the
wavelength of the radiation corresponding to the boundary between
the two color informational channels. In more specific embodiments,
the boundary is set so kb is about 600 nm (.+-.2 nm). In yet
further embodiments the boundary is set so as to satisfy the
following relationships; .lamda..sub.b>580 nm or
.lamda..sub.b>590 nm, where .lamda..sub.b is the wavelength of
the radiation corresponding to the boundary between the two color
informational channels. Also, the boundary is further set so as to
satisfy one of .lamda..sub.b.ltoreq.620 nm,
.lamda..sub.b.ltoreq.610 nm, or .lamda..sub.b.ltoreq.600 nm.
[0054] In yet further particular embodiments, the provided optical
channel system is configured and arranged so as to include a first
filtering sub-system that is disposed between light coming from the
area being viewed and the input end of the electro-optical device.
Such a first filtering sub-system is more particularly configured
so the light being received at the input end of the electro-optical
device is separated into the two first color informational
channels. In more particular embodiments, the first filtering
sub-system is configured so that a boundary is set between the two
first color informational channels, where the boundary is in a
predetermined range of values of wavelengths of radiation. The
first filtering sub-system is further configurable so as to set the
boundary between the two optical channels as herein described.
[0055] In further embodiments, the provided optical channel system
is configured so as to include a second filtering sub-system that
is arranged so as to be operably coupled to an output end of the
electro-optical device and so as to be viewable by an observer. In
particular embodiments, the second filtering sub-system is
configured so light in two second color informational channels is
presented to the observer. In particular embodiments, the
wavelengths of light in the two second color informational channels
are within the boundaries or ranges that define each of the two
first color informational channels of the first filtering
sub-system.
[0056] In a particularly preferred embodiment, the second filtering
subsystem is configured so that the transmission characteristics of
the two second color informational channels do not cross-each other
and so that there are no overlapping portions as described further
herein. Alternatively, the second filtering subsystem is configured
so that the transmission characteristics of the two second color
informational channels cross-each other at a predetermined point,
more specifically at the boundary the two first color informational
channels.
[0057] In yet further embodiments, the provided first filtering
sub-system is configured so that the boundary set between the two
first color informational channels is such that one of the two
first color informational channels includes wavelengths of
radiation that are generally characterized as being longer than
wavelengths of radiation of the other of the two first color
informational channels and correspondingly such that said other of
the two first color informational channels includes wavelengths of
radiation that are generally characterized as being shorter than
wavelengths of radiation of said one of the two first color
informational channels. Also, the second filtering sub-system is
configured so that the two second color informational channels are
such that one of the two second color informational channels
includes wavelengths of radiation that are generally characterized
as being longer than wavelengths of radiation of the other of the
two second color informational channels and correspondingly such
that said other of the two second color informational channels
includes wavelengths of radiation that are generally characterized
as being shorter than wavelengths of radiation of said one of the
two second color informational channels.
[0058] In particular embodiments, the provided second filtering
sub-system is configured so light from the second filtering
sub-system in said one of the second color informational channels
is in a narrower range than a light range of the corresponding
first color informational channel, and the light from the second
filtering sub-system in said another of the second color
informational channels is in a narrower range than a light range of
the corresponding first color informational channel. In more
particular embodiments, the second filtering sub-system is
configured such that light from the second filtering sub-system in
one of the second color informational channels is light
predominantly in the range of between about 580 nm and 595 nm, and
light exiting from the second filtering sub-system in the another
of the second color informational channels is light predominantly
in the range of between about 530 nm and 555 nm. Also, as discussed
above, it is recognized that a display device can function as and
constitute a second light filter sub-system that can be positioned
at a light-output end of an electro-optical viewing device of the
invention.
[0059] In yet further embodiments, each color informational channel
can be characterized or defined by a curve representative of a
transmission characteristic. Typically, such curves include a
portion where the transmissivity of the channel decreases as a
function of the wavelength of the radiation towards cut-off point
corresponding to an essentially 0% transmissivity. In more
particular embodiments, the optical channel system is configured so
the boundary between the two color informational channels
corresponds to a 50% cut-off point for the respective transmission
characteristic of each of the two color informational channels. In
further embodiments, the optical channel system is configured so
the boundary between the two color informational channels
corresponds to a less than 50% cut-off point for the respective
transmission characteristic of each of the two color informational
channels, or a 10% cut-off point for the respective transmission
characteristic of each of the two color informational channels.
This shall not be limiting as it is within the skill of those
knowledgeable in the art, to select and use other points or
combination of points with respect to the cut-off point for
establishing the boundary to fit a particular usage and filtering
sub-system/filtering mechanism.
[0060] In yet further embodiments, provided first filtering
sub-system is configured so the boundary between the two first
color informational channels is set so as to satisfy the one of the
following relationships 580.ltoreq..lamda..sub.b.ltoreq.620 nm, or
590.ltoreq..lamda..sub.b<610 nm, where .lamda..sub.b is the
wavelength of the radiation corresponding to the boundary between
the two color informational channels. In more specific embodiments,
the boundary is set so .lamda..sub.b is about 600 nm (.+-.2 nm). In
further embodiments the boundary is set so as to satisfy the
following relationships; .lamda..sub.b>580 nm or
.lamda..sub.b>590 nm, where .lamda..sub.b is the wavelength of
the radiation corresponding to the boundary between the two color
informational channels. Also, the boundary is further set so as to
satisfy one of .lamda..sub.b.ltoreq.620 nm,
.lamda..sub.b.ltoreq.610 nm or .lamda..sub.b.ltoreq.600 nm.
[0061] In further embodiments, the method of the present invention
further includes adding a certain amount of noise to the image
data. This noise, which is random or gaussian is added before the
image data is presented to the viewer. Such noise can be in the
form of random light or dark speckles in the image. The addition of
noise has been found to advantageously help the brain of the viewer
to decode the color information being presented and thereby
presenting a rich, fully-colored image to the viewer.
[0062] Referring now to the various figures of the drawing wherein
like reference characters refer to like parts, there is shown
diagrammatically in FIG. 1 a color night vision system 10 embodying
the methodology of the present invention including the path
followed by the light (e.g., light path) in such a system. The
illustrated color night vision system 10 broadly illustrates the
filtering techniques of the present invention and includes an
objective lens 14 as is known in the art, a filtering system 15, an
image intensifier tube 20, and an eyepiece 24.
[0063] The color night vision system 10 is configured/arranged so
that the entering light rays 12 pass through the objective lens 14
and then through a first filtering part 17a of the filter system
15. The light exiting the first filtering part 17a in turn passes
to an image intensifier tube 20, night vision device or other
electro-optical device, in which the received or inputted light is
intensified therein using the technique appropriate for the device
being utilized and from which a light output is provided. The light
output from the image intensifier tube 20 in turn passes through
the second filtering part 17b of the filtering system 15. The light
passing through the second filtering part 17b typically passes
through the eyepiece 24 so an observer 26 views the light exiting
the eyepiece. The filtering system 15, more particularly the first
and second filtering parts 17a, b, are arranged with respect to the
image intensifier tube 20, as further described herein, so the
observer 26 visualizes or sees a full color image while looking
through the eyepiece 24.
[0064] The filtering system 15 also is configured and arranged so
that each of the filtering parts 17a, b successively and
alternatively filters the light between each of two band passes
using any of a number of filtering techniques (e.g., absorption,
reflective filtering techniques). Also, the filtering system 15,
more particularly the filtering parts 17a, b thereof, are
configured, arranged and controlled such that filtering by the
first filtering part 17a is complemented by the filtering of the
second filtering part 17b. Stated another way, the width of the
band of light being filtered by the first filtering part 17a is
complemented or is the same as the width of the band of light being
filtered by the second filtering part 17b. As indicated herein in a
preferred embodiment the band of light of the second filtering part
17b while generally corresponding to the band of light being
filtered by the first filtering part, is different.
[0065] In further embodiments, each of the filtering parts 17a, b
comprises two filter elements, or a plurality of two filtering
elements, each filter element being any of a number of filters or
filter systems known to those skilled in the art and each being
characterized as one of transmitting, absorbing or reflecting light
having a wavelength larger or smaller than a predetermined
wavelength. Each of the first and second filtering parts 17a, b is
appropriately configured, arranged and/or controlled depending upon
the type of filter being used so that a filter element of the first
filtering part 17a is in effect, if not actually alternatively and
successively placed at the input end of the image intensifying tube
20 and so a filter element of the second filtering part 17b is in
effect, if not actually alternatively and successively placed at
the output end of the image intensifying tube as herein described.
As indicated herein the filter elements can embody any of a number
of filtering techniques or types of filter known to those skilled
in the art, including electrically operated filters (e.g., LCD
types of filter structures) as well as apparatus where the
individual filter elements (e.g., glass filters, etc.) are rotated
and/or oscillated so as to be alternatively and successively placed
forward and behind the image intensifying tube 20.
[0066] The two filter elements of the first and second filtering
parts in effect form or define the two color informational channels
of the methodology of the present invention. Where the two filter
elements of the first filtering part 17a essentially form or define
the two first color informational channels and two filter elements
of the second filtering part 17b essentially form or define the two
second color informational channels.
[0067] Referring now to FIG. 2, there is shown an embodiment of a
color night vision system 100 according to the present invention
that includes an objective lens 14, a filtering system 115, an
image intensifier tube 20, and an eyepiece 24. Reference shall be
made to the foregoing discussion regarding FIG. 1 for common
features (e.g., features in which the reference numeral is the
same). In this embodiment, the filtering system 115 comprises a
first filter wheel 116 disposed generally forward of the image
intensifier tube 20 and a second filter wheel that is disposed so
as to be generally behind the image intensifier tube (e.g., in the
optical path behind the output of image intensifier tube).
[0068] In this embodiment, the color night vision system 10 is
configured and arranged so that the entering light rays 12 pass
through the objective lens 14 and then through one part of the
first filter wheel 116. The light exiting the one part of the first
filter wheel 116 in turn passes to an image intensifier tube 20,
night vision device or other electro-optical device, in which the
received or inputted light is intensified therein using the
technique appropriate for the device being utilized and from which
a light output is provided. The light output from the image
intensifier tube 20 in turn passes through a part of the second
filter wheel 122. The light passing through the part of the second
filter wheel 122 typically passes through an eyepiece 24 so an
observer 26 views the light exiting the eyepiece. The filter wheels
116, 122 are arranged with respect to the image intensifier tube
20, as further described herein, so the observer 26 visualizes or
sees a full color image while looking through the eyepiece 24.
[0069] Each of the filter wheels 116, 122 is preferably composed of
two filters or filter sections, more particularly a plurality of
such two filters or filter sections, that selectively filter light
so that light having a predetermined bandwidth is sensed by the
input of the image intensifier tube. As indicated herein, the
filters or filter sections making up each of the filter wheels
embody any of a number of filtering techniques known to those
skilled in the art, including but not limited to absorption and
reflective filtering techniques. The following discussion describes
the present invention using a filtering technique in which light is
being filtered so the light to be sensed and observed passes
through each of the filters or filter sections. It is within the
skill of those knowledgeable in the art, to adapt the below
described techniques and designs so as to be useable with filters
embodying other filtering techniques (e.g., filters that use
reflected light).
[0070] The filter wheels 16, 22 of the color night vision system 10
further are appropriately secured to a rotating or oscillating
shaft 119 or axle that is mounted generally parallel to the optical
axis of the image intensifier tube 20. The axle 119 is spun or
oscillated using any of a number of techniques known to those
skilled in the art including manual rotation or by means of a small
motor 118. More particularly, the axle 119 is spun or oscillated at
a rate so that the filter sections of the filter wheels 116, 122
pass the eye faster than the eye's flicker rate (generally over 20
cycles/second) such that the different color images coming to the
eye of the observer 26 fuse or merge. Stated another way, the axle
119 is spun or oscillated at a rate such that the switching between
the different filter filters or filter sections is fast enough that
the observer sees a merging of the different color images,
producing the impression of viewing a full-color scene.
[0071] The first filter wheel 116 or filter disk is mounted to the
axle 119 so that the filter sections thereof are alternatively and
successively placed and passed in front or forward of the imaging
sensor of the image intensifier tube 20. In the illustrated
embodiment, the first filter wheel 116 is arranged so as to pass
behind the objective lens 14, however, it is within the scope of
the present invention for the first filter wheel to be arranged so
as to pass forward of the objective lens 14. The second filter
wheel 122 is affixed to the axle 119 so as to be disposed at the
rear of the image intensifier tube 20 and so that when a certain
section of the first filter wheel 116 is positioned in front of the
optical device's sensor, a corresponding section of the second
filter wheel 122 is positioned behind the output screen of the
image intensifier tube. Alternatively, the second filter wheel 122
is arranged so it is disposed behind the eyepiece 24.
[0072] In this manner and when each of the filter wheels 116,122
comprises two filters or filter sections, when the first filter or
filter section of the first filter wheel 116 is positioned in front
of the image intensifier tube 20, the first filter or filter
section of the second wheel 122 is positioned between the observer
26 and the output of the image intensifier tube 20. Likewise, when
the second filter or filter section of the first filter wheel 116
is disposed in front of the image intensifier tube 20, the second
filter or filter section of the second filter wheel 122 is
positioned between the observer 26 and the output of the image
intensifier tube.
[0073] More specifically, and with reference to the filter wheel
130a illustrated in FIG. 3A, each of the first and second filter
wheels 116, 122 comprises two types of filters, i.e. a first filter
132 and second filter 134, whereby the first filter passes
radiation having a wavelength than is generally shorter than the
wavelength of the radiation be passed by the second filter, i.e.
the first filter is a "high pass" or "short-wave pass" filter and
the second filter is a "low pass" or long-wave pass" filter. Thus,
as the first and second filter wheels 116, 122 are rotated, the
first and second filters 132, 134 are alternatively and
successively rotated through the optical path on either side of the
image intensifier tube.
[0074] In another exemplary embodiment, and with reference to the
filter wheel 130b illustrated in FIG. 3B, each of the first and
second filter wheels 116, 122 comprise a plurality or more of the
two different types of filters that are alternatively arranged
around the circumference of the filter wheels. More specifically,
each of the first and second filter wheels 116, 122 comprise a
plurality or more of pairs of the two different types of filters
132, 134 so that each of the different types of filters are
alternatively arranged around the circumference of the filter
wheel. In the illustrated embodiment, the filter wheel 130b
comprises two first filters 132 and two second filters 134 that are
alternatively arranged about the circumference of the illustrated
filter wheel.
[0075] In further embodiments, the different types of filters 132,
134 of each of the first and second filter wheels 116, 122 are
composed, configured and/or arranged using any of a number of
techniques known to those skilled in the art such that each are
characterized by a unique characteristic (e.g., a transmission
characteristic) and such that the unique characteristic for one
filter 132 crosses the characteristic for the other filter 134 at a
predetermined point with respect to the cut off point for each of
the filters. In this way, the filtering system 115 formed by first
and second filter wheels 116, 122 embodying filters that are each
characterizable by a transmission characteristic, passes light
through the image intensifier tube 20 in the region where the two
transmission characteristics overlap each other when both of the
first or second filters 132, 134 are disposed in front of and
behind the image intensifier tube 20.
[0076] As discussed above, and depicted in FIG. 4, an
electro-optical device 10 (such as a color night vision device or a
thermal electro-optical device or sensor) of the invention can
utilize a display device as a second light filter sub-system. Thus,
as shown in FIG. 4, entering light 12 passes through device
objective lens 14 and a first filter 22 to be received to a
charge-coupled device 24 at the device output side that transmits
the output to display device 28 which can provide a color display
(e.g., via the wavelengths of light emitted by the display, or the
light from the phosphors that comprise the display) to viewer which
correspond to the result produced by the above described filtered
output.
[0077] Referring now also to FIG. 5A there is shown an exemplary
graph of the percent (%) light transmitted through each of the
filters that make up the first filter wheel 116 or the first
filtering part 17a versus wavelength of light. This graph
illustrates the composite transmission characteristic of the
filtering system 115 of the exemplary night vision system 100 when
using such filters. One curve 164 illustrates an exemplary
transmission characteristic of a filter that is composed,
configured and/or arranged so as to be generally characterized as a
long-wave pass filter. The other curve 166 illustrates an exemplary
transmission characteristic for a filter that is composed,
configure and/or arranged so as to be generally characterized as
being a short-wave pass filter. In addition and as shown in FIG.
5A, the long-wave pass filter and the short-wave pass filter also
are composed, configured and/or arranged so that falling edge of
the transmission characteristic of each filter approaching the
cut-off of the respective filter cross each other respectively at a
point 168. Consequently, and as illustrated therein, the light have
wavelengths lying in the region 169 defined or delineated by the
overlapping transmission characteristics is passed to the image
intensifier tube 20 by either of the filters.
[0078] In further embodiments, the long-wave pass filter and the
short-wave pass filter are each configured, composed and/or
arranged so that the respective transmission characteristics of
each filter cross each other, namely the crossover point 168 is
located so as to be in a range of wavelengths from about 580 nm to
about 620 nm, more particularly in the range of from about 580 nm
to about 600 nm or in the range of from about 590 nm to about 610
nm. In a more specific embodiment, the long-wave pass filter and
the short-wave pass filter are each configured, composed and/or
arranged so the crossover point 168 is at about 600 nm (e.g., .+-.2
nm).
[0079] In more particular embodiments, the long-wave pass filter
and the short-wave pass filter are configured, composed and/or
arranged so that the respective transmission characteristics of
each filter is at about the 50% from the cut-off point of the
respective filter when the transmission characteristics of the
filters cross each other. In further embodiments, the long-wave
pass filter and the short-wave pass filter are configured, composed
and/or arranged so that the respective transmission characteristics
of each filter is at about to a less than 50% cut-off point for the
respective transmission characteristic of each of the two color
informational channels, or at about a 10% cut-off point for the
respective transmission characteristic of each of the two color
informational channels.
[0080] Referring now also to FIG. 5B there is shown an exemplary
graph of the percent (%) light transmitted through each of the
filters that make up the second filter wheel 122 or the second
filtering part 17b versus wavelength of light. This graph further
illustrates the composite transmission characteristic of the
filtering system 115 of the exemplary night vision system 100 when
using such filters. One curve 464 illustrates an exemplary
transmission characteristic of a filter that is composed,
configured and/or arranged so as to be generally characterized as a
long-wave pass filter. The other curve 466 illustrates an exemplary
transmission characteristic for a filter that is composed,
configure and/or arranged so as to be generally characterized as
being a short-wave pass filter. In addition and as shown in FIG.
5B, the long-wave pass filter and the short-wave pass filter also
are composed, configured and/or arranged so that the transmission
characteristic of each filter does not cross each other. In an
alternative embodiment, and as illustrated in FIG. 4A, the
long-wave pass filter and the short-wave pass filter also can be
composed, configured and/or arranged so that the transmission
characteristic of each filter does cross each other such as at the
predetermined point 168 illustrated in FIG. 5A.
[0081] As indicated above, the electro-optical device for use in
the color night vision system of the present invention can be a
thermal electro-optical such as for example the device being
illustrated in FIG. 4. Referring now to FIG. 7A, there is a
schematic view of another color night vision system 10a according
to the present invention that embodies one or more thermal
electro-optical devices, and in exemplary embodiments, two thermal
electro-optical devices or thermal sensors where one is longer wave
sensor (e.g., 8-12 microns) and the other is a shorter wave sensor
(e.g., 4-6 microns). In the illustrated system, the light rays 300
from the scene being observed enter the two thermal sensors, the
longer wave sensor 310 and the shorter wave sensor 320. The output
from these sensors is provided to a display 330 and the images from
these sensors are produced alternately on the display 330. A two
segment filter wheel 340 also is provided and which is rotated by a
motor 350. The filter wheel is positioned and rotated such that
when the image from the longer wave sensor 310 is on the display,
it is seen through one filter segment by the observer 360 and when
the image from the shorter wave sensor 320 is on the display, it is
seen through the other filter segment.
[0082] Referring now to FIG. 7B, there is a schematic view of a
color night vision system I Ob that is an embodiment of the color
night vision system of FIG. 7A. This system 10b embodies one or
more thermal electro-optical devices, and in exemplary embodiments,
two thermal electro-optical devices or thermal sensors where one is
longer wave sensor (e.g., 8-12 microns) and the other is a shorter
wave sensor (e.g., 4-6 microns). In the illustrated system, the
image output from both sensors 310, 320 are inputted to a two-color
display 410. The image outputs are processed such that the image of
a scene 400 from the longer wave sensor 310 and the image from the
longer wave sensor 320 are displayed in an interleaved manner on
the two-color display 410. In more particular embodiments, the
two-color display is made up of two different colored interleaved
phosphors, 430 and 440. In further embodiments, one phosphor is
constituted so it produces a narrow wavelength band of light that
is less than .lamda..sub.b (the wavelength of the radiation
corresponding to the boundary between the two color informational
channels) and the other phosphor is constituted so as to produce a
narrow wavelength of light that is greater than .lamda..sub.b.
[0083] In this way, two optical channels are established for
viewing by the observer 360. As indicated herein the boundary is
set so as to satisfy the following relationship
580.gtoreq..lamda..sub.b.gtoreq.620 nm,. In more specific
embodiments, the boundary is set so as to satisfy one of the
following relationships 580.gtoreq..lamda..sub.b.gtoreq.600 nm,
590.gtoreq..lamda..sub.b.gtoreq.610 nm or .lamda..sub.b is about
600 nm (.+-.2 nm).
[0084] Referring now to FIG. 7C, there is a schematic view of
another embodiment of a color night vision system 10c according ton
the present system, where the image display is omitted for clarity.
Such a system 10c is configurable so as to include the mechanisms
described in FIGS. 7A-B for displaying the image outputted by the
thermal electro-optical device, imaging device or camera 510. In
the illustrated embodiment, the imaging device or camera 510 is
arranged so the longer wavelength sensor 540 and the shorter
wavelength sensor 550, are disposed within the camera 510 and a
beam splitters 530 is disposed in the optical path from the optics
520. In this way, the light rays 500 from the scene being observed
pass through the optics 520 and the beam splitter 530 splits the
light so light in one spectral range is passed to the longer wave
sensor 310 and so light in one spectral range is passed to the
shorter wave sensor 320. The outputs from the different sensors are
outputted to the display as herein described in either of FIGS. 7A
and B.
[0085] As indicated above, the color night vision system 10, 100 of
either embodiment is configurable so as to use reflective filtering
techniques or rejection filters. This type of filter is configured
so as to work by reflecting light (i.e., not absorbing light) in a
wavelength range that is not wanted and transmitting light in a
wavelength range that is desired or wanted. For example, and with
reference to FIG. 6A, there is shown an exemplary characteristic or
curve 264 for a long-wave rejection filter that is configured so as
to generally reflect light having wavelengths shorter than that
delineated by the characteristic such as the light having
wavelengths lying in the region 272 of the graph. Also, and with
reference to FIG. 6B, there is shown an exemplary characteristic or
curve 266 for a short-wave rejection filter that is configured so
as to reflect light having wavelengths generally longer than that
delineated by the characteristic or curve such as light having the
wavelengths lying in the region 274 of the graph.
[0086] In the foregoing, the light being transmitted is the wanted
light that is, for example to be sensed and amplified by the image
intensifier tube 20. Alternatively, the color night vision system
10, 100 can be configured and arranged so that the light being
reflected is the wanted light and the light being transmitted is
the unwanted light. In this way, rejection filters can be used to
form a complimentary set of long-wave pass filters and short-wave
pass filters.
[0087] In further embodiments, the color night vision system 10,
100 further includes a noise mechanism or circuitry that adds noise
to each of the two color informational channels as herein
described.
[0088] Although a preferred embodiment of the invention has been
described using specific terms, such description is for
illustrative purposes only, and it is to be understood that changes
and variations may be made without departing from the spirit or
scope of the following claims.
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