U.S. patent application number 17/132554 was filed with the patent office on 2022-02-03 for 3 mos camera.
This patent application is currently assigned to PANASONIC I-PRO SENSING SOLUTIONS CO., LTD.. The applicant listed for this patent is PANASONIC I-PRO SENSING SOLUTIONS CO., LTD.. Invention is credited to Yota HASHIMOTO, Yuji KINIWA, Yuuichi TAKENAGA.
Application Number | 20220038610 17/132554 |
Document ID | / |
Family ID | |
Filed Date | 2022-02-03 |
United States Patent
Application |
20220038610 |
Kind Code |
A1 |
KINIWA; Yuji ; et
al. |
February 3, 2022 |
3 MOS CAMERA
Abstract
A 3 MOS camera includes a first prism that causes a first image
sensor to receive IR light of light from an observation part, a
second prism that causes a second image sensor to receive visible
light of A % (A: a predetermined real number) of the light from the
observation part, a third prism that causes a third image sensor to
receive remaining visible light of (100-A)% of the light from the
observation part, and a video signal processor that combines a
color video signal based on imaging outputs of the second image
sensor and the third image sensor and an IR video signal based on
an imaging output of the first image sensor and outputs the
combined signal to a monitor, the second image sensor and the third
image sensor being respectively bonded to positions optically
shifted by substantially one pixel.
Inventors: |
KINIWA; Yuji; (Fukuoka,
JP) ; HASHIMOTO; Yota; (Fukuoka, JP) ;
TAKENAGA; Yuuichi; (Fukuoka, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PANASONIC I-PRO SENSING SOLUTIONS CO., LTD. |
Fukuoka |
|
JP |
|
|
Assignee: |
PANASONIC I-PRO SENSING SOLUTIONS
CO., LTD.
Fukuoka
JP
|
Appl. No.: |
17/132554 |
Filed: |
December 23, 2020 |
International
Class: |
H04N 5/225 20060101
H04N005/225; H04N 5/232 20060101 H04N005/232; H04N 5/265 20060101
H04N005/265; H04N 9/04 20060101 H04N009/04; H04N 9/097 20060101
H04N009/097; G02B 5/26 20060101 G02B005/26; G02B 5/20 20060101
G02B005/20; G02B 27/10 20060101 G02B027/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 31, 2020 |
JP |
2020-131042 |
Claims
1. A 3 MOS camera comprising: a first prism that causes a first
image sensor to receive IR light of light from an observation part;
a second prism that causes a second image sensor to receive A % of
the visible light of the light from the observation part, wherein A
is a predetermined real number, and wherein the visible light from
the observation part not received by the second image sensor is
denoted as remaining visible light comprising (100-A)% of the
visible light of the light from the observation part; a third prism
that causes a third image sensor to receive the remaining visible
light comprising (100-A)% of the visible light of the light from
the observation part; and a video signal processor that combines a
color video signal based on imaging outputs of the second image
sensor and the third image sensor and an IR video signal based on
an imaging output of the first image sensor to produce a combined
signal, and outputs the combined signal to a monitor, wherein the
second image sensor and the third image sensor are respectively
bonded to positions optically shifted by substantially one
pixel.
2. The 3 MOS camera according to claim 1, further comprising: a
first reflection film formed on the first prism that reflects the
IR light of the light from the observation part, and transmits the
visible light of the light from the observation part therethrough;
a second reflection film formed on the second prism that reflects
the A % of the visible light of the light from the observation part
transmitted through the first reflection film, and transmits the
remaining visible light comprising (100-A)% of the visible light of
the light from the observation part transmitted through the first
reflection film; and wherein the remaining visible light comprising
(100-A)% of the visible light of the light from the observation
part transmitted through the second reflection film is incident on
the third prism.
3. The 3 MOS camera according to claim 1, wherein a value of A %
and a value of (100-A)% are substantially equal.
4. The 3 MOS camera according to claim 1, wherein the second image
sensor comprises a color filter comprising red, green, and blue
filters, the third image sensor comprises a color filter comprising
red, green, and blue filters, the green color filter of the color
filter of the second image sensor is located in each pixel of the
second image sensor, the green color filter of the color filter of
the third image sensor is located in each pixel of the third image
sensor, and the video signal processor selects a pixel value based
on the green color filters in each pixel to generate the color
video signal.
5. The 3 MOS camera according to claim 4, wherein the third image
sensor is disposed so as to be optically shifted by one pixel in at
least one of a horizontal direction and a vertical direction with
respect to the second image sensor.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The present disclosure relates to a 3 MOS camera.
2. Background Art
[0002] In recent years, attention has been paid to a diagnosis
method in which, at the time of surgery or examination, ICG
(indocyanine green) is administered as a fluorescent reagent into a
subject, and the ICG is excited by emission of excitation light or
the like to capture and observe a near-infrared fluorescence image
emitted by the ICG together with a subject image. For example,
JP-A-2016-75825 discloses an imaging device having a blue
separation prism that reflects a part of blue component light of
incident light and near-infrared light in a specific wavelength
region and transmits light other than the above light, a red
separation prism that reflects a part of red component light of
incident light and near-infrared light in a specific wavelength
region and transmits light other than the above light, and a green
separation prism into which the light transmitted through the red
separation prism is incident.
[0003] In a configuration in JP-A-2016-75825, a partial light
amount of the near-infrared light of light from a diseased part or
the like is incident on each of the plurality of color separation
prisms in a shared manner and imaged. For this reason, for example,
there is a problem in that light specialized in the wavelength
region of the near-infrared light cannot be received by a
corresponding imaging element. Therefore, it is difficult to output
a clearer fluorescence image of an observation part to which the
fluorescent reagent is administered at the time of surgery or
examination described above, and there is room for improvement in
that a doctor or the like can more easily grasp the diseased part.
Each of blue, red, and green lights is specially imaged. Therefore,
there is room for improvement in enhancing resolution of a video by
imaging visible light.
SUMMARY OF THE INVENTION
[0004] The present disclosure has been devised in view of the
above-mentioned circumstances, and a purpose thereof is to provide
a 3 MOS camera that achieves both generation of a clearer
fluorescence video of an observation part to which a fluorescent
reagent is administered and resolution enhancement of a color image
of the observation part to assist a doctor or the like in easily
grasping a diseased part.
[0005] The present disclosure provides a 3 MOS camera including a
first prism that causes a first image sensor to receive IR light of
light from an observation part, a second prism that causes a second
image sensor to receive visible light of A % (A: a predetermined
real number) of the light from the observation part, a third prism
that causes a third image sensor to receive remaining visible light
of (100-A)% of the light from the observation part, and a video
signal processor that combines a color video signal based on
imaging outputs of the second image sensor and the third image
sensor and an IR video signal based on an imaging output of the
first image sensor and outputs the combined signal to a monitor,
the second image sensor and the third image sensor being
respectively bonded to positions optically shifted by substantially
one pixel.
[0006] According to the present disclosure, it is possible to
achieve both the generation of the clearer fluorescence video of
the observation part to which the fluorescent reagent is
administered and the resolution enhancement of the color image of
the observation part, and thus to assist the doctor or the like in
easily grasping the diseased part.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1A is a block diagram showing an internal configuration
example of a 3 MOS camera according to a first embodiment.
[0008] FIG. 1B is a block diagram showing another internal
configuration example of the 3 MOS camera 1 according to the first
embodiment.
[0009] FIG. 2 is a diagram showing a structural example of a
spectral prism shown in FIG. 1.
[0010] FIG. 3A is a diagram showing an arrangement example of color
filters of imaging elements 151 and 152.
[0011] FIG. 3B is an explanatory diagram of a problem in a case
where the color filters of the imaging elements 151 and 152 are
configured in a Bayer array and are disposed with half pixel
shifting.
[0012] FIG. 4A is a graph showing an example of spectral
characteristics of a dichroic mirror.
[0013] FIG. 4B is a graph showing an example of spectral
characteristics of a beam splitter.
[0014] FIG. 5 is a graph showing an example of a relationship
between visible light division ratio and sensitivity, dynamic
range, and resolution in a case where exposure times of second
visible light and first visible light are the same.
[0015] FIG. 6 is a graph showing an example of the relationship
between visible light division ratio and sensitivity, dynamic
range, and resolution in a case where a ratio of the exposure times
of the second visible light and the first visible light is
10:1.
[0016] FIG. 7 is a graph showing an example of the relationship
between visible light division ratio and sensitivity, dynamic
range, and resolution in a case where the ratio of the exposure
times of the second visible light and the first visible light is
100:1.
[0017] FIG. 8 is a graph showing an example of the relationship
between visible light division ratio and sensitivity, dynamic
range, and resolution in a case where the ratio of the exposure
times of the second visible light and the first visible light is
1:10.
[0018] FIG. 9 is a diagram showing a display example of a
visible/IR combined video signal generated by the 3 MOS camera
according to the first embodiment on a monitor.
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENT
[0019] Hereinafter, embodiments that specifically disclose a 3 MOS
camera according to the present disclosure will be described in
detail with reference to drawings as appropriate.
[0020] However, more detailed description than necessary may be
omitted. For example, detailed description of a well-known matter
and redundant description of substantially the same configuration
may be omitted. This is to prevent the following description from
being unnecessarily redundant and to facilitate understanding by
those skilled in the art. The accompanying drawings and the
following description are provided for those skilled in the art to
fully understand the present disclosure, and are not intended to
limit subject matters described in claims thereby.
[0021] FIG. 1A is a block diagram showing an internal configuration
example of a 3 MOS camera 1 according to a first embodiment.
[0022] FIG. 1B is a block diagram showing another internal
configuration example of the 3 MOS camera 1 according to the first
embodiment. The 3 MOS camera 1 includes a lens 11, a spectral prism
13, imaging elements 151, 152, and 153, and a video signal
processing unit 17. The video signal processing unit 17 includes
camera signal processing units 191, 192, and 193, a pixel shifting
combination/resolution enhancement processing unit 21, and a
visible/IR combination processing unit 23. As shown in FIG. 1B, the
3 MOS camera 1 may include a video signal processing unit 17A
(refer to FIG. 1B) having a long/short exposure combination/wide
dynamic range processing unit 21A, instead of the video signal
processing unit 17 (refer to FIG. 1A). Although not shown, the 3
MOS camera 1 may include both the video signal processing unit 17
(refer to FIG. 1A) and the video signal processing unit 17A (refer
to FIG. 1B). Each configuration will be described in detail.
[0023] The 3 MOS camera 1 is used for a medical observation system
in which excitation light in a predetermined wavelength band (for
example, 760 nm to 800 nm) is emitted to a fluorescent reagent (for
example, indocyanine green; hereinafter referred to as "ICG")
administered in advance to an observation part (for example,
diseased part) in a subject such as a patient and the observation
part that emits fluorescent light on a long wavelength side (for
example, 820 to 860 nm) based on the excitation light is imaged, at
the time of surgery or examination, for example. An image (for
example, video of the observation part) captured by the 3 MOS
camera 1 is displayed on a monitor MN1 (refer to FIG. 9) and
assists a user such as a doctor in executing a medical procedure.
The spectral prism 13 will be described as examples used in the
medical observation system described above. However, the use
thereof is not limited to medical usage and the prism may be used
for industrial usage.
[0024] Although not shown in FIG. 1, a part of an objective side
(in other words, tip side) of the 3 MOS camera 1 with respect to
the lens 11 is configured by a scope that is inserted through the
observation part (for example, diseased part; the same applies
hereinafter). This scope is, for example, a main portion of a
medical instrument such as a rigid endoscope inserted into the
observation part and is a light guide member capable of guiding
light L1 from the observation part to the lens 11.
[0025] The lens 11 is attached to the objective side (in other
words, tip side) of the spectral prism 13 and collects the light L1
from the observation part (for example, reflected light at the
observation part). Collected light L2 is incident on the spectral
prism 13.
[0026] The spectral prism 13 receives the light L2 from the
observation part and splits the light into first visible light V1,
a second visible light V2, and IR light N1. The spectral prism 13
has a configuration having an IR prism 31, visible prisms 32 and 33
(refer to FIG. 2). The first visible light V1 is incident on the
imaging element 151 disposed so as to face the visible prism 32.
The second visible light V2 is incident on the imaging element 152
disposed so as to face the visible prism 33. The IR light N1 is
incident on the imaging element 153 disposed so as to face the IR
prism 31. A detailed structural example of the spectral prism 13
will be described below with reference to FIG. 2.
[0027] The imaging element 151 as an example of a second image
sensor includes, for example, a charge coupled device (CCD) or a
complementary metal oxide semiconductor
[0028] (CMOS) in which a plurality of pixels suitable for imaging
visible light are arranged, and an exposure control circuit (not
shown) using an electronic shutter. In the CCD or CMOS constituting
the imaging element 151, at least a microlens, a color filter, and
a light receiving element are disposed, for example, corresponding
to each pixel. The microlens collects incident light (visible
light). The color filter transmits visible light of a specific
color component (wavelength) transmitted through the microlens. The
color filter of the imaging element 151 is disposed in a Bayer
array (refer to FIG. 3A) such as red (R), green (G), green (G), and
blue (B). The specific color component indicates, for example, red
(R), green (G), and blue (B). The light receiving element receives
light of the specific color component (wavelength) transmitted
through the color filter. The imaging element 151 is disposed so as
to face the visible prism 32 (refer to FIG. 2). The imaging element
151 captures an image based on the first visible light V1 that is
incident for a first exposure time determined by the exposure
control circuit based on an exposure control signal CSH1 from the
camera signal processing unit 191. The imaging element 151
generates a video signal V1V of the observation part by imaging and
outputs the signal to the video signal processing unit 17.
[0029] The imaging element 152 as an example of a third image
sensor includes, for example, a CCD or a CMOS in which a plurality
of pixels suitable for imaging visible light are arranged, and an
exposure control circuit (not shown) using an electronic shutter.
In the CCD or CMOS constituting the imaging element 152, at least a
microlens, a color filter, and a light receiving element are
arranged, for example, corresponding to each pixel. The microlens
collects incident light (visible light). The color filter transmits
visible light of a specific color component (wavelength)
transmitted through the microlens. The color filter of the imaging
element 152 is disposed in the Bayer array (refer to FIG. 3A) such
as red (R), green (G), green (G), and blue (B). The specific color
component indicates, for example, red (R), green (G), and blue (B).
The light receiving element receives light of the specific color
component (wavelength) transmitted through the color filter. The
imaging element 152 is disposed so as to face the visible prism 33
(refer to FIG. 2). The imaging element 152 captures an image based
on the second visible light V2 that is incident for a second
exposure time determined by the exposure control circuit based on
an exposure control signal CSH2 from the camera signal processing
unit 192.
[0030] The imaging element 152 generates a video signal V2V of the
observation part by imaging and outputs the signal to the video
signal processing unit 17.
[0031] The imaging element 153 as an example of a first image
sensor includes, for example, a CCD or a CMOS in which a plurality
of pixels suitable for imaging IR light are arranged. The imaging
element 153 is disposed so as to face the IR prism 31 (refer to
FIG. 2). The imaging element 153 captures an image based on the
incident IR light N1. The imaging element 153 generates a video
signal N1V of the observation part by imaging and outputs the
signal to the video signal processing unit 17.
[0032] The video signal processing unit 17 is configured of a
processor such as a digital signal processor (DSP) or a field
programmable gate array (FPGA). The camera signal processing units
191 to 193, the pixel shifting combination/resolution enhancement
processing unit 21, and the visible/IR combination processing unit
23 are executed by the processor described above.
[0033] The camera signal processing unit 191 performs various types
of camera signal processing using the video signal V1V from the
imaging element 151 to generate a first visible video signal V1VD
of the observation part, and outputs the signal to the pixel
shifting combination/resolution enhancement processing unit 21 or
the long/short exposure combination/wide dynamic range processing
unit 21A. The camera signal processing unit 191 generates the
exposure control signal CSH1 for determining the first exposure
time of the imaging element 151 and outputs the signal to the
imaging element 151. The imaging element 151 controls the exposure
time of the first visible light V1 based on the exposure control
signal CSH1.
[0034] The camera signal processing unit 192 performs various types
of camera signal processing using the video signal V2V from the
imaging element 152 to generate a second visible video signal V2VD
of the observation part, and outputs the signal to the pixel
shifting combination/resolution enhancement processing unit 21 or
the long/short exposure combination/wide dynamic range processing
unit 21A. Although the details will be described below, brightness
(sensitivity) of the first visible video signal V1VD and brightness
of the second visible video signal V2VD may be substantially the
same (including the same) or may be different. In particular, the
closer the brightness (sensitivity) of the first visible video
signal V1VD and the brightness of the second visible video signal
V2VD are to substantially the same (including the same), the higher
an effect of resolution enhancement is. The camera signal
processing unit 192 generates the exposure control signal CSH2 for
determining the exposure time of the imaging element 152 and
outputs the signal to the imaging element 152.
[0035] The imaging element 152 controls the second exposure time of
the second visible light V2 based on the exposure control signal
CSH2. Although the details will be described below, the first
exposure time and the second exposure time may be the same (refer
to FIG. 5) or may be different (refer to FIGS. 6 to 8), and the
same applies hereinafter.
[0036] The camera signal processing unit 193 performs various types
of camera signal processing using the video signal N1V from the
imaging element 153 to generate an IR video signal N1VD of the
observation part, and outputs the signal to the visible/IR
combination processing unit 23.
[0037] The pixel shifting combination/resolution enhancement
processing unit 21 receives two video signals (specifically, the
first visible video signal V1VD from the camera signal processing
unit 191 and the second visible video signal V2VD from the camera
signal processing unit 192). The closer the brightness of the first
visible video signal V1VD and the brightness of the second visible
video signal V2VD are to the same, the higher the effect of
resolution enhancement by the pixel shifting combination/resolution
enhancement processing unit 21 is. Combination/pixel interpolation
processing is performed in consideration of a spatial positional
relationship between the first visible video signal V1VD and the
second visible video signal V2VD, and thus it is possible to
generate a high-resolution video signal VVD with high
resolution.
[0038] The pixel shifting combination/resolution enhancement
processing unit 21 performs combination processing on the received
two input video signals (that is, combination of the first visible
video signal V1VD generated by the camera signal processing unit
191 based on the imaging of the imaging element 151 bonded to the
visible prism 32 and the second visible video signal V2VD generated
by the camera signal processing unit 192 based on the imaging of
the imaging element 152 bonded to the visible prism 33) to generate
the high-resolution video signal VVD. With the combination
processing (refer to above) on the received two input video
signals, the pixel shifting combination/resolution enhancement
processing unit 21 can generate the high-resolution video signal
VVD having higher resolution than the first visible video signal
V1VD or the second visible video signal V2VD. The pixel shifting
combination/resolution enhancement processing unit 21 outputs the
high-resolution video signal VVD to the visible/IR combination
processing unit 23. The generation of the high-resolution video
signal VVD by the pixel shifting combination/resolution enhancement
processing unit 21 will be described below with reference to FIG.
3A.
[0039] In the 3 MOS camera 1, the video signal processing unit 17
generates the high-resolution video signal VVD by pixel shifting.
Therefore, in the spectral prism 13 (refer to FIG. 2), when the
imaging element 151 on which the first visible light V1 is incident
and the imaging element 152 on which the second visible light V2 is
incident are respectively bonded to the corresponding visible
prisms 32 and 33, it is necessary to optically shift positions of
the imaging element 151 and the imaging element 152 by
substantially one pixel (for example, in the horizontal or vertical
direction, or in both directions) to perform the bonding (refer to
FIG. 3A). Accordingly, the pixel shifting combination/resolution
enhancement processing unit 21 can generate the high-resolution
video signal VVD by the pixel shifting based on the imaging of the
imaging elements 151 and 152 which are disposed in an optically
shifted manner by substantially one pixel (refer to above). The
substantially one pixel includes one pixel, may not be exactly one
pixel, and may include, for example, a distance deviation of one
pixel plus or minus 0.25 pixels. The closer an amount of pixel
shifting is to one pixel, the higher the effect of resolution
enhancement by the pixel shifting combination/resolution
enhancement processing unit 21 is.
[0040] The long/short exposure combination/wide dynamic range
processing unit 21A receives and superimposes the two video signals
having different brightness (sensitivity) (specifically, the first
visible video signal V1VD from the camera signal processing unit
191 and the second visible video signal V2VD from the camera signal
processing unit 192) for combining the signals to generate a wide
dynamic range video signal VVDA. The long/short exposure
combination/wide dynamic range processing unit 21A superimposes and
combines the two video signals having different brightness
(sensitivity) and thus can generate the wide dynamic range video
signal VVDA with an apparently wider dynamic range than the first
visible video signal V1VD or the second visible video signal V2VD.
The long/short exposure combination/wide dynamic range processing
unit 21A outputs the wide dynamic range video signal VVDA to the
visible/IR combination processing unit 23.
[0041] The visible/IR combination processing unit 23 receives and
superimposes the high-resolution video signal VVD from the pixel
shifting combination/resolution enhancement processing unit 21 and
the IR video signal N1VD from the camera signal processing unit 193
for combining the signals to generated a visible/IR combined video
signal IMVVD. With the visible/IR combined video signal IMVVD, the
resolution is enhanced by the combination processing after the
pixel shifting. Therefore, a state around the observation part (for
example, surgical field) becomes visually clear and a state of the
diseased part can be clarified in detail by the fluorescent light
emission of the fluorescent reagent such as ICG (refer to FIG. 9).
The visible/IR combination processing unit 23 may output the
visible/IR combined video signal IMVVD to the monitor MN1 or send
the signal to a recording device (not shown) for accumulation.
[0042] The monitor MN1 constitutes, for example, an image console
(not shown) disposed in a surgery room at the time of surgery or
examination, and displays the visible/IR combined video signal
IMVVD of the observation part generated by the 3 MOS camera 1.
Accordingly, the user such as doctor can visually recognize the
visible/IR combined video signal IMVVD displayed on the monitor MN1
to grasp in detail the part that emits fluorescent light in the
observation part. The recording device is a recorder capable of
recording data of the visible/IR combined video signal IMVVD
generated by the 3 MOS camera 1, for example.
[0043] FIG. 2 is a diagram showing a structural example of the
spectral prism 13 shown in FIG. 1. Hereinafter, the structural
example of the spectral prism 13 shown in FIG. 1 will be mainly
described with reference to FIG. 2. The spectral prism 13 includes
the IR prism 31 (an example of a first prism), the visible prism 32
(an example of a second prism), and the visible prism 33 (an
example of a third prism). The IR prism 31, the visible prism 32,
and the visible prism 33 are sequentially assembled in an optical
axis direction of the light L2 collected by the lens 11.
[0044] The IR prism 31 as an example of the first prism includes an
incident surface 31a on which the light L2 is incident, a
reflection surface 31b on which a dichroic mirror DYM1 that
reflects the IR light of the light L2 is formed, and an emission
surface 31c from which the IR light is emitted. The dichroic mirror
DYM1 (an example of first reflection film) is formed on the
reflection surface 31b by vapor deposition or the like, reflects
the IR light (for example, IR light in the wavelength band of 800
nm or more) of the light L2, and transmits light (for example,
light of about 400 nm to 800 nm) other than the IR light of the
light L2 (refer to FIG. 4A). Specifically, the IR light (refer to
above) of the light L2 incident on the incident surface 31a of the
IR prism 31 is reflected by the reflection surface 31b. This IR
light is reflected by the reflection surface 31b, is then totally
reflected by the incident surface 31a of the IR prism 31, and is
incident on the imaging element 153 through the emission surface
31c.
[0045] FIG. 4A is a graph showing an example of spectral
characteristics of the dichroic mirror DYM1. The horizontal axis of
FIG. 4A indicates wavelength [nm: nanometer (the same applies
hereinafter)], and the vertical axis indicates reflectance or
transmittance. A characteristic TP1 indicates the transmittance of
the dichroic mirror DYM1. According to the characteristic TP1, the
dichroic mirror DYM1 can transmit the light of about 400 nm to 800
nm. A characteristic RF1 indicates the reflectance of the dichroic
mirror DYM1. According to the characteristic RF1, the dichroic
mirror DYM1 can reflect the IR light of 800 nm or more. Therefore,
all the IR light having a light amount indicated by an area AR1 (in
other words, the IR light of the light L2) can be incident on the
imaging element 153.
[0046] The visible prism 32 as an example of the second prism
includes an incident surface 32a on which the light (an example of
first transmitted light) transmitted through the dichroic mirror
DYM1 is incident, a reflection surface 32b on which a beam splitter
BSP1 for reflecting a partial light amount of the transmitted light
(specifically, visible light) is formed, and an emission surface
32c from which reflected visible light of the partial light amount
is emitted. The beam splitter BSP1 (an example of second reflection
film) is formed on the reflection surface 32b by vapor deposition
or the like, reflects visible light having a partial (for example,
around A % of the light incident on the incident surface 32a; A is
a predetermined real number, for example, 50) light amount of the
visible light incident on the incident surface 32a, and transmits
visible light having a remaining (100-A)% (for example, around 50%
of the light incident on the incident surface 32a) light amount
thereof (refer to FIG. 4B). Specifically, the visible light having
the partial (for example, 50%) light amount of the visible light
incident on the incident surface 32a of the visible prism 32 is
reflected by the reflection surface 32b. This part of the visible
light is reflected by the reflection surface 32b, is then totally
reflected by the incident surface 32a of the visible prism 32, and
is incident on the imaging element 151 through the emission surface
32c. In the spectral prism 13 shown in FIG. 1, a ratio of visible
light reflected by the beam splitter BSP1 is not limited to 50% and
may be in a range of 30% to 50%, for example.
[0047] The visible prism 33 as an example of the third prism has an
incident surface 33a on which the visible light having the
remaining light amount transmitted through the beam splitter BSP1
is incident and an emission surface 33c from which the visible
light having the remaining light amount is emitted. Specifically,
the visible light having the remaining light amount transmitted
through the beam splitter BSP1 is incident on the visible prism 33,
is emitted as it is, and is incident on the imaging element 152
(refer to FIG. 4B).
[0048] FIG. 4B is a graph showing an example of spectral
characteristics of the beam splitter BSP1. The horizontal axis of
FIG. 4B indicates wavelength [nm], and the vertical axis indicates
reflectance or transmittance. A characteristic TP2 indicates
transmittance and reflectance (about 50% at 400 nm to 800 nm) of
the beam splitter BSP1 in the spectral prism 13 shown in FIG. 2.
With the characteristic TP2, the beam splitter BSP1 as an example
of the second reflection film can reflect light having a light
amount of about 50% (mainly visible light) of the light of about
400 nm to 800 nm and can transmit light having a remaining light
amount of about 50% (mainly visible light) thereof. Therefore,
visible light having a light amount indicated by an area AR2 (for
example, visible light having light amount of about 50%) can be
incident on the imaging element 151. The visible light having the
light amount indicated by the area AR2 (for example, visible light
having light amount of about 50%) can be incident on the imaging
element 152.
[0049] Next, the arrangement of color filters BYR1 and BYR2 of the
imaging elements 151 and 152 will be described with reference to
FIG. 3A. FIG. 3A is a diagram showing an arrangement example of the
color filters BYR1 and BYR2 of the imaging elements 151 and 152.
The color filter BYR1 is a color filter constituting the imaging
element 151 and is disposed in the Bayer array consisting of the
color filters of red (R), green (G), green (G), and blue (B) in any
four adjacent pixels in the horizontal and vertical directions, for
example. In the Bayer array, more green (G) is disposed than red
(R) and blue (B) in any four pixels.
[0050] This is because human vision is known to react most
sensitively to green (G). Similarly, the color filter BYR2 is a
color filter constituting the imaging element 152 and is disposed
in the Bayer array consisting of the color filters of red (R),
green (G), green (G), and blue (B) in any four adjacent pixels in
the horizontal and vertical directions, for example.
[0051] As shown in FIG. 3A, the imaging elements 151 and 152 are
disposed with an offset of one pixel, and thus the color filters
BYR1 and BYR2 are disposed so as to be offset by one pixel.
Although FIG. 3A shows an example in which the offset of one pixel
is added, the color filters BYR1 and BYR2 may be disposed with an
offset of substantially one pixel (refer to above). Therefore, with
the pixel shifting of the offset of substantially one pixel (refer
to above), the green (G) pixel of one Bayer array (for example, the
color filter BYR1) is disposed on the blue (B) pixel or the red (R)
pixel of the other Bayer array (for example, the color filter
BYR2). In other words, the green (G) color filter is disposed for
all pixels. Accordingly, the pixel shifting combination/resolution
enhancement processing unit 21 that receives the first visible
video signal V1VD and the second visible video signal V2VD can
generate the high-resolution video signal VVD having high
resolution as compared with a video signal in a case where the
pixel shifting by substantially one pixel is not performed, by
selectively using light transmitted through the green (G) color
filter, which has the highest ratio of contributing to resolution
of a luminance signal in each pixel, of the color filters BYR1 and
BYR2 of the Bayer array stacked in two layers (refer to FIG.
3A).
[0052] A problem in a case where the color filters of the imaging
elements 151 and 152 are disposed with a pixel shifting offset by a
half pixel will be described with reference to FIG. 3B. FIG. 3B is
an explanatory diagram of a problem in a case where the color
filters BYR1 and BYR2 of the imaging elements 151 and 152 are
configured in the Bayer array and disposed with the half pixel
shifting. The horizontal axis and the vertical axis of FIG. 3B are
both frequencies, where fs indicates sampling frequency and fs/2
indicates Nyquist frequency.
[0053] In a case where the color filters of the imaging elements
151 and 152 are stacked and disposed with the pixel shifting offset
by the half pixel, it is found that false color or moire, which is
not present in the subject, is detected near the Nyquist frequency
(fs/2) as shown in FIG. 3B. When such false color or moire is
detected, the image quality of the color video signal deteriorates.
On the other hand, in order to solve such a problem, in the first
embodiment, the color filters BYR1 and BYR2 are disposed with the
optical offset of one pixel as shown in FIG. 3A. Accordingly, in
the high-resolution video signal VVD generated by the pixel
shifting combination/resolution enhancement processing unit 21,
there is no detection of the false color or moire as shown in FIG.
3B near the Nyquist frequency (fs/2) and the image quality is
accurately enhanced.
[0054] FIG. 5 is a graph showing an example of a relationship
between visible light division ratio and sensitivity GAN1, dynamic
range DRG1, and resolution RSO1 in a case where exposure times of
the second visible light V2 and the first visible light V1 are the
same. The horizontal axis of FIG. 5 is the visible light division
ratio. In other words, the visible light division ratio is a ratio
at which the beam splitter BSP1 reflects the visible light
transmitted through the dichroic mirror DYM1. For example, in a
case where the visible light division ratio is 10% (that is,
90:10), the beam splitter BSP1 reflects the visible light of 10% of
the visible light transmitted through the dichroic mirror DYM1 and
transmits the visible light of 90% thereof. That is, the ratio
light amount of the second visible light
[0055] V2:light amount of the first visible light V1 is 90:10.
Another visible light division ratio can be considered in the same
manner as the specific example described above. The vertical axis
of FIG. 5 shows the sensitivity GAN1, the dynamic range DRG1, and
the resolution RSO1 of the high-resolution video signal VVD
generated by the video signal processing unit 17.
[0056] FIG. 5 shows an example in which the exposure times for the
imaging elements 152 and 151 by the electronic shutter are
controlled to be the same. Therefore, it is considered that the
sensitivity GAN1 transitions according to a characteristic (for
example, a linear function) that the sensitivity is the maximum as
the visible light division ratio is smaller (for example, the
maximum (100%) and the brightest when the ratio is 0%) and the
sensitivity is the minimum (for example, the darkest at 50%) when
the ratio is 50%. This is because the sensitivity is determined by
the brightness of the brighter second visible light V2 of the
brightness of the first visible video signal V1VD based on the
first visible light V1 and the brightness of the second visible
video signal V2VD based on the second visible light V2.
[0057] It is considered that the dynamic range DRG1 transitions
according to a characteristic that the dynamic range increases
similarly as the visible light division ratio is smaller in a range
larger than zero (for example, about +80 dB when the ratio is
0.01%) and the dynamic range is the minimum (for example, 0 dB)
when the ratio is 50%. This is because a difference between a dark
portion and a bright portion tends to widen as the visible light
division ratio is smaller in the high-resolution video signal
VVD.
[0058] It is considered that the resolution RSO1 transitions
according to a characteristic that the resolution is the minimum
contrarily as the visible light division ratio is smaller (for
example, the maximum of 1 time when the ratio is 0%) and the
resolution is the maximum (for example, 1.1 times) when the ratio
is 50%. This is because a difference in pixel value between
adjacent pixels is small as the visible light division ratio is
larger and thus it is easy to realize high resolution by pixel
shifting.
[0059] FIG. 6 is a graph showing an example of a relationship
between visible light division ratio and sensitivity GAN2, dynamic
range DRG2, and resolution RSO2 in a case where a ratio of the
exposure times of the second visible light V2 and the first visible
light V1 is 10:1. The horizontal axis of FIG. 6 is the visible
light division ratio, and description thereof will be omitted since
the description is the same as that in FIG. 5. The vertical axis of
FIG. 6 shows the sensitivity GAN2, the dynamic range DRG2, and the
resolution RSO2 of the high-resolution video signal VVD generated
by the video signal processing unit 17.
[0060] FIG. 6 shows an example in which a difference is provided
such that a ratio of the exposure times for the imaging elements
152 and 151 by the electronic shutter is 10:1. It is considered, as
in the case of the sensitivity GAN1 shown in FIG. 5, that the
sensitivity GAN2 transitions according to a characteristic (for
example, a linear function) that the sensitivity is the maximum as
the visible light division ratio is smaller (for example, the
maximum (100%) and the brightest when the ratio is 0%) and the
sensitivity is the minimum (for example, the darkest at 50%) when
the ratio is 50%. This is because a brightness ratio of the second
visible video signal V2VD and the first visible video signal V1VD
is obtained by multiplying the ratio of the exposure times for the
imaging elements 152 and 151 of 10:1 by a light amount ratio of the
second visible light V2 and the first visible light V1, and the
sensitivity is determined by the brightness of the brighter second
visible video signal V2VD of the second visible video signal V2VD
and the first visible video signal V1VD.
[0061] When a difference is provided such that the ratio of the
exposure times for the imaging elements 152 and 151 is, for
example, 10:1 as compared with when the exposure time thereof is
the same, it is considered that the difference between the bright
portion and the dark portion is likely to appear further clearly
and thus it is possible to gain more dynamic range, in the
high-resolution video signal VVD. Therefore, it is considered that
the dynamic range DRG2 transitions according to a characteristic
that the dynamic range increases similarly as the visible light
division ratio is smaller in a range larger than zero (for example,
about +80 dB when the ratio is 0.1%) and the dynamic range is the
minimum (for example, +20 dB) when the ratio is 50%. That is, it is
possible to gain +20 dB even with a minimum value in the example of
FIG. 6.
[0062] When the difference is provided such that the ratio of the
exposure times for the imaging elements 152 and 151 by the
electronic shutter is 10:1, it is considered that the ratio light
amount of light incident on the imaging element 152:light amount of
light incident on the imaging element 151 =100:1 in a case where
the visible light division ratio is 10% (the ratio second visible
light V2:first visible light V1 =90:10). That is, the dark portion
is hardly projected by the first visible light V1 and the bright
portion is hardly projected by the second visible light V2, and
thus it can be considered that it is almost difficult to gain a
resolution when two video signals are superimposed. Therefore, it
is considered that the resolution RSO2 transitions over small
values (for example, the minimum of 1 time at 0% and about 1.02
times at 50%) regardless of the visible light division ratio.
[0063] FIG. 7 is a graph showing an example of a relationship
between visible light division ratio and sensitivity GAN2, dynamic
range DRG3, and resolution RSO3 in a case where the ratio of the
exposure times of the second visible light V2 and the first visible
light V1 is 100:1. The horizontal axis of FIG. 7 is the visible
light division ratio, and description thereof will be omitted since
the description is the same as that in FIG. 5. The vertical axis of
FIG. 7 shows the sensitivity GAN2, the dynamic range DRG3, and the
resolution RSO3 of the high-resolution video signal VVD generated
by the video signal processing unit 17.
[0064] FIG. 7 shows an example in which a considerable difference
is provided such that the ratio of the exposure times for the
imaging elements 152 and 151 by the electronic shutter is 100:1. It
is considered, as in the case of the sensitivity GAN2 shown in FIG.
6, that the sensitivity GAN2 transitions according to a
characteristic (for example, a linear function) that the
sensitivity is the maximum as the visible light division ratio is
smaller (for example, the maximum (100%) and the brightest when the
ratio is 0%) and the sensitivity is the minimum (for example, the
darkest at 50%) when the ratio is 50%. This is because a brightness
ratio of the second visible video signal V2VD and the first visible
video signal V1VD is obtained by multiplying the ratio of the
exposure times for the imaging elements 152 and 151 of 100:1 by a
light amount ratio of the second visible light V2 and the first
visible light V1, and the sensitivity is determined by the
brightness of the brighter second visible video signal V2VD of the
second visible video signal V2VD and the first visible video signal
V1VD.
[0065] When a considerable difference is provided such that the
ratio of the exposure times for the imaging elements 152 and 151
is, for example, 100:1 as compared with when the exposure time
thereof is the same, it is considered that the difference between
the bright portion and the dark portion is likely to appear
furthermore clearly and thus it is possible to gain more dynamic
range, in the high-resolution video signal VVD. Therefore, it is
considered that the dynamic range DRG3 transitions according to a
characteristic that the dynamic range increases similarly as the
visible light division ratio is smaller in a range larger than zero
(for example, about +80 dB when the ratio is 1%) and the dynamic
range is the minimum (for example, +40 dB) when the ratio is 50%.
That is, it is possible to gain +40 dB even with a minimum value in
the example of FIG. 7.
[0066] When the difference is provided such that the ratio of the
exposure times for the imaging elements 152 and 151 by the
electronic shutter is 100:1, it is considered that the ratio light
amount of light incident on the imaging element 152:light amount of
light incident on the imaging element 151 =1000:1 in the case where
the visible light division ratio is 10% (the ratio second visible
light V2:first visible light V1 =90:10). That is, the dark portion
is hardly projected since the second visible light V2 is too bright
and the bright portion is hardly projected since the first visible
light V1 is too dark, and thus it can be considered that it is
almost difficult to gain a resolution when two video signals are
superimposed as compared with the example of FIG. 6. Therefore, it
is considered that the resolution RSO3 transitions over small
values (for example, the minimum of 1 time at 0% and about 1.001
times at 50%) regardless of the visible light division ratio.
[0067] FIG. 8 is a graph showing an example of a relationship
between visible light division ratio and sensitivity GAN3, dynamic
range DRG4, and resolution RSO4 in a case where the ratio of the
exposure times of the second visible light V2 and the first visible
light V1 is 1:10. The horizontal axis of FIG. 8 is the visible
light division ratio, and description thereof will be omitted since
the description is the same as that in FIG. 5. The vertical axis of
FIG. 8 shows the sensitivity GAN3, the dynamic range DRG4, and the
resolution RSO4 of the high-resolution video signal VVD generated
by the video signal processing unit 17.
[0068] FIG. 8 shows an example in which a difference is provided
such that the ratio of the exposure times for the imaging elements
152 and 151 by the electronic shutter is 1:10.
[0069] Contrary to the example of FIG. 6, when the difference is
provided such that the ratio of the exposure times for the imaging
elements 152 and 151 is, for example, 1:10, it is considered that
the light amount of light incident on the imaging element 152 and
the light amount of light incident on the imaging element 151 are
substantially equal due to cancellation of the visible light
division ratio and the exposure time ratio in the case where the
visible light division ratio is 10% (second visible light V2:first
visible light V1 =90:10), for example. Therefore, it is considered
that the sensitivity GAN3 transitions according to a characteristic
that the sensitivity transitions substantially constant so as to be
the minimum when the visible light division ratio is from 0% to 10%
(in other words, in a case where light amounts incident on the
imaging elements 152 and 151 do not change much) and the
sensitivity increases monotonically in a linear function until the
visible light division ratio is larger than 10% and reaches 50%.
For example, the brightness is the maximum (50%, that is, -6 dB)
when the visible light division ratio is 50%. This is because a
brightness ratio of the second visible video signal V2VD and the
first visible video signal V1VD is obtained by multiplying the
ratio of the exposure times for the imaging elements 152 and 151 of
1:10 by a light amount ratio of the second visible light V2 and the
first visible light V1, and the sensitivity is determined by the
brightness of a brighter video signal of the second visible video
signal V2VD and the first visible video signal V1VD.
[0070] When a difference is provided such that the ratio of the
exposure times for the imaging elements 152 and 151 is, for
example, 1:10 as compared with when the exposure time thereof is
the same, it is considered that the difference in brightness is
easier to obtain as the visible light division ratio is smaller in
a range larger than 0%, but the difference between the bright
portion and the dark portion is less likely to appear as the
visible light division ratio is higher and thus it is difficult to
gain more dynamic range, in the high-resolution video signal VVD.
Therefore, the dynamic range DRG4 increases as the visible light
division ratio is smaller in a range larger than 0% (for example,
about +80 dB at 0.001%). However, when the visible light division
ratio is 10%, the brightness of the second visible video signal
V2VD and the brightness of the first visible video signal V1VD are
substantially equal due to the cancellation of the visible light
division ratio and the ratio of the exposure times for the imaging
elements 152 and 151 of 1:10 and the dynamic range DRG4 is the
minimum. When the visible light division ratio exceeds 10%, the
brightness of the second visible video signal V2VD is different
again from the brightness of the first visible video signal V1VD
and the dynamic range DRG4 is large. When the visible light
division ratio is 50%, the ratio of the brightness of the second
visible video signal V2VD and the brightness of the first visible
video signal V1VD is 1:10 by the multiplication of the ratio of the
exposure times for the imaging elements 152 and 151 of 1:10 and the
dynamic range is +20 dB.
[0071] When the difference is provided such that the ratio of the
exposure times for the imaging elements 152 and 151 by the
electronic shutter is 1:10, it is considered that the light amount
of light incident on the imaging element 152 and the light amount
of light incident on the imaging element 151 are substantially
equal in the case where the visible light division ratio is 10%
(the ratio second visible light V2:first visible light V1 =90:10),
for example (refer to above). That is, when the cancellation of the
visible light division ratio and the exposure time ratio (1:10)
occurs (for example, when the visible light division ratio is 10%),
the first visible video signal V1VD based on the first visible
light V1 and the second visible video signal V2VD based on the
second visible light V2 have the same brightness. Therefore, it is
considered that the resolution RSO4 transitions according to a
characteristic that the resolution is the maximum and the
resolution decreases from the maximum value at a visible light
division ratio at which the cancellation is less likely to
occur.
[0072] FIG. 9 is a diagram showing a display example of the
visible/IR combined video signal IMVVD generated by the 3 MOS
camera 1 according to the first embodiment on the monitor MN1. The
visible/IR combined video signal IMVVD shown in FIG. 9 is generated
based on imaging at the observation part (for example, around liver
and pancreas) of the patient who is the subject and is displayed on
the monitor MN1. In FIG. 9, the fluorescent reagent of ICG, which
is administered in advance to the diseased part in a body of the
patient before surgery or examination, emits light, and a place
that emits the light (for example, diseased part FL1) is shown so
as to be known in the visible/IR combined video signal IMVVD. The
high-resolution video signal VVD having the high resolution is
generated by the pixel shifting combination/resolution enhancement
processing unit 21. Therefore, a clear video of the surgical field
such as an observation target can be obtained with the visible/IR
combined video signal IMVVD. In this manner, the 3 MOS camera 1 can
generate the visible/IR combined video signal IMVVD, which allows
the user such as doctor to grasp the details of the observation
part with high image quality and to easily specify a position of
the diseased part, and display the signal on the monitor MN1, at
the time of surgery or examination, for example.
[0073] As described above, the 3 MOS camera 1 according to the
first embodiment is provided with the first prism (for example, IR
prism 31) that causes the imaging element 153 to receive the IR
light of the light L2 from the observation part (for example,
diseased part in the subject), the second prism (for example,
visible prism 32) that reflects the visible light of A % of the
light L2 from the observation part (for example, diseased part in
the subject) and causes the imaging element 151 to receive the
remaining (100-A)% thereof, and the third prism (for example,
visible prism 33) that causes the imaging element 152 to receive
the remaining visible light of (100-A)% thereof. The 3 MOS camera 1
is provided with the video signal processing unit 17 that combines
the color video signal based on the imaging outputs of the imaging
element 151 and the imaging element 152, which are respectively
bonded to the positions optically shifted by substantially one
pixel, and the IR video signal based on the imaging output of the
imaging element 153, and outputs the combined signal to the monitor
MN1.
[0074] Accordingly, the 3 MOS camera 1 can separate (split), by the
spectral prism 13, the IR light specialized in a fluorescent region
of the fluorescent reagent of the light from the observation part
(for example, diseased part) to which the fluorescent reagent (for
example, ICG) is administered in advance in the subject such as
patient at the time of surgery or examination, for example.
[0075] The 3 MOS camera 1 can generate an RGB color video signal
having high resolution based on the imaging outputs of the imaging
elements 151 and 152, which are optically shifted by substantially
one pixel, obtained by reflecting the part of the visible light of
the light from the observation part and transmitting the remaining
visible light thereof on the beam splitter BSP1. The 3 MOS camera 1
can generate an RGB color video signal with an expanded dynamic
range by combining the imaging outputs of the imaging elements 151
and 152. The 3 MOS camera 1 can generate and output clearer
fluorescence images in both the IR light and the visible light and
thus achieve both the generation of a clearer fluorescence video of
the observation part to which the fluorescent reagent is
administered and the resolution enhancement of the color image of
the observation part to assist the doctor or the like in easily
grasping the diseased part.
[0076] The first reflection film (for example, dichroic mirror
DYM1) that reflects the IR light is formed on the first prism. The
second reflection film (for example, beam splitter BSP1) that
reflects the visible light of A % of the visible light transmitted
through the first reflection film and transmits the visible light
of (100-A)% thereof is formed on the second prism. The visible
light of (100-A)% that transmits through the second reflection film
is incident on the third prism. The dichroic mirror DYM1 first
splits the IR light of the light from the observation part (for
example, diseased part), and the visible light transmitted through
the dichroic mirror DYM1 is split by the beam splitter BSP1.
Therefore, it is possible to improve the efficiency of the
splitting in the dichroic mirror DYM1 and the beam splitter
BSP1.
[0077] A value of A % and a value of the remaining (100-A)% are
substantially equal. The A value becomes substantially 50, and
light having equal brightness is incident on each of the color
filters BYR1 and BYR2, which are optically shifted by substantially
one pixel. Therefore, the 3 MOS camera 1 can effectively generate
the highest resolution RGB color video signal.
[0078] The color filter BYR1 having red (R), green (G), and blue
(B) of the imaging element 151 and the color filter BYR2 having red
(R), green (G), and blue (B) of the imaging element 152 are
disposed such that the green (G) color filter is located in each
pixel. The video signal processing unit 17 selects a pixel value
based on the green (G) color filter disposed so as to be located in
each pixel and mainly uses the selected pixel value to generate the
luminance signal among the color video signals. Accordingly, the
video signal processing unit 17 can generate the high-resolution
video signal VVD having high resolution as compared with the video
signal in a case where the pixel shifting by substantially one
pixel is not performed, by selectively using light transmitted
through the green (G) color filter, which has the highest ratio of
contributing to resolution of a luminance signal in each pixel, of
the color filters BYR1 and BYR2 of the Bayer array stacked in two
layers (refer to FIG. 3A).
[0079] This is based on the fact that the green (G) color filter is
known to have the highest proportion of contributing to the
resolution of the luminance signal since human vision is most
sensitive to green (G).
[0080] The imaging element 152 is disposed so as to be optically
shifted by one pixel in at least one of the horizontal direction or
the vertical direction with respect to the imaging element 151.
Accordingly, the video signal processing unit can generate the
high-resolution video signal VVD by the pixel shifting based on the
imaging of the imaging elements 151 and 152 which are disposed in
an optically shifted manner by substantially one pixel (refer to
above).
[0081] The 3 MOS camera 1 controls the ratio of the exposure times
of the imaging elements 151 and 152 to be the same or different.
Accordingly, the 3 MOS camera 1 can generate high-quality video
signals that adaptively realize sensitivity, dynamic range, and
resolution fitted to the preference of the user according to the
ratio of the exposure times of the imaging elements 151 and 152 and
the reflectance of the visible light by the beam splitter BSP1
(refer to FIGS. 5 to 8).
[0082] Although various embodiments are described with reference to
the drawings, it goes without saying that the present disclosure is
not limited to such examples. It is obvious to those skilled in the
art that various modification examples, change examples,
substitution examples, addition examples, deletion examples, and
equivalent examples can be conceived within the scope of the
claims. Of course, it is understood that the various examples
belong to the technical scope of the present disclosure. Further,
the respective constituent elements in the various embodiments
described above may be randomly combined in the scope of not
departing from the spirit of the invention.
[0083] For example, the IR prism 31 is illustrated as an example of
the first prism in the first embodiment described above, but the
first prism may not be limited to the IR prism 31. For example, in
a case where the first prism is not a visible prism that reflects
the visible light, the first prism may be a prism that reflects the
IR light and light in another wavelength band (for example,
wavelength band of ultraviolet ray) other than the visible light of
the light L2. Accordingly, instead of the IR video signal, a video
obtained by combining, for example, a video signal based on imaging
of the ultraviolet ray and an RGB color video signal with enhanced
resolution and expanded dynamic range can be output to the monitor
MN1 or the like.
[0084] In the spectral prism 13 shown in FIG. 2, an example in
which the IR prism 31 is disposed most on the objective side has
been described, but the IR prism 31 may not be disposed on the most
objective side. For example, the IR prism 31 may be disposed at any
of the positions of the visible prisms 32 and 33. With the bonding
of the imaging elements 151 and 152 to the visible prisms 32 and 33
with the optical shift of substantially one pixel (refer to above),
it is possible to obtain the same effect as that of the 3 MOS
camera 1 according to the first embodiment described above
regardless of the position of the IR prism 31 on the spectral prism
13.
[0085] The present disclosure is useful as the 3 MOS camera that
achieves both the generation of the clearer fluorescence video of
the observation part to which the fluorescent reagent is
administered and the resolution enhancement of the color image of
the observation part to assist the doctor or the like in easily
grasping the diseased part.
[0086] The present application is based upon Japanese Patent
Application (Patent Application No. 2020-131042 filed on Jul. 31,
2020), the content of which is incorporated herein by
reference.
* * * * *