U.S. patent application number 13/088973 was filed with the patent office on 2013-08-22 for endoscope apparatus, method, and computer readable medium.
The applicant listed for this patent is Kenta MATSUBARA, Hiroshi YAMAGUCHI. Invention is credited to Kenta MATSUBARA, Hiroshi YAMAGUCHI.
Application Number | 20130217968 13/088973 |
Document ID | / |
Family ID | 45040270 |
Filed Date | 2013-08-22 |
United States Patent
Application |
20130217968 |
Kind Code |
A9 |
MATSUBARA; Kenta ; et
al. |
August 22, 2013 |
ENDOSCOPE APPARATUS, METHOD, AND COMPUTER READABLE MEDIUM
Abstract
An endoscope apparatus comprising an irradiating section that
switches over time between irradiating a target with light in a
first wavelength region and light in a second wavelength region; a
light receiving section that receives returned light from the
target; a movement identifying section that identifies movement of
the target, based on an image of the target captured using returned
light from the target irradiated by light in the first wavelength
region; a control section that that predicts timings at which a
phase of the movement of the target is a predetermined phase, based
on the movement identified by the movement identifying section, and
causes the irradiating section to emit light in the second
wavelength region at the predicted timings; and an image generating
section that generates an image of the target based on the returned
light received by the light receiving section at the predicted
timings.
Inventors: |
MATSUBARA; Kenta; (KANAGAWA,
JP) ; YAMAGUCHI; Hiroshi; (KANAGAWA, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MATSUBARA; Kenta
YAMAGUCHI; Hiroshi |
KANAGAWA
KANAGAWA |
|
JP
JP |
|
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20120265014 A1 |
October 18, 2012 |
|
|
Family ID: |
45040270 |
Appl. No.: |
13/088973 |
Filed: |
April 18, 2011 |
Current U.S.
Class: |
600/118 |
Current CPC
Class: |
A61B 1/00186 20130101;
A61B 1/0638 20130101; A61B 1/063 20130101; A61B 1/043 20130101 |
Class at
Publication: |
600/118 |
International
Class: |
A61B 1/06 20060101
A61B001/06 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 19, 2010 |
JP |
2010-096279 |
Claims
1. An endoscope apparatus comprising: an irradiating section that
switches over time between irradiating a target with light in a
first wavelength region and light in a second wavelength region; a
light receiving section that receives returned light from the
target irradiated with the light from the irradiating section; a
movement identifying section that identifies movement of the
target, based on a first image of the target captured as a result
of the light receiving section receiving first returned light,
which is returned light from the target irradiated by the light in
the first wavelength region; a timing predicting section that
predicts a plurality of timings at which a phase of the movement of
the target is a predetermined phase, based on the movement
identified by the movement identifying section; a control section
that causes the irradiating section to emit the light in the second
wavelength region at the timings predicted by the timing predicting
section and causes the light receiving section to receive second
returned light, which is returned light from the target irradiated
by the light in the second wavelength region; and an image
generating section that generates a second image of the target
based on the second returned light received by the light receiving
section at the timings predicted by the timing predicting
section.
2. The endoscope apparatus according to claim 1, wherein the
control section causes the light receiving section to receive the
first returned light at one or more timings between temporally
adjacent timings among the timings predicted by the timing
predicting section, and the image generating section generates the
first image at each of the one or more timings, based on the first
returned light received by the light receiving section.
3. The endoscope apparatus according to claim 1, wherein the
control section causes the light receiving section to receive the
second returned light at each of the timings predicted by the
timing predicting section, over a period longer than the period
during which the light receiving section receives the first
returned light to capture one of the first images.
4. The endoscope apparatus according to claim 1, further comprising
a light receiving time setting section that sets length of a light
receiving period during which the light receiving section receives
the second returned light at the timings predicted by the timing
predicting section, based on the movement identified by the
movement identifying section, wherein the control section causes
the light receiving section to receive the second returned light
for the period length set by the light receiving time setting
section.
5. The endoscope apparatus according to claim 4, wherein the light
receiving time setting section identifies movement amount of the
target at the timings predicted by the timing predicting section,
based on the movement identified by the movement identifying
section, and sets the light receiving period to be longer when the
identified movement amount is larger.
6. The endoscope apparatus according to claim 1, wherein the light
in the second wavelength region is excitation light that excites a
luminescent substance in the target, and the second returned light
is luminescent light generated by the luminescent substance being
excited by the excitation light.
7. The endoscope apparatus according to claim 1, wherein the light
in the second wavelength region is light in a narrower band than
the light in the first wavelength region.
8. The endoscope apparatus according to claim 1, wherein the light
in the first wavelength region is light in a visible wavelength
region.
9. The endoscope apparatus according to claim 1, wherein the image
generating section generates the second image by adding together
signals indicating an amount of the second returned light received
by the light receiving section at each of the timings predicted by
the timing predicting section.
10. The endoscope apparatus according to claim 1, wherein the
control section causes light receiving elements of the light
receiving section to receive the second returned light at the
timings predicted by the timing predicting section, and causes the
light receiving elements to receive the first returned light at one
or more timings between temporally adjacent timings among the
timings predicted by the timing predicting section.
11. The endoscope apparatus according to claim 1, wherein the light
receiving section includes: a first light receiving section having
a plurality of light receiving elements that receive the first
returned light; and a second light receiving section having a
plurality of light receiving elements that receive the second
returned light.
12. The endoscope apparatus according to claim 11, further
comprising a light splitting section that splits light in a
wavelength region of the first returned light and light in a
wavelength region of the second returned light into different
optical paths, wherein the first light receiving section receives
the first returned light resulting from the splitting by the light
splitting section, and the second light receiving section receives
the second returned light resulting from the splitting by the light
splitting section.
13. The endoscope apparatus according to claim 11, wherein the
control section causes the light receiving elements of the second
light receiving section to have multiple exposures to the second
returned light at the timings predicted by the timing predicting
section.
14. A method for controlling an endoscope apparatus including an
irradiating section that emits light and a light receiving section
that receives returned light from a target irradiated with the
light from the irradiating section, the method comprising:
identifying movement of the target, based on a first image of the
target captured as a result of the light receiving section
receiving first returned light, which is returned light from the
target irradiated by light in a first wavelength region; predicting
a plurality of timings at which a phase of the movement of the
target is a predetermined phase, based on the identified movement;
causing the irradiating section to switch from emitting the light
in the first wavelength region to emitting the light in the second
wavelength region at the predicted timings, and causing the light
receiving section to receive second returned light, which is
returned light from the target irradiated by light in a second
wavelength region; and generating a second image of the target
based on the second returned light received by the light receiving
section at the predicted timings.
15. A computer readable medium storing thereon a program for use by
an endoscope apparatus including an irradiating section that emits
light and a light receiving section that receives returned light
from a target irradiated with the light from the irradiating
section, the program causing a computer to function as: an
irradiation control section that causes the irradiating section to
switch over time between irradiating the target with light in a
first wavelength region and light in a second wavelength region a
movement identifying section that identifies movement of the
target, based on a first image of the target captured as a result
of the light receiving section receiving first returned light,
which is returned light from the target irradiated by the light in
the first wavelength region; a timing predicting section that
predicts a plurality of timings at which a phase of the movement of
the target is a predetermined phase, based on the movement
identified by the movement identifying section; a control section
that causes the irradiation control section to emit the light in
the second wavelength region at the timings predicted by the timing
predicting section and causes the light receiving section to
receive second returned light, which is returned light from the
target irradiated by the light in the second wavelength region; and
an image generating section that generates a second image of the
target based on the second returned light received by the light
receiving section at the timings predicted by the timing predicting
section.
Description
BACKGROUND
[0001] 1. Technical Field
[0002] The present invention relates to an endoscope apparatus, a
method, and a computer readable medium. The contents of the
following Japanese patent application are incorporated herein by
reference, [0003] NO. 2010-096279 filed on Apr. 19, 2010.
[0004] 2. Related Art
[0005] A technique is known for obtaining a fluorescent image via
multiple exposure each time respiration or pulse of an organism
enters a prescribed state, as shown in Patent Document 1, for
example. Another technique is known for capturing an image of a
heart only in a diastolic state, based on the waveform of an
electrocardiogram, to obtain a detailed still image without blur,
as shown in Patent Document 2, for example. Yet another technique
is known for capturing a plurality of radiographic images at
timings when identical pulse phases are detected from a subject and
superimposing these radiographic images on each other, as shown in
Patent Document 3, for example.
Patent Document 1: Japanese Patent Application Publication No.
2009-236846
Patent Document 2: Japanese Patent Application Publication No.
2008-93220
Patent Document 3: Japanese Patent Application Publication No.
2008-188165
[0006] When capturing an image of a target under observation using
weak light with a low intensity, as in fluorescent observation, it
is necessary to expose the target to light for a long time due the
increased signal-to-noise ratio. If the target moves during the
long exposure time, the fluorescent image becomes blurred. Movement
of the target is not limited to the pulse-like motion of
respiration or a heart beat, and may also include a combination of
a variety of movements such as the peristaltic movement of
intestines. In this case, image blue occurs when image capturing is
performed based on a cardiographic signal or respiration signal.
Therefore, there is a problem that weak light images with little
blur and high signal-to-noise ratios cannot be obtained.
SUMMARY
[0007] In order to solve the above problems, according to a first
aspect related to the innovations herein, provided is an endoscope
apparatus comprising an irradiating section that switches over time
between irradiating a target with light in a first wavelength
region and light in a second wavelength region; a light receiving
section that receives returned light from the target irradiated
with the light from the irradiating section; a movement identifying
section that identifies movement of the target, based on a first
image of the target captured as a result of the light receiving
section receiving first returned light, which is returned light
from the target irradiated by the light in the first wavelength
region; a timing predicting section that predicts a plurality of
timings at which a phase of the movement of the target is a
predetermined phase, based on the movement identified by the
movement identifying section; a control section that causes the
irradiating section to emit the light in the second wavelength
region at the timings predicted by the timing predicting section
and causes the light receiving section to receive second returned
light, which is returned light from the target irradiated by the
light in the second wavelength region; and an image generating
section that generates a second image of the target based on the
second returned light received by the light receiving section at
the timings predicted by the timing predicting section.
[0008] The control section may cause the light receiving section to
receive the first returned light at one or more timings between
temporally adjacent timings among the timings predicted by the
timing predicting section, and the image generating section may
generate the first image at each of the one or more timings, based
on the first returned light received by the light receiving
section.
[0009] The control section may cause the light receiving section to
receive the second returned light at each of the timings predicted
by the timing predicting section, over a period longer than the
period during which the light receiving section receives the first
returned light to capture one of the first images.
[0010] The endoscope apparatus may further comprise a light
receiving time setting section that sets length of a light
receiving period during which the light receiving section receives
the second returned light at the timings predicted by the timing
predicting section, based on the movement identified by the
movement identifying section, and the control section may cause the
light receiving section to receive the second returned light for
the period length set by the light receiving time setting
section.
[0011] The light receiving time setting section may identify
movement amount of the target at the timings predicted by the
timing predicting section, based on the movement identified by the
movement identifying section, and set the light receiving period to
be longer when the identified movement amount is larger.
[0012] The light in the second wavelength region may be excitation
light that excites a luminescent substance in the target, and the
second returned light is luminescent light generated by the
luminescent substance being excited by the excitation light.
[0013] The light in the second wavelength region may be light in a
narrower band than the light in the first wavelength region.
[0014] The light in the first wavelength region may be light in a
visible wavelength region.
[0015] The image generating section may generate the second image
by adding together signals indicating an amount of the second
returned light received by the light receiving section at each of
the timings predicted by the timing predicting section.
[0016] The control section may cause light receiving elements of
the light receiving section to receive the second returned light at
the timings predicted by the timing predicting section, and cause
the light receiving elements to receive the first returned light at
one or more timings between temporally adjacent timings among the
timings predicted by the timing predicting section.
[0017] The light receiving section may include a first light
receiving section having a plurality of light receiving elements
that receive the first returned light and a second light receiving
section having a plurality of light receiving elements that receive
the second returned light.
[0018] The endoscope apparatus may further comprise a light
splitting section that splits light in a wavelength region of the
first returned light and light in a wavelength region of the second
returned light into different optical paths, the first light
receiving section may receive the first returned light resulting
from the splitting by the light splitting section, and the second
light receiving section may receive the second returned light
resulting from the splitting by the light splitting section.
[0019] The control section may cause the light receiving elements
of the second light receiving section to have multiple exposures to
the second returned light at the timings predicted by the timing
predicting section.
[0020] The summary clause does not necessarily describe all
necessary features of the embodiments of the present invention. The
present invention may also be a sub-combination of the features
described above.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 shows an exemplary endoscope apparatus 10 according
to an embodiment of the present invention.
[0022] FIG. 2 shows an exemplary block configuration of the image
capturing condition determining section 202.
[0023] FIG. 3 is a schematic view of an exemplary configuration of
a light receiving unit of the image capturing section 124.
[0024] FIG. 4 shows exemplary timings of capturing the illumination
light images and the characteristic observation light images.
[0025] FIG. 5 shows an exemplary table of information stored by the
light receiving time setting section 230.
[0026] FIG. 6 shows another exemplary configuration of a light
receiving unit of the image capturing section 124.
[0027] FIG. 7 shows exemplary image capturing timings by the first
light receiving unit 625 and the second light receiving unit
605.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0028] Hereinafter, some embodiments of the present invention will
be described. The embodiments do not limit the invention according
to the claims, and all the combinations of the features described
in the embodiments are not necessarily essential to means provided
by aspects of the invention.
[0029] FIG. 1 shows an exemplary endoscope apparatus 10 according
to an embodiment of the present invention. The endoscope apparatus
10 of the present embodiment captures an image of an analyte 20,
which is a living creature.
[0030] In the present embodiment, the endoscope apparatus 10
captures an image of the analyte 20 by irradiating the analyte 20
with illumination light. The endoscope apparatus 10 identifies the
movement of the analyte 20 based on image content of a plurality of
illumination light images. The endoscope apparatus 10 irradiates
the analyte 20 with characteristic observation light at each of a
plurality of timings at which the phase of the movement of the
analyte 20 is a prescribed phase. The endoscope apparatus 10
generates a single characteristic observation light image by
superimposing the plurality of images obtained using the
characteristic observation light on each other. As a result, the
endoscope apparatus 10 can generate a characteristic observation
light image with higher signal strength than a case where the
images are not combined. Therefore, even when the intensity of the
light returned from the analyte 20 irradiated with the
characteristic observation light is weak or when the analyte 20
moves, the endoscope apparatus 10 can provide an observer such as a
doctor with a characteristic observation light image having a
relatively high SN ratio.
[0031] The analyte 20 in the present embodiment may be an internal
organ such as the stomach, intestines, or the like inside a living
creature such as a person, for example. The analyte 20 may be the
outside or the inside lining of an internal organ. In the present
embodiment, the region serving as the image capturing target of the
endoscope apparatus 10 is referred to as the analyte 20. The
endoscope apparatus 10 includes an insertion section 120, a light
source 110, a control apparatus 100, a fluorescent agent injection
apparatus 170, a recording apparatus 150, a display apparatus 140,
and a treatment tool 180. An enlarged view of the tip of the
insertion section 120 is shown in section A of FIG. 1.
[0032] The insertion section 120 includes an insertion opening 122,
an image capturing section 124, and a light guide 126. The tip of
the insertion section 120 includes an objective lens 125 as a
portion of the image capturing section 124. The tip includes an
irradiating section 128a and an irradiating section 128b as a
portion of the light guide 126. The irradiating section 128a and
the irradiating section 128b may each include an objective lens for
light emission. The irradiating section 128a and the irradiating
section 128b can be referred to collectively as the irradiating
section 128. The tip also includes a nozzle 121.
[0033] The insertion section 120 is inserted into an organism. A
treatment tool 180, such as forceps, for treating the analyte 20 is
inserted into the insertion opening 122. The insertion opening 122
guides the treatment tool 180 inserted thereto to the tip. The
treatment tool 180 can have a variety of tip shapes. The nozzle 121
discharges water or air toward the analyte 20.
[0034] The light guide 126 guides the light emitted by the light
source 110 to the irradiating section 128. The light guide 126 can
be realized using optical fiber, for example. The irradiating
section 128 emits the light guided by the light guide 126 toward
the analyte 20. The image capturing section 124 receives the light
returning from the analyte 20 via the objective lens 125 to capture
an image of the analyte 20.
[0035] The image capturing section 124 can capture illumination
light images and characteristic observation light images. The image
capturing section 124 captures an illumination light image of the
analyte 20 using illumination light with a relatively broad
bandwidth in the visible light band. When capturing an illumination
light image, the light source 110 emits substantially white light
in the visible light region. The illumination light includes light
in the red wavelength region, the green wavelength region, and the
blue wavelength region, for example. The illumination light emitted
by the light source 110 is emitted toward the analyte 20 from the
irradiating section 128a via the light guide 126. The objective
lens 125 receives returned light in the visible wavelength region,
which is light resulting from the analyte 20 reflecting and
scattering the illumination light. The image capturing section 124
captures an image via the objective lens 125 using the returned
light from the analyte 20.
[0036] The characteristic observation light image may be a
luminescent light image obtained using luminescent light, which is
an example of the returned light from the analyte 20, for example.
Fluorescent and phosphorescent light are included in the scope of
the luminescent light. Furthermore, in addition to
photoluminescence caused by excitation light or the like, the
luminescent light can result from chemical luminescence,
triboluminescence, or thermoluminescence. In the description of the
present embodiment, the endoscope apparatus 10 captures a
fluorescent light image as an example of the luminescent light
image, using fluorescent light generated by photoluminescence.
[0037] When capturing a fluorescent light image of the analyte 20,
the light source 110 generates excitation light. The excitation
light generated by the light source 110 is emitted toward the
analyte 20 from the irradiating section 128b, via the light guide
126. A fluorescent substance in the analyte 20 is excited by the
excitation light, and therefore emits fluorescent light. The image
capturing section 124 captures the fluorescent light image of the
analyte 20 using the fluorescent returned light. As shown in FIG.
1, the irradiating section 128a and the irradiating section 128b
may be provided at different positions on the tip, but can instead
be provided at the same position on the insertion section 120 to
function as an irradiating section providing both illumination
light and excitation light.
[0038] The fluorescent substance is an example of a luminescent
substance. The fluorescent substance may be injected to the analyte
20 from the outside. The fluorescent substance may be indo cyanine
green (ICG), for example. The fluorescent agent injection apparatus
170 may inject the ICG into the blood vessels of an organism using
an intravenous injection. The amount of ICG that the fluorescent
agent injection apparatus 170 injects into the analyte 20 is
controlled by the control apparatus 100 to maintain a substantially
constant concentration of ICG in the organism. The ICG is excited
by infrared rays with a wavelength of 780 nm, for example, and
generates fluorescent light whose primary spectrum is in a
wavelength band of 830 nm. In the present embodiment, the image
capturing section 124 captures the fluorescent light image of the
analyte 20 using the fluorescent light generated by the ICG.
[0039] The fluorescent substance can be a substance other than ICG.
If structural components, such as cells, of the analyte 20 already
contain a fluorescent substance, the image capturing section 124
may capture the fluorescent light image of the analyte 20 using the
organism's own fluorescent light as the returned light.
[0040] In addition to the fluorescent light image, the
characteristic observation light image may be a narrow-band light
image captured by irradiating the analyte 20 with narrow-band
light. The irradiating section 128b may irradiate the analyte 20
with narrow-band blue light in a blue wavelength region. The
narrow-band blue light may be light in a narrower band than the
light in the blue wavelength region in the illumination light. Most
of the emitted narrow-band blue light is reflected and scattered by
the surface of the analyte 20, to be input to the objective lens
125. As a result, a narrow-band light image in which the surface of
the analyte 20 is enhanced can be obtained. In the present
embodiment, the characteristic observation light image includes a
fluorescent light image generated using excitation light and a
narrow-band blue light image generated using the narrow-band blue
light.
[0041] The image capturing section 124 can capture the image of the
analyte 20 using a variety of methods other than the light returned
when the analyte 20 is irradiated with the illumination light, the
excitation light, and the narrow-band light. For example, the image
capturing section 124 can capture an image of the analyte 20 using
electromagnetic radiation, such as X-rays or y rays, or particle
rays such as alpha rays. The image capturing section 124 may
capture the image of the analyte 20 using sound waves, electric
waves, or electromagnetic waves with a variety of wavelengths.
[0042] The control apparatus 100 includes an image generating
section 200, an image capturing condition determining section 202,
and a control section 204. The image generating section 200
generates an output image to be output to the outside, based on the
images captured by the image capturing section 124. For example,
the image generating section 200 may output the generated output
image to at least one of the recording apparatus 150 and the
display apparatus 140. More specifically, the image generating
section 200 generates an image from the plurality of images
captured by the image capturing section 124, and outputs this image
to at least one of the recording apparatus 150 and the display
apparatus 140. The image generating section 200 may output the
output image to at least one of the recording apparatus 150 and the
display apparatus 140 via a communication network such as the
Internet.
[0043] The image capturing condition determining section 202
identifies relative movement of the analyte 20 with respect to the
tip of the insertion section 120, based on the illumination light
images generated by the image generating section 200. The image
capturing condition determining section 202 determines image
capturing conditions for capturing the images of the analyte 20,
based on the identified movement of the analyte 20. The image
capturing conditions include the type of illumination light
radiated to the analyte 20, the exposure timing, the exposure
duration, and the like. The control section 204 controls the image
capturing section 124 and the light source 110 based on the image
capturing conditions determined by the image capturing condition
determining section 202.
[0044] More specifically, the image capturing condition determining
section 202 identifies the movement of the analyte 20 based on the
image content of a plurality of illumination light images. The
image capturing condition determining section 202 determines the
timings at which the fluorescent light images are to be captured to
be the timings at which the phase of the movement of the analyte 20
matches a prescribed phase. The image capturing condition
determining section 202 determines exposure conditions for
capturing the fluorescent light image at each timing. The image
generating section 200 generates a single fluorescent output image
by superimposing the fluorescent light images on each other.
[0045] The display apparatus 140 displays images including the
fluorescent light images and the illumination light images
generated by the image generating section 200. The recording
apparatus 150 records the images generated by the image generating
section 200 in a non-volatile recording medium. For example, the
recording apparatus 150 may store the images in a magnetic
recording medium such as a hard disk or in an optical recording
medium such as an optical disk.
[0046] The endoscope apparatus 10 described above can provide an
observer with a fluorescent image having relatively little blur and
a relatively high SN ratio. Therefore, even if the analyte 20 moves
and the fluorescent light from the analyte 20 is relatively weak,
the control apparatus 100 can provide the observer with a
relatively clear fluorescent image.
[0047] FIG. 2 shows an exemplary block configuration of the image
capturing condition determining section 202. The image capturing
condition determining section 202 includes a movement identifying
section 210, a timing predicting section 220, and a light receiving
time setting section 230.
[0048] The irradiating section 128 of the endoscope apparatus 10
irradiates the analyte 20 with illumination light as an example of
light in the first wavelength region and excitation light as an
example of light in the second wavelength region, and switches
between these two types of light over time. For example, the
irradiating section 128a may emit the illumination light and the
irradiating section 128b may emit the excitation light.
[0049] As an example, when the light source 110 includes a visible
light source and an excitation light source, the control section
204 can cause the irradiating section 128a to emit the illumination
light by driving the visible light source. When switching from the
illumination light to the excitation light, the control section 204
can cause the excitation light from the excitation light source to
be emitted from the irradiating section 128b. The illumination
light source may be a discharge lamp such as a xenon lamp, a
semiconductor light emitting element such as an LED, or the like.
The excitation light source may be a semiconductor light emitting
element such as a diode laser.
[0050] When switching from the illumination light to the excitation
light, the emission of the illumination light from the irradiating
section 128a can be stopped by inserting an illumination light
cutoff filter that blocks the illumination light into the optical
path from the visible light source while the visible light source
continues to emit light. The illumination light cutoff filter may
be a filter that blocks at least light in the visible light
wavelength region, and may be a light-blocking filter that
substantially prevents light from passing therethrough. Similarly,
the switching from the excitation light to the illumination light
can be achieved using an excitation light cutoff filter. The
illumination light cutoff filter and the excitation light cutoff
filter can be realized using filters whose light passing features
can be electrically controlled, such as liquid crystal filters. The
control section 204 can switch the emitted light by electrically
controlling the light passing characteristics of these filters.
When switching from the illumination light to the excitation light,
the control section 204 may prevent the emission of the
illumination light from the irradiating section 128a by stopping
the driving of the LED serving as the illumination light
source.
[0051] If the analyte 20 is irradiated with excitation light and
narrow-band blue light as an example of the light in the second
wavelength region, the light source 110 may include a narrow-band
blue light source. The narrow-band blue light source can be
realized using a narrow-band blue light passing filter that
selectively passes light in the wavelength region of the
narrow-band blue light and the visible light source. For example,
the narrow-band blue light can be emitted from the irradiating
section 128a by inserting the narrow-band blue light passing filter
in the optical path from the visible light source. The narrow-band
blue light passing filter can also be realized using a filter whose
light passing characteristics are electrically controlled, such as
a liquid crystal filter. The control section 204 can switch between
emitting the narrow-band blue light and emitting the illumination
light by electrically controlling the light passing characteristics
of the narrow-band blue light passing filter. As another example,
the light source 110 may include a separate narrow-band light
source that generates narrow-band blue light, in addition to the
visible light source. The narrow-band light source may be a
semiconductor light emitting element such as an LED or diode laser.
The control section 204 can cause the narrow-band blue light to be
emitted from at least one of the irradiating section 128a and the
irradiating section 128b by driving the narrow-band light
source.
[0052] The image capturing section 124 receives the returned light
from the analyte 20 irradiated with the light from the irradiating
section 128. When excitation light is emitted to excite the ICG in
the analyte 20, the returned light includes fluorescent light
generated as a result of the ICG being excited by the excitation
light. When light in a narrower band than the illumination light,
e.g. narrow-band blue light, is emitted, the returned light
includes light in the narrow-band blue region that results from the
narrow-band blue light being reflected and scattered by the analyte
20.
[0053] The movement identifying section 210 acquires, from the
image generating section 200, illumination light images captured by
the image capturing section 124 receiving returned illumination
light, which is the returned light from the analyte 20 irradiated
with the illumination light. The returned illumination light is an
example of first returned light. The movement identifying section
210 identifies the movement of the analyte 20, which is the image
capturing target, based on the illumination light images.
[0054] The timing predicting section 220 predicts timings at which
the phase of the movement of the analyte 20 will be a predetermined
phase, based on the movement identified by the movement identifying
section 210. The control section 204 of the control apparatus 100
emits excitation light, which is an example of light in the second
wavelength region, from the irradiating section 128b at the timings
predicted by the timing predicting section 220, and the image
capturing section 124 receives fluorescent light that is the
returned light from the analyte 20 irradiated with the excitation
light. The fluorescent light is an example of second returned
light. The image generating section 200 generates a fluorescent
light image for output by superimposing on each other the
fluorescent light images captured by the image capturing section
124 at the plurality of timings predicted by the timing predicting
section 220.
[0055] When the characteristic observation light images are
captured using narrow-band blue light, the control section 204
emits narrow-band blue light, which is an example of light in the
second wavelength region, from the irradiating section 128a at the
timings predicted by the timing predicting section 220, and the
image capturing section 124 receives returned light in a relatively
narrow wavelength region in the blue wavelength region, and this is
the returned light from the analyte 20 irradiated with the
narrow-band blue light. This returned light in the narrow
wavelength region is an example of second returned light. The image
generating section 200 generates a narrow-band blue light image for
output by superimposing on each other the narrow-band blue light
images captured by the image capturing section 124 at the timings
predicted by the timing predicting section 220. It should be noted
that the narrow-band light is not limited to narrow-band blue
light. For example, narrow-band green light in the green wavelength
region or narrow-band red light in the red wavelength region may be
used as the narrow-band light. As another example, relatively
narrow-band light in the ultra violet wavelength region or in the
infrared wavelength region may be used.
[0056] The light receiving time setting section 230 sets the light
receiving period during which the image capturing section 124
receives the fluorescent light at the timings predicted by the
timing predicting section 220, based on the movement identified by
the movement identifying section 210. Specifically, the light
receiving time setting section 230 identifies the amount of
movement of the analyte 20 at the timings predicted by the timing
predicting section 220, based on the movement identified by the
movement identifying section 210. The light receiving time setting
section 230 sets the length of the light receiving period to be
greater when the identified movement amount is greater. More
specifically, the light receiving time setting section 230
identifies the movement amount of the analyte 20 per unit time at
the timings predicted by the timing predicting section 220, based
on the movement identified by the movement identifying section 210.
The light receiving time setting section 230 sets the length of the
light receiving period to be greater when the movement amount
identified per unit time is greater.
[0057] The control section 204 causes the excitation light to be
emitted from the irradiating section 128 for at least the time
period determined by the light receiving time setting section 230.
The control section 204 causes the image capturing section 124 to
receive the fluorescent light for the period identified by the
light receiving time setting section 230. When narrow-band blue
light is used to capture the characteristic observation light
image, the control section 204 causes narrow-band blue light to be
emitted from at least one of the irradiating section 128a and the
irradiating section 128b. The control section 204 causes the image
capturing section 124 to receive the narrow-band blue returned
light for the period determined by the light receiving time setting
section 230. By controlling the image capturing conditions of the
image capturing condition determining section 202, the light
receiving period can be set to be shorter when the movement of the
analyte 20 per unit time is greater. Therefore, the blur in the
fluorescent light image and the narrow-band blue light image can be
further decreased.
[0058] The function of the control apparatus 100 may be implemented
by a computer. Specifically, by installing a program implementing
the function of the control apparatus 100 in a computer, the
computer may function as the image generating section 200, the
components of the image capturing condition determining section
202, and the control section 204. This program may be stored in a
computer readable recording medium such as a CD-ROM or hard disk,
and may be provided to the computer by having the computer read the
program from the recording medium. The program may be provided to
the computer via a network.
[0059] FIG. 3 is a schematic view of an exemplary configuration of
a light receiving unit of the image capturing section 124. The
light receiving unit includes a wavelength filter section 300 and a
light receiving section 310. The returned light from the analyte 20
passes through the objective lens 125 and the wavelength filter
section 300 to be received by the light receiving section 310.
[0060] The wavelength filter section 300 includes a plurality of
blue light passing filters 301 that selectively pass light in the
blue wavelength region, a plurality of green light passing filters
302 that selectively pass light in the green wavelength region, and
a plurality of red light passing filters 303 that pass at least
light in the red wavelength region. In FIG. 3, the blue light
passing filters 301a and 301b, green light passing filters 302a to
302d, and red light passing filters 303a and 303c are shown. The
blue light passing filter 301a, two green light passing filters
302a, and a red light passing filter 303a are arranged in a matrix
to form one wavelength filter unit. The wavelength filter section
300 may have a wavelength filter array in which a plurality of such
wavelength filter units are arranged in a matrix, in the same
manner as the light passing filters within a wavelength filter
unit.
[0061] The light receiving section 310 may be formed by arranging a
plurality of light receiving elements at positions to selectively
receive light passed by the blue light passing filters 301, the
green light passing filters 302, and the red light passing filters
303. Specifically, the light receiving section 310 may have a light
receiving element array in which a plurality of blue light
receiving sections 311 that selectively receive light in the blue
wavelength region, a plurality of green light receiving sections
312 that selectively receive light in the green wavelength region,
and a plurality of red light receiving sections 313 that receive at
least light in the red wavelength region are arranged
two-dimensionally.
[0062] More specifically, a blue light receiving section 311a
receives light passed by a blue light passing filter 301a, a green
light receiving section 312a receives light passed by a green light
passing filter 302a, and a red light receiving section 313a
receives light passed by a red light passing filter 303a. Each
light receiving element may be an image capturing element, such as
a CCD or a CMOS. When illumination light is emitted from the
irradiating section 128a, the image capturing section 124 can
capture an illumination light image of visible light using the blue
light receiving sections 311, the green light receiving sections
312, and the red light receiving sections 313.
[0063] Here, in addition to light in the red wavelength region, the
red light passing filters 303 can also pass the wavelength region
of the fluorescent light emitted by the ICG. In other words, the
red light passing filters 303 selectively pass light in the red
wavelength region and in the fluorescent light wavelength region.
When excitation light is emitted from the irradiating section 128a,
the fluorescent light emitted by the ICG passes through the red
light passing filters 303 to be received by the red light receiving
sections 313. Accordingly, the image capturing section 124 can
capture the fluorescent light images using the red light receiving
sections 313. It is preferable that at least the red light passing
filters 303 have light passing frequencies to substantially block
light in the wavelength region of the excitation light, such that
at least the red light receiving sections 313 receiving the
fluorescent light do not receive light in the wavelength region of
the excitation light. An excitation light cutoff filter than blocks
light in the wavelength region of the excitation light may be
provided over the entire surface functioning as the wavelength
filter section 300.
[0064] If narrow-band blue light images are being captured as the
characteristic observation light images simultaneously with the
fluorescent light images, the narrow-band blue returned light is
received by the blue light receiving sections 311. The image
capturing section 124 can capture the narrow-band blue light images
using the blue light receiving sections 311.
[0065] FIG. 4 shows exemplary timings of capturing the illumination
light images and the characteristic observation light images. The
illumination light images 400-1 to 400-5 are captured within one
cycle of the movement of the analyte 20. The illumination light
images 400-6 to 400-10 are captured in the next cycle of the
movement of the analyte 20, and the illumination light images
400-11 to 400-15 are captured in the cycle after that. The
illumination light images 400 are captured by exposing the light
receiving section 310 to the illumination light over a
predetermined time period .DELTA.1. By repeating this exposure over
a predetermined image capturing period, a series of illumination
light images 400 are captured. The image capturing section 124 can
capture the illumination light images 400 using the blue light
receiving sections 311, the green light receiving sections 312, and
the red light receiving sections 313.
[0066] The movement identifying section 210 detects the movement of
the analyte 20 based on the illumination light images 400-1 to
400-3. For example, the movement identifying section 210 may
identify the position and shape of a specified object captured in
each of the illumination light images 400-1 to 400-3, using image
processing such as object extraction. In this way, the movement
identifying section 210 detect the movement of the analyte 20 in
real time. The movement identifying section 210 may set the target
of the object extraction to be a distinct object from among a
plurality of objects extracted from the illumination light images
400. This distinct object may be the object that is farthest from
other objects in an image feature value coordinate system. The
object that is farthest from other objects in the image feature
value coordinate system may refer to the object that is farthest
from a closest object in the image feature value coordinate
system
[0067] The movement identifying section 210 identifies positional
change over time of the object, based on the time at which the
illumination light images 400-1 to 400-3 were captured and the
position of the object in these illumination light images 400. The
movement identifying section 210 also identifies the shape change
over time of the object, based on the time at which the
illumination light images 400-1 to 400-3 were captured and the
position of the object in these illumination light images 400.
[0068] The timing predicting section 220 predicts a period during
which the position and shape of the object remain substantially
constant. For example, the timing predicting section 220 may
identify timings at which the displacement of the object per unit
time is less than a predetermined threshold value and the
deformation of the object per unit time is less than a
predetermined threshold value. The index for the change in shape
can be the size of the object. In the example of FIG. 4, the
position and shape of the object are predicted to be substantially
constant for longer than a predetermined period after the
illumination light image 400-3 is captured. For example, until a
timing before the illumination light image 400-4 is captured, the
position and the shape of the object are predicted to be
substantially constant.
[0069] After the illumination light image 400-3 is captured, the
control section 204 causes excitation light and narrow-band blue
light to be emitted from the irradiating section 128 for at least a
time period .DELTA.2. As a result, the image capturing section 124
captures the fluorescent light image 410-1 and the narrow-band blue
light image 420-1. More specifically, the image capturing section
124 can capture the fluorescent light image 410-1 using the red
light receiving sections 313 and capture the narrow-band blue light
image 420-1 using the blue light receiving sections 311.
[0070] Here, the time period .DELTA.2 is longer than the time
period .DELTA.1. In other words, the control section 204 causes the
light receiving section to receive fluorescent light and
narrow-band blue returned light at each of the timings predicted by
the timing predicting section 220, over a time period that is
longer than the time period .DELTA.1 during which the light
receiving section 310 receives illumination returned light to
capture one illumination light image 400. As a result, the acquired
fluorescent light image 410-1 and narrow-band blue light image
420-1 are clearer than images acquired when the exposure time is
the same as the exposure time for the illumination light image.
[0071] After the fluorescent light image 410-1 and the fluorescent
light image 420-2 are captured, the control section 204 captures
the illumination light images 400-4 and 400-5. More specifically,
the control section 204 captures the illumination light images
400-4 and 400-5 by exposing the light receiving section 310 to the
illumination light during prescribed image capturing periods for
the predetermined time period .DELTA.1.
[0072] After the time t1, the movement of the analyte 20 in the
period from t1 to t2 and in the period from t2 to t3 is
substantially the same as the movement in the period from t0 to t1.
In this case, the control section 204 switches between image
capturing with the illumination light and image capturing with the
characteristic observation light at the same timings that the
illumination light images 400-1 to 400-5, the fluorescent light
image 410-1, and the narrow-band blue light image 420-1 are
captured at. As a result, the image capturing section 124 captures
the illumination light images 400-1 to 400-15, the fluorescent
light images 410-2 and 410-3, and the narrow-band blue light images
420-2 and 420-3.
[0073] In this way, the image capturing section 124 captures a
plurality of images using the illumination light while capturing
images using the characteristic observation light. In other words,
the control section 204 causes the light receiving section 310 to
receive visible returned light at one or more timings between
temporally adjacent timings among the timings of the image
capturing using the characteristic observation light. The image
generating section 200 generates the illumination light image based
on each of the one or more timings, based on the visible returned
light received by the light receiving section 310.
[0074] As described in relation to FIG. 3, the red light receiving
sections 313 can receive fluorescent light and light in the red
wavelength region, and therefore the red light receiving sections
313 used for capturing the illumination light images can also be
used to capture the fluorescent light images. In other words, the
control section 204 causes the red light receiving sections 313 of
the light receiving section 310 to receive fluorescent light at the
timings of the image capturing using the characteristic observation
light. The control section 204 also causes the red light receiving
sections 313 to receive the illumination returned light at one or
more timings between temporally adjacent timings among the timings
of the image capturing using the characteristic observation
light.
[0075] The image generating section 200 generates the fluorescent
light image 430 for output by superimposing corresponding pixels of
the fluorescent light images 410-1, 410-2, and 410-3 on each other.
The image generating section 200 generates the narrow-band blue
light image 440 for output by superimposing corresponding pixels of
the narrow-band blue light images 420-1, 420-2, and 420-3 on each
other. In this way, the image generating section 200 generates the
fluorescent light image 430 by adding together signals indicating
the amount of fluorescent light received by the light receiving
section 310 at each of the timings predicted by the timing
predicting section 220. The image generating section 200 may apply
a binning process to the fluorescent light images 430.
[0076] The image generating section 200 may perform the
superimposition to generate the fluorescent light image 430 after
applying the binning process as image processing to each of the
fluorescent light images 410-1, 410-2, and 410-3. As another
example, the image capturing section 124 may perform the binning
process on the image capture signals of the fluorescent light
images 410-1, 410-2, and 410-3, and output the resulting signals to
the image generating section 200. In other words, when reading the
image corresponding to the fluorescent light image 410-1, the image
capturing section 124 may perform binning reading and output the
result to the image generating section 200 as the image capture
signal of the fluorescent light image 410-1. The image generating
section 200 generates the fluorescent light image 410-1 based on
this image capture signal. The fluorescent light images 410-2 and
410-3 may be generated from the image capture signals obtained via
binning reading in the same manner. The image generating section
200 may then generate the fluorescent light image 430 by
superimposing the fluorescent light images 410-1, 410-2, and 410-3
obtained form the binning reading.
[0077] The image generating section 200 generates the narrow-band
blue light image 440 by adding together the signals indicating the
amount of narrow-band blue light received by the light receiving
section 310 at each of the timings predicted by the timing
predicting section 220. The process for generating the narrow-band
blue light image 440 is the same as the process for generating the
fluorescent light image 430, and therefore further description is
omitted. The image generating section 200 outputs the generated
fluorescent light image 430 and narrow-band blue light image 440 to
the outside, e.g. to the display apparatus 140 and the recording
apparatus 150.
[0078] In this way, the endoscope apparatus 10 can acquire a
characteristic observation light image with relatively little blur
by capturing characteristic observation light images at timings at
which the movement of the analyte 20 has substantially the same
phase. Furthermore, by superimposing the characteristic observation
light images on each other, the endoscope apparatus 10 can acquire
a characteristic observation light image with a high SN ratio by
decreasing the random noise, for example.
[0079] In the example of FIG. 4, the image capturing section 124
captures characteristic observation light images at a single
movement phase in each cycle of the movement of the analyte 20.
However, the endoscope apparatus 10 can capture characteristic
observation light images at each of a plurality of different
phases. For example, the image capturing section 124 may capture
characteristic observation light images at each of a plurality of
different movement phases in each cycle of the movement of the
analyte 20. The image generating section 200 may then generate one
characteristic observation light image to be output for each
movement phase, by superimposing the characteristic observation
light images at each movement phase on each other. The display
apparatus 140 may switch to display the characteristic observation
light image corresponding to the current movement phase, in
synchronization with the display of the illumination light
image.
[0080] FIG. 5 shows an exemplary table of information stored by the
light receiving time setting section 230. The light receiving time
setting section 230 stores allowable exposure times in association
with displacement amounts and deformation amounts. The displacement
amount may indicate the change amount per unit time of the position
of the object in the image, for example. The deformation amount may
refer to the change amount per unit time of the size of the object
in the image, for example. The exposure time is the maximum value
for the time period over which the light receiving section 310 can
be exposed when capturing a single characteristic observation light
image to be used in the superimposition. The light receiving time
setting section 230 references this table to determined the
exposure time .DELTA.2 when capturing one characteristic
observation light image.
[0081] More specifically, the movement identifying section 210
extracts the distinct object from each of the illumination light
images 400, and identifies the size of the distinct object and the
position of the center of the distinct object in the plane of the
image. The light receiving time setting section 230 calculates the
change amount of the center position of the distinct object per
unit time, based on the center position of the distinct object in
each illumination light image 400. The light receiving time setting
section 230 calculates the change in size of the distinct object
per unit time, based on the size of the distinct object in each
illumination light image 400.
[0082] The light receiving time setting section 230 references the
table to select the exposure time stored in association with the
displacement amount closest to the calculated change amount of the
displacement. If different deformation amounts are associated with
the displacement amount closest to the calculated change amount of
the displacement, the light receiving time setting section 230
selects the exposure time stored in association with the
deformation amount closest to the calculated change amount of the
size. The light receiving time setting section 230 determines a
value no greater than the selected exposure time to be used as the
time period .DELTA.2 of the exposure when capturing a
characteristic observation light image. As a result, a suitable
maximum value can be determined for the exposure time to restrict
image blurring, according to the displacement amount or to the
displacement amount and deformation amount.
[0083] Every time a characteristic observation light image is
captured, the image generating section 200 stores the
characteristic observation light image is a temporary storage
memory. Furthermore, the image generating section 200 adds the
exposure time used for the characteristic observation light image,
as determined by the light receiving time setting section 230, to
an exposure time counter that has an initial value of 0. When the
exposure time counter exceeds a predetermined value, the image
generating section 200 may superimpose the characteristic
observation light images stored in the memory onto each other to
generate one characteristic observation light image for output and
initialize the exposure time counter. As a result, when the analyte
20 moves little and a longer exposure time is used for capturing
the characteristic observation light image, the image generating
section 200 can generate the one characteristic observation light
image for output from a lower number of characteristic observation
light images. Therefore, when the analyte 20 moves little, the
characteristic observation light image for output can be updated
more frequently.
[0084] In the above description, the fluorescent light is received
by the red light receiving sections 313. Instead, the wavelength
filter section 300 may include fluorescent light receiving elements
that selectively receive fluorescent light and are separate from
the red light receiving elements. For example, a fluorescent light
passing filter may be provided in place of one of the two green
light passing filters 302a shown in FIG. 3. In this case, the light
receiving element at the corresponding position can function as a
fluorescent light receiving element that selectively receives
fluorescent light.
[0085] FIG. 6 shows another exemplary configuration of a light
receiving unit of the image capturing section 124. The image
capturing section 124 of the present embodiment includes a light
receiving unit that receives fluorescent light and a light
receiving unit that captures images using illumination returned
light, and these two light receiving units are distanced from each
other. Specifically, the image capturing section 124 includes a
first light receiving unit 625, which has a first wavelength filter
section 620 and a first light receiving section 630, and a second
light receiving unit 605, which has a second wavelength filter
section 600 and a second light receiving section 610. The image
capturing section 124 includes a light splitting section 650 in
addition to the objective lens 125, as the image capturing optical
system.
[0086] The light splitting section 650 splits, into different
optical paths, the visible light and the fluorescent light included
in the returned light from the analyte 20 passed through the
objective lens 125. The light splitting section 650 guides the
resulting fluorescent light to the second light receiving unit 605
and guides the resulting visible light to the first light receiving
unit 625. The light splitting section 650 may be realized by a
dichromatic mirror or a dichromatic prism. The first light
receiving section 630 receives the illumination returned light from
the splitting. The second light receiving section 610 receives the
fluorescent light from the splitting.
[0087] The first wavelength filter section 620 may have a visible
light wavelength filter array in which blue light passing filters,
green light passing filters, and red light passing filters are
arranged in the same manner as in the wavelength filter section
300. In the present embodiment, red light passing filters of the
first wavelength filter section 620 need not pass light in the
fluorescent light wavelength region as long as they pass light in
the red wavelength region. The first light receiving section 630
may have a light receiving element array in which light receiving
elements are arranged in the same manner as in the light receiving
section 310. The light receiving elements of the first light
receiving section 630 can receive the illumination returned light.
The illumination light images can be captured by the first light
receiving section 630 receiving the illumination returned light
resulting from the splitting by the light splitting section
650.
[0088] The second wavelength filter section 600 has light passing
characteristics to pass at least fluorescent light. The second
wavelength filter section 600 may have light passing
characteristics to block at least excitation light. The second
wavelength filter section 600 may have light passing
characteristics to block light in the visible light wavelength
spectrum. If the second light receiving unit 605 substantially
receives only light in the fluorescent light wavelength region as a
result of the returned light being split by the light splitting
section 650, the second wavelength filter section 600 need not be
provided. If the second light receiving section 610 receives
fluorescent light in a plurality of different wavelength regions to
capture fluorescent light images in different wavelength regions,
wavelength filters that pass light in different wavelength regions
may be provided in a two-dimensional arrangement.
[0089] The second light receiving section 610 receives fluorescent
light passed through the second wavelength filter section 600. The
second light receiving section 610 may have a light receiving
element array in which light receiving elements that can receive
fluorescent light are arranged in the same manner as in the light
receiving section 310. With the light receiving units of the
present embodiment, the illumination light images and fluorescent
light images can be captured by different light receiving units.
Therefore, it is easy to capture a single fluorescent light image
for output by performing multiple exposures of the second light
receiving section 610 to the fluorescent light. Furthermore, the
illumination light images and the fluorescent light images can be
captured at the same time.
[0090] FIG. 7 shows exemplary image capturing timings by the first
light receiving unit 625 and the second light receiving unit 605.
In FIG. 7, the image capturing section 124 captures a plurality of
illumination light images 700 and a fluorescent light image 710-3
for output.
[0091] The illumination light images 700-1 to 700-8 are captured in
one cycle of the analyte 20 movement. The illumination light images
700-9 to 700-16 are captured in the next cycle of the analyte 20
movement, and the illumination light images 700-17 to 700-24 are
captured in the cycle after that. The illumination light images 700
are captured by exposing the light receiving section 310 to the
illumination light during the predetermined time period .DELTA.1.
By repeating this exposure over a predetermined image capturing
period, a series of illumination light images 700 are captured.
[0092] The movement identifying section 210 detects the movement of
the analyte 20 based on the illumination light images 700-1 to
700-3. The process by which the movement identifying section 210
identifies the analyte 20 movement is the same as the process
described in relation to FIGS. 4 and 5 by which the movement
identifying section 210 identifies the movement of the analyte 20
from the illumination light images 400, and therefore further
description is omitted. In the example of FIG. 7, it is predicted
that the position and size of the object will remain substantially
constant for longer than the predetermined time period after the
illumination light image 700-3 is captured. For example, the
position and size of the object are predicted to remain constant
for longer than double the image capturing period of an
illumination light image.
[0093] After the illumination light image 700-3 is captured, the
control section 204 causes excitation light to be emitted from the
irradiating section 128b for at least a time period .DELTA.2 and
exposes the second light receiving section 610. The control section
204 continues to expose the first light receiving section 630 to
the illumination light emitted from the irradiating section 128a
while the excitation light is also being emitted. Due to the
splitting by the light splitting section 650, the second light
receiving section 610 is exposed to the fluorescent light in the
returned light from the analyte 20 and the first light receiving
section 630 is exposed to the illumination light in the returned
light from the analyte 20.
[0094] Here, the time period .DELTA.2 is longer than the time
period .DELTA.1. For example, the time period .DELTA.2 may be an
integer multiple, greater than 1, of the time period .DELTA.1. The
first light receiving section 630 may be exposed a plurality of
times within the period in which the second light receiving section
610 is exposed to the fluorescent light. In the example of FIG. 7,
three illumination light images 700-4 to 700-6 are obtained by
exposing the first light receiving section 630 three times. In this
way, the control section 204 causes the second light receiving
section 610 to receive fluorescent light over a period during which
the first light receiving section 630 performs a plurality of image
captures using the illumination light.
[0095] After the fluorescent light image 710-6 is captured, the
control section 204 captures the illumination light images 700-7
and 700-8. More specifically, the control section 204 captures the
illumination light images 700-7 and 700-8 by exposing the first
light receiving section 630 to the illumination light for
predetermined image capturing periods over the predetermined time
period .DELTA.1. In this way, the control section 204 captures the
illumination light images 700 at prescribed image capturing periods
in the period from the time t0 to t1.
[0096] Here, after the second light receiving section 610 is
exposed to the fluorescent light, the control section 204 does not
read the received light signals from the light receiving elements
of the second light receiving section 610, and so the light
receiving elements of the second light receiving section 610 hold
the received light signals. More specifically, the charge generated
by the exposure of the light receiving elements of the second light
receiving section 610 is held by each light receiving element.
[0097] After the time t1, the movement of the analyte 20 in the
period from t1 to t2 and in the period from t2 to t3 is
substantially the same as the movement in the period from t0 to t1.
In this case, image capturing with the illumination light is
performed at the same timings that the illumination light images
700-1 to 700-8 were captured at. As a result, the image capturing
section 124 captures the illumination light images 700-9 to 700-24.
The illumination light images 700 captured by the image capturing
section 124 are output to the outside, e.g. to the display
apparatus 140 and the recording apparatus 150.
[0098] During the time period from t1 to t3, the control section
204 performs multiple exposures of the second light receiving
section 610 at second timings corresponding to fluorescent light
exposure timings in the time period from t0 to t1 while the light
receiving elements of the second light receiving section 610
continue to hold the received light signals. In this way, the
control section 204 causes the light receiving elements of the
second light receiving section 610 to receive multiple exposures to
the fluorescent light at a plurality of timings. Therefore, as
shown generally in the fluorescent light images 710-1 to 710-3, the
signal amount gradually increases each time an exposure is
performed. After the second light receiving section 610 is exposed
to the fluorescent light three times, the control section 204 reads
the received light signals from the light receiving elements of the
second light receiving section 610 and causes the image generating
section 200 to generate the fluorescent light image 710-3 for
output. The image capturing section 124 may perform the binning
process on the image capture signal of the fluorescent light image
710-3, and output the resulting signal to the image generating
section 200. In other words, the image capturing section 124 may
perform binning reading when reading the fluorescent light image
710-3.
[0099] Since the fluorescent light image for output is obtained by
multiple exposures of the second light receiving section 610 to the
fluorescent light, a longer exposure time can be effectively
ensured. Therefore, a fluorescent light image for output with a
high SN ratio can be obtained. Furthermore, in the same manner as
the image capturing flow described in relation to FIG. 4, a
fluorescent light image for output with little image blur can be
obtained by performing exposure at timings when the movement of the
analyte 20 is at substantially the same phase.
[0100] A plurality of fluorescent light images may be generated
without performing multiple exposures, by reading the received
light signals from the light receiving elements of the second light
receiving section 610 for each fluorescent light exposure period
and using the superimposition process described in relation to FIG.
4 or the like. The image generating section 200 may generate the
fluorescent light image for output by superimposing a plurality of
fluorescent light images captured by the second light receiving
section 610 receiving light. In this way, the image generating
section 200 can generate the fluorescent light image for output
with a relatively high SN ratio by performing multiple exposures of
the second light receiving section 610 or by superimposing
fluorescent light images captured at different timings on each
other. In other words, the image generating section 200 can
generate a fluorescent light image of the analyte 20 based on the
fluorescent light received by the light receiving section at the
plurality of timings predicted by the timing predicting section
220.
[0101] The time period .DELTA.2 of the fluorescent light image
capturing may be set by the light receiving time setting section
230 in the same manner as described in relation to FIGS. 4 and 5.
The movement identifying section 210 may detect the movement of the
analyte 20 based on the content of illumination light images 700
captured during the fluorescent light image capturing, such as the
illumination light images 700-4 to 700-6. The control section 204
may expose the second light receiving section 610 to the
fluorescent light on the condition that the position and/or size of
the object identified by the movement identifying section 210 is
within a predetermined range. In other words, when the position
and/or size of the object is outside of the predetermined range,
the control section 204 may stop the exposure of the second light
receiving section 610 to the fluorescent light, for example, to
stop the image capturing of the fluorescent light images by the
second light receiving section 610. By detecting the movement of
the analyte 20 from illumination light images 700 including
illumination light images 700 captured during the fluorescent light
image capturing, the fluorescent light exposure time can be made as
long as possible. Furthermore, even if the analyte 20 moves in an
unexpected manner, significant blur in the fluorescent light image
for output can be prevented in advance by the control section 204
stopping the exposure of the second light receiving section 610
and/or stopping the emission of excitation light from the
irradiating section 128b.
[0102] If the total amount of fluorescent light exceeds a
predetermined value, the control section 204 may stop the multiple
exposure of the second light receiving section 610. More
specifically, the control section 204 gradually adds the duration
of the fluorescent light exposure time to the exposure time counter
having an initial value of 0. When the exposure time counter
exceeds a predetermined value, the control section 204 reads the
received light signals from the light receiving elements of the
second light receiving section 610 and causes the image generating
section 200 to generate the fluorescent light image for output. The
control section 204 then initializes the exposure time counter. As
a result, when the analyte 20 moves little and a longer exposure
time is used for capturing the fluorescent light images, the image
generating section 200 can generate one fluorescent light image for
output from a shorter exposure time. Therefore, when the analyte 20
moves little, the fluorescent light image for output can be updated
more frequently.
[0103] While the embodiments of the present invention have been
described, the technical scope of the invention is not limited to
the above described embodiments. It is apparent to persons skilled
in the art that various alterations and improvements can be added
to the above-described embodiments. It is also apparent from the
scope of the claims that the embodiments added with such
alterations or improvements can be included in the technical scope
of the invention.
[0104] The operations, procedures, steps, and stages of each
process performed by an apparatus, system, program, and method
shown in the claims, embodiments, or diagrams can be performed in
any order as long as the order is not indicated by "prior to,"
"before," or the like and as long as the output from a previous
process is not used in a later process. Even if the process flow is
described using phrases such as "first" or "next" in the claims,
embodiments, or diagrams, it does not necessarily mean that the
process must be performed in this order.
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