Imaging device and fluorescent endoscope device

Abstract

An imaging device 52 comprises: a color separation optical element 521 for separating incident light into three light beams, specifically light L1 in a first wavelength band including a wavelength band of first fluorescence which is emitted from a first fluorescent reagent and in which the peak wavelength of fluorescence emission is 700-800 nm, light L2 in a second wavelength band including a wavelength band of second fluorescence which is emitted from a second fluorescent reagent and in which the peak wavelength of fluorescence emission is on the longer-wavelength side of the peak wavelength of the first fluorescence, and light L3 in a third wavelength band including a portion of the wavelength band of visible light; a first imaging element 522 for imaging the light L1 in the first wavelength band; a second imaging element 523 for imaging the light L2 in the second wavelength band; and a third imaging element 524 for imaging the light L3 in the third wavelength band.

Description

Imaging device and fluorescence endoscope device

[0001] The present invention relates to an imaging device and a fluorescence endoscope device.

[0002] Conventionally, there has been known a fluorescence endoscope device that irradiates an observation target (a subject such as a human) with visible light such as excitation light or white light emitted from a light source device, and observes the fluorescence emitted from a fluorescent reagent contained in the observation target by the irradiation of the excitation light (see, for example, Patent Document 1).

[0003] The fluorescence endoscope device described in Patent Document 1 is capable of observing first and second fluorescence of two different wavelength bands corresponding to two types of first and second fluorescent reagents. Specifically, the fluorescence endoscope device includes a first light source that emits visible light (hereinafter referred to as white light), a second light source that emits first excitation light corresponding to the first fluorescent reagent, and a third light source that emits second excitation light corresponding to the second fluorescent reagent. The fluorescence endoscope device also includes first and second image capture elements. The first image capture element is irradiated with light from an observation target and captures images of the white light reflected by the observation target. The second image capture element captures both the first fluorescence emitted from the first fluorescent reagent contained in the observation target when irradiated with the first excitation light and the second fluorescence emitted from the second fluorescent reagent contained in the observation target when irradiated with the second excitation light.

[0004] International Publication No. 2017 / 047140

[0005] A known first fluorescent reagent is one that emits a first fluorescence having a peak wavelength near 700 nm when irradiated with a first excitation light. A known second fluorescent reagent is one that emits a second fluorescence having a peak wavelength near 800 nm when irradiated with a second excitation light. The first fluorescent reagent is also sensitive to the second excitation light, and may emit the first fluorescence even when irradiated with the second excitation light. The second fluorescent reagent is also sensitive to the first excitation light, and may emit the second fluorescence even when irradiated with the first excitation light. The use of such first and second fluorescent reagents in the fluorescence endoscope device described in Patent Document 1 presents the following problem. Specifically, the first and second fluorescence are imaged by the same first imaging element. Therefore, when attempting to observe the first and second fluorescence simultaneously, it is difficult to determine whether a high-brightness area in the image obtained by imaging with the first imaging element is due to the first fluorescence or the second fluorescence.

[0006] Therefore, there is a demand for a technique that can easily distinguish between the first and second fluorescent lights.

[0007] The present invention has been made in view of the above, and an object of the present invention is to provide an imaging device and a fluorescence endoscope device that can easily distinguish between the first and second fluorescence.

[0008] In order to solve the above-described problems and achieve the object, the imaging device of the present invention comprises a color separation optical element that separates incident light into three light beams: light of a first wavelength band that includes the wavelength band of a first fluorescence emitted from a first fluorescent reagent, the peak fluorescence wavelength of which is from 700 nm to 800 nm; light of a second wavelength band that includes the wavelength band of a second fluorescence emitted from a second fluorescent reagent, the peak fluorescence wavelength of which is longer than the peak wavelength of the first fluorescence; and light of a third wavelength band that includes a part of the wavelength band of visible light; a first imaging element that images the light of the first wavelength band; a second imaging element that images the light of the second wavelength band; and a third imaging element that images the light of the third wavelength band.

[0009] The fluorescence endoscope device according to the present invention includes a first light source that emits normal light including a wavelength band of visible light, a second light source that emits first excitation light for exciting a first fluorescent reagent having a peak fluorescence emission wavelength in the vicinity of 700 nm, a third light source that emits second excitation light for exciting a second fluorescent reagent having a peak fluorescence emission wavelength in the vicinity of 800 nm, and a third light source that emits incident light including light of a first wavelength band that includes the wavelength band of the first fluorescence emitted from the first fluorescent reagent and light of a second wavelength band that includes the wavelength band of the second fluorescence emitted from the second fluorescent reagent. a color separation optical element that separates light into three light beams, light of a first wavelength band and light of a third wavelength band including a part of the wavelength band of visible light; a first image sensor that captures the light of the first wavelength band; a second image sensor that captures the light of the second wavelength band; and a third image sensor that captures the light of the third wavelength band; and a processor that controls operations of the first light source, the second light source, the third light source, the first image sensor, the second image sensor, and the third image sensor, wherein the first wavelength band includes a red wavelength band of visible light, and the second wavelength band includes a blue wavelength band of visible light, and the third wavelength band includes a green wavelength band of visible light; the processor alternately turns on the first light source and at least one of the second light source and the third light source; at a timing when the first light source is turned on, generates a normal light image corresponding to the normal light based on a first captured image obtained by causing the first image capture element to capture light of the first wavelength band, a second captured image obtained by causing the second image capture element to capture light of the second wavelength band, and a third captured image obtained by causing the third image capture element to capture light of the third wavelength band; and at a timing when the at least one light source is turned on, generates a fluorescence image corresponding to at least one of the first fluorescence and the second fluorescence based on at least one of the first captured image obtained by causing the first image capture element to capture light of the first wavelength band and the second captured image obtained by causing the second image capture element to capture light of the second wavelength band.

[0010] Furthermore, a fluorescence endoscope device according to the present invention includes a first light source that emits normal light including a wavelength band of visible light, a second light source that emits first excitation light for exciting a first fluorescent reagent having a peak fluorescence emission wavelength in the vicinity of 700 nm, a third light source that emits second excitation light for exciting a second fluorescent reagent having a peak fluorescence emission wavelength in the vicinity of 800 nm, a color separation optical element that separates incident light into three light beams: light of a first wavelength band that includes the wavelength band of the first fluorescence emitted from the first fluorescent reagent, light of a second wavelength band that includes the wavelength band of the second fluorescence emitted from the second fluorescent reagent, and light of a third wavelength band that includes a part of the wavelength band of visible light, a first image sensor that images the light of the first wavelength band, a second image sensor that images the light of the second wavelength band, and a third image sensor that images the light of the third wavelength band, and the first light source the processor simultaneously turns on the first light source and at least one of the second light source and the third light source, and generates a fluorescence image corresponding to at least one of the first fluorescence and the second fluorescence based on at least one of a first image obtained by imaging light in the first wavelength band using the first imaging element and a second image obtained by imaging light in the second wavelength band using the second imaging element, and generates a third image obtained by imaging light in the third wavelength band using the third imaging element as a normal light image corresponding to the normal light.

[0011] According to the imaging device and fluorescence endoscope device of the present invention, it is possible to easily distinguish between the first and second fluorescence.

[0012] FIG. 1 is a diagram showing the configuration of a fluorescence endoscope apparatus according to an embodiment. FIG. 2 is a diagram showing the absorption spectrum of a first fluorescent reagent. FIG. 3 is a diagram showing the absorption spectrum of a second fluorescent reagent. FIG. 4 is a diagram explaining the wavelengths of first and second excitation light. FIG. 5 is a block diagram showing the configuration of a camera head and a control device. FIG. 6 is a diagram showing the configuration of an imaging unit. FIG. 7 is a diagram showing the wavelength band (first wavelength band) of light imaged by a first imaging element. FIG. 8 is a diagram showing the wavelength band (third wavelength band) of light imaged by a third imaging element. FIG. 9 is a diagram showing the wavelength band (second wavelength band) of light imaged by a second imaging element. FIG. 10 is a diagram showing the operation of the light source device and the first to third imaging elements in a third fluorescence observation mode. FIG. 11 is a diagram showing the operation of the light source device and the first to third imaging elements in a first fluorescence observation mode. FIG. 12 is a diagram showing the operation of the light source device and the first to third imaging elements in a second fluorescence observation mode. FIG. 13 is a diagram explaining a first modification of the embodiment. Fig. 14 is a diagram illustrating a first modification of the embodiment. Fig. 15 is a diagram illustrating a first modification of the embodiment. Fig. 16 is a diagram illustrating a first modification of the embodiment. Fig. 17 is a diagram illustrating a first modification of the embodiment. Fig. 18 is a diagram illustrating a second modification of the embodiment. Fig. 19 is a diagram illustrating a second modification of the embodiment.

[0013] Hereinafter, a mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings. Note that the present invention is not limited to the embodiment described below. Furthermore, in the description of the drawings, the same parts are given the same reference numerals.

[0014] [Configuration of Fluorescence Endoscope Apparatus] Fig. 1 is a diagram showing the configuration of a fluorescence endoscope apparatus 1 according to an embodiment. The fluorescence endoscope apparatus 1 is an endoscope apparatus that uses an endoscope to perform fluorescence observation of an observation target (inside a living organism). As shown in Fig. 1, this fluorescence endoscope apparatus 1 includes an insertion section 2, a light source device 3, a light guide 4, a camera head 5, a first transmission cable 6, a display device 7, a second transmission cable 8, a control device 9, and a third transmission cable 10.

[0015] In this embodiment, the insertion section 2 is a rigid endoscope. That is, the insertion section 2 has an elongated shape that is entirely rigid or partially flexible and partially rigid, and is inserted into an observation object. The insertion section 2 includes an optical system (not shown) that includes one or more lenses and focuses the normal light and first and second excitation lights reflected by the observation object, as well as the first and second fluorescence emitted from the first and second fluorescent reagents contained in the observation object. Hereinafter, for convenience of explanation, the normal light and first and second excitation lights reflected by the observation object, as well as the first and second fluorescence emitted from the first and second fluorescent reagents contained in the observation object, will be referred to as a subject image.

[0016] An excitation light cut filter 22 (FIG. 1) that removes the first and second excitation lights contained in the focused subject image is disposed at the proximal end (eyepiece 21) of the insertion portion 2. The excitation light cut filter 22 is not limited to being disposed in the insertion portion 2, and may be disposed in the camera head 5.

[0017] One end of a light guide 4 is connected to the light source device 3. As shown in FIG. 1 , the light source device 3 includes first to third light sources 31 to 33. The first light source 31 supplies normal light (hereinafter referred to as white light) including a wavelength band of visible light to one end of the light guide 4 under the control of the control device 9. The second light source 32 supplies first excitation light to one end of the light guide 4 for exciting a first fluorescent reagent contained in the observation object. The third light source 33 supplies second excitation light to one end of the light guide 4 for exciting a second fluorescent reagent contained in the observation object.

[0018] The first to third light sources 31 to 33 may be configured by LEDs (Light Emitting Diodes) or semiconductor lasers.

[0019] Here, the first fluorescent reagent has the following characteristics. FIG. 2 is a diagram showing the absorption spectrum of the first fluorescent reagent. In FIG. 2, the horizontal axis represents wavelength [nm], and the vertical axis represents absorbance of the absorption spectrum. As shown in FIG. 2, the peak wavelength of the absorption spectrum of the first fluorescent reagent is near 680 [nm]. Therefore, in order to increase the intensity of the first fluorescence emitted from the first fluorescent reagent, it is preferable to use excitation light having a wavelength near 680 [nm] as the first excitation light. Furthermore, when excited by the first excitation light, the first fluorescent reagent emits first fluorescence having a wavelength near 700 [nm].

[0020] The second fluorescent reagent has the following characteristics. FIG. 3 is a diagram showing the absorption spectrum of the second fluorescent reagent. In FIG. 3, the horizontal axis represents wavelength [nm], and the vertical axis represents absorbance of the absorption spectrum. As shown in FIG. 3, the peak wavelength of the absorption spectrum of the second fluorescent reagent is near 800 [nm]. Therefore, in order to increase the intensity of the second fluorescence emitted from the second fluorescent reagent, it is preferable to use excitation light having a wavelength near 800 [nm] as the second excitation light. Furthermore, when excited by the second excitation light, the second fluorescent reagent emits second fluorescence having a wavelength near 800 [nm].

[0021] Fig. 4 is a diagram illustrating the wavelengths of the first and second excitation light. Specifically, Fig. 4 is a diagram showing the wavelengths of the first and second excitation light relative to the absorption spectra of the first and second fluorescent reagents shown in Figs. 2 and 3. In Fig. 4, the curve indicated by the symbol "CL1" represents the absorption spectrum of the first fluorescent reagent. The curve indicated by the symbol "CL2" represents the absorption spectrum of the second fluorescent reagent. The wavelength indicated by the symbol "P1" represents the wavelength of the first excitation light. The wavelength indicated by the symbol "P2" represents the wavelength of the second excitation light.

[0022] 4, the absorption spectrum of the second fluorescent reagent shown by curve CL2 is also sensitive to the first excitation light having a wavelength P1 in the vicinity of 680 nm, and the second fluorescent reagent emits the second fluorescent light even when irradiated with the first excitation light. Therefore, when observing the first and second fluorescent lights simultaneously, it is difficult to distinguish between the first and second fluorescent lights.

[0023] Furthermore, as can be seen from the absorption spectrum of the first fluorescent reagent shown by curve CL1 in Figure 4, the first fluorescent reagent is insensitive to the second excitation light having a wavelength P2 in the vicinity of 800 [nm], and does not emit the first fluorescence even when irradiated with the second excitation light.

[0024] In this embodiment, the light source device 3 is configured as a separate entity from the control device 9, but this is not limited to this, and a configuration in which the light source device 3 and the control device 9 are provided in the same housing may also be adopted.

[0025] One end of the light guide 4 is detachably connected to the light source device 3. The other end of the light guide 4 is detachably connected to the insertion section 2. The light guide 4 propagates the white light and the first and second excitation light supplied from the light source device 3 (first to third light sources 31 to 33) from one end to the other end, and supplies them to the insertion section 2. The white light and the first and second excitation light supplied to the insertion section 2 are emitted from the tip of the insertion section 2 and irradiated onto the observation object. The white light and the first and second excitation light irradiated onto the observation object and reflected by the observation object, as well as the first and second fluorescence (subject image) emitted from the first and second fluorescent reagents contained in the observation object, are each collected by an optical system within the insertion section 2.

[0026] The camera head 5 is detachably connected to the proximal end (eyepiece 21 ( FIG. 1 )) of the insertion section 2. The camera head 5 captures an image of a subject after light is collected by the insertion section 2 and the first and second excitation lights have been removed by the excitation light cut filter 22. For ease of explanation, the image signal obtained by imaging with the camera head 5 will hereinafter be collectively referred to as a captured image. Furthermore, the subject image after the first and second excitation lights have been removed by the excitation light cut filter 22 will be referred to as an excitation light-removed subject image. The detailed configuration of the camera head 5 will be described later in the section "Configuration of the Camera Head."

[0027] One end of the first transmission cable 6 is detachably connected to the control device 9. The other end of the first transmission cable 6 is detachably connected to the camera head 5. The first transmission cable 6 transmits the captured image output from the camera head 5 to the control device 9, and also transmits the control signal, synchronization signal, clock, power, and the like sent from the control device 9 to the camera head 5.

[0028] The captured images and the like transmitted from the camera head 5 to the control device 9 via the first transmission cable 6 may be transmitted as optical signals or as electrical signals. The same applies to the transmission of control signals, synchronization signals, and clocks from the control device 9 to the camera head 5 via the first transmission cable 6.

[0029] The display device 7 is configured with a display using a liquid crystal or organic EL (Electro Luminescence) display, etc., and displays an image based on a video signal from the control device 9 under the control of the control device 9 .

[0030] One end of the second transmission cable 8 is detachably connected to the display device 7. The other end of the second transmission cable 8 is detachably connected to the control device 9. The second transmission cable 8 transmits the video signal processed by the control device 9 to the display device 7.

[0031] The control device 9 includes controllers such as a CPU (Central Processing Unit) and an MPU (Micro Processing Unit), and comprehensively controls the operations of the light source device 3, the camera head 5, and the display device 7. The control device 9 is not limited to a CPU or an MPU, and may include an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), a GPU (Graphics Processing Unit), or the like. The detailed configuration of the control device 9 will be described later in the section "Configuration of the Control Device."

[0032] One end of the third transmission cable 10 is detachably connected to the light source device 3. The other end of the third transmission cable 10 is detachably connected to the control device 9. The third transmission cable 10 transmits a control signal from the control device 9 to the light source device 3.

[0033] [Configuration of Camera Head] Next, a description will be given of the configuration of the camera head 5. Fig. 5 is a block diagram showing the configuration of the camera head 5 and the control device 9. As shown in Fig. 5, the camera head 5 includes a lens unit 51, an imaging unit 52, and a communication unit 53.

[0034] The lens unit 51 is configured using one or more lenses, and forms an image of the subject from which excitation light has been removed on the imaging surfaces of the first to third image sensors 522 to 524, respectively.

[0035] FIG. 6 is a diagram showing the configuration of the imaging unit 52. FIG. 7 is a diagram showing the wavelength band (first wavelength band) of light imaged by the first imaging element 522. FIG. 8 is a diagram showing the wavelength band (third wavelength band) of light imaged by the third imaging element 524. FIG. 9 is a diagram showing the wavelength band (second wavelength band) of light imaged by the second imaging element 523. In FIGS. 7 to 9, the horizontal axis represents wavelength [nm] and the vertical axis represents transmittance [%]. In addition, in FIGS. 7 to 9, the red, green, and blue wavelength bands are represented by the letters "R," "G," and "B," respectively, the wavelength band of the first fluorescence is represented by the letter "700," and the wavelength band of the second fluorescence is represented by the letter "800."

[0036] The imaging unit 52 corresponds to an imaging device according to the present invention. The imaging unit 52 generates a captured image by capturing an image of a subject from which excitation light has been removed. As shown in FIGS. 5 and 6 , the imaging unit 52 includes a prism 521, first to third image sensors 522 to 524, and a signal processing unit 525.

[0037] The prism 521 corresponds to a color separation optical element according to the present invention and separates the incident light into three light beams: light L1 ( FIG. 6 ) in a first wavelength band that includes the wavelength band of the first fluorescent light, light L2 ( FIG. 6 ) in a second wavelength band that includes the wavelength band of the second fluorescent light, and light L3 ( FIG. 6 ) in a third wavelength band that includes a part of the wavelength band of visible light.

[0038] In this embodiment, the first wavelength band light L1 is light in the wavelength band from 600 nm to 760 nm, which includes the red wavelength band of visible light and the wavelength band of the first fluorescent light. The second wavelength band light L2 is light in the wavelength band, which includes the blue wavelength band of visible light from 400 nm to 500 nm and the second fluorescent light wavelength band from 800 nm to 900 nm. The third wavelength band light L3 is light in the green wavelength band of visible light.

[0039] Specifically, as shown in Fig. 6, the prism 521 is a prism formed by combining three light-transmitting members 521a to 521c. Here, the two light-transmitting members 521a and 521c have triangular prism shapes extending in a direction perpendicular to the plane of Fig. 6. The light-transmitting member 521c has a quadrangular prism shape extending in a direction perpendicular to the plane of Fig. 6. A first dichroic filter 521d is provided at the interface between the two light-transmitting members 521a and 521b. A second dichroic filter 521e is provided at the interface between the two light-transmitting members 521b and 521c.

[0040] The first dichroic filter 521d corresponds to the first reflective optical element according to the present invention. This first dichroic filter 521d has the property of reflecting light L2 in the second wavelength band and transmitting light in other wavelength bands. Therefore, of the subject image from which the excitation light has been removed that is incident on the prism 521, the light L2 in the second wavelength band is reflected by the first dichroic filter 521d, is totally reflected within the light-transmitting member 521a, and then travels toward the second image sensor 523 ( FIGS. 6 and 9 ).

[0041] The second dichroic filter 521e corresponds to a second reflective optical element according to the present invention. This second dichroic filter 521e has the property of reflecting light L1 in a first wavelength band and transmitting light in other wavelength bands. Therefore, of the light transmitted through the first dichroic filter 521e, light L1 in the first wavelength band is reflected by the second dichroic filter 521e, is totally reflected within the translucent member 521b, and then travels toward the first image sensor 522 ( FIGS. 6 and 7 ). On the other hand, light L3 in a third wavelength band transmitted through the second dichroic filter 521e travels through the translucent member 521c and then travels toward the third image sensor 524 ( FIGS. 6 and 8 ).

[0042] The first to third image sensors 522 to 524 receive incident light and convert it into an electrical signal (analog signal). Examples of the first to third image sensors 522 to 524 include a CMOS (Complementary Metal Oxide Semiconductor), which is a rolling shutter type image sensor in which multiple pixels are arranged two-dimensionally in horizontal line units, and a CCD (Charge Coupled Device), which is a global shutter type image sensor.

[0043] Then, under the control of the control device 9, the first image sensor 522 captures the light L1 of the first wavelength band separated by the prism 521 from the subject image from which the excitation light has been removed. For ease of explanation, the captured image generated by the first image sensor 522 will be referred to as the first captured image below.

[0044] Furthermore, the second image sensor 523, under the control of the control device 9, captures light L2 of the second wavelength band separated by the prism 521 from the subject image from which the excitation light has been removed. For ease of explanation, the captured image generated by the second image sensor 523 will be referred to as the second captured image below.

[0045] Furthermore, under the control of the control device 9, the third image sensor 524 captures light L3 of a third wavelength band separated by the prism 521 from the subject image from which the excitation light has been removed. For ease of explanation, the captured image generated by the third image sensor 524 will be referred to as the third captured image below.

[0046] Note that no color filters, in which three filter groups are grouped according to the wavelength bands of light to be transmitted (red, green, blue) and arranged in a specific format (e.g., Bayer array), are provided on the light receiving surfaces of the first to third image sensors 522 to 524. In other words, the first to third image sensors 522 to 524 are so-called monochrome image sensors.

[0047] The first to third captured images may have different numbers of pixels, or may have the same number of pixels.

[0048] The signal processing unit 525 performs signal processing on the captured images (analog signals) generated by the first to third image sensors 522 to 524 and outputs the captured images (digital signals) under the control of the control device 9. For example, the signal processing unit 525 performs signal processing on the captured images (analog signals) generated by the first to third image sensors 522 to 524, such as processing to remove reset noise, processing to multiply the analog signals by an analog gain that amplifies the analog signals (hereinafter referred to as analog gain adjustment), and A / D conversion.

[0049] The communication unit 53 functions as a transmitter that transmits the captured images sequentially output from the imaging unit 52 to the control device 9 via the first transmission cable 6 .

[0050] The communication unit 53 may transmit the first to third captured images to the control device 9 in order, or may transmit the first to third captured images simultaneously.

[0051] [Configuration of Control Device] Next, the configuration of the control device 9 will be described with reference to Fig. 5. The control device 9 corresponds to a processor according to the present invention. As shown in Fig. 5, the control device 9 includes a communication unit 91, a processing module 92, a control unit 93, an input unit 94, an output unit 95, and a storage unit 96.

[0052] The communication unit 91 functions as a receiver that receives the captured images sequentially transmitted from the camera head 5 (communication unit 53 ) via the first transmission cable 6 .

[0053] Under the control of the control unit 93, the processing module 92 processes the captured images sequentially transmitted from the camera head 5 (communication unit 53) and received by the communication unit 91. As shown in FIG. 5 , the processing module 92 includes an image processing unit 921 and a display control unit 922.

[0054] The image processing unit 921 performs image processing on the input captured image (the captured image received by the communication unit 91). Examples of the image processing include optical black subtraction processing (clamp processing), white balance adjustment processing, demosaic processing, color correction matrix processing, gamma correction processing, YC processing for converting RGB signals into luminance color difference signals (Y, Cb / Cr signals), digital gain adjustment for multiplying by a digital gain, noise removal, and filtering for enhancing structure.

[0055] The image processing executed on the first to third captured images may be different from each other, or may be the same.

[0056] Under the control of the control unit 93, the display control unit 922 generates a video signal for displaying the captured image after image processing has been performed by the image processing unit 921. Then, the display control unit 922 outputs the video signal to the display device 7 via the second transmission cable 8.

[0057] The control unit 93 is realized by a controller such as a CPU or an MPU executing various programs stored in the storage unit 96, and controls the operations of the light source device 3, the camera head 5, and the display device 7, as well as the operation of the entire control device 9. Note that the control unit 93 is not limited to a CPU or an MPU, and may include an ASIC, an FPGA, a GPU, or the like.

[0058] The input unit 94 is configured using operation devices such as a mouse, a keyboard, and a touch panel, and receives user operations from a user such as a surgeon. The input unit 94 then outputs an operation signal corresponding to the user operation to the control unit 93.

[0059] The output unit 95 is configured using a speaker, a printer, etc., and outputs various information.

[0060] The storage unit 96 stores programs executed by the control unit 93, information necessary for the processing of the control unit 93, and the like.

[0061] [Operation of Fluorescence Endoscope Apparatus] Next, the operation of the above-described fluorescence endoscope apparatus 1 will be described. In this embodiment, the fluorescence endoscope apparatus 1 is set to one of first to third fluorescence observation modes in response to, for example, a user operation on the input unit 94. The first fluorescence observation mode is a mode in which fluorescence observation is performed using the first fluorescence. The second fluorescence observation mode is a mode in which fluorescence observation is performed using the second fluorescence. The third fluorescence observation mode is a mode in which fluorescence observation is performed using both the first and second fluorescence. Below, the operation of the fluorescence endoscope apparatus 1 will be described for each of the first to third fluorescence observation modes. It is assumed that the object to be observed contains both the first and second fluorescent reagents.

[0062] [Operation of the Fluorescence Endoscope Device in the Third Fluorescence Observation Mode] Figure 10 is a diagram showing the operation of the light source device 3 and the first to third image pickup elements 522 to 524 in the third fluorescence observation mode. Specifically, (a) of Figure 10 is a time chart showing the operation state of the first light source 31. (b) of Figure 10 is a time chart showing the operation state of the second light source 32. (c) of Figure 10 is a time chart showing the operation state of the third light source 33. (d) of Figure 10 is a time chart showing the operation state of the first image pickup element 522. (e) of Figure 10 is a time chart showing the operation state of the third image pickup element 524. (f) of Figure 10 is a time chart showing the operation state of the second image pickup element 523. 10(a) to 10(c), for convenience of explanation, the white light is represented by the letters "WLI," the first excitation light is represented by the letters "700," and the second excitation light is represented by the letters "800." Also, in Figures 10(d) to 10(f), for convenience of explanation, the first captured image generated by capturing light in the red wavelength band is represented by the letters "R," the first captured image generated by capturing the first fluorescent light is represented by the letters "700," the third captured image generated by capturing light in the green wavelength band (light L3 of the third wavelength band) is represented by the letters "G," the second captured image generated by capturing light in the blue wavelength band is represented by the letters "B," and the second captured image generated by capturing the second fluorescent light is represented by the letters "800." In the third fluorescence observation mode, the control unit 93 controls the operations of the light source device 3 and the first to third image pickup elements 522 to 524 as follows.

[0063] 10(a) to 10(c), the control unit 93 turns on the first light source 31 and turns off the second and third light sources 32 and 33 during the first frame period T1 of the first and second frame periods T1 and T2. Here, the first and second frame periods T1 and T2 are the same period and are alternately repeated.

[0064] Furthermore, as shown in (a) to (c) of Figures 10A to 10C, during the second frame period T2 of the first and second frame periods T1 and T2, the control unit 93 turns off the first light source 31 and turns on the second and third light sources 32 and 33.

[0065] The control unit 93 then causes the first to third image pickup elements 522 to 524 to perform image pickup operations during the alternately repeated first and second frame periods T1 and T2.

[0066] Specifically, in a first frame period T1, the first image sensor 522 captures light in the red wavelength band (light L1 in the first wavelength band) separated by the prism 521 from the subject image from which the excitation light has been removed, and generates a first captured image (hereinafter referred to as a red channel image). In addition, in a second frame period T2, the first image sensor 522 captures first fluorescence (light L1 in the first wavelength band) separated by the prism 521 from the subject image from which the excitation light has been removed, and generates a first captured image (hereinafter referred to as a first fluorescence image).

[0067] In addition, the second image sensor 523 captures light in the blue wavelength band (light L2 in the second wavelength band) separated by the prism 521 from the subject image from which the excitation light has been removed, during the first frame period T1, to generate a second captured image (hereinafter referred to as a blue channel image). In addition, the second image sensor 523 captures second fluorescence (light L2 in the second wavelength band) separated by the prism 521 from the subject image from which the excitation light has been removed, during the second frame period T2, to generate a second captured image (hereinafter referred to as a second fluorescence image).

[0068] Furthermore, the third image sensor 524 captures light in the green wavelength band (light L3 in the third wavelength band) separated by the prism 521 from the subject image from which the excitation light has been removed, during the first frame period T1, to generate a third captured image (hereinafter referred to as a green channel image). Also, during the second frame period T2, the third image sensor 524 captures an image in a state in which the amount of incident light is substantially zero, to generate a third captured image.

[0069] Under the control of the control unit 93, the image processing unit 921 performs image processing on each of the first to third captured images received by the communication unit 91. The image processing unit 921 also generates a normal light image, which is a color image corresponding to white light, from the red channel image, green channel image, and blue channel image. Furthermore, the image processing unit 921 superimposes the normal light image and the first and second fluorescent light images using, for example, a known alpha blending process or additive blending process, to generate a superimposed image in which the area where the first fluorescent light is emitted and the area where the second fluorescent light is emitted can be distinguished. The display control unit 922 then generates a video signal corresponding to the superimposed image and outputs it to the display device 7. As a result, the superimposed image is displayed on the display device 7.

[0070] [Operation of the Fluorescence Endoscope Device in the First Fluorescence Observation Mode] Figure 11 is a diagram showing the operation of the light source device 3 and the first to third image pickup elements 522 to 524 in the first fluorescence observation mode. Specifically, Figures 11(a) to 11(f) correspond to Figures 10(a) to 10(f), respectively. In the first fluorescence observation mode, the control unit 93 controls the operation of the light source device 3 and the first to third image pickup elements 522 to 524 as follows.

[0071] As shown in (a) to (c) of Figures 11A to 11C, the control unit 93 turns on the first light source 31 and turns off the second and third light sources 32 and 33 during the first frame period T1 of the first and second frame periods T1 and T2.

[0072] 11(a) to 11(c), the control unit 93 turns off the first and third light sources 31 and 33 and turns on the second light source 32 during the second frame period T2 of the first and second frame periods T1 and T2. That is, the third light source 33 is not used in the first fluorescence observation mode.

[0073] The control unit 93 then causes the first to third image pickup elements 522 to 524 to perform image pickup operations during the alternately repeated first and second frame periods T1 and T2.

[0074] Specifically, in the first frame period T1, the first image sensor 522 captures light in the red wavelength band (light L1 in the first wavelength band) separated by the prism 521 from the subject image from which the excitation light has been removed, to generate a first captured image (red channel image). In addition, in the second frame period T2, the first image sensor 522 captures first fluorescence (light L1 in the first wavelength band) separated by the prism 521 from the subject image from which the excitation light has been removed, to generate a first captured image (first fluorescence image).

[0075] The second image sensor 523 captures light in the blue wavelength band (light L2 in the second wavelength band) separated by the prism 521 from the subject image from which excitation light has been removed, during the first frame period T1, to generate a second captured image (blue channel image). The second image sensor 523 captures light in the blue wavelength band (light L2 in the second wavelength band) separated by the prism 521 from the subject image from which excitation light has been removed, during the second frame period T2, to generate a second captured image.

[0076] Furthermore, the third image sensor 524 captures light in the green wavelength band (light L3 in the third wavelength band) separated by the prism 521 from the subject image from which the excitation light has been removed, during the first frame period T1, to generate a third captured image (green channel image). Also, during the second frame period T2, the third image sensor 524 captures an image in a state in which the amount of incident light is substantially zero, to generate a third captured image.

[0077] Under the control of the control unit 93, the image processing unit 921 performs image processing on each of the first to third captured images received by the communication unit 91. The image processing unit 921 also generates a normal light image, which is a color image corresponding to white light, from the red channel image, green channel image, and blue channel image. Furthermore, the image processing unit 921 superimposes the normal light image and the first fluorescent light image, for example, using a known alpha blending process or additive blending process, to generate a superimposed image in which the area from which the first fluorescent light is emitted is distinguishable. The display control unit 922 then generates a video signal corresponding to the superimposed image and outputs it to the display device 7. As a result, the superimposed image is displayed on the display device 7.

[0078] [Operation of the Fluorescence Endoscope Device in the Second Fluorescence Observation Mode] Figure 12 is a diagram showing the operation of the light source device 3 and the first to third image pickup elements 522 to 524 in the second fluorescence observation mode. Specifically, Figures 12(a) to 12(f) correspond to Figures 10(a) to 11(f), respectively. In the second fluorescence observation mode, the control unit 93 controls the operation of the light source device 3 and the first to third image pickup elements 522 to 524 as follows.

[0079] As shown in (a) to (c) of Figures 12A to 12C, the control unit 93 turns on the first light source 31 and turns off the second and third light sources 32 and 33 during the first frame period T1 of the first and second frame periods T1 and T2.

[0080] 12(a) to 12(c), the control unit 93 turns off the first and second light sources 31 and 32 and turns on the third light source 33 during the second frame period T2 of the first and second frame periods T1 and T2. That is, the second light source 32 is not used in the second fluorescence observation mode.

[0081] The control unit 93 then causes the first to third image pickup elements 522 to 524 to perform image pickup operations during the alternately repeated first and second frame periods T1 and T2.

[0082] Specifically, the first image sensor 522 captures light in the red wavelength band (light L1 in the first wavelength band) separated by the prism 521 from the subject image from which excitation light has been removed, during the first frame period T1, to generate a first captured image (red channel image). Also, during the second frame period T2, the first image sensor 522 captures an image in a state in which the amount of incident light is substantially zero, to generate a first captured image.

[0083] The second image sensor 523 captures light in the blue wavelength band (light L2 in the second wavelength band) separated by the prism 521 from the subject image from which the excitation light has been removed, during the first frame period T1, to generate a second captured image (blue channel image). The second image sensor 523 also captures second fluorescence (light L2 in the second wavelength band) separated by the prism 521 from the subject image from which the excitation light has been removed, during the second frame period T2, to generate a second captured image (second fluorescence image).

[0084] Furthermore, the third image sensor 524 captures light in the green wavelength band (light L3 in the third wavelength band) separated by the prism 521 from the subject image from which the excitation light has been removed, during the first frame period T1, to generate a third captured image (green channel image). Also, during the second frame period T2, the third image sensor 524 captures an image in a state in which the amount of incident light is substantially zero, to generate a third captured image.

[0085] The image processing unit 921, under the control of the control unit 93, performs image processing on each of the first to third captured images received by the communication unit 91. The image processing unit 921 also generates a normal light image, which is a color image corresponding to white light, from the red channel image, green channel image, and blue channel image. Furthermore, the image processing unit 921 superimposes the normal light image and the second fluorescent light image, for example, using a known alpha blending process or additive blending process, to generate a superimposed image in which the area from which the second fluorescent light is emitted is distinguishable. The display control unit 922 then generates a video signal corresponding to the superimposed image and outputs it to the display device 7. As a result, the superimposed image is displayed on the display device 7.

[0086] The present embodiment described above provides the following advantages. The image capturing unit 52 according to this embodiment includes a prism 521 that separates incident light into three light beams, namely, light beams L1 to L3, in the first to third wavelength bands, and first to third image capturing elements 522 to 524 that capture the light beams L1 to L3, respectively. That is, the incident light containing the first and second fluorescence is separated into the first fluorescence (light beam L1 in the first wavelength band) and the second fluorescence (light beam L2 in the second wavelength band), and the first and second fluorescence beams are captured by the first and second image capturing elements 522 and 523, which are separate image capturing elements. Therefore, the image capturing unit 52 according to this embodiment makes it easy to distinguish between the first and second fluorescence beams.

[0087] Incidentally, when white light and the first and second excitation lights are emitted from the light source device 3, autofluorescence may be generated as described below. Specifically, when the white light and the first and second excitation lights emitted from the light source device 3 propagate to the observation target, autofluorescence is generated from components forming the propagation path when the white light and the first and second excitation lights are irradiated onto the components. The same phenomenon occurs when the subject image collected by the insertion portion 2 propagates to the imaging unit 52. Such autofluorescence has a wavelength band that includes the wavelength bands of the first and second fluorescence and causes noise in fluorescence observation. In this embodiment, the prism 521 limits the wavelength band of light reaching the first imaging element 522. Similarly, the prism 521 limits the wavelength band of light reaching the second imaging element 523. Therefore, the noise component due to the autofluorescence described above can be limited when fluorescence observation using the first fluorescence is performed, thereby enabling good fluorescence observation using the first fluorescence. Similarly, since the noise components due to the autofluorescence described above can be limited when performing fluorescence observation using the second fluorescence, fluorescence observation using the second fluorescence can be performed satisfactorily.

[0088] Here, the first wavelength band includes the wavelength band of the first fluorescence and the red wavelength band. The second wavelength band includes the wavelength band of the second fluorescence and the blue wavelength band. That is, since the wavelength bands of the first fluorescence and the red wavelength band are very close to each other, for example, if the position of the first imaging element 522 is adjusted so that a first captured image (R channel image) captured by the first imaging element 522 using light in the red wavelength band is in focus, the first fluorescence image will also be in focus. Furthermore, even if a second captured image (B channel image) captured by the second imaging element 523 using light in the blue wavelength band is not in focus, this does not significantly affect the resolution of the normal light image. Therefore, the position of the second imaging element 523 is adjusted so that a second captured image (second fluorescence image) captured by the second imaging element 523 using the second fluorescence is in focus. With this configuration, the first and second fluorescent images can be made to have good resolution.

[0089] Other Embodiments Although the embodiments for carrying out the present invention have been described above, the present invention should not be limited to the above-described embodiments. In the above-described embodiments, the peak wavelength of the first fluorescence is not limited to around 700 nm, but may be around 800 nm, which is on the longer wavelength side. In this case, the peak wavelength of the second fluorescence is longer than the peak wavelength of the first fluorescence, and may be around 1000 nm.

[0090] In the above-described embodiment, the following modified examples 1 and 2 may be adopted.

[0091] (Variation 1) Figures 13 to 17 are diagrams illustrating Variation 1 of the embodiment. Specifically, Figure 13 is a diagram corresponding to Figure 6. Figures 14 to 16 are diagrams corresponding to Figures 7 to 9, respectively. Figures 17(a) to 17(f) are diagrams corresponding to Figures 10(a) to 10(f), respectively. Note that in Figure 17(e), for convenience of explanation, the third captured image generated by capturing light in the red, green, and blue wavelength bands (light L3 in the third wavelength band) is represented by the letters "WLI."

[0092] As shown in FIG. 13, the imaging unit 52 of this modified example 1 differs from the imaging unit 52 described in the above-mentioned embodiment in the characteristics of the first and second dichroic filters 521d and 521e and in that a color filter 524a is provided on the imaging surface of the third imaging element 524.

[0093] The first dichroic filter 521d according to the first modification has the property of reflecting light L2 in the second wavelength band and transmitting light in other wavelength bands. Here, the light L2 in the second wavelength band according to the first modification is light in the wavelength band from 800 nm to 900 nm, which includes the wavelength band of the second fluorescence. Therefore, of the subject image from which excitation light has been removed that is incident on the prism 521, the light L2 in the second wavelength band is reflected by the first dichroic filter 521d, is totally reflected within the translucent member 521a, and then travels toward the second image sensor 523 ( FIGS. 13 and 16 ).

[0094] The second dichroic filter 521e according to the first modification has the property of reflecting light L1 in a first wavelength band and transmitting light in other wavelength bands. Here, the first wavelength band light L1 according to the first modification is light in a wavelength band from 700 nm to 800 nm, which includes the wavelength band of the first fluorescence. Therefore, of the light transmitted through the first dichroic filter 521, the light L1 in the first wavelength band is reflected by the second dichroic filter 521e, undergoes total reflection within the translucent member 521b, and then travels toward the first image sensor 522 ( FIGS. 13 and 14 ). Meanwhile, the light in the red, green, and blue wavelength bands (light L3 in a third wavelength band) transmitted through the second dichroic filter 521e travels through the translucent member 521c and then travels toward the third image sensor 524 ( FIGS. 13 and 15 ).

[0095] The color filter 524a is a color filter in which three filter groups are grouped according to the wavelength bands of light (red, green, blue) to be transmitted, and are arranged in a specific format (for example, a Bayer array). Specifically, the color filter 524a has an R filter group that mainly transmits light in the red wavelength band, a B filter group that mainly transmits light in the blue wavelength band, and a G filter group that mainly transmits light in the green wavelength band.

[0096] Next, we will explain the operation of the fluorescence endoscope device 1 according to Modification 1. For convenience of explanation, we will explain the operation of the fluorescence endoscope device 1 in the third fluorescence observation mode out of the first to third fluorescence observation modes. In the third fluorescence observation mode, the control unit 93 controls the operation of the light source device 3 and the first to third image sensors 522 to 524 as follows.

[0097] As shown in FIGS. 17A to 17C, the control unit 93 constantly lights up the first to third light sources 31 to 33 during the first and second frame periods T1 and T2.

[0098] The control unit 93 then causes the first to third image pickup elements 522 to 524 to perform image pickup operations during the alternately repeated first and second frame periods T1 and T2.

[0099] Specifically, the first image sensor 522 captures the first fluorescence (light L1 of the first wavelength band) separated by the prism 521 from the subject image from which the excitation light has been removed during the first and second frame periods T1 and T2, respectively, and generates the first captured image (first fluorescence image).

[0100] In addition, the second image sensor 523 captures the second fluorescence (light L2 of the second wavelength band) separated by the prism 521 from the subject image from which the excitation light has been removed during the first and second frame periods T1 and T2, respectively, and generates second captured images (second fluorescence images).

[0101] Furthermore, the third image sensor 524 captures light in the red, green, and blue wavelength bands (light L3 in the third wavelength band) separated by the prism 521 from the subject image from which the excitation light has been removed during the first and second frame periods T1 and T2, respectively, and generates third captured images (hereinafter referred to as normal light images).

[0102] The image processing unit 921, under the control of the control unit 93, performs image processing on each of the first to third captured images received by the communication unit 91. The image processing unit 921 also superimposes the normal light image and the first and second fluorescent light images using, for example, known alpha blending or additive blending, to generate a superimposed image in which the area where the first fluorescent light is emitted and the area where the second fluorescent light is emitted can be distinguished. The display control unit 922 then generates a video signal corresponding to the superimposed image and outputs it to the display device 7. As a result, the superimposed image is displayed on the display device 7.

[0103] Even when the configuration according to the modified example 1 described above is adopted, the same effects as those of the above-described embodiment are achieved.

[0104] (Variation 2) FIGS. 18 and 19 are diagrams illustrating Variation 2 of the embodiment. Specifically, FIG. 18 corresponds to FIG. 1. FIGS. 19(a) to 19(c) and FIGS. 19(e) to 19(g) correspond to FIGS. 10(a) to 10(f), respectively. FIG. 19(d) is a time chart showing the operating state of the fourth light source 34. Note that in FIG. 19(d), for ease of explanation, the third excitation light is represented by the number "500." Also, in FIG. 19(f), for ease of explanation, the third captured image generated by capturing the third fluorescence is represented by the number "500."

[0105] As shown in FIG. 18, the light source device 3 according to the second modification example is configured by adding a fourth light source 34 to the light source device 3 described in the above embodiment.

[0106] The fourth light source 34 supplies third excitation light for exciting a third fluorescent reagent contained in the observation object to one end of the light guide 4. The fourth light source 34 may be configured by an LED or a semiconductor laser.

[0107] Here, when the third fluorescent reagent is excited by the third excitation light, it emits a third fluorescent light having a peak wavelength in the vicinity of 500 [nm].

[0108] The excitation light cut filter 22 according to the second modification removes the first to third excitation light beams contained in the subject image collected by the insertion section 2. The subject image from which excitation light has been removed, which will be described below, is the subject image from which the first to third excitation light beams have been removed by the excitation light cut filter 22.

[0109] Next, the operation of the fluorescence endoscope apparatus 1 according to Modification 2 will be described. For ease of explanation, the operation of the fluorescence endoscope apparatus 1 in a fourth fluorescence observation mode in which fluorescence observation is performed using the first to third fluorescence will be described below. It is assumed that the observation target contains all of the first to third fluorescent reagents. In the fourth fluorescence observation mode, the control unit 93 controls the operation of the light source device 3 and the first to third image sensors 522 to 524 as follows:

[0110] As shown in (a) of Figure 19 to (d) of Figure 10, during the first frame period T1 of the first and second frame periods T1 and T2, the control unit 93 turns on the first light source 31 and turns off the second to fourth light sources 32 to 34.

[0111] Furthermore, as shown in (a) to (d) of Figures 19A to 19D, during the second frame period T2 of the first and second frame periods T1 and T2, the control unit 93 turns off the first light source 31 and turns on the second to fourth light sources 32 to 34.

[0112] The control unit 93 then causes the first to third image pickup elements 522 to 524 to perform image pickup operations during the alternately repeated first and second frame periods T1 and T2.

[0113] Specifically, in the first frame period T1, the first image sensor 522 captures light in the red wavelength band (light L1 in the first wavelength band) separated by the prism 521 from the subject image from which the excitation light has been removed, to generate a first captured image (red channel image). In addition, in the second frame period T2, the first image sensor 522 captures first fluorescence (light L1 in the first wavelength band) separated by the prism 521 from the subject image from which the excitation light has been removed, to generate a first captured image (first fluorescence image).

[0114] The second image sensor 523 captures light in the blue wavelength band (light L2 in the second wavelength band) separated by the prism 521 from the subject image from which the excitation light has been removed, during the first frame period T1, to generate a second captured image (blue channel image). The second image sensor 523 also captures second fluorescence (light L2 in the second wavelength band) separated by the prism 521 from the subject image from which the excitation light has been removed, during the second frame period T2, to generate a second captured image (second fluorescence image).

[0115] Furthermore, the third image sensor 524 captures light in the green wavelength band (light L3 in the third wavelength band) separated by the prism 521 from the subject image from which the excitation light has been removed, during the first frame period T1, to generate a third captured image (green channel image). Also, the third image sensor 524 captures third fluorescence (light L3 in the third wavelength band) separated by the prism 521 from the subject image from which the excitation light has been removed, during the second frame period T2, to generate a third captured image (hereinafter referred to as a third fluorescence image).

[0116] Under the control of the control unit 93, the image processing unit 921 performs image processing on each of the first to third captured images received by the communication unit 91. The image processing unit 921 also generates a normal light image, which is a color image corresponding to white light, from the red channel image, green channel image, and blue channel image. Furthermore, the image processing unit 921 superimposes the normal light image and the first to third fluorescent light images using, for example, a known alpha blending process or additive blending process, to generate a superimposed image in which the area where the first fluorescent light is emitted, the area where the second fluorescent light is emitted, and the area where the third fluorescent light is emitted can be distinguished. The display control unit 922 then generates a video signal corresponding to the superimposed image and outputs it to the display device 7. As a result, the superimposed image is displayed on the display device 7.

[0117] Even when the configuration according to the second modified example described above is adopted, the same effects as those of the above-described embodiment are achieved.

[0118] REFERENCE SIGNS LIST 1 Fluorescence endoscope device 2 Insertion section 3 Light source device 4 Light guide 5 Camera head 6 First transmission cable 7 Display device 8 Second transmission cable 9 Control device 10 Third transmission cable 21 Eyepiece section 22 Excitation light cut filter 31 First light source 32 Second light source 33 Third light source 34 Fourth light source 51 Lens unit 52 Imaging section 53 Communication section 91 Communication section 92 Processing module 93 Control section 94 Input section 95 Output section 96 Storage section 521 Prism 521a to 521c Light-transmitting member 521d First dichroic filter 521e Second dichroic filter 522 First imaging element 523 Second imaging element 524 Third imaging element 524a Color filter 525 Signal processing section 921 Image processing unit 922 Display control unit CL1, CL2 Curves L1 Light of first wavelength band L2 Light of second wavelength band L3 Light of third wavelength band P1, P2 Wavelength T1 First frame period T2 Second frame period

Claims

1. An imaging device comprising: a color separation optical element that separates incident light into three light beams: light of a first wavelength band that includes the wavelength band of a first fluorescence emitted from a first fluorescent reagent having a fluorescent emission peak wavelength from 700 nm to 800 nm; light of a second wavelength band that includes the wavelength band of a second fluorescence emitted from a second fluorescent reagent having a fluorescent emission peak wavelength that is longer than the peak wavelength of the first fluorescence; and light of a third wavelength band that includes a part of the wavelength band of visible light; a first imaging element that captures the light of the first wavelength band; a second imaging element that captures the light of the second wavelength band; and a third imaging element that captures the light of the third wavelength band.

2. The imaging device according to claim 1, wherein the peak wavelength of the first fluorescence is in the vicinity of 700 nm, and the peak wavelength of the second fluorescence is in the vicinity of 800 nm.

3. An imaging device as described in claim 2, wherein the first wavelength band includes a red wavelength band in visible light, the second wavelength band includes a blue wavelength band in visible light, and the third wavelength band includes a green wavelength band in visible light.

4. The imaging device described in claim 3, wherein the color separation optical element comprises a first reflecting optical element and a second reflecting optical element, wherein the first reflecting optical element reflects light of the second wavelength band which includes the blue wavelength band of 400 nm to 500 nm and the second fluorescent wavelength band of 800 nm to 900 nm, and the second reflecting optical element reflects light of the first wavelength band of 600 nm to 760 nm which includes the red wavelength band and the first fluorescent wavelength band, and transmits light of the green wavelength band, out of the light which has passed through the first reflecting optical element.

5. The imaging device according to claim 2, wherein the third wavelength band includes red, green, and blue wavelength bands of visible light.

6. The imaging device described in claim 5, wherein the color separation optical element comprises a first reflecting optical element and a second reflecting optical element, wherein the first reflecting optical element reflects light in the second wavelength band from 800 nm to 900 nm, which includes the wavelength band of the second fluorescence, and the second reflecting optical element reflects light in the second wavelength band from 700 nm to 800 nm, which includes the wavelength band of the first fluorescence, out of the light that has passed through the first reflecting optical element, and transmits light in the red, green, and blue wavelength bands.

7. A first light source that emits normal light including a wavelength band of visible light; a second light source that emits first excitation light for exciting a first fluorescent reagent having a peak fluorescent emission wavelength in the vicinity of 700 nm; a third light source that emits second excitation light for exciting a second fluorescent reagent having a peak fluorescent emission wavelength in the vicinity of 800 nm; a color separation optical element that separates incident light into three light beams: light of a first wavelength band that includes the wavelength band of the first fluorescence emitted from the first fluorescent reagent, light of a second wavelength band that includes the wavelength band of the second fluorescence emitted from the second fluorescent reagent, and light of a third wavelength band that includes a part of the wavelength band of visible light; a first image sensor that captures the light of the first wavelength band; a second image sensor that captures the light of the second wavelength band; and a third image sensor that captures the light of the third wavelength band. the processor controls operations of the first light source, the second light source, the third light source, the first image capture element, the second image capture element, and the third image capture element, wherein the first wavelength band includes a red wavelength band of visible light, the second wavelength band includes a blue wavelength band of visible light, and the third wavelength band includes a green wavelength band of visible light; the processor alternately turns on the first light source and at least one of the second light source and the third light source, and generates, at a timing when the first light source is turned on, a normal light image corresponding to the normal light based on a first captured image obtained by the first image capture element capturing light of the first wavelength band, a second captured image obtained by the second image capture element capturing light of the second wavelength band, and a third captured image obtained by the third image capture element capturing light of the third wavelength band, a fluorescence endoscope device that generates, at a timing when the at least one light source is turned on, a fluorescence image corresponding to at least one of the first fluorescence and the second fluorescence, based on at least one of the first captured image obtained by causing the first image sensor to capture an image of light in the first wavelength band and the second captured image obtained by causing the second image sensor to capture an image of light in the second wavelength band.

8. A first light source that emits normal light including a wavelength band of visible light; a second light source that emits first excitation light for exciting a first fluorescent reagent having a peak fluorescence emission wavelength in the vicinity of 700 nm; a third light source that emits second excitation light for exciting a second fluorescent reagent having a peak fluorescence emission wavelength in the vicinity of 800 nm; a color separation optical element that separates incident light into three light beams: light of a first wavelength band that includes the wavelength band of the first fluorescence emitted from the first fluorescent reagent, light of a second wavelength band that includes the wavelength band of the second fluorescence emitted from the second fluorescent reagent, and light of a third wavelength band that includes a part of the wavelength band of visible light; a first image sensor that captures the light of the first wavelength band; a second image sensor that captures the light of the second wavelength band; and a third image sensor that captures the light of the third wavelength band. a processor that controls operations of the first light source, the second light source, the third light source, the first image capture element, the second image capture element, and the third image capture element, wherein the third wavelength band includes red, green, and blue wavelength bands of visible light, and the processor simultaneously turns on the first light source and at least one of the second light source and the third light source, and generates a fluorescence image corresponding to at least one of the first fluorescence and the second fluorescence based on at least one of a first image obtained by causing the first image capture element to capture light of the first wavelength band and a second image obtained by causing the second image capture element to capture light of the second wavelength band, and generates a third image obtained by causing the third image capture element to capture light of the third wavelength band as a normal light image corresponding to the normal light.

Images