Fluorescent endoscopic device

Abstract

A fluorescent endoscopic device 1 comprises: a first light source 31 that emits ordinary light; a second light source 32 that emits first excitation light for exciting a first fluorescent reagent; a third light source 33 that emits second excitation light for exciting a second fluorescent reagent; a color separation optical element that separates, from first fluorescence emitted from the first fluorescent reagent, second fluorescence emitted from the second fluorescent reagent and reflected light of ordinary light from an object being observed; first and second imaging elements 522, 523; and a processor 9. The processor 9 turns on the second and third light sources 32, 33 alternately. At the timing at which the third light source 33 is turned on, the processor 9 uses, as a display image, a first captured image which is obtained by causing the first imaging element 522 to capture the second fluorescence and the reflected light of the ordinary light. At the timing at which the second light source 32 is turned on, the processor 9 uses, as the display image, a second captured image which is obtained by causing the second imaging element 523 to capture the first fluorescence.

Description

Fluorescence endoscope device

[0001] The present invention relates to a fluorescence endoscope apparatus.

[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] Here, in order to distinguish between the first and second fluorescence, a configuration using the following optical system and three image sensors is conceivable. The optical system is an optical system such as a dichroic prism that separates the reflected white light reflected by the observation object, the first fluorescence, and the second fluorescence. The three image sensors are image sensors that capture the reflected white light and the first and second fluorescence separated by the optical system. However, a configuration using the above-described optical system and three image sensors results in an increase in size of the optical system.

[0007] Therefore, there is a demand for a technique that can avoid an increase in the size of the optical system and easily distinguish between the first and second fluorescent lights.

[0008] The present invention has been made in view of the above, and an object of the present invention is to provide a fluorescence endoscope apparatus that can avoid an increase in the size of the optical system and can easily distinguish between the first and second fluorescence.

[0009] In order to solve the above-mentioned problems and achieve the object, 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 fluorescent emission peak wavelength in the vicinity of 700 nm, a third light source that emits second excitation light for exciting a second fluorescent reagent having a fluorescent emission peak wavelength in the vicinity of 800 nm, and a third light source that emits either a first fluorescence emitted from the first fluorescent reagent contained in an observation object by irradiation with the first excitation light or a second fluorescence emitted from the second fluorescent reagent contained in the observation object by irradiation with the second excitation light, as well as light reflected from the observation object and the other of the first fluorescence and the second fluorescence. a first image capturing element that captures the one fluorescence and the reflected light of the ordinary light; a second image capturing element that captures the other fluorescence; and a processor that controls operations of the first light source, the second light source, the third light source, the first image capturing element, and the second image capturing element, wherein the processor alternately turns on the second light source and the third light source, turns on one of the second light source and the third light source, and causes the first image capturing element to capture the one fluorescence and the reflected light of the ordinary light at a timing when the one fluorescence is emitted, turns on the other of the second light source and the third light source, and causes the second image capturing element to capture the other fluorescence at a timing when the other fluorescence is emitted.

[0010] According to the fluorescence endoscope apparatus of the present invention, it is possible to avoid an increase in the size of the optical system and to easily distinguish between the first and second fluorescence.

[0011] 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 and emission spectrum of a first fluorescent reagent. FIG. 3 is a diagram showing the absorption spectrum and emission spectrum of a second fluorescent reagent. FIG. 4 is a block diagram showing the configuration of a camera head and a control device. FIG. 5 is a diagram showing the configuration of an imaging unit. FIG. 6 is a diagram showing the spectrum of each light incident on an excitation light cut filter, the spectral spectrum of a color filter, and the spectral reflection spectrum of a dichroic filter. FIG. 7 is a diagram explaining the operation of a fluorescence endoscope apparatus. FIG. 8 is a diagram explaining the operation of a fluorescence endoscope apparatus. FIG. 9 is a diagram explaining a modified example of the embodiment.

[0012] 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.

[0013] [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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] The first to third light sources 31 to 33 may be configured by LEDs (Light Emitting Diodes) or semiconductor lasers.

[0018] Here, the first fluorescent reagent has the following characteristics. Fig. 2 is a diagram showing the absorption spectrum and emission 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 and fluorescence emission of the emission spectrum. In Fig. 2, the absorption spectrum is shown by a dashed line, and the emission spectrum is shown by a solid line.

[0019] The peak wavelength of the absorption spectrum of the first fluorescent reagent is near 680 nm, as shown in Figure 2. Therefore, in order to increase the intensity of the first fluorescence emitted from the first fluorescent reagent, it is preferable to use excitation light in a wavelength band including a wavelength near 680 nm as the first excitation light. Also, the peak wavelength of the emission spectrum of the first fluorescent reagent is near 700 nm, as shown in Figure 2.

[0020] The second fluorescent reagent has the following characteristics. Fig. 3 is a diagram showing the absorption spectrum and emission spectrum of the second fluorescent reagent. In Fig. 3, the horizontal axis represents wavelength [nm], and the vertical axis represents the intensity of the absorption spectrum and emission spectrum. In Fig. 3, the absorption spectrum is shown by a dashed line, and the emission spectrum is shown by a solid line.

[0021] The peak wavelength of the absorption spectrum of the second fluorescent reagent is near 780 nm, as shown in Figure 3. Therefore, in order to increase the intensity of the second fluorescence emitted from the second fluorescent reagent, it is preferable to use excitation light in a wavelength band including a wavelength near 780 nm as the second excitation light. Also, the peak wavelength of the emission spectrum of the second fluorescent reagent is near 800 nm, as shown in Figure 3.

[0022] 3, the second fluorescent reagent is also sensitive to excitation light having a wavelength near 700 nm, i.e., the first excitation light, and emits the second fluorescence even when irradiated with the first excitation light. Therefore, when observing the first and second fluorescence simultaneously, it is difficult to distinguish between the first and second fluorescence.

[0023] 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.

[0024] 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.

[0025] 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."

[0026] 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.

[0027] 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.

[0028] 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 .

[0029] 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.

[0030] 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."

[0031] 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.

[0032] [Configuration of Camera Head] Next, a description will be given of the configuration of the camera head 5. Fig. 4 is a block diagram showing the configuration of the camera head 5 and the control device 9. As shown in Fig. 4, the camera head 5 includes a lens unit 51, an imaging unit 52, and a communication unit 53.

[0033] 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 and second image sensors 522 and 523, respectively.

[0034] FIG. 5 is a diagram showing the configuration of the imaging unit 52. FIG. 6 is a diagram showing the spectrum of each light beam incident on the excitation light cut filter 22, the spectrum of the color filter 522a, and the spectral reflection spectrum of the dichroic filter 521b. Specifically, (a) of FIG. 6 corresponds to the emission spectrum of the second fluorescence shown in FIG. 3 and shows the spectrum of the second fluorescence incident on the excitation light cut filter 22. (b) of FIG. 6 corresponds to the emission spectrum of the first fluorescence shown in FIG. 2 and shows the spectrum of the first fluorescence incident on the excitation light cut filter 22. (d) of FIG. 6 is a diagram showing the spectrum of the color filter 522a. (e) of FIG. 6 is a diagram showing the spectral reflection spectrum of the dichroic filter 521b.

[0035] The imaging unit 52 is a part that generates a captured image by capturing an image of a subject from which excitation light has been removed. As shown in Figures 4 and 5, the imaging unit 52 includes a prism 521, first and second image sensors 522 and 523, and a signal processing unit 524.

[0036] The prism 521 has a substantially cubic shape formed by combining two triangular prism-shaped light-transmitting members 521a (FIG. 5). A dichroic filter 521b is provided at the interface between the two light-transmitting members 521a.

[0037] The dichroic filter 521b corresponds to a color separation optical element according to the present invention. As shown in FIG. 6E, this dichroic filter 521b has the property of reflecting light in a wavelength band near 700 nm and transmitting light in other wavelength bands. Therefore, of the subject image that has entered the prism 521 and from which the excitation light has been removed, most of the reflected white light WL ( FIG. 5 ) and second fluorescence FL2 ( FIG. 5 ) after the first and second excitation lights have been removed by the excitation light cut filter 22 are transmitted through the dichroic filter 521b (prism 521). Then, as shown in FIG. 5 , the reflected white light WL and second fluorescence FL2 travel toward the first image sensor 522. Meanwhile, of the subject image that has entered the prism 521 and from which the excitation light has been removed, most of the first fluorescence FL1 ( FIG. 5 ) after the first and second excitation lights have been removed by the excitation light cut filter 22 is reflected by the dichroic filter 521b. The first fluorescence FL1 then travels toward the second image sensor 523.

[0038] The first and second image sensors 522 and 523 receive incident light and convert it into an electrical signal (analog signal). Examples of the first and second image sensors 522 and 523 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.

[0039] Then, under the control of the control device 9, the first image sensor 522 captures an image of the light that has passed through the prism 521. For ease of explanation, the image captured by the first image sensor 522 will be referred to as a white-fluorescence-mixed image below.

[0040] Here, a color filter 522a is provided on the light receiving surface of the first image sensor 522, as shown in FIGS.

[0041] The color filter 522a is a color filter in which three filter groups are grouped according to the wavelength bands of light to be transmitted (red, green, blue) and are arranged in a specific format (for example, Bayer array).

[0042] Specifically, the color filter 522a includes an R filter group that primarily transmits light in the red wavelength band, a B filter group that primarily transmits light in the blue wavelength band, and a G filter group that primarily transmits light in the green wavelength band. In FIG. 6D, the spectrum of the R filter group is shown by the curve CR, the spectrum of the G filter group is shown by the curve CG, and the spectrum of the B filter group is shown by the curve CB. As can be seen from the curves CR, CG, and CB shown in FIG. 6D and the spectrum of the reflected white light WL shown in FIG. 6B, the R filter group is also sensitive to the second fluorescence FL2 (wavelength band near 800 nm), as can be seen from the curve CR shown in FIG. 6D and the spectrum of the second fluorescence FL2 shown in FIG. 6A.

[0043] The second image sensor 523 captures an image of the light reflected by the dichroic filter 521b under the control of the control device 9. For ease of explanation, the image captured by the second image sensor 523 will be referred to as a fluorescent image below. Note that the light receiving surface of the second image sensor 523 is not provided with a color filter 522a like the first image sensor 522. In other words, the second image sensor 523 is a so-called monochrome image sensor.

[0044] The number of pixels in the white-fluorescence mixed image and the number of pixels in the fluorescent image may be different or the same.

[0045] The signal processing unit 524 outputs a captured image (digital signal) by performing signal processing on the captured image (analog signal) generated by the first and second imaging elements 522 and 523 under the control of the control device 9. For example, the signal processing unit 524 performs signal processing on the captured image (analog signal) generated by the first and second imaging elements 522 and 523, such as processing to remove reset noise, processing to multiply the analog signal by an analog gain that amplifies the analog signal (hereinafter referred to as analog gain adjustment), and A / D conversion.

[0046] 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 .

[0047] The communication unit 53 may transmit the white-fluorescence-mixed image and the fluorescent image to the control device 9 in that order, or may transmit the white-fluorescence-mixed image and the fluorescent image simultaneously.

[0048] [Configuration of Control Device] Next, the configuration of the control device 9 will be described with reference to Fig. 4. The control device 9 corresponds to a processor according to the present invention. As shown in Fig. 4, 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.

[0049] 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 .

[0050] 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. 4 , the processing module 92 includes an image processing unit 921 and a display control unit 922.

[0051] 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.

[0052] The image processing performed on the white-fluorescence mixed image and the image processing performed on the fluorescent image may be different from each other, or may be the same.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] The output unit 95 is configured using a speaker, a printer, etc., and outputs various information.

[0057] 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.

[0058] [Operation of Fluorescence Endoscope Apparatus] Next, the operation of the above-described fluorescence endoscope apparatus 1 will be described. FIGS. 7 and 8 are diagrams illustrating the operation of the fluorescence endoscope apparatus 1. Specifically, FIG. 7(a) is a time chart showing the operating state of the first light source 31. FIG. 7(b) is a time chart showing the operating state of the second light source 32. FIG. 7(c) is a time chart showing the operating state of the third light source 33. FIG. 8(a) is a diagram showing a fluorescence image F2. Note that FIG. 8(a) shows only two images as the fluorescence image F2: a fluorescence image F2a captured in the first frame period T1 and a fluorescence image F2b captured in the second frame period T2 of the first and second frame periods T1 and T2 arranged in chronological order. The first and second frame periods T1 and T2 are the same period and alternately repeat. FIG. 8(b) is a diagram showing a white-fluorescence-mixed image F1. Note that (b) of FIG. 8 illustrates only two white-fluorescence-mixed images F1: a white-fluorescence-mixed image F1a captured in the first frame period T1 and a white-fluorescence-mixed image F1b captured in the second frame period T2 of the first and second frame periods T1 and T2, which are arranged in chronological order. The area Ar1 indicated by the dashed line in (a) of FIG. 8 and the area Ar2 indicated by the solid line in (b) of FIG. 8 represent the same subject. The area Ar3 indicated by the solid line in (a) of FIG. 8 is a region where the intensity of the first fluorescence FL1 is high. The area Ar4 indicated by the solid line in (b) of FIG. 8 is a region where the intensity of the second fluorescence FL2 is high. (c) of FIG. 8 illustrates a difference image F1' showing the difference in brightness levels between corresponding pixels in the two white-fluorescence-mixed images F1a and F1b. (d) of FIG. 8 illustrates a superimposed image F3 displayed on the display device 7.

[0059] The control unit 93 controls the operations of the light source device 3 and the first and second image pickup elements 522 and 523 as described below.

[0060] 7A, the control unit 93 continuously lights up the first light source 31 during the alternating first and second frame periods T1 and T2, and constantly emits white light from the first light source 31. Note that, since FIG. 7A shows a period shorter than the cycle in which dimming control is performed, the white light is emitted at a constant intensity.

[0061] 7B and 7C, the control unit 93 turns off the second light source 32 and turns on the third light source 33 during the first frame period T1 of the alternately repeated first and second frame periods T1 and T2. On the other hand, the control unit 93 turns on the second light source 32 and turns off the third light source 33 during the second frame period T2. That is, the control unit 93 turns on the second and third light sources 32 and 33 alternately.

[0062] The control unit 93 then causes the first and second image pickup elements 522 and 523 to perform image pickup operations during the first and second frame periods T1 and T2 that are alternately repeated.

[0063] Specifically, the first image sensor 522 captures the reflected white light WL and the second fluorescence FL2 during the first frame period T1 to generate a white-fluorescence-mixed image F1a (FIG. 8(b)). This white-fluorescence-mixed image F1a corresponds to the first captured image according to the present invention. Furthermore, the first image sensor 522 captures only the reflected white light WL during the second frame period T2 to generate a white-fluorescence-mixed image F1b (FIG. 8(b)). This white-fluorescence-mixed image F1b corresponds to the third captured image according to the present invention.

[0064] The second image sensor 523 captures an image in a state where the amount of incident light is substantially zero during the first frame period T1, and generates a fluorescence image F2a ((a) in FIG. 8). The second image sensor 523 captures an image of the first fluorescence FL1 during the second frame period T2, and generates a fluorescence image F2b ((a) in FIG. 8). The fluorescence image F2b corresponds to the second captured image according to the present invention.

[0065] Under the control of the control unit 93, the image processing unit 921 performs image processing on the white-fluorescence-mixed image F1 and the fluorescent image F2 received by the communication unit 91. Furthermore, under the control of the control unit 93, the image processing unit 921 calculates the difference in brightness levels between corresponding pixels in the two chronologically arranged white-fluorescence-mixed images F1a and F1b, as shown in FIGS. 8B and 8C, to generate a difference image F1'. Here, the brightness level may be, for example, a brightness value or a pixel value. Based on the difference image F1', the image processing unit 921 determines that an area Ar4 (FIG. 8C) with a different brightness level is an area from which the second fluorescent light FL2 is emitted. The image processing unit 921 then superimposes the white-fluorescence-mixed image F1a and the fluorescent image F2b using a known alpha blending process or additive blending process to generate a superimposed image F3 (FIG. 8D) in which the determined area Ar4 is identified by a specific color or the like. Then, the display control unit 922 generates a video signal corresponding to the superimposed image F3 and outputs it to the display device 7. As a result, the display device 7 displays the superimposed image F3.

[0066] The above-described embodiment provides the following advantages. The fluorescence endoscope device 1 according to this embodiment includes a dichroic filter 521b that separates the first fluorescence FL1 from the reflected white light WL and the second fluorescence FL2. In the fluorescence endoscope device 1, the control device 9 alternately turns on the second and third light sources 32 and 33. The control device 9 also turns on the third light source 33 and causes the first image sensor 522 to capture the reflected white light WL and the second fluorescence FL2 at the timing when the second fluorescence FL2 is emitted (first frame period T1). Meanwhile, the control device 9 turns on the second light source 32 and causes the second image sensor 523 to capture the first fluorescence FL1 at the timing when the first fluorescence FL1 is emitted (second frame period T2). In other words, the first fluorescence FL1 is not captured by the first image sensor 522. Similarly, the second imaging element 523 does not image the second fluorescence FL2. Therefore, it is easy to distinguish between the first and second fluorescence FL1 and FL2. Furthermore, the optical system (the prism 521 including the dichroic filter 521b) that separates the reflected white light WL and the second fluorescence FL2 from the first fluorescence FL1 is also compact. As described above, the fluorescence endoscope device 1 according to this embodiment can avoid an increase in the size of the optical system and easily distinguish between the first and second fluorescence FL1 and FL2.

[0067] The white-fluorescence-mixed image F1a contains a mixture of reflected white light WL and second fluorescence FL2. Therefore, it is necessary to distinguish between the reflected white light WL and the second fluorescence FL2. In the fluorescence endoscope device 1 according to this embodiment, the control device 9 continuously turns on the first light source 31 during the alternating first and second frame periods T1 and T2, causing the first light source 31 to constantly emit white light. The control device 9 also calculates the difference in brightness levels between corresponding pixels in the two white-fluorescence-mixed images F1a and F1b generated during the first and second frame periods T1 and T2, and determines that the area Ar4 with the different brightness levels is the area from which the second fluorescence FL2 is emitted. This makes it easy to distinguish between the reflected white light WL and the second fluorescence FL2.

[0068] 6(b), the intensity of the reflected white light WL decreases as the wavelength increases from about 700 nm. In other words, by using the first image sensor 522 to capture images of the reflected white light WL and the second fluorescence FL2, it is easier to distinguish between the reflected white light WL and the fluorescence than, for example, using the first image sensor 522 to capture images of the reflected white light WL and the first fluorescence FL1.

[0069] Other Embodiments Up to this point, embodiments for carrying out the present invention have been described, but the present invention should not be limited to the above-described embodiments. FIG. 9 is a diagram illustrating a modified embodiment. Specifically, FIG. 9 is a diagram corresponding to FIG. 5. In the above-described embodiment, the dichroic filter 521b has the property of transmitting the reflected light WL of white light and the second fluorescence FL2 and reflecting the first fluorescence FL1. However, this is not limiting. For example, the configuration of the image capture unit 52 according to the modified example shown in FIG. 9 may be adopted. The dichroic filter 521b constituting the image capture unit 52 according to the modified example shown in FIG. 9 has the property of transmitting the first fluorescence FL1 and reflecting the reflected light WL of white light and the second fluorescence FL2. The reflected light WL of white light and the second fluorescence FL2 that have passed through the prism 521 proceed toward the first image capture element 522. Meanwhile, the first fluorescence FL1 that have passed through the prism 521 proceed toward the second image capture element 523.

[0070] In the above-described embodiment, one fluorescence according to the present invention is the second fluorescence FL2, and the other fluorescence according to the present invention is the first fluorescence FL1, but this is not limiting. One fluorescence according to the present invention may be the first fluorescence FL1, and the other fluorescence according to the present invention may be the second fluorescence FL2.

[0071] 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 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 Light-transmitting member 521b Dichroic filter 522 First imaging element 522a Color filter 523 Second imaging element 524 Signal processing section 921 Image processing section 922 Display control section Ar1 to Ar4 Areas CB, CG, CR Curves F1, F1a, F1b: White fluorescence mixed image F1': Difference image F2, F2a, F2b: Fluorescence image F3: Superimposed image FL1: First fluorescence FL2: Second fluorescence T1: First frame period T2: Second frame period WL: Reflected white light

Claims

1. A first light source that emits normal light including the 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 near 700 nm; a third light source that emits second excitation light for exciting a second fluorescent reagent having a peak fluorescence emission wavelength near 800 nm; a color separation optical element that separates either a first fluorescence emitted from the first fluorescent reagent contained in the observation object when irradiated with the first excitation light or a second fluorescence emitted from the second fluorescent reagent contained in the observation object when irradiated with the second excitation light, as well as reflected light of the normal light from the observation object and the other of the first fluorescence and the second fluorescence; a first image sensor that captures the one fluorescence and the reflected light of the normal light; and a second image sensor that captures the other fluorescence. a processor that controls operations of the first light source, the second light source, the third light source, the first image sensor, and the second image sensor, wherein the processor: alternately turns on the second light source and the third light source; turns on one of the second and third light sources, and at the timing when the one fluorescence is emitted, causes the first image sensor to capture an image of the one fluorescence and the reflected light of the normal light, thereby obtaining a first captured image, which is used as an image for display; and turns on the other of the second and third light sources, and at the timing when the other fluorescence is emitted, causes the second image sensor to capture an image of the other fluorescence, which is used as an image for display.

2. A fluorescence endoscope device according to claim 1, wherein the color separation optical element transmits the one of the fluorescent light and the reflected light of the ordinary light, thereby allowing the one of the fluorescent light and the reflected light of the ordinary light to travel to the first imaging element, and reflects the other of the fluorescent light, thereby allowing the other of the fluorescent light to travel to the second imaging element.

3. A fluorescence endoscope device according to claim 1, wherein the color separation optical element reflects the one of the fluorescent light and the reflected light of the ordinary light, thereby allowing the one of the fluorescent light and the reflected light of the ordinary light to travel to the first imaging element, and transmits the other of the fluorescent light, thereby allowing the other of the fluorescent light to travel to the second imaging element.

4. The fluorescence endoscope device according to claim 1, wherein the processor continuously lights the first light source while alternately lighting the second light source and the third light source.

5. The fluorescence endoscope device according to claim 1, wherein the processor turns on the other light source, and at the timing when the other fluorescence is emitted, calculates the difference in brightness levels between corresponding pixels in a third captured image obtained by imaging the reflected light of the normal light with the first imaging element and the first captured image that is arranged in chronological order relative to the third captured image, and determines that an area with different brightness levels is an area from which one of the fluorescence beams is emitted.

6. A fluorescence endoscope device according to claim 1, wherein the one fluorescence is the second fluorescence, and the other fluorescence is the first fluorescence.

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