Endoscope and image capturing unit provided therein

Abstract

An endoscope and an image capturing unit provided therein, the endoscope including a viewing mirror and an image capturing unit housed inside the viewing mirror. The image capturing unit includes: first and second prisms; a reflective film disposed between the slopes of the first and second prisms; a first fine tuning filter on which the visible light transmitted through the first prism is incident through the reflective film; a first image sensor facing the first trimming filter; a second fine tuning filter on which the near-infrared light transmitted through the second prism is incident through the reflective film; and a second image sensor facing the second trimming filter. The first prism is fixed to the second prism, the first trimming filter is fixed to the first prism, and the second trimming filter is fixed to the second prism.

Description

[0001] This application is a divisional application of application No. 202111164001.6, filed on September 30, 2021, entitled "Endoscope and Image Capture Unit disposed therein". Technical Field

[0002] This disclosure relates to an endoscope and an image capture unit disposed in the endoscope. Background Technology

[0003] Patent Document 1 discloses an endoscope in which a single image sensor, including an RGB color filter and an infrared light (IR) filter, is arranged near the tip of the endoscope. In the endoscope of Patent Document 1, the patient's biological tissue is alternately irradiated with visible light and excitation light, and thus visible light image data and near-infrared light image data are acquired alternately on the time axis by a single image sensor. However, the endoscope of Patent Document 1 has the problem that it cannot acquire visible light image data and near-infrared light image data at the same timing. Furthermore, four types of pixels are provided in the single image sensor, including red pixels, green pixels, blue pixels, and IR pixels. Therefore, there is a problem that noise may appear in the infrared light image signal output from each IR pixel of the image sensor, and the image quality of the final generated near-infrared light image data may be degraded.

[0004] Meanwhile, Patent Document 2 discloses an endoscope in which a four-color separation prism and four image sensors are arranged in a camera head. In the endoscope of Patent Document 2, light emitted from a relay lens is separated into four light components—red, green, blue, and near-infrared—by the four-color separation prism, and each of the four light components is then received by a corresponding image sensor among the four image sensors. The endoscope of Patent Document 2 can simultaneously acquire visible light image data and near-infrared light image data. On the other hand, since the four image sensors are arranged at a position far from the tip of the observation mirror (optical tube), the light intensity (light quantity) of visible light and near-infrared light (especially near-infrared light) decreases during the period before the visible light and near-infrared light associated with the patient's biological tissue reaches the four image sensors. As a result, there is a problem of image quality degradation of both visible light and near-infrared light image data. Furthermore, since the overall size of the four-color separation prism is relatively large, it is necessary to arrange the four-color separation prism, for example, in a camera head. For this reason, in order to guide the visible and near-infrared light reflected by the patient's biological tissue from the tip of the endoscope to the four-color separation prism, expensive optical components (such as relay lenses) need to be provided in the endoscope, and the overall manufacturing cost of the endoscope may increase.

[0005] Patent Document 1: JP-A-2016-209143

[0006] Patent Document 2: JP-A-2019-000339 Summary of the Invention

[0007] From the above perspective, the purpose of this disclosure is to provide an endoscope that can improve the image quality of visible light image data and near-infrared light image data indicating a patient's biological tissues, while reducing manufacturing costs; and an image capture unit disposed in the endoscope.

[0008] One aspect of this disclosure provides an endoscope comprising: an observation mirror to be inserted into a patient's body; and an image capture unit housed within the observation mirror and configured to receive light associated with the patient's biological tissue in order to capture an image of the biological tissue. The image capture unit includes: a first prism; a second prism facing the first prism; a reflective film disposed between the inclined surfaces of the first and second prisms and configured to separate light associated with biological tissue into visible light and near-infrared light; a first fine-tuning filter configured to transmit light in the visible region and block light in the near-infrared region, wherein visible light transmitted through the first prism is incident on the first fine-tuning filter via the reflective film; a first image sensor facing the first fine-tuning filter to receive visible light transmitted through the first fine-tuning filter and configured to convert the received visible light into an electrical signal; a second fine-tuning filter configured to transmit light in the near-infrared region and block light in the visible region, wherein near-infrared light transmitted through the second prism is incident on the second fine-tuning filter via the reflective film; and a second image sensor facing the second fine-tuning filter to receive near-infrared light transmitted through the second fine-tuning filter and configured to convert the received near-infrared light into an electrical signal. The first prism is fixed to the second prism, the first fine-tuning filter is fixed to the first prism, and the second fine-tuning filter is fixed to the second prism.

[0009] According to the above configuration, the first prism and the second prism are fixed to each other. Further, the first fine-tuning filter is fixed to the first prism, and the second fine-tuning filter is fixed to the second prism. Using this configuration, the overall size of the image capture unit can be reduced, and the image capture unit can be housed inside the observation mirror. Since the image capture unit is housed inside the observation mirror, the visible light and near-infrared light associated with the patient's biological tissue are effectively received by the first image sensor and the second image sensor, respectively. As described above, since the electrical signal indicating biological tissue (visible light image signal) is acquired by the first image sensor without reducing the signal-to-noise ratio (SNR), the image quality of the visible light image data indicating biological tissue is improved. Furthermore, since the electrical signal indicating biological tissue (near-infrared light image signal) is acquired by the second image sensor without reducing the SNR, the image quality of the near-infrared image data indicating biological tissue is improved. Since the visible light image signal and the near-infrared light image signal are acquired at the same timing, the time axis of each frame of the visible light image data and the time axis of each frame of the near-infrared light image data are matched to each other. Therefore, since the time axes of the visible light image data frames and the near-infrared light image data frames are matched, the accuracy of the synthesized image data generated by combining the visible light and near-infrared light image data is improved. Furthermore, since the image capture unit is housed inside the endoscope, there is no need to provide expensive relay lenses or similar devices on the endoscope to guide visible and near-infrared light from the patient's biological tissue to the image capture unit, thus reducing the overall manufacturing cost of the endoscope. Therefore, an endoscope that can improve the image quality of visible light and near-infrared light image data indicating the patient's biological tissue while reducing manufacturing costs can be provided.

[0010] In an endoscope, a first image sensor can be fixed to a first fine-tuning filter, and a second image sensor can be fixed to a second fine-tuning filter.

[0011] According to the above configuration, the size of the entire image capture unit can be reduced, and the image capture unit can be housed inside the observation mirror. In this respect, for example, the image capture unit can be housed inside an observation mirror with a small inner diameter.

[0012] In an endoscope, the image capture unit can be positioned near the tip of the endoscope facing the biological tissue.

[0013] With the above configuration, since the image capture unit is positioned near the tip of the endoscope facing the biological tissue, the first and second image sensors can effectively receive visible and near-infrared light associated with the patient's biological tissue. As a result, the image quality of the visible and near-infrared image data acquired through the endoscope is improved.

[0014] In the endoscope, the image acquisition unit may further include: an infrared light shielding film disposed between the first trimmer filter and the first image sensor, configured to transmit light in the visible region and shield light in the near-infrared region; and a visible light shielding film disposed between the second trimmer filter and the second image sensor, configured to transmit light in the near-infrared region and shield light in the visible region. The infrared and visible light shielding films may be configured to shield excitation light emitted into biological tissue in the band with a center wavelength of 700 nm to 800 nm.

[0015] According to the above configuration, since the excitation light emitted into biological tissue in the 700nm to 800nm ​​wavelength band is shielded by the infrared light shielding film and the visible light shielding film, it is possible to appropriately prevent the excitation light from adversely affecting the image quality of visible light image data and near-infrared light image data.

[0016] In the endoscope, the image capture unit may further include a lens unit fixed to the first prism to guide light associated with biological tissue toward the first prism.

[0017] According to the above configuration, due to the lens unit, visible and near-infrared light associated with biological tissue can be effectively incident on the first prism, ensuring an appropriate viewing angle for the image capture unit. Furthermore, since no gap is provided between the lens unit and the first prism, dust and other contaminants can be appropriately prevented from entering the gap, and the burden required for endoscope maintenance can be reduced.

[0018] In an endoscope, the distance between the tip of the lens unit and the end face of the endoscope facing the biological tissue can be in the range of 0.5 mm to 5 mm.

[0019] According to the above configuration, since the distance between the tip of the lens unit and the endoscope's biological tissue-facing tip is in the range of 0.5mm to 5mm, the first and second image sensors can effectively receive visible and near-infrared light reflected by the patient's biological tissue. Furthermore, an appropriate viewing angle for the image capture unit can be ensured.

[0020] The endoscope may also include a first support member configured to support a lens unit, a first prism, and a second prism, and housed within an observation mirror. The first support member may be fixed to the lens unit, the first prism, and the second prism.

[0021] According to the above configuration, since the lens unit, the first prism, and the second prism are supported and fixed by the first support member, the strength of the entire image capture unit can be improved by the first support member.

[0022] The endoscope may also include a second support member that is fixed to the first support member and the viewing endoscope and housed inside the viewing endoscope.

[0023] According to the above configuration, the first support member fixed to the image capture unit is fixed to the observation lens via the second support member. In this way, the image capture unit can be reliably fixed to the observation lens via the first and second support members.

[0024] In an endoscope, the first image sensor may include a CMOS image sensor configured to generate a visible light image signal indicating a normal image of the biological tissue based on visible light forming an inverted image of the biological tissue.

[0025] According to the above configuration, since the first image sensor is a CMOS image sensor configured to generate a visible light image signal indicating a normal image of biological tissue, visible light image data and near-infrared image data can be acquired at the same timing. Specifically, when the first image sensor is a CCD image sensor, image inversion processing needs to be performed separately on the image processing circuit side to generate visible light image data indicating a normal image of biological tissue based on the visible light image signal indicating the inverted image of biological tissue. For this reason, it is possible that the generation timing of the visible light image data is later than the generation timing of the near-infrared image data, and it is difficult to acquire visible light image data and near-infrared image data at the same timing on the image processing circuit side. However, when the first image sensor is a CMOS image sensor, since image inversion processing does not need to be performed on the image processing circuit side, visible light image data and near-infrared image data can be acquired at the same timing on the image processing circuit side.

[0026] In an endoscope, the first image sensor and the second image sensor can have the same configuration.

[0027] Based on the above configuration, since it is not necessary to prepare different types of image sensors for the first and second image sensors, the manufacturing cost of the endoscope can be reduced. For example, a CMOS image sensor including a Bayer pattern color filter array can be applied to both the first and second image sensors.

[0028] In an endoscope, the imaging surfaces of the first image sensor and the second image sensor can be perpendicular to each other.

[0029] According to the above configuration, since the imaging surfaces of the first image sensor and the second image sensor are perpendicular to each other, the size of the entire image capture unit can be reduced, and the image capture unit can be successfully housed inside the observation mirror.

[0030] In an endoscope, the visible light channel formed by the combination of a reflective film, a first fine-tuning filter, and an infrared light shielding film can have spectral characteristics such that the transmittance of light in the 720nm to 1050nm band is 0.1% or less, and the near-infrared light channel formed by the combination of a reflective film, a second fine-tuning filter, and a visible light shielding film can have spectral characteristics such that the transmittance of light in the 400nm to 798nm band is 0.5% or less.

[0031] According to the above configuration, the visible light channel formed by the combination of the reflective film, the first fine-tuning filter, and the infrared light shielding film has spectral characteristics such that the transmittance of light in the 720nm to 1050nm band is 0.1% or less. Therefore, it is possible to appropriately prevent both excitation light in the 700nm to 800nm ​​band and near-infrared light emitted onto biological tissue from adversely affecting the image quality of the visible light image data. Furthermore, the near-infrared light channel formed by the combination of the reflective film, the second fine-tuning filter, and the visible light shielding film has spectral characteristics such that the transmittance of light in the 400nm to 798nm band is 0.5% or less. Therefore, it is possible to appropriately prevent both excitation light in the 700nm to 800nm ​​band and visible light emitted onto biological tissue from adversely affecting the image quality of the near-infrared light image data.

[0032] One aspect of this disclosure provides an image capture unit housed within the viewing endoscope of an endoscope and configured to receive light associated with a patient's biological tissue in order to capture an image of the biological tissue. The image capture unit includes: a first prism; a second prism facing the first prism; a reflective film disposed between the inclined surfaces of the first and second prisms and configured to separate light associated with biological tissue into visible light and near-infrared light; a first fine-tuning filter configured to transmit light in the visible region and block light in the near-infrared region, wherein visible light transmitted through the first prism is incident on the first fine-tuning filter via the reflective film; a first image sensor facing the first fine-tuning filter to receive visible light transmitted through the first fine-tuning filter and configured to convert the received visible light into an electrical signal; a second fine-tuning filter configured to transmit light in the near-infrared region and block light in the visible region, wherein near-infrared light transmitted through the second prism is incident on the second fine-tuning filter via the reflective film; and a second image sensor facing the second fine-tuning filter to receive near-infrared light transmitted through the second fine-tuning filter and configured to convert the received near-infrared light into an electrical signal. The first prism is fixed to the second prism, the first fine-tuning filter is fixed to the first prism, and the second fine-tuning filter is fixed to the second prism.

[0033] According to this disclosure, an endoscope is provided that can improve the image quality of visible light image data and near-infrared light image data indicating a patient's biological tissues while reducing manufacturing costs; and an image capture unit disposed in the endoscope. Attached Figure Description

[0034] Figure 1 This is an exploded perspective view of the endoscope according to this embodiment.

[0035] Figure 2 This is a cross-sectional view showing the endoscope according to this embodiment.

[0036] Figure 3 This is a diagram illustrating examples of the reflective properties of a visible light reflective film relative to visible light and the transmission properties of a visible light reflective film relative to near-infrared light.

[0037] Figure 4 This is a diagram illustrating an example of the transmission characteristics of the first and second fine-tuning filters.

[0038] Figure 5 This is a diagram illustrating examples of the transmission characteristics of infrared light shielding films and visible light shielding films.

[0039] Figure 6This is a diagram illustrating examples of the spectral transmission characteristics of the visible light channel and the near-infrared light channel.

[0040] Figure 7 This is a diagram showing the transmission characteristics of an RGB color filter in the visible light channel and an RGB color filter in the near-infrared light channel.

[0041] Figure 8 This is a schematic diagram illustrating a CMOS image sensor including a Bayer patterned RGB color filter.

[0042] Figure 9 This is a diagram showing the configuration of an endoscope system.

[0043] Figure 10 This is a diagram illustrating an example of synthesized image data obtained by combining visible light image data and near-infrared light image data. Detailed Implementation

[0044] In the following description, an endoscope 1 according to an embodiment of the present disclosure (hereinafter referred to as "this embodiment") will be described with reference to the accompanying drawings. For ease of description, the dimensions of each component shown in the drawings may differ from the actual dimensions of each component.

[0045] In the description of this embodiment, for ease of description, the X-axis, Y-axis, and Z-axis directions of the endoscope 1 may be appropriately mentioned. These directions are for... Figure 1 The relative orientation of the endoscope 1 shown is defined by one of the X-axis, Y-axis, and Z-axis being orthogonal to the other two axes. The Z-axis corresponds to the extension direction of the observation scope 3 of the endoscope 1.

[0046] First, the following will refer to Figure 1 and Figure 2 The configuration of endoscope 1 according to this embodiment is described. Figure 1 This is an exploded perspective view of the endoscope 1 according to this embodiment. Figure 2 This is a cross-sectional view of the endoscope 1 in which the image capture unit 2 is housed inside the observation mirror 3.

[0047] like Figure 1 and Figure 2 As shown, endoscope 1 includes an observation mirror 3, an image capture unit 2, a light guide 4, a first support member 5, a second support member 6, and a lens cover 7. By inserting endoscope 1 into a patient's body, healthcare workers can observe biological tissues, such as those inside the patient's body, in real time. Endoscope 1 can be a rigid endoscope, for example, used in laparoscopic surgery. Endoscope 1 is not limited to rigid endoscopes.

[0048] Both visible light and near-infrared light image data of the patient's biological tissues can be simultaneously acquired using endoscope 1. In this regard, in laparoscopic surgery, fluorescent contrast agents that emit near-infrared light (such as indocyanine green (ICG)) are used. When the ICG is irradiated with excitation light (laser), the ICG emits near-infrared light. The central wavelength λ of the laser serving as the excitation light is, for example, in the range of 700 nm to 800 nm, more specifically, in the range of 785 nm to 795 nm. After the ICG is injected into the patient's vein, healthcare workers can visually identify the diseased area where the ICG is located by visually recognizing the near-infrared light image data acquired through endoscope 1. In this way, healthcare workers, such as surgeons, can perform surgical treatment (such as resection of the diseased area) on the diseased area identified by the ICG.

[0049] The observation mirror 3 is a portion of the endoscope 1 that is to be inserted into the patient's body. The observation mirror 3 is configured as, for example, a rigid tube having a space S. The outer diameter of the observation mirror 3 is, for example, approximately 10 mm, and the inner diameter of the observation mirror 3 is, for example, approximately 9 mm. The image capture unit 2 is configured to receive visible light and near-infrared light associated with the patient's biological tissue in order to capture an image of the biological tissue. Specifically, the image capture unit 2 is configured to receive visible light reflected by the patient's biological tissue and near-infrared light emitted from a fluorescent contrast agent (ICG, etc.) remaining in the biological tissue in order to capture an image of the biological tissue. In this embodiment, the image capture unit 2 is housed inside the space S of the observation mirror 3. In this respect, the image capture unit 2 is reduced to such a extent that the image capture unit 2 can be housed inside the observation mirror 3 having an inner diameter of approximately 9 mm. Furthermore, the image capture unit 2 is disposed at the tip 3a of the observation mirror 3 (see...). Figure 2 Near the patient. With the endoscope 1 inserted into the patient's body, the tip 3a of the observation endoscope 3 faces the patient's biological tissue. The specific configuration of the image capture unit 2 will be described later.

[0050] Light guide 4 is configured to guide visible light emitted from a visible light source (not shown) and excitation light emitted from an excitation light source (not shown) toward the patient's biological tissue. Light guide 4 comprises a plurality of optical fibers through which the visible light and excitation light propagate. Figure 1 From a simplified illustrative viewpoint, only a portion of the light guide 4 is shown; however, the light guide 4 is housed within the space S of the observation mirror 3 and extends along the Z-axis to both the visible light source and the excitation light source. Visible light emitted from the light guide 4 is reflected by the biological tissue and then received by the image capture unit 2. Further, the excitation light emitted from the light guide 4 is emitted onto a fluorescent contrast agent (such as ICG) that remains in the biological tissue. Subsequently, by irradiation with the excitation light, the near-infrared light (fluorescence) emitted from the fluorescent contrast agent is received by the image capture unit 2.

[0051] like Figure 2 As shown, the first support member 5 is housed within the space S of the observation mirror 3 and is configured to support the image capture unit 2. Specifically, the first support member 5 is fixed to the image capture unit 2 by adhesive. More specifically, the first support member 5 is configured to support the lens unit 20, the first prism 21, and the second prism 22 disposed in the image capture unit 2, and is fixed to the lens unit 20, the first prism 21, and the second prism 22 by adhesive. In this way, the overall strength of the image capture unit 2 can be improved by the first support member 5.

[0052] The second support member 6 is housed within the space S of the observation mirror 3 and is fixed to the first support member 5 and the observation mirror 3 by adhesive. The second support member 6 includes an insertion hole 62 into which the light guide 4 is inserted, an insertion hole 63 into which the lens unit 20 is inserted, and an insertion hole 64 into which the lens cover 7 is inserted. When the light guide 4 is inserted into the insertion hole 62, the light guide 4 is supported by the second support member 6. The insertion holes 63 and 64 are in communication with each other. When the lens cover 7 is inserted into the insertion hole 64, the lens cover 7 is fixed and supported by the second support member 6. The front surface 65 of the second support member 6, the front surface 7a of the lens cover 7, and the end face 4a of the light guide 4 form the tip end face 1a of the endoscope 1 facing biological tissue.

[0053] As described above, since the first support member 5 is fixed to the image capture unit 2, and the second support member 6 is fixed to the first support member 5 and the observation mirror 3, the image capture unit 2 can be reliably fixed to the observation mirror 3 through the first support member 5 and the second support member 6.

[0054] (Specific configuration of image capture unit 2)

[0055] Next, the following will refer to Figure 2 Describe the specific configuration of image capture unit 2. For example... Figure 2 As shown, the image capture unit 2 includes a lens unit 20, a first prism 21, a second prism 22, and a visible light reflective film 27 (an example of a reflective film). The image capture unit 2 also includes a first fine-tuning filter 23, an infrared light shielding film 28, a first image sensor 24, and a first circuit board 32. The image capture unit 2 further includes a second fine-tuning filter 25, a visible light shielding film 29, a second image sensor 26, and a second circuit board 33.

[0056] Lens unit 20 is configured to guide visible and near-infrared light from biological tissue toward first prism 21. To widen the image angle (viewing angle) of image capture unit 2 and more effectively acquire visible and near-infrared light from biological tissue, it is preferable to position lens unit 20 near the tip 3a of observation mirror 3 or near the tip face 1a of endoscope 1. In this embodiment, the distance in the Z-axis direction between the incident surface 20a of lens unit 20 (which is the tip of lens unit 20) and the tip face 1a of endoscope 1 is in the range of 0.5 mm to 5 mm. Preferably, the distance in the Z-axis direction between the incident surface 20a and the tip face 1a is in the range of 0.5 mm to 2 mm. More preferably, the distance in the Z-axis direction between the incident surface 20a and the tip face 1a is in the range of 0.5 mm to 1 mm.

[0057] The lens unit 20 and the first prism 21 are fixed to each other via the first support member 5. At this point, the emitting surface 20b of the lens unit 20 and the incident surface 21b of the first prism 21 are in contact with each other, and there is no gap between the lens unit 20 and the first prism 21. Therefore, dust and the like can be properly prevented from entering the gap, and the burden of maintenance required for the endoscope 1 can be reduced.

[0058] The first prism 21 and the second prism 22 are configured as right-angle prisms. The first prism 21 and the second prism 22 are formed of, for example, transparent glass or transparent plastic. The first prism 21 and the second prism 22 face each other and are fixed together by adhesive. Specifically, the first prism 21 and the second prism 22 are fixed together with the inclined plane 21a of the first prism 21 and the inclined plane 22a of the second prism 22 facing each other. Therefore, since the first prism 21 and the second prism 22 fixed together are cuboid in shape, the overall size of the image capture unit 2 can be reduced, and the image capture unit 2 can be housed inside the observation mirror 3.

[0059] A visible light reflective film 27 (an example of a reflective film) is disposed between the inclined surface 21a of the first prism 21 and the inclined surface 22a of the second prism 22. In this embodiment, after the visible light reflective film 27 is formed on either the inclined surface 21a or the inclined surface 22a, the first prism 21 and the second prism 22 are fixed to each other via an adhesive. The visible light reflective film 27 is configured to separate visible light and near-infrared light from biological tissue. More specifically, the visible light reflective film 27 is configured to reflect visible light emitted from biological tissue and transmitted through the lens unit 20 and the first prism 21 toward the first fine-tuning filter 23. Further, the visible light reflective film 27 is configured to transmit near-infrared light emitted from biological tissue and transmitted through the lens unit 20 and the first prism 21 toward the second fine-tuning filter 25.

[0060] Since the inclined surfaces 21a of the first prism 21 and 22a of the second prism 22 are tilted at 45 degrees relative to the Z-axis, the visible light reflective film 27 is also tilted at 45 degrees relative to the Z-axis. Therefore, the visible light reflective film 27 reflects visible light, changing its propagation direction by 90 degrees, and transmits near-infrared light, ensuring that its propagation direction remains unchanged. As described above, the propagation direction of visible light is converted from the Z-axis to the Y-axis by the visible light reflective film 27, while the propagation direction of near-infrared light traveling in the Z-axis direction is not changed by the visible light reflective film 27.

[0061] The visible light reflective film 27 is a dichroic mirror made of a dielectric multilayer film formed by alternately stacking dielectric films with high refractive index (high refractive index layer) and dielectric films with low refractive index (low refractive index layer). For example, TiO2 (with a refractive index of n...) can be used as the material for the high refractive index layer. H =2.35). As a material for the low refractive index layer, for example, SiO2 (refractive index n) can be used. L =1.47). The number of high-refractive-index layers and the number of low-refractive-index layers are both, for example, 80.

[0062] Figure 3 Examples of the reflective properties of the visible light reflective film 27 relative to visible light and the transmittance properties of the visible light reflective film 27 relative to near-infrared light are shown. For example... Figure 3 As shown, the visible light reflective film 27 reflects visible light, resulting in a reflectivity of 90% or higher relative to visible light in the 400nm to 650nm wavelength range. On the other hand, the visible light reflective film 27 reflects almost no near-infrared light in the 800nm ​​to 1050nm wavelength range. In other words, the visible light reflective film 27 transmits visible light, resulting in a transmittance of 10% or lower relative to visible light in the 400nm to 650nm wavelength range. Furthermore, the visible light reflective film 27 transmits most of the near-infrared light in the 800nm ​​to 1050nm wavelength range.

[0063] The first fine-tuning filter 23 is fixed to the first prism 21 by an adhesive. The incident surface 23b of the first fine-tuning filter 23 and the emitting surface 21c of the first prism 21 are in contact with each other by the adhesive. The first fine-tuning filter 23 is configured to transmit light in the visible region (visible light) and shield light in the near-infrared region (near-infrared light). Light reflected and transmitted through the first prism 21 by the visible light reflective film 27 is incident on the first fine-tuning filter 23. The first fine-tuning filter 23 transmits the visible light component of the incident light incident on the first fine-tuning filter 23 and shields the near-infrared light component of the incident light. Figure 4 An example of the transmission characteristics of the first fine-tuning filter 23 is shown. For example... Figure 4As shown, the first fine-tuning filter 23 has a transmittance of 90% or higher for visible light in the 400nm to 600nm band, while its transmittance for near-infrared light at wavelengths of 800nm ​​or higher is 20% or lower. The first fine-tuning filter 23 is formed of colored glass that shields infrared light.

[0064] An infrared light shielding film 28 is disposed between the first trimmer filter 23 and the first image sensor 24 in the Y-axis direction. In this embodiment, after the infrared light shielding film 28 is formed on the emitting surface 23a of the first trimmer filter 23, the first trimmer filter 23 and the first image sensor 24 are fixed to each other by an adhesive. The infrared light shielding film 28 is configured to transmit light in the visible region (visible light) and shield light in the near-infrared region (near-infrared light) and excitation light emitted to biological tissue and included in the band having a center wavelength of 700 nm to 800 nm. The infrared light shielding film 28 transmits the visible light component of the incident light, which passes through the first trimmer filter 23 and is incident on the infrared light shielding film 28, shielding the near-infrared light component of the incident light. Figure 5 An example of the transmission characteristics of the infrared light shielding film 28 is shown. For example... Figure 5 As shown, the infrared shielding film 28 has a transmittance of 95% or higher for visible light in the 400nm to 650nm band, and a transmittance of 1% or lower for light with wavelengths of 700nm or higher.

[0065] The infrared light shielding film 28 is a dichroic mirror made of a dielectric multilayer film formed by alternating layers of high-refractive-index and low-refractive-index layers. For example, TiO2 (refractive index n) can be used as the material for the high-refractive-index layer. H =2.35). As a material for the low refractive index layer, for example, SiO2 (refractive index n) can be used. L =1.47). The number of high-refractive-index layers and the number of low-refractive-index layers are both, for example, 50.

[0066] Therefore, visible light reflected by the patient's biological tissue is incident on the first image sensor 24 through a visible light channel formed by the combination of a visible light reflective film 27, a first fine-tuning filter 23 and an infrared light shielding film 28. Figure 6 An example of the spectral transmission characteristics of a visible light channel formed by a combination of a visible light reflective film 27, a first fine-tuning filter 23, and an infrared light shielding film 28 is shown. Figure 6As shown, the visible light channel has a transmittance of 80% or higher for visible light in the 400nm to 600nm band, and a transmittance of 0.1% or lower for light in the 720nm to 1050nm band. In this respect, the visible light channel preferably has spectral characteristics such that the transmittance of light in the 720nm to 1050nm band is 0.01% or less.

[0067] A first image sensor 24 is mounted on a first circuit board 32 and arranged such that its imaging surface faces the first trimmer filter 23 and the infrared shielding film 28 in the Y-axis direction. The first image sensor 24 is fixed to the first trimmer filter 23 by adhesive, with the infrared shielding film 28 inserted therebetween. The first image sensor 24 is configured to receive visible light transmitted through a visible light channel formed by the combination of the visible light reflector 27, the first trimmer filter 23, and the infrared shielding film 28, and convert the received visible light into an electrical signal.

[0068] The first image sensor 24 is a complementary metal-oxide-semiconductor (CMOS) image sensor or a charge-coupled device (CCD) image sensor. In this respect, since the visible light incident on the image capture unit 2 is reflected once by the visible light reflective film 27 before incident on the first image sensor 24, the image of the biological tissue incident on the first image sensor 24 is an inverted image. On the other hand, the first image sensor 24 is preferably a CMOS image sensor because a CMOS image sensor can generate a visible light image signal indicating a normal image of the biological tissue based on the visible light that forms the inverted image. In this respect, by adjusting the order in which the charge accumulated in the photodiodes of the CMOS image sensor is read, a visible light image signal indicating a normal image of the biological tissue can be generated.

[0069] like Figure 8As shown, the first image sensor 24 includes a Bayer pattern color filter array and a photodiode array having multiple photodiodes arranged in a matrix. The color filter array includes multiple red filters, multiple green filters, and multiple blue filters. In the Bayer pattern color filter array, the number of green filters is twice the number of red filters and the number of blue filters. Each photodiode included in the photodiode array faces one of the multiple color filters (red filter, green filter, and blue filter). Therefore, the first image sensor 24 converts the received visible light into an electrical signal to generate a visible light image signal (raw data) indicating an image of biological tissue, and then transmits the generated visible light image signal via wire 35 to a visible light image data generation circuit 41 (see...). Figure 9 Subsequently, the visible light image data generation circuit 41 generates visible light image data by performing image data conversion processing (raw data -> RGB data) on the visible light image signal (raw data). In the following description, the red filter, green filter, and blue filter in the color filter array can be collectively referred to as "RGB color filters".

[0070] Figure 7 The transmission characteristics of the RGB color filter on the visible light channel are shown. Visible light from biological tissue passes through the visible light channel of the image capture unit 2 and then through the RGB color filter of the first image sensor 24. The visible light that has passed through the RGB color filter is then received by a photodiode. Figure 7 As shown, regarding the transmission characteristics of the red filter in the visible light channel, the transmittance of light at wavelengths of 720 nm or greater is 0.1% or less. Regarding the transmission characteristics of the green filter in the visible light channel, the transmittance of light at wavelengths of 720 nm or greater is 0.1% or less. Regarding the transmission characteristics of the blue filter in the visible light channel, the transmittance of light at wavelengths of 720 nm or greater is 0.1% or less.

[0071] In this manner, excitation light with a center wavelength of 700 nm to 800 nm (more specifically, excitation laser with a center wavelength of 785 nm to 795 nm) is emitted onto the biological tissue, and near-infrared light is appropriately prevented from passing through the RGB color filter. As a result, by appropriately preventing the excitation light and near-infrared light from being received by the photodiode of the first image sensor 24, the accuracy or reliability of visible light image data indicating the biological tissue is improved.

[0072] The second fine-tuning filter 25 is fixed to the second prism 22 by an adhesive. The incident surface 25b of the second fine-tuning filter 25 and the emitting surface 22b of the second prism 22 are in contact with each other via the adhesive. The second fine-tuning filter 25 is configured to transmit light in the near-infrared region (near-infrared light) and shield light in the visible region (visible light). Light transmitted through the visible light reflective film 27 and the second prism 22 is incident on the second fine-tuning filter 25. The second fine-tuning filter 25 transmits the near-infrared component of the incident light and shields the visible light component of the incident light. Figure 4 An example of the transmission characteristics of the second fine-tuning filter 25 is shown. For example... Figure 4 As shown, the second fine-tuning filter 25 has a transmittance of 90% or more relative to near-infrared light with a wavelength of 850 nm or greater, while the second fine-tuning filter 25 has a transmittance of 1% or less relative to visible light in the 400 nm to 750 nm band. The second fine-tuning filter 25 is formed of colored glass that shields visible light.

[0073] A visible light shielding film 29 is disposed between the second trimmer filter 25 and the second image sensor 26 in the Z-axis direction. In this embodiment, after the visible light shielding film 29 is formed on the emitting surface 25a of the second trimmer filter 25, the second trimmer filter 25 and the second image sensor 26 are fixed to each other via an adhesive. The visible light shielding film 29 is configured to transmit light in the near-infrared region (near-infrared light) and shield light in the visible region (visible light) and excitation light emitted to biological tissue and included in the band having a center wavelength of 700 nm to 800 nm. The visible light shielding film 29 transmits the near-infrared component of the incident light, which is transmitted through the second trimmer filter 25 and incident on the visible light shielding film 29, thus shielding the visible light component of the incident light. Figure 5 An example of the transmission characteristics of the visible light shielding film 29 is shown. For example... Figure 5 As shown, the transmittance of the visible light shielding film 29 relative to near-infrared light with a wavelength of 850 nm or greater is 95% or greater, while the transmittance of the visible light shielding film 29 relative to light in the 700 nm to 800 nm band is 1% or less.

[0074] The visible light shielding film 29 is a dichroic mirror made of a dielectric multilayer film formed by alternating layers of high-refractive-index and low-refractive-index layers. For example, TiO2 (refractive index n) can be used as the material for the high-refractive-index layer. H =2.35). As a material for the low refractive index layer, for example, SiO2 (refractive index n) can be used. L =1.47). The number of high-refractive-index layers and the number of low-refractive-index layers are both, for example, 50.

[0075] Therefore, near-infrared light emitted from the fluorescent contrast agent present in biological tissue is incident on the second image sensor 26 through the near-infrared light channel formed by the combination of visible light reflective film 27, second fine-tuning filter 25 and visible light shielding film 29. Figure 6 An example of the spectral transmission characteristics of a near-infrared light channel formed by a combination of a visible light reflective film 27, a second fine-tuning filter 25, and a visible light shielding film 29 is shown. Figure 6 As shown, the near-infrared light channel has a transmittance of 90% or more relative to near-infrared light with a wavelength of 870 nm or greater, and a transmittance of 0.5% or less relative to light in the 400 nm to 798 nm band. In this respect, the near-infrared light channel preferably has spectral characteristics such that the transmittance of light in the 400 nm to 798 nm band is 0.01% or less.

[0076] The second image sensor 26 is mounted on the second circuit board 33 and arranged such that its imaging surface faces the second trimmer filter 25 and the visible light shielding film 29 in the Z-axis direction. The second image sensor 26 is fixed to the second trimmer filter 25 by adhesive, with the visible light shielding film 29 inserted therebetween. The imaging surface of the second image sensor 26 is perpendicular to the imaging surface of the first image sensor 24. The second image sensor 26 is configured to receive near-infrared light transmitted through a near-infrared light channel formed by the combination of the visible light reflector 27, the second trimmer filter 25, and the visible light shielding film 29, and convert the received near-infrared light into an electrical signal.

[0077] The second image sensor 26 converts the received near-infrared light into an electrical signal to generate a near-infrared image signal indicating an image of biological tissue, and then transmits the generated near-infrared image signal to the near-infrared image data generation circuit 42 via wire 36 (see...). Figure 9 Subsequently, the near-infrared light image data generation circuit 42 generates near-infrared light image data by performing predetermined processing on the near-infrared light image signal.

[0078] The second image sensor 26 is a CMOS image sensor or a CCD image sensor. In this respect, from the perspective of manufacturing cost of the endoscope 1, the second image sensor 26 and the first image sensor 24 preferably have the same configuration. In this case, it is not necessary to prepare different types of image sensors for the first image sensor 24 and the second image sensor 26, which can reduce the manufacturing cost of the endoscope 1. For example, similar to the first image sensor 24, the second image sensor 26 may include a Bayer pattern color filter array and a photodiode array having a plurality of photodiodes arranged in a matrix. In the following description, it is assumed that the second image sensor 26 includes a Bayer pattern color filter array.

[0079] Figure 7 The transmission characteristics of the RGB color filter on the near-infrared light channel are shown. Near-infrared light emitted from a fluorescent contrast agent present on biological tissue passes through the near-infrared light channel of the image capture unit 2 and then through the RGB color filter of the second image sensor 26. The near-infrared light passing through the RGB color filter is then received by a photodiode. Figure 7 As shown, regarding the transmission characteristics of the blue filter in the near-infrared light channel, the transmittance of light in the 400nm to 798nm band is 0.5% or less, while the transmittance of light near the 850nm wavelength is the highest. Similarly, regarding the transmission characteristics of the green filter in the near-infrared light channel, the transmittance of light in the 400nm to 798nm band is 0.5% or less, while the transmittance of light near the 850nm wavelength is the highest. Similarly, regarding the transmission characteristics of the red filter in the near-infrared light channel, the transmittance of light in the 400nm to 798nm band is 0.5% or less, while the transmittance of light near the 850nm wavelength is the highest. Further, as... Figure 7 As shown, based on the spectral characteristics of the fluorescence (near-infrared light) emitted from the fluorescent contrast agent, the center wavelength of the near-infrared light exists near a wavelength of 830 nm.

[0080] Therefore, even if the second image sensor 26 includes a Bayer patterned color filter array, the near-infrared light output from the fluorescent contrast agent can be converted into an electrical signal, and visible light and excitation light are appropriately prevented from being received by the photodiode of the second image sensor 26. Thus, the manufacturing cost of the endoscope 1 is reduced, and the accuracy or reliability of near-infrared image data indicating biological tissue is improved.

[0081] Furthermore, in the single image sensor disclosed in Patent Document 1, there are four types of pixels: blue pixels, green pixels, red pixels, and infrared pixels. Therefore, there are problems such as low pixel values ​​for IR pixels, potential noise in the near-infrared light image signal output from a single IR pixel of the image sensor, and potential degradation of the image quality of the near-infrared light image data. Meanwhile, in the second image sensor 26, since all pixels are IR pixels, the pixel value of each IR pixel can be increased through H / V pixel addition processing (which is the process of adding the pixel values ​​of adjacent pixels in the horizontal (H) direction and the vertical (V) direction). In this way, by increasing the pixel value of each IR pixel through H / V pixel addition processing in the second image sensor 26, noise is less likely to appear in the near-infrared light image signal output from the second image sensor 26, and the accuracy or reliability of near-infrared light image data indicating biological tissue is improved.

[0082] Next, we will refer to the following. Figure 9 Description of endoscopic system 100. Figure 9 This is a diagram showing the configuration of the endoscope system 100. (As shown) Figure 9 As shown, the endoscope system 100 includes an endoscope 1, which includes an image capture unit 2, an image processing circuit 40, and a display unit 50. Figure 9 For ease of description, only a portion of the configuration of the endoscope 1 and the image processing circuit 40 is shown. The image processing circuit 40 includes a visible light image data generation circuit 41, a near-infrared light image data generation circuit 42, a composite image data generation circuit 43, and an output interface 44.

[0083] The image processing circuit 40 is configured to generate image data indicating biological tissue based on the image signal (digital signal) transmitted from the image capture unit 2, and then transmit the generated image data to the display unit 50. The image processing circuit 40 generates the image data at a predetermined frame rate (e.g., 60 fps). There is no particular limitation on the frame rate of the image data. In this embodiment, the image processing circuit 40 can generate visible light image data and near-infrared light image data at the same timing and the same frame rate.

[0084] The image processing circuit 40 may include: a microcomputer comprising one or more processors and one or more memories; and electronic circuitry comprising passive and active components (e.g., transistors). The processor may be, for example, at least one of a central processing unit (CPU), a microprocessor unit (MPU), and a graphics processing unit (GPU). The memory may include read-only memory (ROM) and random access memory (RAM). In addition to or instead of a microcomputer, the image processing circuit 40 may be a non-von Neumann computer, such as an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA).

[0085] As described above, the visible light image data generation circuit 41 is configured to receive a visible light image signal (RAW data) from the first image sensor 24, and then generate visible light image data based on the visible light image signal. The visible light image data generation circuit 41 transmits the visible light image data to the composite image data generation circuit 43 and the output interface 44.

[0086] The near-infrared light image data generation circuit 42 is configured to receive near-infrared light image signals from the second image sensor 26, and then generate near-infrared light image data based on the near-infrared light image signals. The near-infrared light image data generation circuit 42 transmits the near-infrared light image data to the composite image data generation circuit 43 and the output interface 44.

[0087] The composite image data generation circuit 43 is configured to generate composite image data by synthesizing received visible light image data and near-infrared light image data. The composite image data generation circuit 43 can generate composite image data after the near-infrared light image data is colored with a predetermined color (fluorescent color). Since the near-infrared light image data shows biological tissue containing fluorescent contrast agents such as ICG, when the near-infrared light image data is colored with the predetermined color, the biological tissue containing the fluorescent contrast agent (disease part) is highlighted and displayed on the composite image data (e.g., see...). Figure 10 Therefore, healthcare workers such as surgeons can clearly identify diseased parts by visually recognizing synthetic image data displayed on display unit 50.

[0088] Visible light image data, near-infrared light image data, and composite image data are transmitted to display unit 50 via output interface 44. Display unit 50 is configured to display at least one of the visible light image data, near-infrared light image data, and composite image data. The image data transmitted to display unit 50 can be appropriately changed according to the operation of the endoscope system 100 by the healthcare worker. Display unit 50 can be a liquid crystal display or an organic EL display, or it can be a transmissive or non-transmissive head-mounted display mounted on the head of the healthcare worker.

[0089] According to this embodiment, the first prism 21 and the second prism 22, which are right-angle prisms, are fixed to each other. A first fine-tuning filter 23 is fixed to the first prism 21 and the first image sensor 24, and a second fine-tuning filter 25 is fixed to the second prism 22 and the second image sensor 26. Furthermore, the imaging surfaces of the first image sensor 24 and the second image sensor 26 are perpendicular to each other. With this configuration, the overall size of the image capture unit 2 can be reduced, and the image capture unit 2 can be housed within the space S of the observation mirror 3, which has a small inner diameter. Since the image capture unit 2 is housed within the space S near the tip face 1a of the endoscope 1, visible light and near-infrared light associated with the patient's biological tissue are effectively received by the first image sensor 24 and the second image sensor 26, respectively. In this way, the image quality of the visible light image data indicating biological tissue is improved because the visible light image signal indicating biological tissue is acquired by the first image sensor 24 without reducing the signal-to-noise ratio (SNR). Furthermore, the image quality of the near-infrared light image data indicating biological tissue is improved because the near-infrared light image signal indicating biological tissue is acquired by the second image sensor 26. Since the visible light image signal and the near-infrared light image signal are acquired at the same timing, the time axis of each frame of the visible light image data and the time axis of each frame of the near-infrared light image data are matched. Therefore, because the time axes of the visible light image data frames and the near-infrared light image data frames are matched, the accuracy of the synthesized image data generated by synthesizing the visible light image data and the near-infrared light image data is improved. Furthermore, since the image capture unit 2 is housed inside the space S of the observation mirror 3, it is not necessary to provide expensive relay lenses or the like on the observation mirror 3 to guide the visible light and near-infrared light from the patient's biological tissue to the image capture unit 2, thereby reducing the overall manufacturing cost of the endoscope 1. Therefore, an endoscope 1 can be provided that can improve the image quality of visible light image data, near-infrared light image data, and synthesized image data indicating the patient's biological tissue while reducing manufacturing costs.

[0090] According to this embodiment, when the first image sensor 24 is a CMOS image sensor configured to generate a visible light image signal indicating a normal image of biological tissue, visible light image data and near-infrared image data can be acquired at the same timing. Specifically, when the first image sensor 24 is a CCD image sensor, image inversion processing needs to be performed separately on the image processing circuit 40 side to generate visible light image data indicating a normal image of biological tissue based on the visible light image signal indicating an inverted image of biological tissue. For this reason, the generation timing of the visible light image data may be later than the generation timing of the near-infrared image data, and it is difficult to acquire visible light image data and near-infrared image data at the same timing on the image processing circuit side 40. However, when the first image sensor 24 is a CMOS image sensor, since image inversion processing does not need to be performed on the image processing circuit 40 side, visible light image data and near-infrared image data can be acquired at the same timing on the image processing circuit side.

[0091] According to this embodiment, the visible light channel formed by the combination of the visible light reflective film 27, the first fine-tuning filter 23, and the infrared light shielding film 28 has spectral characteristics such that the transmittance of light in the 720 nm to 1050 nm band is 0.1% or less. Therefore, it is possible to appropriately prevent both the excitation light in the 700 nm to 800 nm band and the near-infrared light emitted onto biological tissue from adversely affecting the accuracy or reliability of the visible light image data. Furthermore, the near-infrared light channel formed by the combination of the visible light reflective film 27, the second fine-tuning filter 25, and the visible light shielding film 29 has spectral characteristics such that the transmittance of light in the 400 nm to 798 nm band is 0.5% or less. Therefore, it is possible to appropriately prevent the excitation light and visible light emitted onto biological tissue from adversely affecting the accuracy or reliability of the near-infrared light image data. Furthermore, in the second image sensor 26, the pixel value of each IR pixel is increased by H / V pixel addition, making it less likely for noise to appear in the near-infrared light image signal output from the second image sensor 26, and improving the accuracy or reliability of the near-infrared light image data.

[0092] While embodiments of the present invention have been described above, it should be understood that the scope of the invention should not be construed as limited to the descriptions herein. Those skilled in the art should understand that these embodiments are merely examples, and various modifications can be made to the embodiments within the scope of the invention described in the claims. The scope of the invention should be determined based on the scope of the invention as described in the claims and its equivalents.

[0093] In this embodiment, the visible light reflective film 27 has been described as an example of a reflective film that separates visible light and near-infrared light from biological tissue; however, the reflective film is not limited to a visible light reflective film. For example, a reflective film that separates visible light and near-infrared light can be a near-infrared light reflective film configured to transmit visible light and reflect near-infrared light. In this case, the positions of the first prism 21 and the second prism 22 are interchanged, and the positions of the first fine-tuning filter 23 on which the infrared light shielding film 28 is formed and the second fine-tuning filter 25 on which the visible light shielding film 29 is formed are interchanged. Furthermore, the positions of the first image sensor 24 and the second image sensor 26 are interchanged. Similarly, the near-infrared light reflective film is also a dichroic mirror made of a dielectric multilayer film formed by alternately stacking dielectric films with high refractive index (high refractive index layer) and dielectric films with low refractive index (low refractive index layer).

[0094] In this embodiment, the first prism 21 and the second prism 22 are configured as right-angle prisms, but the shape of the first prism 21 or the second prism 22 is not limited to a right-angle triangular prism.

[0095] The first image sensor 24 and the second image sensor 26 can have different configurations. For example, the second image sensor 26 may not include a color filter array. In this case, since the near-infrared light channel arranged in front of the second image sensor 26 transmits near-infrared light while shielding visible light and excitation light, only near-infrared light can be incident on the photodiode of the second image sensor 26.

Claims

1. An endoscope comprising: a scope to be inserted into a patient's body; and an image capturing unit housed inside the scope and configured to receive light associated with a biological tissue of the patient so as to capture an image of the biological tissue, wherein the image capturing unit comprises: a first prism; a second prism facing the first prism; a reflective film disposed between a slope of the first prism and a slope of the second prism and configured to separate the light associated with the biological tissue into visible light and near-infrared light; a first fine-tuning filter configured to transmit light in a visible region and shield light in a near-infrared region, the visible light transmitted through the first prism being incident on the first fine-tuning filter via the reflective film; a first image sensor facing the first fine-tuning filter so as to receive the visible light transmitted through the first fine-tuning filter and configured to convert the received visible light into an electrical signal; a second fine-tuning filter configured to transmit light in a near-infrared region and shield light in a visible region, the near-infrared light transmitted through the second prism being incident on the second fine-tuning filter via the reflective film; a second image sensor facing the second fine-tuning filter so as to receive the near-infrared light transmitted through the second fine-tuning filter and configured to convert the received near-infrared light into an electrical signal; and a lens unit fixed to the first prism so as to direct the light associated with the biological tissue toward the first prism, wherein the first prism is fixed to the second prism, wherein the first fine-tuning filter is fixed to the first prism, wherein the second fine-tuning filter is fixed to the second prism, wherein the first image sensor is fixed to the first fine-tuning filter, wherein the second image sensor is fixed to the second fine-tuning filter, and the image capturing unit is located within a distal end portion of the scope.

2. The endoscope according to claim 1, wherein the image capturing unit is arranged near a tip end face of the scope facing the biological tissue.

3. The endoscope according to claim 1 or 2, wherein the image capturing unit further comprises: an infrared light shielding film disposed between the first fine-tuning filter and the first image sensor and configured to transmit light in the visible region and shield light in the near-infrared region; and a visible light shielding film disposed between the second fine-tuning filter and the second image sensor and configured to transmit light in the near-infrared region and shield light in the visible region, and wherein the infrared light shielding film and the visible light shielding film are configured to shield excitation light emitted to the biological tissue and included in a wavelength band having a center wavelength of 700 nm to 800 nm.

4. The endoscope according to claim 1, wherein a distance between a tip end of the lens unit and a tip end face of the scope facing the biological tissue is in a range of 0.5 mm to 5 mm.

5. The endoscope according to claim 1 or 4, further comprising: ​ ​ a first support member configured to support the lens unit, the first prism, and the second prism and housed inside the scope, wherein the first support member is fixed to the lens unit, the first prism, and the second prism.

6. The endoscope according to claim 5, further comprising: a second support member fixed to the first support member and the scope and housed inside the scope.

7. The endoscope according to claim 1 or 2, wherein the first image sensor includes a CMOS image sensor configured to generate a visible light image signal indicative of a normal image of the biological tissue based on visible light forming an inverted image of the biological tissue.

8. The endoscope according to claim 1 or 2, wherein the first image sensor and the second image sensor have the same configuration.

9. The endoscope according to claim 1 or 2, wherein imaging surfaces of the first image sensor and the second image sensor are perpendicular to each other.

10. The endoscope according to claim 3, wherein a visible light channel formed by a combination of the reflective film, the first fine adjustment filter, and the infrared light shielding film has spectral characteristics such that a transmittance of light in a wavelength band of 720 nm to 1050 nm is 0.1% or less, and wherein a near-infrared light channel formed by a combination of the reflective film, the second fine adjustment filter, and the visible light shielding film has spectral characteristics such that a transmittance of light in a wavelength band of 400 nm to 798 nm is 0.5% or less.

11. The endoscope according to claim 1 or 2, wherein the scope is a portion of the endoscope to be inserted into the patient's body, wherein the first fine adjustment filter is attached to the first prism, wherein the second fine adjustment filter is attached to the second prism, wherein the first image sensor is attached to the first fine adjustment filter, and wherein the second image sensor is attached to the second fine adjustment filter.

12. An image capturing unit housed inside a scope of the endoscope according to any one of claims 1 to 11 and configured to receive light associated with a biological tissue of a patient so as to capture an image of the biological tissue, the image capturing unit comprising: a first prism; a second prism facing the first prism; a reflective film disposed between a slope of the first prism and a slope of the second prism and configured to separate light associated with a biological tissue into visible light and near-infrared light; a first fine adjustment filter configured to transmit light in a visible region and shield light in a near-infrared region, the visible light transmitted through the first prism being incident on the first fine adjustment filter via the reflective film; a first image sensor facing the first fine adjustment filter so as to receive the visible light transmitted through the first fine adjustment filter and configured to convert the received visible light into an electrical signal; a second fine-tuning filter configured to transmit light in a near-infrared region and to shield light in a visible region, near-infrared light transmitted through the second prism being incident on the second fine-tuning filter via the reflective film; and a second image sensor facing the second fine-tuning filter so as to receive near-infrared light transmitted through the second fine-tuning filter and configured to convert the received near-infrared light into an electrical signal; and a lens unit fixed to the first prism so as to direct light associated with the biological tissue toward the first prism, wherein the first prism is fixed to the second prism, wherein the first fine-tuning filter is fixed to the first prism, wherein the second fine-tuning filter is fixed to the second prism, wherein the first image sensor is fixed to the first fine-tuning filter, wherein the second image sensor is fixed to the second fine-tuning filter, and the image capture unit is located within a distal portion of a viewing scope.

Images