Imaging system and near-infrared fluorescent endoscope

Abstract

The utility model discloses an imaging system and a near-infrared fluorescent endoscope. The imaging system comprises an endoscope, a coupling lens and a camera module, the field angle of the endoscope is larger than or equal to 80 degrees, the endoscope is used for collecting visible light and near-infrared fluorescence from a target object, and the overall length of the imaging system is smaller than 400 mm; the coupling lens is arranged on an optical axis of the endoscope and is used for coupling an image of the endoscope to the camera module; the camera module comprises a dichroscope, a visible light camera and a near-infrared camera, the dichroscope is arranged on the optical axis of the coupling lens and used for dividing light from the coupling lens into near-infrared fluorescence and visible light, the wavelength of the visible light is 380-700 nm, and the wavelength of the near-infrared fluorescence is 850-1700 nm; the visible light camera is used for imaging visible light from the dichroscope, the near-infrared camera is used for imaging near-infrared fluorescence from the dichroscope, the total three-dimensional size of the camera module is smaller than 40mm * 40mm * 40mm, and the mass of the camera module is smaller than 150g. Therefore, the imaging system is small in size and compact in structure.

Description

Technical Field

[0001] This invention relates to the field of optical molecular imaging, and more particularly to an imaging system and a near-infrared fluorescence endoscope. Background Technology

[0002] In recent years, with the leap from minimally invasive surgery to the era of precision medicine, "smaller trauma and faster recovery" are the biggest highlights of promoting new surgical techniques. However, minimally invasive surgery also places greater demands on the skills of surgeons. Fluorescence laparoscopy is a new type of surgical aid, also known as intraoperative "Beidou navigation," giving surgeons "eagle eyes" to more clearly and easily identify blood vessels, bile ducts, and other tissue structures during surgery, thereby avoiding collateral damage to blood vessels and making surgery safer and more precise. Fluorescence laparoscopy can serve as an "intraoperative navigation map," helping surgeons to more clearly and easily identify the location of tumors during surgery. In laparoscopic gastrointestinal tumor surgery, how to accurately locate early tumors and their resection margins; how to observe the blood supply to the anastomosis to ensure adequate blood flow and reduce anastomotic leakage; and how to precisely define the scope of lymph node dissection to ensure thorough intraoperative lymph node removal.

[0003] To address these issues, doctors began experimenting with ICG (indocyanine green)-labeled near-infrared (NIR) imaging fluorescence laparoscopy to precisely locate gastrointestinal tumors under laparoscopy, label sentinel lymph nodes, perform lymphatic drainage navigation, and assess intraoperative anastomotic blood supply. The application of ICG imaging technology in medical research can be traced back to the 1950s, initially used as a dye in cardiac, ophthalmic, and neurosurgical procedures. In the last decade or so, its fluorescence properties have been applied to sentinel lymph node tracing and navigation, tissue blood supply assessment, and lymph node tracing in visual surgical procedures.

[0004] With the advent of ICG-labeled near-infrared imaging laparoscopic systems in recent years, ICG has been gradually adopted in laparoscopic surgery. Its applications mainly include two aspects: intravenous injection to assess tissue blood supply; and local injection around the tumor for tumor localization and lymph node navigation. Fluorescence imaging reveals tiny lesions or lymph node metastases invisible under visible light, making surgery safer and more precise. However, current fluorescence laparoscopes are relatively large and require significant space. Utility Model Content

[0005] This invention provides an imaging system and a near-infrared fluorescence endoscope.

[0006] The imaging system of this application includes an endoscope, a coupling lens, and a camera module. The endoscope is used to collect visible light and near-infrared fluorescence from a target object. The field of view of the endoscope is greater than or equal to 80°, and the overall length of the imaging system is less than 400mm. The coupling lens is arranged on the optical axis of the endoscope and is used to couple the image from the endoscope to the camera module. The camera module includes a dichroic mirror, a visible light camera, and a near-infrared camera. The dichroic mirror is arranged on the optical axis of the coupling lens and is used to separate the light from the coupling lens into near-infrared fluorescence and visible light. The wavelength of the visible light is 380nm-700nm, and the wavelength of the near-infrared fluorescence is 850nm-1700nm. The visible light camera is used to image the visible light from the dichroic mirror, and the near-infrared camera is used to image the near-infrared fluorescence from the dichroic mirror. The total three-dimensional dimensions of the camera module are less than 40mm×40mm×40mm, and the mass is less than 150 grams.

[0007] This allows the endoscope to achieve a large field of view while keeping the size and weight of the endoscope and camera module small, resulting in a compact imaging system structure and high space utilization.

[0008] In some implementations, the working distance of the endoscope is greater than or equal to 10 mm; and / or,

[0009] The outer diameter of the endoscope is less than or equal to 10 mm; and / or,

[0010] The magnification of the endoscope is less than 0.2; and / or,

[0011] The depth of field of the endoscope is greater than 100mm.

[0012] In some implementations, the endoscope includes an objective lens group for collecting visible light and near-infrared fluorescence from the target object and forming an intermediate image;

[0013] The objective lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged axially from the object side to the image side. The object side and the image side of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are all spherical.

[0014] The refractive index of the first lens is 1.7 to 1.9, the radius of curvature of the object side of the first lens at the optical axis is -40 mm to -20 mm, the radius of curvature of the image side of the first lens at the optical axis is 1 mm to 5 mm, and the thickness of the first lens is 5 mm to 10 mm; and / or,

[0015] The refractive index of the second lens is 1.9 to 2.1; the radius of curvature of the object side of the second lens at the optical axis is -5 mm to -1 mm; the radius of curvature of the image side of the second lens at the optical axis is -5 mm to -1 mm; and the thickness of the second lens is 1 mm to 5 mm; and / or,

[0016] The refractive index of the third lens is 1.4–1.6, the radius of curvature of the object side of the third lens at the optical axis is 1 mm–5 mm, the radius of curvature of the image side of the third lens at the optical axis is -5 mm–-1 mm, and the thickness of the third lens is 1 mm–5 mm; and / or,

[0017] The refractive index of the fourth lens is 1.6 to 1.8; the radius of curvature of the object side of the fourth lens at the optical axis is -5 mm to -1 mm; the radius of curvature of the image side of the fourth lens at the optical axis is -15 mm to -5 mm; and the thickness of the fourth lens is 1 mm to 5 mm; and / or,

[0018] The refractive index of the fifth lens is 1.7–1.9; the radius of curvature of the object-side surface of the fifth lens at the optical axis is -100 mm to -50 mm; the radius of curvature of the image-side surface of the fifth lens at the optical axis is 1 mm to 5 mm; and the thickness of the fifth lens is 1 mm to 5 mm; and / or,

[0019] The refractive index of the sixth lens is 1.4 to 1.6, the radius of curvature of the object side of the sixth lens at the optical axis is 1 mm to 5 mm, the radius of curvature of the image side of the sixth lens at the optical axis is -5 mm to -1 mm, and the thickness of the sixth lens is 1 mm to 5 mm.

[0020] The third and fourth lenses are cemented together to form a lens group, and the fifth and sixth lenses are cemented together to form a lens group;

[0021] The distance between the first lens and the second lens is 5mm to 10mm; and / or,

[0022] The distance between the second and third lenses is 1mm to 5mm; and / or,

[0023] The distance between the fourth and fifth lenses is 0.5mm to 1.5mm; and / or,

[0024] The optical back cutoff of the objective lens group is 1mm to 5mm.

[0025] In some embodiments, the endoscope includes a relay lens group, and the number of relay lens groups is multiple. The multiple relay lens groups are arranged along the optical axis and are used to collect visible light and near-infrared fluorescence from the target object and image it on the end of the endoscope near the dichroic mirror.

[0026] The relay lens group includes a first group of relay lenses and a second group of relay lenses arranged axially from the object side to the image side. The two groups of relay lenses are arranged symmetrically. The first group of relay lenses includes a first relay lens, a second relay lens and a third relay lens arranged axially from the object side to the image side. The object side and the image side of the first relay lens, the second relay lens and the third relay lens are all spherical.

[0027] The refractive index of the first relay mirror is 1.7–1.9, the radius of curvature of the object side of the first relay mirror at the optical axis is 10 mm–15 mm, the radius of curvature of the image side of the first relay mirror at the optical axis is 1 mm–5 mm, and the thickness of the first relay mirror is 1 mm–5 mm; and / or,

[0028] The refractive index of the second relay mirror is 1.5–1.7; the radius of curvature of the object-side surface of the second relay mirror at the optical axis is 1 mm–5 mm; the radius of curvature of the image-side surface of the second relay mirror at the optical axis is -10 mm–-5 mm; and the thickness of the second relay mirror is 50 mm–100 mm; and / or,

[0029] The refractive index of the third relay mirror is 1.5 to 1.7, the radius of curvature of the object side of the third relay mirror at the optical axis is -10 mm to -5 mm, the radius of curvature of the image side of the third relay mirror at the optical axis is -50 mm to -20 mm, and the thickness of the third relay mirror is 1 mm to 5 mm.

[0030] The first relay lens, the second relay lens, and the third relay lens are cemented together to form a lens group;

[0031] The distance between the first group of repeaters and the second group of repeaters is 1mm to 5mm; and / or,

[0032] The distance between two adjacent relay lens groups is 20mm to 30mm; and / or,

[0033] The optical back cutoff of the relay lens group is 10mm to 15mm.

[0034] In some embodiments, the coupling lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged axially from the object side to the image side, wherein the object side and the image side of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are all spherical.

[0035] The refractive index of the first lens is 1.5 to 1.7, the radius of curvature of the object side of the first lens at the optical axis is 1 mm to 5 mm, the radius of curvature of the image side of the first lens at the optical axis is -10 mm to -5 mm, and the thickness of the first lens is 1 mm to 5 mm; and / or,

[0036] The refractive index of the second lens is 1.5 to 1.7, the radius of curvature of the object-side surface of the second lens at the optical axis is 1 mm to 5 mm, the radius of curvature of the image-side surface of the second lens at the optical axis is -5 mm to -1 mm, and the thickness of the second lens is 1 mm to 5 mm; and / or,

[0037] The refractive index of the third lens is 1.5 to 1.7, the radius of curvature of the object side of the third lens at the optical axis is -4.5 mm to -0.5 mm, the radius of curvature of the image side of the third lens at the optical axis is 1 mm to 5 mm, and the thickness of the third lens is 1 mm to 5 mm; and / or,

[0038] The refractive index of the fourth lens is 1.5–1.7; the radius of curvature of the object-side surface of the fourth lens at the optical axis is 1 mm–5 mm; the radius of curvature of the image-side surface of the fourth lens at the optical axis is 1 mm–5 mm; and the thickness of the fourth lens is 1 mm–5 mm; and / or,

[0039] The refractive index of the fifth lens is 1.5–1.7; the radius of curvature of the object-side surface of the fifth lens at the optical axis is 1 mm–5 mm; the radius of curvature of the image-side surface of the fifth lens at the optical axis is 200 mm–300 mm; and the thickness of the fifth lens is 5 mm–10 mm; and / or,

[0040] The refractive index of the sixth lens is 1.5 to 1.7, the radius of curvature of the object side of the sixth lens at the optical axis is -5 mm to -1 mm, the radius of curvature of the image side of the sixth lens at the optical axis is -5 mm to -1 mm, and the thickness of the sixth lens is 1 mm to 5 mm.

[0041] The second and third lenses are cemented together to form a lens group, and the fourth and fifth lenses are cemented together to form a lens group;

[0042] The distance between the first lens and the second lens is 1mm to 5mm; and / or,

[0043] The distance between the third lens and the fourth lens is 1mm to 5mm; and / or,

[0044] The distance between the fifth and sixth lenses is 1mm to 5mm; and / or,

[0045] The optical back focal length of the coupling lens is 20mm to 25mm.

[0046] In some embodiments, the dichroic mirror is a long-pass dichroic mirror and / or a short-pass dichroic mirror, and the cutoff wavelength of the dichroic mirror is 800nm-1000nm.

[0047] In some embodiments, the imaging system includes a first filter and a second filter. The first filter is disposed between the near-infrared camera and the dichroic mirror and is used to filter near-infrared fluorescence entering the near-infrared camera. The second filter is disposed between the visible light camera and the dichroic mirror and is used to filter visible light entering the visible light camera.

[0048] In some embodiments, the first filter is a long-pass filter with a cutoff wavelength greater than or equal to 850 nm; or, the first filter is a band-pass filter with a center wavelength greater than or equal to 850 nm.

[0049] In some embodiments, the second filter is a short-pass filter with a cutoff wavelength of less than 800 nm; or, the second filter is a band-pass filter with a center wavelength of less than 800 nm.

[0050] In some embodiments, the lens surfaces in the endoscope and coupling lens have antireflective coatings or anti-reflective coatings that cover the visible and near-infrared light bands.

[0051] In some implementations, the near-infrared camera in the camera module has a detection range of 850nm-1700nm and a mass of less than 100 grams.

[0052] The near-infrared fluorescence endoscope of this application includes an imaging system and a housing, with the imaging system at least partially disposed within the housing.

[0053] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0054] The above and / or additional aspects and advantages of this invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0055] Figure 1 This is a schematic diagram of the imaging system according to an embodiment of the present invention;

[0056] Figure 2 This is a schematic diagram of the imaging system according to an embodiment of the present invention;

[0057] Figure 3 This is a schematic diagram of the imaging system according to an embodiment of the present invention;

[0058] Figure 4 This is a schematic diagram of the objective lens assembly according to an embodiment of the present invention;

[0059] Figure 5This is a schematic diagram of the relay mirror assembly according to an embodiment of the present invention;

[0060] Figure 6 This is a schematic diagram of the structure of the coupling lens and camera module according to an embodiment of the present invention;

[0061] Figure 7 This is a schematic diagram of the structure of the coupling lens and camera module according to an embodiment of the present invention;

[0062] Figure 8 These are the parameters of each lens in the imaging system of Embodiment 1 of this utility model;

[0063] Figure 9 This is an MTF curve diagram of the imaging system of Embodiment 1 of this utility model;

[0064] Figure 10 This is a dot diagram of the imaging system according to Embodiment 1 of this utility model;

[0065] Figure 11 These are the parameters of each lens in the imaging system of Embodiment 2 of this utility model;

[0066] Figure 12 This is the MTF curve of the imaging system of Embodiment 2 of this utility model;

[0067] Figure 13 This is a dot diagram of the imaging system of Embodiment 2 of this utility model;

[0068] Figure 14 These are the parameters of each lens in the imaging system of Embodiment 3 of this utility model;

[0069] Figure 15 This is the MTF curve of the imaging system of Embodiment 3 of this utility model;

[0070] Figure 16 This is a dot diagram of the imaging system of Embodiment 3 of this utility model;

[0071] Figure 17 This is a distortion curve diagram of the imaging system according to an embodiment of the present invention;

[0072] Figure 18 This is a graph showing the relative illumination curve of the imaging system according to an embodiment of the present invention;

[0073] Figure 19 This is a simulated image of the imaging system according to an embodiment of the present invention;

[0074] Figure 20 This is an MTF curve of the endoscope according to an embodiment of the present invention at different working distances;

[0075] Figure 21This is a diagram showing the optimal spacing of the endoscope at different working distances according to an embodiment of this utility model.

[0076] Explanation of reference numerals in the attached figures: 100, Imaging system; 10, Endoscope; 11, Objective lens group; 111, First lens; 112, Second lens; 113, Third lens; 114, Fourth lens; 115, Fifth lens; 116, Sixth lens; 12, Relay lens group; 13, First relay lens group; 131, First relay lens; 132, Second relay lens; 133, Third relay lens; 14, Second relay lens group; 20, Coupler lens; 21, First lens; 22, Second lens; 23, Third lens; 24, Fourth lens; 25, Fifth lens; 26, Sixth lens; 30, Camera module; 31, Dichroic mirror; 32, Visible light camera; 33, Near-infrared camera; 34, First filter; 35, Second filter. Detailed Implementation

[0077] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0078] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like, indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0079] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections, or mutual communication; direct connections or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0080] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0081] The disclosure below provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numbers and / or reference letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides examples of various specific processes and materials, but a person of ordinary skill in the art will recognize the application of other processes and / or the use of other materials.

[0082] Please see Figure 1-Figure 3The imaging system 100 of the near-infrared fluorescence endoscope according to the embodiments of this application includes an endoscope 10, a coupling lens 20, and a camera module 30. The endoscope 10 is used to collect visible light and near-infrared fluorescence from a target object. The field of view of the endoscope 10 is greater than or equal to 80°, and the overall length of the imaging system 100 is less than 400 mm. The coupling lens 20 is arranged on the optical axis of the endoscope 10 and is used to couple the image of the endoscope 10 to the camera module 30. The camera module 30 includes a dichroic mirror 31, a visible light camera 32, and a near-infrared camera. Camera 33 and dichroic mirror 31 are arranged on the optical axis of coupling lens 20 to separate light from coupling lens 20 into near-infrared fluorescence and visible light. The wavelength of visible light is 380nm-700nm and the wavelength of near-infrared fluorescence is 850nm-1700nm. Visible light camera 32 is used to image the visible light from dichroic mirror 31, and near-infrared camera 33 is used to image the near-infrared fluorescence from dichroic mirror 31. The total three-dimensional dimensions of camera module 30 are less than 40mm×40mm×40mm and the weight is less than 150g.

[0083] This allows the endoscope 10 to achieve a large field of view while keeping the size and weight of the endoscope 10 and camera module 30 relatively small, resulting in a compact imaging system 100 with high space utilization.

[0084] Specifically, the endoscope 10 primarily enters sterile tissues and organs of the human body or enters sterile cavities through surgical incisions, such as laparoscopes, thoracoscopes, and arthroscopes. The advantages of the endoscope 10 include clear imaging, high resolution, and the ability to be equipped with multiple working channels to select multiple fields of view. The endoscope 10 can be a rigid endoscope or a flexible endoscope.

[0085] Visible light is emitted by a visible light source, illuminates a target object, and is reflected by the object. Visible light sources can be halogen lamps, LEDs, xenon lamps, etc. Near-infrared fluorescence is emitted by a near-infrared light source, which excites a fluorescent probe on the target object. Near-infrared light sources can be infrared LEDs or lasers, with excitation wavelengths ranging from 700nm to 900nm and fluorescence wavelengths covering 850nm to 1700nm. The near-infrared fluorescence is received by a near-infrared camera 33, which converts the received fluorescence into image signals, thus achieving near-infrared fluorescence imaging. Near-infrared light is an electromagnetic wave between visible and mid-infrared light.

[0086] The target object can be different parts of the human body, such as the bladder, uterus, rectum, amniotic fluid, nasal cavity, throat, and ears. The field of view (FOP) refers to the size of the field of view that the endoscope 10 can observe; it is the cone angle value with its vertex located at the tip of the endoscope 10, measured in degrees. The FOP is an inherent parameter of the endoscope 10, and different FOPs can be selected for different target objects. FOPs can be 80°, 90°, 100°, 110°, 120°, etc. A larger FOP results in a larger field of view for the endoscope 10; a FOP greater than or equal to 80° ensures comprehensive image acquisition.

[0087] The overall length of the imaging system 100 can be the sum of the lengths of the endoscope 10, coupling lens 20, and camera module 30, the distance between the endoscope 10 and coupling lens 20, and the distance between coupling lens 20 and camera module 30. The overall length of the imaging system 100 is less than 400mm, meaning the working length of the endoscope 10 is less than 400mm. The working length of the endoscope 10 refers to the length it can penetrate into the human body. The working length of the endoscope 10 can be 330mm, 310mm, 290mm, 270mm, 250mm, 230mm, etc. Different working lengths can be selected according to different target objects; for example, the working length of a laryngoscope is greater than or equal to 180mm, and the working length of a sinusoscope is greater than or equal to 175mm. The overall length of the imaging system 100 is less than 400mm, which allows for a reduction in the size of the imaging system 100 while meeting usage requirements, thus making the structure of the imaging system 100 compact.

[0088] The coupling lens 20 can be a lens group formed by multiple lens elements.

[0089] The dichroic mirror 31 is a passive device that does not require external energy; it only requires input light. The dichroic mirror 31 can separate the light from the endoscope 10 into a specific spectrum and change the direction of some of the spectral light paths. It can almost completely transmit light of a certain wavelength while almost completely reflecting light of other wavelengths.

[0090] The visible light camera 32 and the near-infrared camera 33 can be different cameras, such as a regular visible light camera 32 and a near-infrared InGaAs camera; or they can be the same camera, such as a near-infrared enhanced camera. The optical axis of the visible light camera 32 can be perpendicular to the optical axis of the near-infrared camera 33. For ease of use, the reflection angle of the dichroic mirror 3130 can be set to 45°.

[0091] The length, width, and height of the camera module 30 are all less than 40mm, for example, 39mm, 37mm, 35mm, 33mm, 31mm, etc. The length, width, and height of the camera module 30 can be equal or unequal. The mass of the camera module 30 can be the sum of the masses of the dichroic mirror 31, the visible light camera 32, and the near-infrared camera 33; the mass of the camera module 30 can be 148g, 144g, 140g, 136g, 132g, etc.

[0092] In some implementations, the working distance of the endoscope 10 is greater than or equal to 10 mm.

[0093] Specifically, the working distance is the distance between the end face of the endoscope 10 approaching the target object and the target object. The working distance of the endoscope 10 can be 10mm, 12mm, 13mm, 14mm, 15mm, 20mm, etc.

[0094] Thus, by increasing the working distance of the endoscope 10, the working length of the endoscope 10 can be reduced, thereby reducing the size of the endoscope 10 and making the imaging system 100 more compact. At the same time, the length of the endoscope 10 inserted into the patient's body can be reduced, preventing improper operation from causing the endoscope 10 to come into contact with the surface of the target object, thereby reducing the pain caused to the patient.

[0095] In some embodiments, the outer diameter of the endoscope 10 is less than or equal to 10 mm.

[0096] Thus, by reducing the outer diameter of the endoscope 10, the size of the endoscope 10 can be reduced, making the imaging system 100 more compact. At the same time, the volume of the endoscope 10 inserted into the patient's body can be reduced, thereby reducing the pain caused to the patient.

[0097] Specifically, the outer diameter of the endoscope 10 can be 10mm, 9.8mm, 9.6mm, 9.4mm, 9.2mm, 9mm, etc.

[0098] In some implementations, the magnification of the endoscope 10 is less than 0.2.

[0099] Specifically, the magnification of endoscope 10 refers to the ratio of the size of the image formed after light passes through endoscope 10 to the size of the target object. A magnification greater than 1 indicates that the image is magnified; a magnification less than 1 indicates that the image is reduced. The magnification of endoscope 10 can be 0.19, 0.15, 0.11, 0.07, 0.03, etc.

[0100] Thus, by reducing the magnification of the endoscope 10, clear imaging can be achieved while meeting the requirements of a longer working distance and a smaller outer diameter.

[0101] In some implementations, the depth of field of the endoscope 10 is greater than 100 mm.

[0102] Specifically, depth of field refers to the range of distances in front of and behind a target object that can be measured by imaging at the front edge of the camera to obtain a clear image. The depth of field of the endoscope 10 can be 100mm, 130mm, 160mm, 190mm, 220mm, 250mm, etc.

[0103] Thus, by increasing the depth of field of the endoscope 10, the imaging system 100 can achieve clear imaging while maintaining a small size, resulting in a compact structure for the endoscope 10.

[0104] The image quality of endoscope 10 is typically evaluated using angular resolution. Angular resolution is the reciprocal of the resolvable angle of the minimum resolvable equidistant fringe width at a given optical working distance from the entrance pupil center of endoscope 10, expressed in circles per degree [C / (°)]. The formula for calculating angular resolution is: Where r(d) is the limit of recognizable line pairs per millimeter, in line pairs per millimeter (lp / mm), a is the distance from the endoscope tip to the entrance pupil, in millimeters (mm), and d is the working distance of the endoscope 10, in millimeters (mm). The formula for calculating r(d) is: Wherein, D is the entrance pupil diameter of endoscope 10, λ is the working wavelength, and d is the working distance of endoscope 10. According to the national standard "General Requirements for Medical Endoscopes and Accessories", d is taken as 20mm. In one embodiment, the wavelength of visible light is 0.588µm and the angular resolution is 8.0C / (°); in another embodiment, the wavelength of near-infrared light is 1.2µm and the angular resolution is 3.9C / (°); in yet another embodiment, the wavelength of near-infrared light is 1.7µm and the angular resolution is 2.8C / (°).

[0105] Please see Figure 3 and Figure 4 In some embodiments, the endoscope 10 includes an objective lens group 11 for collecting visible light and near-infrared fluorescence from the target object and forming an intermediate image;

[0106] The objective lens group 11 includes a first lens 111, a second lens 112, a third lens 113, a fourth lens 114, a fifth lens 115, and a sixth lens 116 arranged axially from the object side to the image side. The object side and the image side of the first lens 111, the second lens 112, the third lens 113, the fourth lens 114, the fifth lens 115, and the sixth lens 116 are all spherical.

[0107] The refractive index of the first lens 111 is 1.7 to 1.9, the radius of curvature of the object side of the first lens 111 at the optical axis is -40 mm to -20 mm, the radius of curvature of the image side of the first lens 111 at the optical axis is 1 mm to 5 mm, and the thickness of the first lens 111 is 5 mm to 10 mm; and / or,

[0108] The refractive index of the second lens 112 is 1.9 to 2.1; the radius of curvature of the object side of the second lens 112 at the optical axis is -5 mm to -1 mm; the radius of curvature of the image side of the second lens 112 at the optical axis is -5 mm to -1 mm; and the thickness of the second lens 112 is 1 mm to 5 mm; and / or,

[0109] The refractive index of the third lens 113 is 1.4 to 1.6; the radius of curvature of the object side of the third lens 113 at the optical axis is 1 mm to 5 mm; the radius of curvature of the image side of the third lens 113 at the optical axis is -5 mm to -1 mm; and the thickness of the third lens 113 is 1 mm to 5 mm; and / or,

[0110] The refractive index of the fourth lens 114 is 1.6 to 1.8; the radius of curvature of the object side of the fourth lens 114 at the optical axis is -5 mm to -1 mm; the radius of curvature of the image side of the fourth lens 114 at the optical axis is -15 mm to -5 mm; and the thickness of the fourth lens 114 is 1 mm to 5 mm; and / or,

[0111] The refractive index of the fifth lens 115 is 1.7 to 1.9; the radius of curvature of the object side of the fifth lens 115 at the optical axis is -100 mm to -50 mm; the radius of curvature of the image side of the fifth lens 115 at the optical axis is 1 mm to 5 mm; and the thickness of the fifth lens 115 is 1 mm to 5 mm; and / or,

[0112] The refractive index of the sixth lens 116 is 1.4 to 1.6, the radius of curvature of the object side of the sixth lens 116 at the optical axis is 1 mm to 5 mm, the radius of curvature of the image side of the sixth lens 116 at the optical axis is -5 mm to -1 mm, and the thickness of the sixth lens 116 is 1 mm to 5 mm.

[0113] The third lens 113 and the fourth lens 114 are cemented together to form a lens group, and the fifth lens 115 and the sixth lens 116 are cemented together to form a lens group.

[0114] The distance between the first lens 111 and the second lens 112 is 5mm to 10mm; and / or,

[0115] The distance between the second lens 112 and the third lens 113 is 1mm to 5mm; and / or,

[0116] The distance between the fourth lens 114 and the fifth lens 115 is 0.5mm to 1.5mm; and / or,

[0117] The optical back cutoff of objective lens group 11 is 1mm to 5mm.

[0118] Specifically, with the lens as the boundary, the side where the target object is located is called the object side, and the surface of the lens closest to the object side can be called the object-side surface; with the lens as the boundary, the side where the image of the target object is located is called the image side, and the surface of the lens closest to the image side can be called the image-side surface. The first lens 111, the second lens 112, the third lens 113, the fourth lens 114, the fifth lens 115, and the sixth lens 116 can be lenses.

[0119] Thus, the object-side and image-side surfaces of the six lenses are spherical, which allows the objective lens group 11 to greatly reduce image aberrations. Compared with aspherical lenses, the lens manufacturing of the embodiment of this application is simple, which in turn makes the manufacturing of the objective lens group 11 even simpler.

[0120] The refractive index is the ratio of the speed of light in a vacuum to the speed of light in that medium. For example, the refractive index of the first lens 111 is the ratio of the speed of light in a vacuum to the speed of light in the first lens 111. The refractive index is related to the material of the first lens 111; optically denser media have a higher refractive index, and optically less dense media have a lower refractive index. The refractive index of the first lens 111 can be 1.7, 1.75, 1.8, 1.85, 1.9, etc. The refractive index of the second lens 112 can be 1.9, 1.95, 2, 2.05, 2.1, etc. The refractive index of the third lens 113 can be 1.4, 1.45, 1.5, 1.55, 1.6, etc. The refractive index of the fourth lens 114 can be 1.6, 1.65, 1.7, 1.75, 1.8, etc. The refractive index of the fifth lens 115 can be 1.7, 1.75, 1.8, 1.85, 1.9, etc. The refractive index of the sixth lens 116 can be 1.4, 1.45, 1.5, 1.55, 1.6, etc.

[0121] When the lens meets the above-mentioned radius of curvature, it can avoid the lens being too flat or too curved, thereby reducing the design difficulty and assembly sensitivity of the objective lens group 11, and also helping to improve the image quality.

[0122] The sign of the radius of curvature indicates whether the optical surface is convex towards the object side or the image side. When the optical surface (including the object side or the image side) is convex towards the object side, the radius of curvature of the optical surface is positive; when the optical surface (including the object side or the image side) is convex towards the image side, it is equivalent to the optical surface being concave towards the object side, and the radius of curvature of the optical surface is negative.

[0123] The radius of curvature of the object side of the first lens 111 can be any value in the range of [-40mm, -20mm], for example, it can be -40, -35, -30, -25, -20, etc., in mm. The radius of curvature of the image side of the first lens 111 can be any value in the range of [1mm, 5mm], for example, it can be 1, 2, 3, 4, 5, etc., in mm.

[0124] The radius of curvature of the object side surface of the second lens 112 can be any value within the range of [-5mm, -1mm], for example, it can be -5, -4, -3, -2, -1, etc., in mm. The radius of curvature of the image side surface of the second lens 112 can be any value within the range of [-5mm, -1mm], for example, it can be -5, -4, -3, -2, -1, etc., in mm.

[0125] The radius of curvature of the object side of the third lens 113 can be any value in the range of [1mm, 5mm], for example, the value can be 1, 2, 3, 4, 5, etc., in mm. The radius of curvature of the image side of the third lens 113 can be any value in the range of [-5mm, -1mm], for example, the value can be -5, -4, -3, -2, -1, etc., in mm.

[0126] The radius of curvature of the object side of the fourth lens 114 can be any value in the range of [-5mm, -1mm], such as -5, -4, -3, -2, -1, etc., in mm. The radius of curvature of the image side of the fourth lens 114 can be any value in the range of [-15mm, -5mm], such as -15, -13, -11, -9, -7, -5, etc., in mm.

[0127] The radius of curvature of the object side of the fifth lens 115 can be any value in the range of [-100mm, -50mm], such as -100, -90, -80, -70, -60, -50, etc., in mm. The radius of curvature of the image side of the fifth lens 115 can be any value in the range of [1mm, 5mm], such as 1, 2, 3, 4, 5, etc., in mm.

[0128] The radius of curvature of the object side of the sixth lens 116 can be any value in the range of [1mm, 5mm], for example, the value can be 1, 2, 3, 4, 5, etc., in mm. The radius of curvature of the image side of the sixth lens 116 can be any value in the range of [-5mm, -1mm], for example, the value can be -5, -4, -3, -2, -1, etc., in mm.

[0129] By rationally configuring different lens thicknesses, the miniaturization and manufacturability of the objective lens group 11 are optimally balanced, avoiding the situation where excessively thin lenses would affect the strength of the objective lens group 11 and thus impact manufacturing yield.

[0130] The thickness of the first lens 111 can be any value in the range of [5mm, 10mm]. For example, the value can be 5, 6, 7, 8, 9, 10, etc., with the unit being mm.

[0131] The thickness of the second lens 112 can be any value in the range of [1mm, 5mm]. For example, the value can be 1, 2, 3, 4, 5, etc., and the unit is mm.

[0132] The thickness of the third lens 113 can be any value in the range of [1mm, 5mm]. For example, the value can be 1, 2, 3, 4, 5, etc., and the unit is mm.

[0133] The thickness of the fourth lens 114 can be any value in the range of [1mm, 5mm]. For example, the value can be 1, 2, 3, 4, 5, etc., and the unit is mm.

[0134] The thickness of the fifth lens 115 can be any value in the range of [1mm, 5mm]. For example, the value can be 1, 2, 3, 4, 5, etc., and the unit is mm.

[0135] The thickness of the sixth lens 116 can be any value in the range of [1mm, 5mm]. For example, the value can be 1, 2, 3, 4, 5, etc., and the unit is mm.

[0136] By bonding the lenses, the optical axes of the third lens 113 and the fourth lens 114 can be aligned, as can the optical axes of the fifth lens 115 and the sixth lens 116, thus eliminating the chromatic aberration between the third lens 113 and the fourth lens 114, and between the fifth lens 115 and the sixth lens 116. This also facilitates the assembly and adjustment of the objective lens group 11.

[0137] In the manufacturing process of optical lenses, resin bonding or optical bonding is usually used to bond two lenses together, and the adhesive is allowed to harden to fix the lenses, so as to produce a cemented lens assembly.

[0138] The distance between the first lens 111 and the second lens 112 can be any value in the range of [5mm, 10mm]. For example, the value can be 5, 6, 7, 8, 9, 10, etc., in mm.

[0139] The distance between the second lens 112 and the third lens 113 can be any value in the range of [1mm, 5mm]. For example, the value can be 1, 2, 3, 4, 5, etc., and the unit is mm.

[0140] The distance between the fourth lens 114 and the fifth lens 115 can be any value in the range of [0.5mm, 1.5mm]. For example, the value can be 0.5, 0.7, 0.9, 1.1, 1.3, 1.5, etc., in mm.

[0141] Optical back clipping refers to the distance from the center of the last optical plane to the image plane. The optical back clipping of objective lens group 11 can be any value in the range of [1mm, 5mm]. For example, the value can be 1, 2, 3, 4, 5, etc., and the unit is mm.

[0142] By controlling the distance between the lenses and the optical back cutoff of the objective lens group 11 within the above range, the objective lens group 11 can achieve clear imaging while maintaining a small size.

[0143] Please see Figure 3 and Figure 5 In some embodiments, the endoscope 10 includes a relay lens group 12, and there are multiple relay lens groups 12 arranged along the optical axis. The multiple relay lens groups 12 are used to collect visible light and near-infrared fluorescence from the target object and image them on the end of the endoscope 10 near the dichroic mirror 31.

[0144] The relay lens group 12 includes a first group of relay lenses 13 and a second group of relay lenses 14 arranged axially from the object side to the image side. The two groups of relay lenses are arranged symmetrically. The first group of relay lenses 13 includes a first relay lens 131, a second relay lens 132 and a third relay lens 133 arranged axially from the object side to the image side. The object side and the image side of the first relay lens 131, the second relay lens 132 and the third relay lens 133 are all spherical.

[0145] The refractive index of the first relay mirror 131 is 1.7–1.9, the radius of curvature of the object side of the first relay mirror 131 at the optical axis is 10 mm–15 mm, the radius of curvature of the image side of the first relay mirror 131 at the optical axis is 1 mm–5 mm, and the thickness of the first relay mirror 131 is 1 mm–5 mm; and / or,

[0146] The refractive index of the second relay mirror 132 is 1.5 to 1.7; the radius of curvature of the object side of the second relay mirror 132 at the optical axis is 1 mm to 5 mm; the radius of curvature of the image side of the second relay mirror 132 at the optical axis is -10 mm to -5 mm; and the thickness of the second relay mirror 132 is 50 mm to 100 mm; and / or,

[0147] The refractive index of the third relay mirror 133 is 1.5 to 1.7, the radius of curvature of the object side of the third relay mirror 133 at the optical axis is -10 mm to -5 mm, the radius of curvature of the image side of the third relay mirror 133 at the optical axis is -50 mm to -20 mm, and the thickness of the third relay mirror 133 is 1 mm to 5 mm.

[0148] The first relay lens 131, the second relay lens 132, and the third relay lens 133 are cemented together to form a lens group;

[0149] The distance between the first set of repeater mirrors 13 and the second set of repeater mirrors 14 is 1mm to 5mm; and / or,

[0150] The distance between two adjacent relay lens groups 12 is 20mm to 30mm; and / or,

[0151] The optical back focal length of relay lens group 12 is 10mm to 15mm.

[0152] Since the two sets of relay mirrors are symmetrically arranged, the second set of relay mirrors 14 has a third relay mirror 133, a second relay mirror 132, and a first relay mirror 131 arranged sequentially along the object-side to image-side axis. The parameters of the first relay mirror 131 of the first set of relay mirrors 13 are the same as those of the first relay mirror 131 of the second set of relay mirrors 14. The parameters of the second relay mirror 132 of the first set of relay mirrors 13 are the same as those of the second relay mirror 132 of the second set of relay mirrors 14. The parameters of the third relay mirror 133 of the first set of relay mirrors 13 are the same as those of the third relay mirror 133 of the second set of relay mirrors 14.

[0153] Thus, the object side and image side of the six relay mirrors are both spherical, which greatly reduces image aberrations in the relay mirror group 12. Compared with aspherical relay mirrors, the relay mirrors in this embodiment are simple to manufacture, which in turn makes the manufacturing of the relay mirror group 12 even simpler.

[0154] The first relay lens 131 and the third relay lens 133 can be concave lenses, and the second relay lens 132 can be a long convex lens.

[0155] The refractive index of the first repeater mirror 131 can be 1.7, 1.75, 1.8, 1.85, 1.9, etc. The refractive index of the second repeater mirror 132 can be 1.5, 1.55, 1.6, 1.65, 1.7, etc. The refractive index of the third repeater mirror 133 can be 1.5, 1.55, 1.6, 1.65, 1.7, etc.

[0156] When the relay mirror meets the above-mentioned radius of curvature, it can avoid the relay mirror being too flat or too curved, thereby reducing the design difficulty and assembly sensitivity of the relay mirror group 12, and also helping to improve the imaging quality.

[0157] The radius of curvature of the object side of the first relay mirror 131 can be any value in the range of [10mm, 15mm], for example, the value can be 10, 11, 12, 13, 14, 15, etc., in mm. The radius of curvature of the image side of the first relay mirror 131 can be any value in the range of [1mm, 5mm], for example, the value can be 1, 2, 3, 4, 5, etc., in mm.

[0158] The radius of curvature of the object side of the second relay mirror 132 can be any value in the range of [1mm, 5mm], for example, the value can be 1, 2, 3, 4, 5, etc., in mm. The radius of curvature of the image side of the second relay mirror 132 can be any value in the range of [-10mm, -5mm], for example, the value can be -10, -9, -8, -7, -6, -5, etc., in mm.

[0159] The radius of curvature of the object side of the third relay mirror 133 can be any value in the range of [-10mm, -5mm], for example, it can be -10, -9, -8, -7, -6, -5, etc., in mm. The radius of curvature of the image side of the third relay mirror 133 can be any value in the range of [-50mm, -20mm], for example, it can be -50, -40, -30, -20, etc., in mm.

[0160] By rationally configuring the thickness of different relay mirrors, the optimal balance between miniaturization and manufacturability of the relay mirror assembly 12 is achieved, avoiding the situation where the relay mirror is too thin, which would affect the strength of the relay mirror assembly 12 and thus affect the manufacturing yield.

[0161] The thickness of the first relay mirror 131 can be any value in the range of [1mm, 5mm]. For example, the value can be 1, 2, 3, 4, 5, etc., with the unit being mm.

[0162] The thickness of the second relay mirror 132 can be any value in the range of [50mm, 100mm]. For example, the value can be 50, 60, 70, 80, 90, 100, etc., with the unit being mm.

[0163] The thickness of the third relay mirror 133 can be any value in the range of [1mm, 5mm]. For example, the value can be 1, 2, 3, 4, 5, etc., with the unit being mm.

[0164] By bonding the repeater lenses together, the optical axes of the first repeater lens 131, the second repeater lens 132, and the third repeater lens 133 can be aligned, eliminating the chromatic aberration of the first repeater lens 131, the second repeater lens 132, and the third repeater lens 133, and facilitating the assembly and debugging of the repeater lens group 12.

[0165] In the manufacturing process of optical lenses, resin bonding or optical bonding is usually used to bond three relay lenses together, and the glue is allowed to harden to fix the lenses, so as to produce a cemented lens group.

[0166] The distance between the first set of repeater mirrors 13 and the second set of repeater mirrors 14 can be any value in the range of [1mm, 5mm]. For example, the value can be 1, 2, 3, 4, 5, etc., and the unit is mm.

[0167] The distance between two adjacent relay lens groups 12 can be any value in the range of [20mm, 30mm]. For example, the value can be 20, 22, 24, 26, 28, 30, etc., in mm.

[0168] The optical back cutoff of the relay lens group 12 can be any value in the range of [10mm, 15mm]. For example, the value can be 10, 11, 12, 13, 14, 15, etc., in mm.

[0169] By controlling the distance between relay mirrors and the optical back cutoff of relay mirror group 12 within the above range, relay mirror group 12 can achieve clear imaging while maintaining a small size.

[0170] Please see Figure 3 , Figure 6 and Figure 7 In some embodiments, the coupling lens 20 includes a first lens 21, a second lens 22, a third lens 23, a fourth lens 24, a fifth lens 25 and a sixth lens 26 arranged axially from the object side to the image side. The object side and the image side of the first lens 21, the second lens 22, the third lens 23, the fourth lens 24, the fifth lens 25 and the sixth lens 26 are both spherical.

[0171] The refractive index of the first lens 21 is 1.5 to 1.7, the radius of curvature of the object side of the first lens 21 at the optical axis is 1 mm to 5 mm, the radius of curvature of the image side of the first lens 21 at the optical axis is -10 mm to -5 mm, and the thickness of the first lens 21 is 1 mm to 5 mm; and / or,

[0172] The refractive index of the second lens 22 is 1.5 to 1.7, the radius of curvature of the object side of the second lens 22 at the optical axis is 1 mm to 5 mm, the radius of curvature of the image side of the second lens 22 at the optical axis is -5 mm to -1 mm, and the thickness of the second lens 22 is 1 mm to 5 mm; and / or,

[0173] The refractive index of the third lens 23 is 1.5 to 1.7, the radius of curvature of the object side of the third lens 23 at the optical axis is -4.5 mm to -0.5 mm, the radius of curvature of the image side of the third lens 23 at the optical axis is 1 mm to 5 mm, and the thickness of the third lens 23 is 1 mm to 5 mm; and / or,

[0174] The refractive index of the fourth lens 24 is 1.5–1.7; the radius of curvature of the object-side surface of the fourth lens 24 at the optical axis is 1 mm–5 mm; the radius of curvature of the image-side surface of the fourth lens 24 at the optical axis is 1 mm–5 mm; and the thickness of the fourth lens 24 is 1 mm–5 mm; and / or,

[0175] The refractive index of the fifth lens 25 is 1.5–1.7; the radius of curvature of the object-side surface of the fifth lens 25 at the optical axis is 1 mm–5 mm; the radius of curvature of the image-side surface of the fifth lens 25 at the optical axis is 200 mm–300 mm; and the thickness of the fifth lens 25 is 5 mm–10 mm; and / or,

[0176] The refractive index of the sixth lens 26 is 1.5 to 1.7, the radius of curvature of the object side of the sixth lens 26 at the optical axis is -5 mm to -1 mm, the radius of curvature of the image side of the sixth lens 26 at the optical axis is -5 mm to -1 mm, and the thickness of the sixth lens 26 is 1 mm to 5 mm.

[0177] The second lens 22 and the third lens 23 are cemented together to form a lens group, and the fourth lens 24 and the fifth lens 25 are cemented together to form a lens group;

[0178] The distance between the first lens 21 and the second lens 22 is 1mm to 5mm; and / or,

[0179] The distance between the third lens 23 and the fourth lens 24 is 1mm to 5mm; and / or,

[0180] The distance between the fifth lens 25 and the sixth lens 26 is 1mm to 5mm; and / or,

[0181] The optical back focal length of the coupling lens 20 is 20mm to 25mm.

[0182] Thus, the object-side and image-side surfaces of the six lenses are spherical, which allows the coupling lens 20 to greatly reduce image aberrations. Compared to aspherical lenses, the lens manufacturing of the embodiment of this application is simple, which in turn makes the manufacturing of the coupling lens 20 even simpler.

[0183] The refractive index of the first lens 21 can be 1.5, 1.55, 1.6, 1.65, 1.7, etc. The refractive index of the second lens 22 can be 1.5, 1.55, 1.6, 1.65, 1.7, etc. The refractive index of the third lens 23 can be 1.5, 1.55, 1.6, 1.65, 1.7, etc. The refractive index of the fourth lens 24 can be 1.5, 1.55, 1.6, 1.65, 1.7, etc. The refractive index of the fifth lens 25 can be 1.5, 1.55, 1.6, 1.65, 1.7, etc. The refractive index of the sixth lens 26 can be 1.5, 1.55, 1.6, 1.65, 1.7, etc.

[0184] When the lens meets the above-mentioned radius of curvature, it can avoid the lens being too flat or too curved, thereby reducing the design difficulty and assembly sensitivity of the coupling lens 20, and also helping to improve the imaging quality.

[0185] The radius of curvature of the object-side surface of the first lens 21 can be any value in the range of [1mm, 5mm], for example, the value can be 1, 2, 3, 4, 5, etc., in mm. The radius of curvature of the image-side surface of the first lens 21 can be any value in the range of [-10mm, -5mm], for example, the value can be -10, -9, -8, -7, -6, -5, etc., in mm.

[0186] The radius of curvature of the object side surface of the second lens 22 can be any value in the range of [1mm, 5mm], for example, the value can be 1, 2, 3, 4, 5, etc., in mm. The radius of curvature of the image side surface of the second lens 22 can be any value in the range of [-5mm, -1mm], for example, the value can be -5, -4, -3, -2, -1, etc., in mm.

[0187] The radius of curvature of the object-side surface of the third lens 23 can be any value within the range of [-4.5 mm, -0.5 mm], for example, it can be -4.5, -3.5, -2.5, -1.5, -0.5, etc., in mm. The radius of curvature of the image-side surface of the third lens 23 can be any value within the range of [1 mm, 5 mm], for example, it can be 1, 2, 3, 4, 5, etc., in mm.

[0188] The radius of curvature of the object-side surface of the fourth lens 24 can be any value within the range of [1mm, 5mm], for example, the value can be 1, 2, 3, 4, 5, etc., in mm. The radius of curvature of the image-side surface of the fourth lens 24 can be any value within the range of [1mm, 5mm], for example, the value can be 1, 2, 3, 4, 5, etc., in mm.

[0189] The radius of curvature of the object-side surface of the fifth lens 25 can be any value within the range of [1mm, 5mm], for example, it can be 1, 2, 3, 4, 5, etc., in mm. The radius of curvature of the image-side surface of the fifth lens 25 can be any value within the range of [200mm, 300mm], for example, it can be 200, 220, 240, 260, 280, 300, etc., in mm.

[0190] The radius of curvature of the object-side surface of the sixth lens 26 can be any value within the range of [-5mm, -1mm], for example, it can be -5, -4, -3, -2, -1, etc., in mm. The radius of curvature of the image-side surface of the sixth lens 26 can be any value within the range of [-5mm, -1mm], for example, it can be -5, -4, -3, -2, -1, etc., in mm.

[0191] By rationally configuring different lens thicknesses, the optimal balance between miniaturization and manufacturability of the coupling lens 20 is achieved, avoiding the situation where excessively thin lenses would affect the strength of the coupling lens 20 and thus impact manufacturing yield.

[0192] The thickness of the first lens 21 can be any value in the range of [1mm, 5mm]. For example, the value can be 1, 2, 3, 4, 5, etc., with the unit being mm.

[0193] The thickness of the second lens 22 can be any value in the range of [1mm, 5mm]. For example, the value can be 1, 2, 3, 4, 5, etc., with the unit being mm.

[0194] The thickness of the third lens 23 can be any value in the range of [1mm, 5mm]. For example, the value can be 1, 2, 3, 4, 5, etc., with the unit being mm.

[0195] The thickness of the fourth lens 24 can be any value in the range of [1mm, 5mm]. For example, the value can be 1, 2, 3, 4, 5, etc., in mm.

[0196] The thickness of the fifth lens 25 can be any value in the range of [5mm, 10mm]. For example, the value can be 5, 6, 7, 8, 9, 10, etc., in mm.

[0197] The thickness of the sixth lens 26 can be any value in the range of [1mm, 5mm]. For example, the value can be 1, 2, 3, 4, 5, etc., in mm.

[0198] By using cemented lenses, the optical axes of the second lens 22 and the third lens 23 can be aligned, as can the optical axes of the fourth lens 24 and the fifth lens 25, thus eliminating the chromatic aberration between the second lens 22 and the third lens 23, and between the fourth lens 24 and the fifth lens 25. This also facilitates the assembly and adjustment of the coupling lens 20.

[0199] In the manufacturing process of optical lenses, resin bonding or optical bonding is usually used to bond two lenses together, and the adhesive is allowed to harden to fix the lenses, so as to produce a cemented lens assembly.

[0200] The distance between the first lens 21 and the second lens 22 can be any value in the range of [1mm, 5mm]. For example, the value can be 1, 2, 3, 4, 5, etc., and the unit is mm.

[0201] The distance between the third lens 23 and the fourth lens 24 can be any value in the range of [1mm, 5mm]. For example, the value can be 1, 2, 3, 4, 5, etc., and the unit is mm.

[0202] The distance between the fifth lens 25 and the sixth lens 26 can be any value in the range of [1mm, 5mm]. For example, the value can be 1, 2, 3, 4, 5, etc., and the unit is mm.

[0203] The optical back focal length of the coupling lens 20 can be any value in the range of [20mm, 25mm]. For example, the value can be 20, 21, 22, 23, 24, 25, etc., in mm.

[0204] By controlling the distance between the lenses and the optical back cutoff of the coupling lens 20 within the above range, the coupling lens 20 can achieve clear imaging while maintaining a small size.

[0205] In Embodiment 1, the parameters of each lens in the imaging system 100 are as follows: Figure 8 As shown, Figure 9 (a) and Figure 9 (b) The MTF curves of the imaging system 100 in visible and near-infrared light are shown respectively. The MTF curve can be used to evaluate the resolution of the imaging system 100. The horizontal axis of the figure is spatial frequency, and the vertical axis is the MTF value, with a maximum value of 1. The larger the value, the higher the resolution. Under different conditions, such as temperature, the coefficient of thermal expansion of different glass lenses varies, which may lead to deformation. Figure 9 (a) and Figure 9 (b) shows the MTF curve M, which is the diffraction-limited curve, as well as the MTF curves for the other five fields of view. As can be seen from the figure, the MTF curves for the other fields of view are close to the diffraction limit at different spatial frequencies. Therefore, the imaging system achieves optimal resolution with all 100 fields of view approaching the diffraction limit.

[0206] Figure 10 (a) and Figure 10 (b) are point plots of the imaging system 100 in five different fields of view in visible and near-infrared light. The point plots show the point shapes observed on the image side for each point in the object-side field of view. The point plots include a diffraction-limited circle. Figure 10 (a) The radius of the circle, i.e. the Airy Radius, is 28.18 μm, and the root mean square radius of the point shape is the largest, 15.226 μm; Figure 10 (b) The radius of the circle, i.e., the Airy radius, is 51.78 μm, and the maximum root mean square radius (RMS radius) of the point shape is 14.832 μm. It can be seen that the point shapes of the five fields of view of the imaging system 100 are all within or close to the diffraction limit circle. The spot size of each field of view of the imaging system 100 reaches the diffraction limit, achieving a relatively good image quality, indicating that the aberrations of the imaging system 100 are relatively well-controlled.

[0207] In Embodiment 2, the parameters of each lens in the imaging system 100 are as follows: Figure 11 As shown, Figure 12 (a) and Figure 12 (b) MTF curves of imaging system 100 in visible and near-infrared light, respectively. Figure 12 (a) and Figure 12 (b) shows the MTF curve M, which is the diffraction-limited curve, as well as the MTF curves for the other five fields of view. As can be seen from the figure, the MTF curves for the other fields of view are close to the diffraction limit at different spatial frequencies. Therefore, the imaging system achieves optimal resolution with all 100 fields of view approaching the diffraction limit.

[0208] Figure 13 (a) and Figure 13 (b) are point plots of the imaging system 100 in five different fields of view in visible and near-infrared light. The point plots show the point shapes observed on the image side for each point in the object-side field of view. The point plots include a diffraction-limited circle. Figure 13 (a) The radius of the circle, i.e. the Airy Radius, is 28.13 μm, and the root mean square radius of the point shape is the largest, 15.897 μm; Figure 13 (b) The radius of the circle, i.e., the Airy radius, is 51.85 μm, and the maximum root mean square radius (RMS radius) of the point shape is 15.285 μm. It can be seen that the point shapes of the five fields of view of the imaging system 100 are all within or close to the diffraction limit circle. The spot size of each field of view of the imaging system 100 reaches the diffraction limit, achieving a relatively good image quality, indicating that the aberrations of the imaging system 100 are relatively well-controlled.

[0209] In Embodiment 3, the parameters of each lens in the imaging system 100 are as follows: Figure 14 As shown, Figure 15 (a) and Figure 15 (b) MTF curves of imaging system 100 in visible and near-infrared light, respectively. Figure 15 (a) and Figure 15 (b) shows the MTF curve M, which is the diffraction-limited curve, as well as the MTF curves for the other five fields of view. As can be seen from the figure, the MTF curves for the other fields of view are close to the diffraction limit at different spatial frequencies. Therefore, the imaging system achieves optimal resolution with all 100 fields of view approaching the diffraction limit.

[0210] Figure 16 (a) and Figure 16 (b) are point plots of the imaging system 100 in five different fields of view in visible and near-infrared light. The point plots show the point shapes observed on the image side for each point in the object-side field of view. The point plots include a diffraction-limited circle. Figure 16 (a) The radius of the circle, i.e. the Airy Radius, is 26.83 μm, and the root mean square radius of the point shape is the largest, 12.649 μm; Figure 16 (b) The radius of the circle, i.e., the Airy radius, is 50.53 μm, and the maximum root mean square radius (RMS radius) of the point shape is 14.868 μm. It can be seen that the point shapes of the five fields of view of the imaging system 100 are all within or close to the diffraction limit circle. The spot size of each field of view of the imaging system 100 reaches the diffraction limit, achieving a relatively good image quality, indicating that the aberrations of the imaging system 100 are relatively well-preserved.

[0211] Figure 17 (a) and Figure 17 (b) The distortion curves of imaging system 100 in visible and near-infrared light are shown respectively. As can be seen from the figures, the maximum distortion of imaging system 100 at the edge of the visible light field of view is -20.3976%, and the maximum distortion at the edge of the near-infrared field of view is -20.2423%. Thus, the image distortion formed by imaging system 100 is relatively small. Specifically, distortion is the deformation of an image; distortion generally includes barrel distortion and pincushion distortion. The real scene on the object side undergoes deformation on the image plane after passing through imaging system 100, but this distortion does not affect the image sharpness. Lens manufacturers have dedicated instruments and equipment to measure distortion, and distortion correction can be performed later using image algorithms.

[0212] Figure 18 (a) and Figure 18(b) Relative illumination curves for visible light and near-infrared images are shown respectively. Relative illuminance refers to the ratio of illuminance at different coordinate points on the image plane to the illuminance at the center point. The vertical axis represents the normalized illuminance value, and the horizontal axis represents the field of view angle of the lens. Under the same conditions, a smooth transition of the relative illuminance curves for each field of view indicates uniform illuminance within the projected image frame, and the closer the relative illuminance value of each field of view is to 1, the higher the final projected brightness. As can be seen from the figure, the relative illumination of the edge field of view of the visible light and near-infrared images reaches more than 80% of the relative illumination of the center field of view. This embodiment has high image plane illuminance uniformity, which can also be inferred to be the characteristics of high efficiency and high brightness of the system. The principle of high brightness is: numerical aperture = D (entrance pupil diameter) / f (focal length). With the focal length remaining constant, the larger the numerical aperture, the larger the entrance pupil diameter. In optics, the entrance pupil represents the light inlet. The larger the light inlet, the more light energy can be received, and therefore the higher the brightness.

[0213] Figure 19 (a) and Figure 19 (b) The images are simulated effects of visible light and near-infrared light, respectively. The same image is placed at a working distance of 50mm on the object side, and the image size is matched with the field of view on the object side. When the visible light image and near-infrared light image are observed on the image side, the simulated effect of visible light image is obviously clearer than that of near-infrared light image. Although the near-infrared light image is not as clear as the visible light image, the objects in the image can be basically identified.

[0214] Figure 20 (a)- Figure 20 (h) shows the MTF curves of the endoscope 10 at different working distances. As can be seen from the figure, when the working distance of the endoscope 10 is greater than 20 mm, the MTF curve remains basically unchanged. It can be seen that when the working distance of the endoscope 10 is greater than 20 mm, the change in the working distance of the endoscope 10 does not affect the image quality of the image formed by the imaging system 100.

[0215] Figure 21 (a)- Figure 21 (i) is a diagram showing the optimal spacing of the endoscope 10 at different working distances. As can be seen from the diagram, the larger the working distance of the endoscope 10, the smaller the change in the optimal spacing, which means that there is less need to adjust the focus.

[0216] In some embodiments, the dichroic mirror 31 is a long-pass dichroic mirror 31 and / or a short-pass dichroic mirror 31, and the cutoff wavelength of the dichroic mirror 31 is 800nm ​​to 1000nm.

[0217] In this way, the dichroic mirror 31 can separate visible light and near-infrared fluorescence of light from the same scene according to the wavelength difference, ensuring that the imaging system 100 can still achieve the same-view imaging of the same scene when it rotates at different angles.

[0218] The dichroic mirror 31 can transmit and reflect incident light according to wavelength. The long-pass dichroic mirror 31 can transmit incident light with wavelengths greater than the cutoff wavelength and reflect incident light with wavelengths less than the cutoff wavelength. The short-pass dichroic mirror 31 can transmit incident light with wavelengths less than the cutoff wavelength and reflect incident light with wavelengths greater than the cutoff wavelength. The cutoff wavelength of the dichroic mirror 31 can be a point value or a range between any two of 800nm, 840nm, 880nm, 920nm, 960nm, and 1000nm.

[0219] In one embodiment, the dichroic mirror 31 is a long-pass dichroic mirror 31 with a cutoff wavelength of 850 nm, meaning that the dichroic mirror 31 transmits incident light with wavelengths greater than 850 nm and reflects incident light with wavelengths less than 850 nm. In another embodiment, the dichroic mirror 31 is a short-pass dichroic mirror 31 with a cutoff wavelength of 850 nm, meaning that the dichroic mirror 31 transmits incident light with wavelengths less than 850 nm and reflects incident light with wavelengths greater than or equal to 850 nm. A suitable dichroic mirror 31 can be selected according to the target object and actual needs.

[0220] Please see Figure 1 In some embodiments, the imaging system 100 includes a first filter 34 and a second filter 35. The first filter 34 is disposed between the near-infrared camera 33 and the dichroic mirror 31 and is used to filter near-infrared fluorescence entering the near-infrared camera 33. The second filter 35 is disposed between the visible light camera 32 and the dichroic mirror 31 and is used to filter visible light entering the visible light camera 32.

[0221] Thus, the first filter 34 and the second filter 35 can filter light, allowing light of a specific wavelength to pass through while blocking unwanted light, thereby ensuring the effective separation of light of different wavelengths and improving the imaging quality of the visible light camera 32 and the near-infrared camera 33.

[0222] Specifically, the first filter 34 and the near-infrared camera 33 are respectively vertically arranged on the near-infrared fluorescence imaging optical path after the light is split by the dichroic mirror 31. The near-infrared fluorescence is filtered by the first filter 34 and then focused onto the near-infrared camera 33 for imaging.

[0223] The second filter 35 and the visible light camera 32 are respectively vertically arranged in the optical path of the visible light after it has been split by the dichroic mirror 31. The visible light is filtered by the second filter 35 and then converged to the visible light camera 32 for imaging.

[0224] In some embodiments, the first filter 34 is a long-pass filter, and the cutoff wavelength of the first filter 34 is greater than or equal to 850 nm; or,

[0225] The first filter 34 is a bandpass filter, and the center wavelength of the first filter 34 is greater than or equal to 850nm.

[0226] In this way, the first filter 34 can filter out visible light, allowing only near-infrared fluorescence to enter the near-infrared camera 33, thus achieving effective separation of visible light and near-infrared fluorescence and ensuring the imaging quality of the near-infrared camera 33.

[0227] Specifically, the cutoff wavelength of the first filter 34 can be 850nm, 950nm, 1050nm, 1150nm, 1250nm, 1350nm, 1450nm, 1550nm, 1650nm, etc. In one embodiment, the cutoff wavelength of the first filter 34 is 1300nm, that is, the first filter 34 allows light with wavelengths greater than 1300nm to pass through, and cuts off light with wavelengths less than 1300nm.

[0228] In some embodiments, the second filter 35 is a short-pass filter, and the cutoff wavelength of the second filter 35 is less than 800 nm; or,

[0229] The second filter 35 is a bandpass filter, and the center wavelength of the second filter 35 is less than 800nm.

[0230] In this way, the second filter 35 can filter out near-infrared fluorescence, allowing only visible light to enter the visible light camera 32, thus achieving effective separation of visible light and near-infrared fluorescence and ensuring the imaging quality of the visible light camera 32.

[0231] Specifically, the cutoff wavelength of the second filter 35 can be 400nm, 450nm, 500nm, 550nm, 600nm, 650nm, 700nm, 750nm, etc. In one embodiment, the cutoff wavelength of the second filter 35 is 770nm, that is, the second filter 35 allows light with wavelengths less than 770nm to pass through, and cuts off light with wavelengths greater than 770nm.

[0232] In some embodiments, the lens surfaces of both the endoscope 10 and the coupling lens 20 have antireflective coatings or anti-reflective coatings that cover the visible and near-infrared light bands.

[0233] Thus, the antireflective coating or anti-reflective coating can reduce reflections from the lens surfaces in the endoscope 10 and the coupling lens 20, improve the transmittance of the lens, thereby reducing image distortion and improving imaging quality.

[0234] Specifically, the anti-reflective coating and anti-reflective coating can be formed on the lens surface using a vacuum evaporation method, forming a single layer or multiple layers. The anti-reflective coating and anti-reflective coating can be applied to the object-side and image-side surfaces of the lenses in the endoscope 10 and the coupling lens 20.

[0235] In some implementations, the near-infrared camera 33 in the camera module 30 has a detection range of 850nm-1700nm and a mass of less than 100 grams.

[0236] Thus, reducing the mass of the near-infrared camera 33 can reduce the mass of the camera module 30, thereby making the imaging system 100 lighter and easier to use.

[0237] Specifically, the detection range of the near-infrared camera 33, 850nm-1700nm, means that the near-infrared camera 33 can capture and analyze light within the wavelength range of 850nm to 1700nm, such as 850nm, 1000nm, 1150nm, 1300nm, 1450nm, 1600nm, and 1700nm. The near-infrared camera 33 can weigh 95 grams, 90 grams, 85 grams, or 80 grams, etc.

[0238] The near-infrared fluorescence endoscope of this application includes an imaging system 100 and a housing, with the imaging system 100 at least partially disposed within the housing. Thus, the housing provides support and protection for the imaging system 100, reducing damage caused by external impacts. Specifically, the imaging system 100 may be partially or entirely disposed within the housing. The outer diameter of the housing may be 10 mm, and the weight of the near-infrared fluorescence endoscope may be 400 g to 500 g.

[0239] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0240] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. An imaging system for a near-infrared fluorescence endoscope, characterized in that, include: An endoscope for collecting visible light and near-infrared fluorescence from a target object, the endoscope having a field of view greater than or equal to 80°, and the overall length of the imaging system being less than 400 mm; A coupling lens and a camera module, wherein the coupling lens is arranged on the optical axis of the endoscope and is used to couple the image of the endoscope to the camera module; The camera module includes a dichroic mirror, a visible light camera, and a near-infrared camera. The dichroic mirror is arranged on the optical axis of the coupling lens and is used to separate the light from the coupling lens into near-infrared fluorescence and visible light. The wavelength of the visible light is 380nm-700nm, and the wavelength of the near-infrared fluorescence is 850nm-1700nm. The visible light camera is used to image the visible light from the dichroic mirror, and the near-infrared camera is used to image the near-infrared fluorescence from the dichroic mirror. The total three-dimensional dimensions of the camera module are less than 40mm×40mm×40mm, and the mass is less than 150 grams.

2. The imaging system according to claim 1, characterized in that, The working distance of the endoscope is greater than or equal to 10 mm; and / or, The outer diameter of the endoscope is less than or equal to 10 mm; and / or, The magnification of the endoscope is less than 0.2; and / or, The endoscope has a depth of field greater than 100 mm.

3. The imaging system according to claim 1, characterized in that, The endoscope includes an objective lens group for collecting the visible light and near-infrared fluorescence from the target object and forming an intermediate image; The objective lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged axially from the object side to the image side. The object side and the image side of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are all spherical. The first lens has a refractive index of 1.7 to 1.9, a radius of curvature of its object-side surface at the optical axis of -40 mm to -20 mm, a radius of curvature of its image-side surface at the optical axis of 1 mm to 5 mm, and a thickness of 5 mm to 10 mm; and / or, The refractive index of the second lens is 1.9 to 2.1; the radius of curvature of the object-side surface of the second lens at the optical axis is -5 mm to -1 mm; the radius of curvature of the image-side surface of the second lens at the optical axis is -5 mm to -1 mm; and the thickness of the second lens is 1 mm to 5 mm; and / or, The refractive index of the third lens is 1.4 to 1.6, the radius of curvature of the object side of the third lens at the optical axis is 1 mm to 5 mm, the radius of curvature of the image side of the third lens at the optical axis is -5 mm to -1 mm, and the thickness of the third lens is 1 mm to 5 mm; and / or, The refractive index of the fourth lens is 1.6 to 1.8, the radius of curvature of the object side of the fourth lens at the optical axis is -5 mm to -1 mm, the radius of curvature of the image side of the fourth lens at the optical axis is -15 mm to -5 mm, and the thickness of the fourth lens is 1 mm to 5 mm; and / or, The refractive index of the fifth lens is 1.7 to 1.9, the radius of curvature of the object side of the fifth lens at the optical axis is -100 mm to -50 mm, the radius of curvature of the image side of the fifth lens at the optical axis is 1 mm to 5 mm, and the thickness of the fifth lens is 1 mm to 5 mm; and / or, The refractive index of the sixth lens is 1.4 to 1.6, the radius of curvature of the object side of the sixth lens at the optical axis is 1 mm to 5 mm, the radius of curvature of the image side of the sixth lens at the optical axis is -5 mm to -1 mm, and the thickness of the sixth lens is 1 mm to 5 mm. The third lens and the fourth lens are cemented together to form a lens group, and the fifth lens and the sixth lens are cemented together to form a lens group; The distance between the first lens and the second lens is 5mm to 10mm; and / or, The distance between the second lens and the third lens is 1mm to 5mm; and / or, The distance between the fourth lens and the fifth lens is 0.5mm to 1.5mm; and / or, The optical back cutoff of the objective lens group is 1mm to 5mm.

4. The imaging system according to claim 1, characterized in that, The endoscope includes a relay lens group, and there are multiple relay lens groups arranged along the optical axis. The multiple relay lens groups are used to collect the visible light and near-infrared fluorescence from the target object and image them on the end of the endoscope near the dichroic mirror. The relay lens group includes a first group of relay lenses and a second group of relay lenses arranged axially from the object side to the image side. The two groups of relay lenses are arranged symmetrically. The first group of relay lenses includes a first relay lens, a second relay lens, and a third relay lens arranged axially from the object side to the image side. The object side and the image side of the first relay lens, the second relay lens, and the third relay lens are all spherical. The refractive index of the first relay mirror is 1.7–1.9, the radius of curvature of the object-side surface of the first relay mirror at the optical axis is 10 mm–15 mm, the radius of curvature of the image-side surface of the first relay mirror at the optical axis is 1 mm–5 mm, and the thickness of the first relay mirror is 1 mm–5 mm; and / or, The refractive index of the second relay mirror is 1.5 to 1.7, the radius of curvature of the object side of the second relay mirror at the optical axis is 1 mm to 5 mm, the radius of curvature of the image side of the second relay mirror at the optical axis is -10 mm to -5 mm, and the thickness of the second relay mirror is 50 mm to 100 mm; and / or, The refractive index of the third relay mirror is 1.5 to 1.7, the radius of curvature of the object side of the third relay mirror at the optical axis is -10 mm to -5 mm, the radius of curvature of the image side of the third relay mirror at the optical axis is -50 mm to -20 mm, and the thickness of the third relay mirror is 1 mm to 5 mm. The first relay mirror, the second relay mirror, and the third relay mirror are cemented together to form a lens group; The distance between the first group of repeater mirrors and the second group of repeater mirrors is 1mm to 5mm; and / or, The distance between two adjacent relay lens groups is 20mm to 30mm; and / or, The optical back cutoff of the relay lens group is 10mm to 15mm.

5. The imaging system according to claim 1, characterized in that, The coupling lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged axially from the object side to the image side. The object side and image side of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are all spherical. The first lens has a refractive index of 1.5 to 1.7, a radius of curvature of the object-side surface of the first lens at the optical axis of 1 mm to 5 mm, a radius of curvature of the image-side surface of the first lens at the optical axis of -10 mm to -5 mm, and a thickness of 1 mm to 5 mm; and / or, The refractive index of the second lens is 1.5 to 1.7, the radius of curvature of the object-side surface of the second lens at the optical axis is 1 mm to 5 mm, the radius of curvature of the image-side surface of the second lens at the optical axis is -5 mm to -1 mm, and the thickness of the second lens is 1 mm to 5 mm; and / or, The refractive index of the third lens is 1.5 to 1.7, the radius of curvature of the object-side surface of the third lens at the optical axis is -4.5 mm to -0.5 mm, the radius of curvature of the image-side surface of the third lens at the optical axis is 1 mm to 5 mm, and the thickness of the third lens is 1 mm to 5 mm; and / or, The fourth lens has a refractive index of 1.5 to 1.7, a radius of curvature of its object-side surface at the optical axis of 1 mm to 5 mm, a radius of curvature of its image-side surface at the optical axis of 1 mm to 5 mm, and a thickness of 1 mm to 5 mm; and / or, The refractive index of the fifth lens is 1.5 to 1.7, the radius of curvature of the object-side surface of the fifth lens at the optical axis is 1 mm to 5 mm, the radius of curvature of the image-side surface of the fifth lens at the optical axis is 200 mm to 300 mm, and the thickness of the fifth lens is 5 mm to 10 mm; and / or, The refractive index of the sixth lens is 1.5 to 1.7, the radius of curvature of the object side of the sixth lens at the optical axis is -5 mm to -1 mm, the radius of curvature of the image side of the sixth lens at the optical axis is -5 mm to -1 mm, and the thickness of the sixth lens is 1 mm to 5 mm. The second lens and the third lens are cemented together to form a lens group, and the fourth lens and the fifth lens are cemented together to form a lens group; The distance between the first lens and the second lens is 1mm to 5mm; and / or, The distance between the third lens and the fourth lens is 1mm to 5mm; and / or, The distance between the fifth lens and the sixth lens is 1mm to 5mm; and / or, The optical back focal length of the coupling lens is 20mm to 25mm.

6. The imaging system according to claim 1, characterized in that, The dichroic mirror is a long-pass dichroic mirror and / or a short-pass dichroic mirror, and the cutoff wavelength of the dichroic mirror is 800nm-1000nm.

7. The imaging system according to claim 1, characterized in that, The imaging system includes a first filter and a second filter. The first filter is disposed between the near-infrared camera and the dichroic mirror and is used to filter the near-infrared fluorescence entering the near-infrared camera. The second filter is disposed between the visible light camera and the dichroic mirror and is used to filter the visible light entering the visible light camera.

8. The imaging system according to claim 7, characterized in that, The first filter is a long-pass filter, and the cutoff wavelength of the first filter is greater than or equal to 850 nm; or, The first filter is a bandpass filter, and the center wavelength of the first filter is greater than or equal to 850 nm.

9. The imaging system according to claim 7, characterized in that, The second filter is a short-pass filter, and the cutoff wavelength of the second filter is less than 800 nm; or, The second filter is a bandpass filter, and the center wavelength of the second filter is less than 800nm.

10. The imaging system according to claim 1, characterized in that, The lens surfaces of both the endoscope and the coupling lens have anti-reflective coatings covering the visible and near-infrared light bands.

11. The imaging system according to claim 1, characterized in that, The near-infrared camera in the camera module has a detection range of 850nm-1700nm and a mass of less than 100 grams.

12. A near-infrared fluorescence endoscope, characterized in that, The imaging system and housing according to any one of claims 1-11 are included, wherein the imaging system is at least partially disposed in the housing.

Images