Optical imaging system of rigid multi-directional coaxial endoscope and endoscope

Abstract

The application provides an optical imaging system and an endoscope of a rigid multi-direction coaxial endoscope for spine, which comprises, in sequence along an optical axis from an object side to an image side, an objective lens group, a relay rod lens group, a 90-degree optical axis deflection prism, a coupling mirror group and a camera module; the objective lens group comprises, in sequence along the optical axis, a negative lens, a view direction angle prism module and a positive lens; the view direction angle prism module is a three-glued prism structure comprising a first view direction prism, a second view direction prism and a third view direction prism; the second view direction prism is located between the first view direction prism and the third view direction prism; a side of the second view direction prism close to the first view direction prism is a first reflecting surface; a side of the second view direction prism close to the third view direction prism is a second reflecting surface; an upper half of the first reflecting surface is left as an air gap; and a lower half of the first reflecting surface is coated with a metal reflecting film. The application has the advantages of improving the imaging resolution of the endoscope for spine in a limited space, realizing high-definition and large numerical aperture imaging, and long focal depth without focusing operation.

Description

Technical Field

[0001] This invention belongs to the field of rigid endoscope technology, and in particular relates to an optical imaging system and endoscope for a rigid multi-directional coaxial spinal endoscope. Background Technology

[0002] Traditional open surgery has a long history in spinal surgery, but with the advancement of imaging and computer technology research, minimally invasive spinal surgery techniques have made great progress. Minimally invasive techniques have advantages such as less trauma, faster postoperative recovery, and fewer complications. Among them, spinal endoscopy is one of the most promising minimally invasive spinal surgery techniques today and is widely used in clinical practice.

[0003] Currently, the most widely used traditional rigid spinal endoscopes employ a single-channel coaxial endoscope. With a relatively small tube diameter, a significant portion of the space must be reserved for the entry and exit of surgical instruments and saline solution, severely limiting the optical channel space. Since spinal endoscopes typically require a 12°-30° viewing angle for simultaneous surgical manipulation and observation, the viewing angle prism optical system within this small optical channel space restricts the aperture of the imaging beam, thus limiting the system's imaging resolution. Secondly, to facilitate instrument entry and exit, the rear end needs to bend the optical path, traditionally using a tilting mechanism. The 45° optical path endoscope uses a 22.5° reflecting mirror, which causes a certain optical path difference for light with different apertures. This leads to a decrease in image quality in terms of optical principles, further reducing the imaging resolution of the spinal endoscope. Thirdly, spinal surgery requires observation of narrow anatomical structures, such as the intervertebral foramen, which usually requires a field of view greater than 75°. However, the optical path design of traditional endoscope optical systems is difficult to meet the requirements of high resolution and large field of view. It is necessary to adjust the coupling lens at the camera end to achieve focusing. The insufficient depth of focus limits the doctor's observation range and ability to distinguish details of the surgical site. Summary of the Invention

[0004] The problem to be solved by the present invention is to provide an optical imaging system and endoscope for a rigid multi-directional coaxial spinal endoscope that improves the imaging resolution of a spinal endoscope in a confined space, achieves high-definition, large numerical aperture imaging, and has a long depth of focus and does not require focusing operation.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: an optical imaging system for a rigid multi-directional coaxial spinal endoscope, which is arranged sequentially from the object side to the image side along the optical axis as an objective lens group, a relay rod lens group, a 90° optical axis deflection prism, a coupling lens group and a camera module;

[0006] The objective lens group is arranged sequentially along the optical axis as a negative lens, a viewing angle prism module, and a positive lens. The viewing angle prism module is a three-cemented prism structure composed of a first viewing prism, a second viewing prism, and a third viewing prism. The first viewing prism is positioned close to the negative lens, and the second viewing prism is located between the first and third viewing prisms. The side of the second viewing prism closest to the first viewing prism is the first reflecting surface, and the side of the second viewing prism closest to the third viewing prism is the second reflecting surface. The upper half of the first reflecting surface is not coated with a reflective film, leaving an air gap. The lower half of the first reflecting surface is coated with a metal reflective film and cemented together. The sum of the film thickness and the adhesive thickness of the lower half of the first reflecting surface is equal to the thickness of the air gap. The second reflecting surface is coated with an inner reflective film and then cemented together with the third viewing prism.

[0007] The thickness of the air gap is set between 0.005 mm and 0.05 mm, and the incident angle of all light rays within the field of view reflected by the first reflecting surface is set to meet the following total internal reflection condition:

[0008] ;

[0009] Where, θ i Let θ be the angle of incidence, and n be the refractive index of the prism material.

[0010] Furthermore, a black coating is provided on the end faces of the first viewing prism and the positive lens outside the light-transmitting aperture to suppress stray light.

[0011] Furthermore, the relay rod lens group includes 2N+1 rod lenses, wherein the image transmission level N is an integer from 1 to 7, and every two rod lenses are paired along the optical axis, placed in mirror symmetry to form a double telecentric structure with a magnification of -1. The last rod lens is used to collimate the imaging beam into parallel light and to fine-tune the overall length of the front optical path.

[0012] Furthermore, each group of rod lenses has the same structure, which is a composite lens consisting of a convex lens and a concave lens.

[0013] Furthermore, the 90° optical axis deflection prism is one of a 45° plane mirror, a right-angle mirror, or a pentagonal prism.

[0014] Furthermore, the camera module uses a 4K image sensor, and the size of the image sensor is set to match the image size of the coupling lens assembly.

[0015] The present invention also provides an endoscope, including an endoscope body and a handle connected to the endoscope body via a connecting bayonet. The endoscope body has an infusion channel, an imaging channel and an illumination channel inside, and the optical imaging system is located in the imaging channel.

[0016] Furthermore, the endoscope body includes a main body, a tube fixedly connected to the main body, and a bayonet connection end integrally connected to the lower end of the main body and perpendicular to the tube. The tube has an elliptical cross-section. The main body is provided with an infusion interface, which is connected to the infusion channel. Below the bayonet connection end are a first light source interface and an imaging interface. The first light source interface is connected to the illumination channel, and the imaging interface is connected to the imaging channel.

[0017] Furthermore, the lower end of the handle is provided with a second light source interface that communicates with the first light source interface and a cable for electrical connection with the image display system.

[0018] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0019] 1. In order to meet the requirements of the viewing angle deflection of a large aperture beam under limited space size and improve the beam aperture and field of view, the present invention uses a structure combining reflection and total reflection for the viewing angle prism of the objective lens. The first reflecting surface adopts a total reflection angle design, with the upper half uncoated and leaving an air gap, and the lower half coated with a metal reflective film and bonded together. The lower light is reflected by the reflective film, and the upper light is reflected by the total reflection surface, so that the reflected light from the first reflecting surface overlaps with the incident light that first incident on the second viewing angle prism in the field of view on the first reflecting surface, thereby reducing the limitation on the aperture and angle of the imaging beam and greatly improving the imaging resolution.

[0020] 2. The rear optical path of this invention adopts a vertical optical path structure. A 90° optical axis deflection prism is used to fold the rear optical path and the front optical path by 90 degrees, which satisfies the optical path imaging conditions such as Fermat's principle. This can reduce the aberrations caused by reflective optical components, minimize light loss, improve brightness, and improve the imaging quality of the optical system. At the same time, the endoscope body structure designed according to the optical path folded by 90 degrees is also a 90-degree vertical structure, leaving enough space for operation above the endoscope and overcoming the problem of positional obstruction between the pliers handle and other operating instruments and the endoscope handle in actual operation.

[0021] 3. The last set of rod lenses in this invention is used to collimate the imaging beam into parallel light, and together with the coupling lens group, they form the last stage of image transmission and magnification optical system. The magnification optical system is beneficial to improve the focal depth of the endoscope image, thereby eliminating the need for coupling lenses and focusing structures, which can ensure plug-and-play, clear imaging without focusing. Attached Figure Description

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0023] Figure 1 This is a schematic diagram of the structure of an existing endoscope.

[0024] Figure 2 This is a schematic diagram illustrating the application of the rigid multi-directional coaxial spinal endoscope of the present invention in a dual-channel system;

[0025] Figure 3 This is a schematic diagram of the optical imaging system of the rigid multi-directional coaxial spinal endoscope of the present invention;

[0026] Figure 4 This is a schematic diagram of the objective lens assembly and a light path diagram in the optical imaging system of the rigid multi-directional coaxial spinal endoscope of the present invention;

[0027] Figure 5 This is a schematic diagram of the structure of the endoscope of the present invention;

[0028] Figure 6 This is a schematic diagram of the structure of the endoscope body of the present invention;

[0029] Figure 7 yes Figure 6 Enlarged view of the structure in the middle;

[0030] Figure 8 This is a schematic cross-sectional view of the endoscope body of the present invention;

[0031] Figure 9 This is a schematic diagram of the optical imaging system of the rigid multi-directional coaxial spinal endoscope according to Embodiment 1 of the present invention;

[0032] Figure 10 This is a schematic diagram of the objective lens assembly of the optical imaging system of the rigid multi-directional coaxial spinal endoscope according to Embodiment 1 of the present invention.

[0033] Figure 11 This is the modulation transfer function curve of the entire optical system of the rigid multi-directional coaxial spinal endoscope of Embodiment 1 of the present invention;

[0034] Figure 12 This is a schematic diagram of an image formed by the optical imaging system of the rigid multi-directional coaxial spinal endoscope of Embodiment 1 of the present invention on a stripe of 13 lp / mm in the object plane.

[0035] Figure 13 This is the modulation transfer function curve of the entire optical system of the rigid multi-directional coaxial spinal endoscope of Embodiment 2 of the present invention;

[0036] Figure 14 This is a schematic diagram of an image formed by the optical imaging system of the rigid multi-directional coaxial spinal endoscope of Embodiment 2 of the present invention on a stripe of 20 lp / mm in the object plane.

[0037] In the diagram: 1-Objective lens group; 2-Relay rod lens group; 3-90° optical axis deflection angle prism; 4-Coupled lens group; 5-Camera module; 6-Negative lens; 7-Positive lens; 8-First viewing prism; 9-Second viewing prism; 10-Third viewing prism; 11-First reflecting surface; 12-Second reflecting surface; 13-Air gap; 14-Metallic reflective coating; 15-Internal reflective coating; 16-Black coating; 17-Rod lens; 18-Endoscope body; 19-Connecting bayonet; 20-Handle; 21-Irrigation channel; 22-Imaging channel; 23-Illumination channel; 24-Main body; 25-Tube section; 26-Bayonet connection end; 27-Irrigation interface; 28-First light source interface; 29-Imaging interface; 30-Second light source interface; 31-Cable. Detailed Implementation

[0038] To better understand the above-mentioned objects, features, and advantages of the present invention, the following description is provided. Figure 1-14 The present invention will be further described in detail below with reference to specific embodiments. It should be noted that, unless otherwise specified, the technical solutions and features of the present application can be combined with each other.

[0039] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific technical solutions disclosed below.

[0040] The technical solution of the present invention will now be described with reference to specific embodiments. These embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the present invention without creative effort are within the scope of protection of the present invention.

[0041] like Figure 2 As shown, the endoscope described in this invention is applied to a dual-channel system (UBE), that is, the endoscope channel and the working channel are separated. The working channel is used for surgical instrument operation, and the endoscope channel includes an optical imaging channel, a light-guiding fiber bundle illumination channel, and a saline irrigation channel. The independent optical imaging channel provides more space for the optical channel, which increases the optical aperture of the spinal endoscope from the traditional less than or equal to 2 mm to 2.8 mm, and can obtain a larger field of view and higher resolution imaging.

[0042] Based on the above, the technical solution of the present invention provides an optical imaging system for a rigid multi-directional coaxial spinal endoscope, such as... Figure 3 and Figure 4 As shown, from the object side to the image side along the optical axis, the components are arranged in sequence as follows: objective lens group 1, relay rod lens group 2, 90° optical axis deflection angle prism 3, coupling lens group 4, and camera module 5.

[0043] The objective lens group 1 is arranged sequentially along the optical axis as a negative lens 6, a viewing angle prism module, and a positive lens 7. The viewing angle prism module is a three-cemented prism structure composed of a first viewing prism 8, a second viewing prism 9, and a third viewing prism 10. The first viewing prism 8 is positioned close to the negative lens 6, and the second viewing prism 9 is located between the first viewing prism 8 and the third viewing prism 10. The side of the second viewing prism 9 that is close to the first viewing prism 8 is the first reflecting surface 11, and the side of the second viewing prism 9 that is close to the third viewing prism 10 is the second reflecting surface 12. The upper half of the first reflecting surface 11 is not coated with a reflective film, leaving an air gap 13. The lower half of the first reflecting surface 11 is coated with a metal reflective film 14 and cemented together. The sum of the film thickness and the adhesive thickness of the lower half of the first reflecting surface 11 is equal to the thickness of the air gap 13. The second reflecting surface 12 is coated with an inner reflective film 15 and then cemented together with the third viewing prism 10.

[0044] The thickness of the air gap 13 is set between 0.005 mm and 0.05 mm, and the incident angle of all light rays within the field of view reflected by the first reflecting surface 11 meets the following total internal reflection conditions:

[0045] ;

[0046] Where, θ i Let θ be the angle of incidence, and n be the refractive index of the prism material.

[0047] Specifically, objective lens group 1 adopts a retroreflective objective lens structure with a field of view of 75°-110° and an image-side F# number of 3.5-5. The light beam path in objective lens group 1 is as follows: the light beam first enters the negative lens 6, which is used to widen the edge light angle of the heated pupil to achieve wide-angle imaging. After passing through the negative lens 6, the imaging beam first passes through the first viewing prism 8, then through the air gap 13 of the second viewing prism 9, and is reflected by the second reflecting surface 12. After a second reflection by the first reflecting surface 11, it enters the positive lens 7. In order to improve the beam aperture and field of view, the viewing angle prism module uses a reflective... - The viewing objective lens with total internal reflection has a total internal reflection design for the first reflecting surface 11. By leaving an air gap 13 in the upper half of the first reflecting surface 11 and coating the lower half with a metal reflective film 14, the upper incident light beam is reflected by the total internal reflection surface, and the lower light beam is reflected by the metal reflective film 14 in the lower half. Therefore, at the junction of the air gap and the coating of the first reflecting surface 11, there is an overlap between the light beam reflected by the first reflecting surface 11 and the incident light beam that is initially incident on the second viewing prism 9. This reduces the limitation on the aperture and angle of the imaging beam and greatly improves the imaging resolution, which can reach greater than or equal to 13 lp / mm.

[0048] In addition, the lower half of the first reflective surface 11 is coated with a metal reflective film 14 to prevent the beam outside the field of view from directly entering the positive lens 7 and subsequent optical path through the negative lens 6, the first viewing prism 8 and the second viewing prism 9, thus preventing stray light from forming; the third viewing prism 10 serves as an auxiliary support prism to facilitate alignment; the viewing angle range of the viewing prism in the viewing angle prism module is 12°-30°.

[0049] Furthermore, a black coating 16 is provided on the end face of the first viewing prism 8 and the positive lens 7 outside the light-transmitting aperture to suppress stray light.

[0050] Furthermore, the relay rod lens group 2 includes 2N+1 rod lenses 17, wherein the image transmission level N is an integer from 1 to 7. Every two rod lenses 17 are paired along the optical axis and placed in a mirror image symmetrically to form a double telecentric structure with a magnification of -1. The last rod lens 17 is used to collimate the imaging beam into parallel light and to fine-tune the overall length of the front optical path. Each rod lens 17 has the same structure, which is a multi-cement lens composed of a convex lens and a concave lens.

[0051] Specifically, the number of image transmission stages N is configured according to the working length of the endoscope tip, applicable to endoscopes of various working lengths, with the tip working length set between 50 mm and 300 mm. Furthermore, every two rod lenses 17 form a pair, constituting a 1:1 dual telecentric image transmission structure. The advantages of this structure are: 1. High imaging quality and aberration correction: The symmetrical structure effectively corrects aberrations such as spherical aberration, coma, and field curvature; 2. Pupil matching and energy transmission efficiency: The pupils on the object plane and the image plane are matched conjugately through the spectral plane, ensuring efficient energy transmission and avoiding vignetting, making it suitable for use in spinal endoscope systems requiring long-distance, multi-stage image transmission and with strictly limited geometric dimensions; 3. Anti-interference and stability: The long rod lens cemented optical system is relatively insensitive to mechanical vibration and assembly errors, suitable for stable imaging in clinical environments.

[0052] Furthermore, the 90° optical axis deflection angle prism 3 is one of a 45° plane mirror, a right-angle mirror, or a pentagonal prism.

[0053] Specifically, the 90° optical axis deflection prism 3 folds the rear optical path and the front optical path by 90 degrees to form a vertical optical path structure. In actual operation, the coordinate systems of the front and rear handles of the endoscope are orthogonal. During operation, there is only multi-directional coaxial rotation, and the optical path is still equal, which satisfies the optical path imaging conditions such as Fermat's principle. This can reduce the aberrations caused by reflective optical components and improve the imaging quality of the optical system.

[0054] The last group of rod lenses 17 and the coupling lens group 4 form the final stage of the image transmission and magnification optical system. The coupling lens group 4 adopts a symmetrical optical structure design, which has the following advantages in the endoscope optical path: 1. The symmetrical design makes the optical path difference between the edge rays and the paraxial rays cancel each other out, thereby reducing spherical aberration; 2. The symmetrical structure can suppress coma and distortion, and does not introduce additional distortion in the endoscope optical path; 3. The doublet lenses use different dispersion glasses to correct axial chromatic aberration and magnification chromatic aberration; 4. The symmetrical structure makes the curved image field tend to be flat, which is suitable for 4K imaging applications; 5. The incident angle of the edge rays is reasonably controlled, which can reduce edge vignetting and improve the uniformity of image illumination; 6. The magnification optical system is conducive to improving the depth of focus of the endoscope image, so that after removing the coupling lens and focusing structure, it can be used immediately and achieve clear imaging without focusing.

[0055] Furthermore, the camera module 5 employs a 4K image sensor, and the size of the image sensor is set to match the imaging size of the coupling lens group 4, so as to image the magnified image of the coupling lens onto the camera module 5.

[0056] It should be noted that the present invention adopts a wide-spectrum design in the selection of coating and lens materials, with a design wavelength between 0.43 micrometers and 0.7 micrometers. At the same time, the imaging characteristics at a wavelength of 680 nanometers are optimized to improve the imaging quality and better match the detection requirements of bleeding points.

[0057] In addition, the present invention also provides an endoscope, including an endoscope body 18 and a handle 20 connected to the endoscope body 18 via a connecting bayonet 19. The endoscope body 18 is provided with an infusion channel 21, an imaging channel 22 and an illumination channel 23, and the optical imaging system is located in the imaging channel 22.

[0058] Furthermore, the endoscope body 18 includes a main body 24, a tube 25 fixedly connected to the main body 24, and a bayonet connection end 26 integrally connected to the lower end of the main body 24 and perpendicularly arranged to the tube 25. The tube 25 has an elliptical cross-section. The main body 24 is provided with an infusion interface 27, which is connected to the infusion channel 21. Below the bayonet connection end 26, a first light source interface 28 and an imaging interface 29 are provided. The first light source interface 28 is connected to the illumination channel 23, and the imaging interface 29 is connected to the imaging channel 22.

[0059] Furthermore, the lower end of the handle 20 is provided with a second light source interface 30 that communicates with the first light source interface 28 and a cable 31 for electrical connection with the image display system.

[0060] Specifically, such as Figure 1The existing endoscopes shown typically have a 45° tilted optical path and use a 22.5° reflecting mirror, resulting in significant light loss at the lens tip and poor image quality. Furthermore, the 45° tilted handle design obstructs the operation when working above the endoscope, hindering the use of forceps. The endoscope design of this invention, however, addresses this issue. Figures 3-8 As shown, the optical imaging system uses a 90° optical axis deflection prism 3 to fold the rear optical path and the front optical path by 90 degrees, forming a vertical optical path structure. This results in low light loss and high imaging quality. Furthermore, based on the characteristics of the optical path, in the structural design of the endoscope of this invention, the handle 20 is vertically connected to the endoscope body 18 through the connecting bayonet 19. After the optical path is bent by 90 degrees, the handle can be operated coaxially with the endoscope body. Only rotation is required, and the optical path remains equal, resulting in high imaging quality. In addition, the endoscope tube 25 adopts an elliptical structure design, which can be inserted into a sufficiently narrow space. Compared with the traditional circular endoscope tube, which wastes lateral space, the elliptical endoscope tube of this invention reduces the space of the endoscope column while ensuring the size of the imaging channel, making the design more reasonable.

[0061] In addition, by setting up a second light source interface 30, a first light source interface 28 and an illumination channel 23 connected in sequence, the endoscope and the light source system are integrated together. The endoscope is provided with a camera light source by connecting an external light source through the second light source interface 30 at the lower end of the handle 20. The external circuit integration is high, improving hand grip comfort and making operation convenient.

[0062] Example 1

[0063] like Figure 9-12 As shown, the optical system operates at a wavelength of 430nm-700nm, with a field of view of 90° and a viewing angle of 30°. The aperture of the front-end optical components is D=1.8mm, and the total length of the front-end optical path is approximately 220mm. It employs 13 groups of rod lenses, with an entrance pupil diameter D0=0.18. The structural parameters of the objective lens group are as follows: the first, second, and third viewing prisms are made of H-K9L material, and their corresponding total internal reflection angle requirement θ... i The angle is greater than 41.2°. The design tilt angles of the second and first reflective surfaces are 19° and 34°, respectively. The light in the entire field of view satisfies the total reflection condition on the first reflective surface. The air gap thickness on the first reflective surface is 0.005 mm, the air gap cross-sectional length is 0.7 mm, and the cross-sectional length of the metal-coated reflective film is 0.82 mm. Based on the image formed by the 13 lp / mm stripes on the object side, it can be seen that the system resolution is better than 13 lp / mm.

[0064] Example 2

[0065] like Figure 13-14As shown, the optical system is configured with a working wavelength of 430-700nm, a field of view of 110°, a viewing angle of 30°, an aperture of 2.8mm for the front optical path components, a total length of approximately 190mm for the front optical path, and employs 7 groups of rod lenses. The entrance pupil diameter is DO=0.28. The structural parameters of the objective lens group are as follows: the first, second, and third viewing prisms are made of H-K9L material, and their corresponding total internal reflection angle requirement θ is... i The angle is greater than 41.2°. The design tilt angles of the second and first reflective surfaces are 19° and 34°, respectively. The light in the entire field of view satisfies the total reflection condition on the first reflective surface. The air gap thickness on the first reflective surface is 0.005 mm, the air gap cross-sectional length is 0.7 mm, and the cross-sectional length of the metal-coated reflective film is 0.82 mm. Based on the image formed by the 20 lp / mm stripes on the object side, it can be seen that the system resolution is better than 20 lp / mm.

[0066] The above are preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention are included within the scope of protection of the invention.

Claims

1. An optical imaging system for a rigid multi-directional coaxial spinal endoscope, characterized in that: From the object side to the image side, along the optical axis, the components are arranged in sequence: objective lens group, relay rod lens group, 90° optical axis deflection angle prism, coupling lens group, and camera module. The objective lens group is arranged sequentially along the optical axis as a negative lens, a viewing angle prism module, and a positive lens. The viewing angle prism module is a three-cemented prism structure composed of a first viewing prism, a second viewing prism, and a third viewing prism. The first viewing prism is positioned close to the negative lens, and the second viewing prism is located between the first and third viewing prisms. The side of the second viewing prism closest to the first viewing prism is the first reflecting surface, and the side of the second viewing prism closest to the third viewing prism is the second reflecting surface. The upper half of the first reflecting surface is not coated with a reflective film, leaving an air gap. The lower half of the first reflecting surface is coated with a metal reflective film and cemented together. The sum of the film thickness and the adhesive thickness of the lower half of the first reflecting surface is equal to the thickness of the air gap. The second reflecting surface is coated with an inner reflective film and then cemented together with the third viewing prism. The thickness of the air gap is set between 0.005 mm and 0.05 mm, and the incident angle of all light rays within the field of view reflected by the first reflecting surface is set to meet the following total internal reflection condition: ； Where, θ i Let θ be the angle of incidence, and n be the refractive index of the prism material.

2. The optical imaging system of a rigid multi-directional coaxial spinal endoscope according to claim 1, characterized in that: A black coating is applied to the end face of the first viewing prism and positive lens outside the light-transmitting aperture to suppress stray light.

3. The optical imaging system of a rigid multi-directional coaxial spinal endoscope according to claim 1, characterized in that: The relay rod lens group includes 2N+1 rod lenses, where the image transmission level N is an integer from 1 to 7. Every two rod lenses are paired along the optical axis and placed in a mirror-symmetrical manner to form a double telecentric structure with a magnification of -1. The last rod lens is used to collimate the imaging beam into parallel light and to fine-tune the overall length of the front optical path.

4. The optical imaging system of a rigid multi-directional coaxial spinal endoscope according to claim 3, characterized in that: Each group of rod lenses has the same structure, which is a composite lens consisting of a combination of a convex lens and a concave lens.

5. The optical imaging system of a rigid multi-directional coaxial spinal endoscope according to claim 1, characterized in that: The 90° optical axis deflection prism is one of a 45° plane mirror, a right-angle mirror, or a pentagonal prism.

6. The optical imaging system of a rigid multi-directional coaxial spinal endoscope according to claim 1, characterized in that: The camera module uses a 4K image sensor, and the size of the image sensor is set to match the image size of the coupling lens assembly.

7. An endoscope, characterized in that: The device includes an endoscope body and a handle connected to the endoscope body via a connecting bayonet. The endoscope body has an infusion channel, an imaging channel, and an illumination channel inside. The optical imaging system according to any one of claims 1-6 is located within the imaging channel.

8. An endoscope according to claim 7, characterized in that: The endoscope body includes a main body, a tube fixedly connected to the main body, and a bayonet connection end integrally connected to the lower end of the main body and perpendicular to the tube. The tube has an elliptical cross-section. The main body is provided with an infusion interface, which is connected to the infusion channel. Below the bayonet connection end are a first light source interface and an imaging interface. The first light source interface is connected to the illumination channel, and the imaging interface is connected to the imaging channel.

9. An endoscope according to claim 8, characterized in that: The lower end of the handle is provided with a second light source interface that is connected to the first light source interface and a cable for electrical connection with the image display system.

Images