Medical magnification endoscope optical system

Abstract

The application discloses a medical magnification endoscope optical system, comprising a first lens group, a second lens group, a third lens group, a fourth lens group, a filter and a CMOS chip arranged in sequence from an object plane side, the object plane and the CMOS chip are mutually object image conjugate relationship, the first lens group is a negative refractive index lens group, the second lens group, the third lens group and the fourth lens group are all positive refractive index lens groups, a system diaphragm is arranged between the first lens group and the second lens group, the third lens group is used for moving along the optical axis of the endoscope system to zoom and switch a low magnification state and a high magnification state, and the first lens group is provided with a first concave lens towards the object plane side. Compared with the prior art, the application simplifies the zooming mode, the image quality is excellent and stable in the zooming process, the magnification and F number are higher in the high magnification, and the resolution is also higher.

Description

Technical Field

[0001] This invention belongs to the field of endoscopic optical systems, and particularly relates to a medical magnification endoscope optical system. Background Technology

[0002] Endoscopes are currently one of the essential medical devices in clinical practice. With the miniaturization of cameras and the reduction in the diameter of endoscope insertion tips, minimally invasive surgery has emerged. Conventional endoscopes have a relatively large field of view, but their resolution is relatively low, allowing only for physician observation and surgery, and cannot be used for pathological diagnosis. To address the needs of medical observation, surgery, and real-time precise diagnosis, there is a growing demand for endoscopic optical systems capable of zooming. Zoom endoscopes offer a large field of view at low magnification, which is beneficial for surgery, and a smaller field of view but higher resolution at high magnification, which is beneficial for precise diagnosis.

[0003] A magnifying endoscope optical system can switch between a normal low-magnification state and a magnified observation state by moving the lens group along the optical axis, while the focal length also changes. For example, Chinese Patent CN201480016424.5 discloses a magnifying endoscope optical system, which has multiple lens groups and a negative lens coupled to an imaging element. By moving a portion of the lens groups, at least a normal observation state and a close-range magnification state can be switched.

[0004] In existing technologies (such as the aforementioned patent), the movement and adjustment of the lens group during zooming is complex, switching between low-magnification and high-magnification states is inconvenient, and the magnification is not high. Summary of the Invention

[0005] The purpose of this invention is to provide a medical endoscope optical system with high magnification, which simplifies the zooming process, provides excellent and stable image quality during zooming, and offers higher magnification and F-number at high magnification, as well as higher resolution.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a medical magnification endoscope optical system, comprising a first lens group, a second lens group, a third lens group, a fourth lens group, a filter, and a CMOS chip arranged sequentially from the object plane side. The object plane and the CMOS chip have a conjugate relationship between the object and the image. The first lens group is a negative refractive index lens group, while the second, third, and fourth lens groups are all positive refractive index lens groups. A system aperture is provided between the first and second lens groups. The third lens group is used to move along the optical axis of the endoscope system to zoom and switch between low-magnification and high-magnification states. A first concave lens is provided on the side of the first lens group facing the object plane. The ratio of the focal length of the first concave lens to the focal length of the low-magnification endoscope system satisfies the following relationship: In the formula, The focal length of the first concave lens (11) is... This is the focal length of the low-magnification endoscope system. The first lens group consists of multiple lenses, mainly used to collect information from various fields of view on the object side, and has a negative refractive index overall. The system aperture is located between the first and second lens groups. The second, third, and fourth lens groups all have positive refractive indices, precisely focusing the diverging light rays from the first lens group to form an image. The filter (formed by a protective coating) is located in front of the CMOS chip.

[0007] As a further description of the above technical solution:

[0008] The ratio of the focal length of the first lens group to the focal length of the first concave lens satisfies the following relationship: In the formula, This is the focal length of the first lens group.

[0009] As a further description of the above technical solution:

[0010] The ratio of the focal length of the second lens group to the focal length of the low-magnification endoscope system satisfies the following relationship: 3.1 3.5, where, This is the focal length of the second lens group.

[0011] As a further description of the above technical solution:

[0012] The combined focal length of the third and fourth lens groups, when the endoscope is in low magnification mode, has the following relationship with the focal length of the low magnification endoscope system: In the formula, This is the combined focal length of the third and fourth lens groups.

[0013] As a further description of the above technical solution:

[0014] The ratio of the center distances of the system aperture to the center distances of the first and second lens groups satisfies the following relationship: In the formula, The distance from the system aperture to the second mirror group. This represents the distance between the first and second lens groups.

[0015] As a further description of the above technical solution:

[0016] As the working distance (distance from the object surface to the front surface of the first concave lens) changes, the distance between the second and fourth lens groups remains constant during the focusing process of the endoscope system, and the movement direction of the third lens group along the optical axis of the endoscope system is consistent with the movement direction of the object surface.

[0017] As a further description of the above technical solution:

[0018] The ratio of the radius of curvature of the first concave lens on the image plane side to its focal length satisfies the following relationship: In the formula, Let be the radius of curvature of the first concave lens on the side closest to the image plane.

[0019] As a further description of the above technical solution:

[0020] The first concave lens is made of quartz glass, which has good biocompatibility.

[0021] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0022] 1. In this invention, the optical system consists of a first lens group, a system aperture, a second lens group, a third lens group, a fourth lens group, a filter, and a CMOS chip. The object plane is located in front of the first lens group, and the object plane and the CMOS chip have a conjugate relationship. The distance from the object plane to the front surface of the first concave lens in the first lens group is the working distance. The larger the working distance, the larger the field of view at the object line, but the lower the magnification and resolution. Conversely, the smaller the working distance, the smaller the field of view at the object line, but the higher the magnification and resolution. Under normal circumstances, if the object plane moves beyond its depth of field, the image plane will become blurred. To maintain the conjugate relationship between the object plane and the CMOS chip, a zoom mechanism is required. In this design, the third lens group is a zoom group. The movement of the object plane is compensated by the axial movement of the third lens group, and the direction of movement of the third lens group is consistent with the direction of movement of the object plane. During the movement of the third lens group, the positional relationships of the other lens groups remain unchanged. This solution is based on a CMOS chip with a CRA of zero degrees. The effective photosensitive surface diagonal size is less than 1mm, which can achieve accurate imaging with an object field of view of no less than 130 degrees. The overall lens size is less than 1.8mm. The image quality is excellent and stable during zooming. During the back-and-forth movement of the object, the magnification ratio can reach 5.5 times or even higher, and the high-magnification resolution can reach 10um, which meets the requirements of surgical observation and diagnosis with a fine lens.

[0023] 2. In this invention, the front glass is replaced with SILICA, which has better biocompatibility. That is, the material of the first concave lens is quartz glass (silica), which has good biocompatibility, resulting in higher resolution. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the optical structure of a first-scheme optical system for a medical magnifying endoscope.

[0026] Figure 2This is a zoom schematic diagram of a medical magnification endoscope optical system scheme one, where A1 is the low magnification state, B1 is the medium magnification state, and C1 is the high magnification state.

[0027] Figure 3 This is a low-magnification state transfer function diagram of a first-scheme optical system for a medical magnifying endoscope.

[0028] Figure 4 This is a low-magnification state point diagram of a first-scheme optical system for a medical magnifying endoscope.

[0029] Figure 5 This is a mid-magnification state transfer function diagram for a first-scheme optical system for a medical magnifying endoscope.

[0030] Figure 6 This is a mid-magnification state point diagram of a first-scheme optical system for a medical magnifying endoscope.

[0031] Figure 7 This is a high-magnification state transfer function diagram for a first-stage optical system for a medical magnifying endoscope.

[0032] Figure 8 This is a high-magnification state point diagram of a first-scheme optical system for a medical magnifying endoscope.

[0033] Figure 9 This is a schematic diagram of the optical structure of Scheme 2 for a medical magnification endoscope optical system.

[0034] Figure 10 This is a zoom schematic diagram of Scheme 2 for a medical magnification endoscope optical system, where A2 is the low magnification state, B2 is the medium magnification state, and C2 is the high magnification state.

[0035] Figure 11 This is a low-magnification state transfer function diagram of a second scheme for a medical magnifying endoscope optical system.

[0036] Figure 12 This is a low-magnification state point diagram of a second scheme for a medical magnifying endoscope optical system.

[0037] Figure 13 This is a mid-magnification state transfer function diagram for a second scheme of a medical magnification endoscope optical system.

[0038] Figure 14 This is a mid-magnification state point diagram of a second scheme for a medical magnifying endoscope optical system.

[0039] Figure 15 This is a high-magnification state transfer function diagram for a second scheme of a medical magnifying endoscope optical system.

[0040] Figure 16 This is a high-magnification state point diagram of Scheme 2 for a medical magnifying endoscope optical system.

[0041] Figure 17 This is a schematic diagram of the optical structure of Scheme 3 for a medical magnification endoscope optical system.

[0042] Figure 18 This is a zoom schematic diagram of Scheme 3 for a medical magnification endoscope optical system, where A3 is the low magnification state, B3 is the medium magnification state, and C3 is the high magnification state.

[0043] Figure 19 This is a low-magnification state transfer function diagram of Scheme 3 for a medical magnifying endoscope optical system.

[0044] Figure 20 This is a low-magnification state point diagram of Scheme 3 for a medical magnifying endoscope optical system.

[0045] Figure 21 This is a mid-magnification state transfer function diagram for a third scheme of a medical magnification endoscope optical system.

[0046] Figure 22 This is a mid-magnification state point diagram of Scheme 3 for a medical magnification endoscope optical system.

[0047] Figure 23 This is a high-magnification state transfer function diagram for a third scheme of a medical magnifying endoscope optical system.

[0048] Figure 24 This is a high-magnification state point diagram of Scheme 3 for a medical magnifying endoscope optical system.

[0049] Figure 25 This is a schematic diagram of the optical structure of Scheme 4 for a medical magnification endoscope optical system.

[0050] Figure 26 This is a zoom schematic diagram of Scheme 4 for a medical magnification endoscope optical system, where A4 represents the low magnification state, B4 the medium magnification state, and C4 the high magnification state.

[0051] Figure 27 This is a low-magnification state transfer function diagram of Scheme 4 for a medical magnification endoscope optical system.

[0052] Figure 28 This is a low-magnification state point diagram of Scheme 4 for a medical magnification endoscope optical system.

[0053] Figure 29This is a mid-magnification state transfer function diagram for a fourth scheme of a medical magnification endoscope optical system.

[0054] Figure 30 This is a mid-magnification state point diagram of Scheme 4 for a medical magnification endoscope optical system.

[0055] Figure 31 This is a high-magnification state transfer function diagram for a fourth scheme of a medical magnification endoscope optical system.

[0056] Figure 32 This is a high-magnification state point diagram of Scheme 4 for a medical magnification endoscope optical system.

[0057] Legend:

[0058] 1. First lens group; 11. First concave lens; 2. Second lens group; 3. Third lens group; 4. Fourth lens group; 5. Filter; 6. CMOS chip; 7. Object plane; 8. System aperture. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0060] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention. Example 1:

[0061] See the appendix below. Figure 1-8 Tables 1-2 are used to illustrate the magnifying endoscope optical system according to the first embodiment of the present invention.

[0062] The magnifying endoscope optical system, from the object side, consists of a first lens group 1, a system aperture stop 8, a second lens group 2, a third lens group 3, a fourth lens group 4, a filter 5, and a CMOS chip 6. The first lens group 1 comprises three lenses: a first concave lens 11, a plano-concave lens made of quartz; a second lens, two biconcave lenses with the same surface radius of curvature; and a third lens, two biconvex lenses with the same surface radius of curvature. The second and third lenses are made of the same material. The first lens group 1 has a negative refractive index. The system aperture stop 8 is located between the first lens group 1 and the second lens group 2. The second lens group 2 is a biconvex lens with the same surface curvature; the third lens group 3 is a cemented doublet; and the fourth lens group 4 is a plano-convex lens. The second, third, and fourth lens groups 2, 3, and 4 all have positive refractive indices, converging the diverging light rays transmitted from the first lens group 1. The third lens group (3) is a zoom group. As the working distance changes from 10mm to 1.168mm, the third lens group (3) moves 0.75mm along the axis, resulting in a 5.1x change in magnification. Image quality remains stable throughout the zoom process, with the transfer function and dot plot both within the diffraction limit. For a CMOS chip with a diagonal of 1mm, the low-magnification field of view can reach 130 degrees, and the high-magnification resolution can reach 11µm. In this example, the CRA (Critical Area Recognition) of all fields of view is less than 2 degrees, making it suitable for CMOS chips with a CRA of zero degrees.

[0063] Table 1 shows the actual optical structure parameters of the magnifying endoscope scheme one.

[0064] Face number Radius Thickness Ne vd 0 (object surface) Infinity D1 1 Infinity 0.25 1.45846 67.821 2 0.682 0.464 3 -1.222 0.366 1.80610 40.945 4 1.222 0.119 5 2.789 1.505 1.80610 40.945 6 -2.789 0.367 stop Infinity 0.118 8 1.939 1.348 1.55248 63.372 9 -1.939 D2 10 1.204 0.594 1.43780 94.523 11 -1.204 0.350 2.0033 28.316 12 7.704 D3 13 1.891 0.622 1.80400 46.574 14 Infinity 0.197 15 Infinity 0.35 1.51680 64.199 16 Infinity 0.1 17 (Image) Infinity

[0065] Table 2 shows the optical structure zoom data for magnifying endoscope scheme one.

[0066] low multiplier China High D1 10 4.25 1.168 D2 0.185 0.329 0.931 D3 0.852 0.708 0.106 f’ 0.579 0.573 0.536 F number 4.95 4.90 4.64 Magnification -0.054 -0.114 -0.278 Example 2:

[0067] See the appendix below. Figure 9-16 Tables 3-4 illustrate the magnifying endoscope optical system according to the second embodiment of the present invention.

[0068] The magnifying endoscope optical system, from the object side, consists of a first lens group 1, a system aperture stop 8, a second lens group 2, a third lens group 3, a fourth lens group 4, a filter 5, and a CMOS chip 6. The first lens group 1 comprises three lenses: the first lens (first concave lens 11) is a plano-concave lens made of quartz; the second lens consists of two biconcave lenses with different radii of curvature; and the third lens consists of two biconvex lenses with different surface radii of curvature. The second and third lenses are made of different materials. The first lens group 1 has a negative refractive index. The system aperture stop 8 is located between the first lens group 1 and the second lens group 2. The second lens group 2 is a biconvex lens with different surface curvatures; the third lens group 3 is a cemented doublet; and the fourth lens group 4 is a biconvex lens. The second, third, and fourth lens groups 2, and 3 all have positive refractive indices, converging the diverging light rays transmitted from the first lens group 1. The third lens group (3) is a zoom group. As the working distance changes from 10.5mm to 1.211mm, the third lens group (3) moves 0.86mm along the axis. The image quality remains stable throughout the zoom process, with a magnification change of 5.9x. The image quality remains stable during zooming, and the transfer function and dot plot are both within the diffraction limit. For a CMOS chip with a diagonal of 1mm, the low-magnification field of view can reach 130 degrees, and the high-magnification resolution can reach 11µm. In this example, the CRA of all fields of view is less than 2 degrees, which is suitable for CMOS chips with a CRA of zero degrees.

[0069] Table 3 shows the actual optical structure parameters of the magnifying endoscope scheme two.

[0070] Face number Radius Thickness Ne vd 0 (object surface) Infinity D1 1 Infinity 0.271 1.45846 67.821 2 0.703 0.370 3 -1.264 0.351 1.90069 37.051 4 0.9 0.113 5 1.406 0.897 1.56732 42.808 6 -1.280 0.384 stop Infinity 0.120 8 4.446 0.955 1.62041 60.374 9 -1.385 D2 10 2.239 0.465 1.47047 66.885 11 -1.087 0.350 1.92286 20.88 12 -8.769 D3 13 1.886 0.481 1.56888 62.961 14 -6.122 0.313 15 Infinity 0.35 1.51680 64.199 16 Infinity 0.1 17 (Image) Infinity

[0071] Table 4 shows the optical structure zoom data for magnifying endoscope scheme two.

[0072] low multiplier China High D1 10.5 4.244 1.211 D2 0.249 0.527 1.109 D3 0.961 0.683 0.101 f’ 0.570 0.567 0.556 F number 5.06 5.04 4.96 Magnification -0.051 -0.114 -0.3 Example 3:

[0073] See the appendix below. Figure 17-24 Tables 5-6 are used to illustrate the magnifying endoscope optical system according to the third embodiment of the present invention.

[0074] The magnifying endoscope optical system, from the object side, consists of a first lens group 1, a system aperture 8, a second lens group 2, a third lens group 3, a fourth lens group 4, a filter 5, and a CMOS chip 6. The first lens group 1 consists of two lenses: a plano-concave lens made of quartz and a meniscus lens. The first lens group 1 has a negative refractive index. The system aperture 8 is located between the first lens group 1 and the second lens group 2. The second lens group 2 is a biconvex lens with the same surface curvature. The third lens group 3 is a cemented doublet lens, and the fourth lens group 4 is a biconvex lens. The second, third, and fourth lens groups all have positive refractive indices, converging the diverging light rays transmitted from the first lens group 1. The third lens group 3 is a zoom group. As the working distance changes from 10.5 mm to 1.172 mm, the third lens group 3 moves 0.997 mm axially, resulting in a 5.6x change in magnification. The image quality remains stable during zooming, and the transfer function and dot plot are both within the diffraction limit. For a CMOS chip with a diagonal of 1mm, the low-magnification field of view can reach 130 degrees, and the high-magnification resolution can reach 11µm. In this example, the CRA of all fields of view is less than 2 degrees, which is applicable to CMOS chips with a CRA of zero degrees.

[0075] Table 5 shows the actual optical structure parameters of magnifying endoscope scheme three.

[0076] Face number Radius Thickness Ne vd 0 (object surface) Infinity D1 1 Infinity 0.254 1.45846 67.821 2 0.603 0.374 3 -1.037 2.403 1.90366 31.318 4 -3.365 0.250 stop Infinity 0 6 1.658 1.215 1.49700 81.613 7 -1.658 D2 8 2.200 0.408 1.49700 81.613 9 -1.070 0.300 1.90366 31.318 10 -15.157 D3 11 1.572 0.438 1.56888 62.961 12 Infinity 0.2 13 Infinity 0.35 1.51680 64.199 14 Infinity 0.1 15 (Image) Infinity

[0077] Table 6 shows the optical structure zoom data for magnifying endoscope scheme three.

[0078] low multiplier China High D1 10.5 4.243 1.172 D2 0.185 0.471 1.182 D3 1.108 0.822 0.111 f’ 0.589 0.585 0.566 F number 5.04 5.01 4.88 Magnification -0.054 -0.117 -0.3 Example 4:

[0079] See the appendix below. Figure 25-32 Tables 7-8 are used to illustrate the magnifying endoscope optical system according to the fourth embodiment of the present invention.

[0080] The magnifying endoscope optical system, from the object side, consists of a first lens group 1, a system aperture stop 8, a second lens group 2, a third lens group 3, a fourth lens group 4, a filter 5, and a CMOS chip 6. The first lens group 1 consists of two lenses: a first concave lens (first concave lens 11) made of quartz, and a curved cemented doublet lens. The first lens group 1 has a negative refractive index. The system aperture stop 8 is located between the first lens group 1 and the second lens group 2. The second lens group 2 is a biconvex lens with different surface curvatures. The third lens group 3 is a cemented doublet lens, and the fourth lens group 4 is a biconvex lens with different surface curvatures. The second lens group 2, the third lens group 3, and the fourth lens group 4 all have positive refractive indices, converging the diverging light rays transmitted from the first lens group 1. The third lens group (3) is a zoom group. As the working distance changes from 10.5mm to 1.136mm, lens group 3 moves 0.981mm along the axis, resulting in a magnification change of 5.9x. The image quality remains stable during zooming, and the transfer function and dot plot are both within the diffraction limit. For a CMOS chip with a diagonal of 1mm, the low-magnification field of view can reach 130 degrees, and the high-magnification resolution can reach 11µm. In this example, the CRA of all fields of view is less than 2 degrees, making it suitable for CMOS chips with a CRA of zero degrees.

[0081] Table 7 shows the actual optical structure parameters of magnifying endoscope scheme four.

[0082] Face number Radius Thickness Ne vd 0 (object surface) Infinity D1 1 Infinity 0.295 1.45846 67.821 2 0.618 0.338 3 -1.066 0.435 1.90069 37.051 4 0.883 1.0 1.62588 35.714 5 -1.419 0.57 stop Infinity 0.12 7 2.868 1.007 1.53028 60.474 8 -1.301 D2 9 2.368 0.416 1.47047 66.885 10 -1.06 0.35 1.84667 23.828 11 -11.515 D3 12 1.992 0.644 1.65950 62.961 13 -23.481 0.24 14 Infinity 0.35 1.51680 57.385 15 Infinity 0.1 16 (Image) Infinity

[0083] Table 8 shows the optical structure zoom data for magnifying endoscope scheme four.

[0084] low multiplier China High D1 10.5 4.244 1.136 D2 0.19 0.487 1.171 D3 1.092 0.796 0.111 f’ 0.574 0.572 0.560 F number 5.05 5.03 4.95 Magnification -0.051 -0.115 -0.3

[0085] Table 9 Claim values ​​in each embodiment

[0086]

[0087] Working principle:

[0088] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A medical magnifying endoscope optical system, characterized in that, The endoscope system includes a first mirror group (1), a second mirror group (2), a third mirror group (3), a fourth mirror group (4), a filter (5), and a CMOS chip (6) arranged sequentially from the object surface (7). The object surface (7) and the CMOS chip (6) are in a conjugate relationship. The first mirror group (1) is a negative refractive index mirror group, while the second mirror group (2), the third mirror group (3), and the fourth mirror group (4) are all positive refractive index mirror groups. A system aperture (8) is provided between the first mirror group (1) and the second mirror group (2). The third mirror group (3) is used to move along the optical axis of the endoscope system to zoom and switch between low-magnification and high-magnification states. A first concave lens (11) is provided on the side of the first mirror group (1) facing the object surface (7). The ratio of the focal length of the first concave lens (11) to the focal length of the low-magnification system of the endoscope satisfies the following relationship: In the formula, The focal length of the first concave lens (11) is... The focal length for low-magnification endoscope systems.

2. The optical system for a medical magnifying endoscope according to claim 1, characterized in that, The ratio of the focal length of the first lens group (1) to the focal length of the first concave lens (11) satisfies the following relationship: In the formula, The focal length of the first lens group (1) is given.

3. The optical system for a medical magnifying endoscope according to claim 1, characterized in that, The ratio of the focal length of the second lens group (2) to the focal length of the low-magnification endoscope system satisfies the following relationship: 3.1 3.5, where, The focal length of the second lens group (2) is given.

4. The optical system for a medical magnifying endoscope according to claim 1, characterized in that, The combined focal length of the third lens group (3) and the fourth lens group (4) in the low magnification state of the endoscope, compared with the focal length of the low magnification system of the endoscope, satisfies the following relationship: In the formula, The combined focal length of the third lens group (3) and the fourth lens group (4).

5. The optical system for a medical magnifying endoscope according to claim 1, characterized in that, The ratio of the center distances of the system aperture (8) to the center distances of the first lens group (1) and the second lens group (2) satisfies the following relationship: In the formula, The distance from the system aperture (8) to the second mirror group (2) is... The distance between the first mirror group (1) and the second mirror group (2) is denoted as .

6. The optical system for a medical magnifying endoscope according to claim 1, characterized in that, During the zooming process of the endoscope system, the distance between the second mirror group (2) and the fourth mirror group (4) remains unchanged, and the movement direction of the third mirror group (3) along the optical axis of the endoscope system is consistent with the movement direction of the object surface (7).

7. The optical system for a medical magnifying endoscope according to claim 2, characterized in that, The ratio of the radius of curvature of the first concave lens (11) near the image plane to the focal length of the first lens group (1) satisfies the following relationship: In the formula, The radius of curvature of the first concave lens (11) is the side closest to the image plane.

8. The optical system for a medical magnifying endoscope according to claim 1, characterized in that, The first concave lens (11) is made of quartz glass.

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