A rear-group focusing large-field-of-view long-back-focus zoom system and an optical zoom lens

Abstract

The present invention discloses a rear-group focusing large-field-of-view long back-focus zoom system and an optical zoom lens, comprising a first lens group, a second lens group, a third lens group, an aperture device, a fourth lens group and a full target surface; the first lens group, the third lens group and the fourth lens group all have positive focal power, the second lens group has negative focal power, and the fourth lens group includes a focusing group with positive focal power; the second lens group and the third lens group are moved to change the interval between the lens groups to perform magnification change; the focus group is moved to correct the image plane position change under different object distance conditions. The present invention changes magnification by changing the interval between the lens groups; the image plane position change is corrected by moving the focus group; the focus group uses a single lens to achieve the focusing of the zoom system, reduces the focusing structural parts and the driving structure, greatly reduces the cost of the system and has strong practicality; the miniaturization, large-field-of-view, long back-focus magnification change process is achieved by moving two variable focal length lens groups in a certain manner.

Description

Technical Field

[0001] The invention relates to the technical field of monitoring devices, in particular to a rear-group focusing large-field-of-view long-back-focus zoom system and an optical zoom lens. Background Art

[0002] Imaging systems are widely used in both military and civilian fields. In some imaging systems, such as reconnaissance systems and ground remote sensing systems, in order to complete target capture and tracking, it is necessary to integrate a zoom system into the system to obtain clear images of targets at different object distances and different fields of view; the zoom system will not lose the tracking target during the zooming process, and can select the appropriate size of the field of view according to the target characteristics, greatly improving the tracking and monitoring efficiency.

[0003] The traditional zoom system is composed of only one or more fixed focal length lens groups and one or more variable focal length lens groups. The focal length of the system is changed by moving the variable focal length lens group in the lens barrel using mechanical devices such as space cams or fixing the variable focal length lens group in a retractable and movable lens barrel. Both methods change the focal length of the system by changing the optical structure in the system. The focusing structure in the traditional zoom system is generally achieved by moving the front fixed focal length lens group. The front fixed focal length lens group has a relatively large diameter and weight, and the overall length will change accordingly. There will be certain problems in application, and the field of view and back intercept will be limited.

[0004] With the development of the monitoring market, the universality of the detector's large target area and F-mount interface requires large field of view, long back focus and other parameters. Therefore, there is an urgent need for a rear-group focusing zoom system with a large field of view and long back focus. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a zoom system with a large field of view, a long back focus and a rear group focusing.

[0006] In order to solve the above technical problems, the present invention is implemented by the following technical solutions: A rear-group focusing large field of view long back focus zoom system, comprising a first lens group, a second lens group, a third lens group, an aperture device, a fourth lens group and a full target surface which are arranged in sequence from left to right and are in the same optical axis direction; wherein,

[0007] The first lens group, the third lens group and the fourth lens group all have positive optical power, the second lens group has negative optical power, and the fourth lens group includes a focusing group with positive optical power;

[0008] The first lens group and the fourth lens group are fixed fixed focal length lens groups, and the second lens group and the third lens group are variable focal length lens groups that can move along the optical axis; the interval between the lens groups is changed by moving the second lens group and the third lens group so as to change the magnification between the wide-angle end and the telephoto end of the zoom system; and the change in image plane position is corrected under different object distances by moving the focusing group.

[0009] Furthermore, the first lens group includes a first cemented lens and a first single lens corresponding to each other, wherein the first lens of the first cemented lens is a concave lens made of ZF4_CHINA material, the second lens is a convex lens made of HQK3_CDGM material, and the first single lens is a convex lens made of ZK series material.

[0010] Furthermore, the second lens group includes a second single lens and a second cemented lens corresponding to each other, wherein the second single lens is a concave lens made of HZK21_CDGM material, the first lens of the second cemented lens is a concave lens made of HZK3_CDGM material, and the second lens is a convex-concave lens made of high refractive index and low dispersion material.

[0011] Furthermore, the third lens group includes a third single lens and a third cemented lens corresponding to each other, wherein the third single lens is a convex lens made of LAF series materials, the first lens of the third cemented lens is a convex lens made of HZBAF3_CDGM material, and the second lens is a concave lens made of ZF4_CHINA material.

[0012] Furthermore, the fourth lens group also includes a fourth single lens, a fifth single lens and a fourth cemented lens corresponding to each other, wherein the fourth single lens is a concave lens made of LAK series materials, the focusing group is a concave-convex lens made of HQK3L_CDGM materials, the fifth single lens is a convex lens made of HQK3L_CDGM materials, and the first lens of the fourth cemented lens is a convex lens made of HQK3L_CDGM materials, and the second lens is a concave lens made of HZF6_CDGM materials.

[0013] Furthermore, the focusing group is a single lens made of HQK3L material with a focal length of 80mm to 85mm, a side close to the fourth single lens is 8.2mm to 10.2mm away from the fourth single lens, and a side close to the fifth single lens is 11.2mm to 13.2mm away from the fifth single lens.

[0014] Furthermore, assuming that the focal length of the zoom system is f and the entrance pupil diameter is D, wherein the value range of f is 20 mm to 150 mm, and D / f=1 / 3.2 to 1 / 2.6.

[0015] Furthermore, the length of the entire target surface is 20 mm to 25 mm, and the distance from the entire target surface to the fourth cemented mirror, that is, the back intercept is ≥46.5 mm.

[0016] Furthermore, the full field angle of the wide-angle end is ≥60°, and the zoom ratio is ≥7.5.

[0017] The present invention also provides an optical zoom lens, comprising the above-mentioned rear-group focusing large field of view long back focus zoom system, and the light beam reflected by the target object is imaged onto the entire target surface after passing through the rear-group focusing large field of view long back focus zoom system.

[0018] Compared with the prior art, the present invention is beneficial in that:

[0019] The zoom system and optical zoom lens provided by the present invention can change the magnification between the wide-angle end and the telephoto end by changing the interval between each lens group; the change of the image plane position is corrected under different object distances by moving the focusing group; the focusing group can realize the focusing of the zoom system by using a single lens, reducing the focusing structural parts and the driving structure, greatly reducing the cost of the system and having strong practicality; the lenses in the zoom system are made of conventional glass materials, and when the number of lenses is small, the two variable focal length lens groups are moved in a certain manner to realize the miniaturization, large field of view, and long back focus magnification process, while improving the imaging performance, having the advantages of simple structure, easy assembly, high transmittance, etc., being suitable for mass production, and having broad market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0021] The present invention is further described below in conjunction with the accompanying drawings:

[0022] Figure 1 is an overall structural diagram of the zoom system of the present invention;

[0023] Figure 2 yes Figure 1 Detailed structure diagram;

[0024] Figure 3 is a surface distribution diagram of each lens in the zoom system;

[0025] Figure 4 is an optical system diagram of the zoom system when the focal length f=20 mm;

[0026] Figure 5 is an optical system diagram of the zoom system when the focal length f=70 mm;

[0027] Figure 6 is an optical system diagram of the zoom system when the focal length f=150 mm;

[0028] Figure 7 is a cam curve diagram of the zoom system;

[0029] Figure 8 is an optical transfer function curve diagram of the zoom system when the focal length f=20 mm;

[0030] Fig. 9 is an optical transfer function curve diagram of the zoom system when the focal length f=70 mm;

[0031] Fig.10 is an optical transfer function curve diagram of the zoom system when the focal length f=150 mm;

[0032] Fig.11 is a field curvature and distortion curve diagram of the zoom system when the focal length f=20 mm;

[0033] Fig.12 is a field curvature and distortion curve diagram of the zoom system when the focal length is f=70 mm;

[0034] Fig.13 is a field curvature and distortion curve diagram of the zoom system when the focal length f=150 mm;

[0035] 1. The first lens group; 2. The second lens group; 3. The third lens group; 4. The fourth lens group; 5. The entire target surface; 6. The aperture device; 11. The first cemented lens; 12. The first single lens; 21. The second single lens; 22. The second cemented lens; 31. The third single lens; 32. The third cemented lens; 41. The fourth single lens; 42. The focusing group; 43. The fifth single lens; 44. The fourth cemented lens. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0038] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0039] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0041] Embodiment 1

[0042] like Figures 1 to 3A rear-group focusing large-field-of-view long back-focus zoom system shown in the figure comprises a first lens group 1, a second lens group 2, a third lens group 3, an aperture device 6, a fourth lens group 4 and a full target surface 5 which are arranged in sequence from left to right and are in the same optical axis direction; wherein the first lens group 1, the third lens group 3 and the fourth lens group 4 all have positive optical power, the second lens group 2 has negative optical power, the fourth lens group 4 comprises a focusing group 42 with positive optical power, the first lens group 1 and the fourth lens group 4 are fixed fixed focal length lens groups, the second lens group 2 and the third lens group 3 are lenses which can be moved along the optical axis A variable focal length lens group that can move in the direction of the focal length is installed on a mechanical device such as a space cam in the lens barrel to realize the movement of the second lens group 2 and the third lens group 3 to further achieve the purpose of zooming; the interval between the lens groups is changed by moving the second lens group 2 and the third lens group 3 so as to change the magnification between the wide-angle end and the telephoto end of the zoom system, and the full field angle of the wide-angle end is required to be ≥60°, and the magnification ratio is ≥7.5; the focusing group 42 is fixed on the moving structure, and the change of the image plane position is corrected under different object distances by moving the focusing group 42. The moving structure is as simple as possible, and a margin is left for the moving space.

[0043] This embodiment changes the magnification between the wide-angle end and the telephoto end by changing the intervals between the lens groups; the image position change is corrected under different object distances by moving the focusing group 42; the focusing group 42 uses a single lens to achieve the focusing of the zoom system, reducing the focusing structure and the driving structure, greatly reducing the cost of this embodiment and enhancing practicality.

[0044] In one embodiment, the first lens group 1 includes a first cemented lens 11 and a first single lens 12 corresponding to each other, wherein the first lens of the first cemented lens 11 is a concave lens made of ZF4_CHINA material, and the second lens is a convex lens made of HQK3_CDGM material, the rear surface of the first lens of the first cemented lens 11 and the front surface of the second lens are overlapped, and surfaces S1, S2 and S3 are formed at this time, and the first single lens 12 is a convex lens made of ZK series material, and has surfaces S4 and S5.

[0045] In one embodiment, the second lens group 2 includes a second single lens 21 and a second cemented lens 22 corresponding to each other, wherein the second single lens 21 is a concave lens made of HZK21_CDGM material and has surfaces S6 and S7, the first lens of the second cemented lens 22 is a concave lens made of HZK3_CDGM material, and the second lens is a convex-concave lens made of high refractive index and low dispersion material, the rear surface of the first lens of the second cemented lens 22 and the front surface of the second lens coincide, and surfaces S8, S9 and S10 are formed.

[0046] In one embodiment, the third lens group 3 includes a third single lens 31 and a third cemented lens 32 corresponding to each other, wherein the third single lens 31 is a convex lens made of LAF series material, and has surfaces S11 and S12, the first lens of the third cemented lens 32 is a convex lens made of HZBAF3_CDGM material, and the second lens is a concave lens made of ZF4_CHINA material, the rear surface of the first lens of the third cemented lens 32 and the front surface of the second lens are overlapped, at this time, surfaces S13, S14 and S15 are formed, and the aperture device 6 has a surface S16.

[0047] In one embodiment, the fourth lens group 4 also includes a fourth single lens 41, a fifth single lens 43 and a fourth cemented lens 44 corresponding to each other, wherein the fourth single lens 41 is a concave lens made of LAK series material, having surfaces S17 and S18, the focusing group 42 is a concave-convex lens made of HQK3L_CDGM material, having surfaces S19 and S20, the fifth single lens 43 is a convex lens made of HQK3L_CDGM material, having surfaces S21 and S22, the first lens of the fourth cemented lens 44 is a convex lens made of HQK3L_CDGM material, and the second lens is a concave lens made of HZF6_CDGM material, the rear surface of the first lens and the front surface of the second lens of the fourth cemented lens 44 overlap, and surfaces S23, S24 and S25 are formed at this time, and the full target surface 5 has a surface S26, also called an image surface.

[0048] In one embodiment, the focusing group 42 is a single lens made of HQK3L material with a focal length of 83 mm. The side close to the fourth single lens 41 is 9.2 mm away from the fourth single lens 41, and the side close to the fifth single lens 43 is 12.2 mm away from the fifth single lens 43. The single lens is made of conventional glass material, which reduces focusing structures and driving structures, greatly reducing the cost of the present invention.

[0049] In one of the embodiments, the focal length of the zoom system is f and the entrance pupil diameter is D, wherein the value range of f is 20 mm to 150 mm, and the relative aperture D / f=1 / 2.8, which belongs to the lens index and is a conventional experimental setting; the length of the full target surface 5 is 23 mm, and the distance from the full target surface 5 to the fourth cemented mirror 44, i.e., the back intercept, is 46.6 mm; when f=20 mm, the full field of view at the wide-angle end is 60°, and when f=150 mm, the full field of view at the wide-angle end is 8.8°.

[0050] This embodiment uses only 14 lenses, including 4 cemented lenses: the first cemented lens 11, the second cemented lens 22, the third cemented lens 32, and the fourth cemented lens 44, and 6 single lenses: the first single lens 12, the second single lens 21, the third single lens 31, the fourth single lens 41, the focusing group 42, and the fifth single lens 43, which has the characteristics of simple structure, easy assembly, and high transmittance. This embodiment uses conventional glass materials, and with a small number of lenses, realizes miniaturization, a large field of view, and a long back-focus magnification process by moving two variable focal length lens groups in a certain manner, while improving the imaging performance. It has the advantages of simple structure, easy assembly, and high transmittance, and is suitable for mass production and has broad market prospects.

[0051] The parameters of each lens in the zoom system are shown in Table 1:

[0052]

[0053]

[0054] The radius of curvature refers to the radius of curvature of each surface, and the spacing refers to the distance between two adjacent surfaces. For example, the spacing of the surface S1 is the distance between the surface S1 and the surface S2.

[0055] During the zoom process, the three changing positions are shown in Table 2:

[0056]

[0057] When the focal length f = 20mm, the optical system diagram is as follows Figure 4 As shown; when the focal length f = 70mm, the optical system diagram is as follows Figure 5 As shown; when the focal length f = 150mm, the optical system diagram is as follows Figure 6 shown.

[0058] like Figure 7 The cam curve diagram of this embodiment is shown, wherein the horizontal axis is the cam rotation angle, the vertical axis is the moving distance or focal length, and the three curves are respectively the focal length of the zoom optical system, the moving distance of the zoom group, and the moving distance of the compensation group.

[0059] When the focal length f = 20mm, the optical transfer function curve is as follows Figure 8 As shown; when the focal length f = 70mm, the optical transfer function curve is as follows Fig. 9 As shown; when the focal length f = 150mm, the optical transfer function curve is as follows Fig.10 As shown, Figures 8 to 10 The horizontal axis is the number of line pairs per millimeter, and the vertical axis is the contrast value.

[0060] When the focal length f = 20mm, the field curvature and distortion curves are as follows: Fig.11As shown; when the focal length f = 70mm, the field curvature and distortion curves are as follows Fig.12 As shown; when the focal length f = 150mm, the field curvature and distortion curves are as follows Fig.13 shown.

[0061] The main optical indicators of this embodiment are: focal length of 20 mm to 150 mm, field of view of 60° to 8.8°, and F number of 2.8.

[0062] The specific use process of the rear group focusing large field of view and long back focus distance zoom system of the present invention is:

[0063] The light beam incident to the first lens group 1 is converged by the first lens group 1, refracted by the second lens group 2, refracted by the third lens group 3, and imaged on the full target surface 5 through the fourth lens group 4 and the aperture device 6. The relative movement of the variable magnification group of the second lens group 2 and the compensation group of the third lens group 3 realizes the magnification and reduction of the optical system to form an image on the full target surface 5, and the movement of the focusing group 42 in the fourth lens group 4 realizes the optical system to form a clear image at different distances from the object.

[0064] Embodiment 2

[0065] like Figures 1 to 3 Another rear-group focusing large-field-of-view long-back-focus zoom system shown in the figure comprises a first lens group 1, a second lens group 2, a third lens group 3, an aperture device 6, a fourth lens group 4 and a full target surface 5 which are arranged in sequence from left to right and are located in the same optical axis direction; wherein, the first lens group 1, the third lens group 3 and the fourth lens group 4 all have positive optical focal length, the second lens group 2 has negative optical focal length, the fourth lens group 4 comprises a focusing group 42 with positive optical focal length, the first lens group 1 and the fourth lens group 4 are fixed fixed focal length lens groups, the second lens group 2 and the third lens group 3 are variable focal length lens groups which can be moved along the optical axis direction, and the movement of the second lens group 2 and the third lens group 3 is realized on a mechanical device such as a space cam installed in the lens barrel to further achieve the purpose of zooming; the interval between the lens groups is changed by moving the second lens group 2 and the third lens group 3 so as to change the magnification between the wide-angle end and the telephoto end of the zoom system.

[0066] In one embodiment, the focal length of the focusing group 42 is 80 mm, the distance between the side close to the fourth single lens 41 and the fourth single lens 41 is 8.2 mm, and the distance between the side close to the fifth single lens 43 and the fifth single lens 43 is 11.2 mm.

[0067] In one of the embodiments, the focal length of the zoom system is f and the entrance pupil diameter is D, wherein the value range of f is 20 mm to 70 mm, and D / f=1 / 3.2, which is a lens index and a conventional experimental setting.

[0068] In one embodiment, the length of the full target surface 5 is 20 mm, and the distance from the full target surface 5 to the fourth cemented mirror 44, i.e., the back focus is ≥46.5 mm. In this embodiment, the flange distance of the F mount is 46.5 mm, and the back focus needs to be greater than the flange distance of the F mount. The longer the flange distance of the F mount, the greater the design difficulty.

[0069] The other parts and the use process are the same as those in the first embodiment and will not be described in detail here.

[0070] Embodiment 3

[0071] like Figures 1 to 3 Another rear-group focusing large-field-of-view long back-focus zoom system shown in the figure comprises a first lens group 1, a second lens group 2, a third lens group 3, an aperture device 6, a fourth lens group 4 and a full target surface 5 which are arranged in sequence from left to right and are located in the same optical axis direction; wherein, the first lens group 1, the third lens group 3 and the fourth lens group 4 all have positive optical focal length, the second lens group 2 has negative optical focal length, the fourth lens group 4 comprises a focusing group 42 with positive optical focal length, the first lens group 1 and the fourth lens group 4 are fixed fixed focal length lens groups, the second lens group 2 and the third lens group 3 are variable focal length lens groups which can be moved along the optical axis direction, and the movement of the second lens group 2 and the third lens group 3 is realized on a mechanical device such as a space cam installed in the lens barrel to further achieve the purpose of zooming; the interval between the lens groups is changed by moving the second lens group 2 and the third lens group 3 so as to change the magnification between the wide-angle end and the telephoto end of the zoom system.

[0072] In one embodiment, the focal length of the focusing group 42 is 85 mm, the distance between the side close to the fourth single lens 41 and the fourth single lens 41 is 10.2 mm, and the distance between the side close to the fifth single lens 43 and the fifth single lens 43 is 13.2 mm.

[0073] In one of the embodiments, the focal length of the zoom system is f and the entrance pupil diameter is D, wherein the value range of f is 70 mm to 150 mm, and D / f=1 / 2.6, which is a lens index and a conventional experimental setting.

[0074] In one embodiment, the length of the full target surface 5 is 25 mm, and the distance from the full target surface 5 to the fourth cemented mirror 44, that is, the back intercept is ≥46.5 mm.

[0075] The other parts and the use process are the same as those in the first embodiment and will not be described in detail here.

[0076] Embodiment 4

[0077] The present invention also provides an optical zoom lens, comprising the rear-group focusing large field of view long back focus zoom system described in any one of embodiments 1 to 3, wherein the light beam reflected by the target object is imaged onto the full target surface 5 after passing through the rear-group focusing large field of view long back focus zoom system.

[0078] The magnification is changed between the wide-angle end and the telephoto end by changing the interval between the lens groups; the change in the image position is corrected under different object distances by moving the focusing group 42; the focusing group 42 uses a single lens to achieve the focusing of the zoom system, reducing the focusing structure and the driving structure, greatly reducing the cost of the system and having strong practicality; the lenses in the zoom system are made of conventional glass materials, and with a small number of lenses, a miniaturized, large field of view, and long back-focus magnification process is achieved by moving two variable focal length lens groups in a certain manner, while improving the imaging performance. It has the advantages of simple structure, easy assembly, high transmittance, etc., is suitable for mass production, and has broad market prospects.

[0079] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A rear-group focusing zoom system with a large field of view and a long back focus distance, characterized in that: The invention comprises only four lens groups, namely, a first lens group (1), a second lens group (2), a third lens group (3), an aperture device (6), a fourth lens group (4) and a full target surface (5) which are arranged in sequence from left to right and are located in the same optical axis direction; wherein, The first lens group (1), the third lens group (3) and the fourth lens group (4) all have positive optical power, the second lens group (2) has negative optical power, and the fourth lens group (4) includes a focusing group (42) with positive optical power; The first lens group (1) and the fourth lens group (4) are fixed fixed focal length lens groups, and the second lens group (2) and the third lens group (3) are variable focal length lens groups that can move along the optical axis direction; by moving the second lens group (2) and the third lens group (3), the interval between the lens groups is changed so as to change the magnification between the wide-angle end and the telephoto end of the zoom system; by moving the focus group (42), the change of the image plane position is corrected under different object distance conditions; Assume that the focal length of the zoom system is f and the entrance pupil diameter is D, wherein the value range of f is 20 mm to 150 mm, and D / f=1 / 3.2 to 1 / 2.6; The full field angle of the wide-angle end is ≥60°, and the zoom ratio is ≥7.

5.

2. The rear-group focusing zoom system with large field of view and long back focus according to claim 1, characterized in that: The first lens group (1) comprises a first cemented lens (11) and a first single lens (12) corresponding to each other, wherein the first lens of the first cemented lens (11) is a concave lens made of ZF4_CHINA material, the second lens is a convex lens made of HQK3_CDGM material, and the first single lens (12) is a convex lens made of ZK series material.

3. The rear-group focusing zoom system with large field of view and long back focus distance according to claim 1, characterized in that: The second lens group (2) comprises a second single lens (21) and a second cemented lens (22) corresponding to each other, wherein the second single lens (21) is a concave lens made of HZK21_CDGM material, and the first lens of the second cemented lens (22) is a concave lens made of HZK3_CDGM material, and the second lens is a convex-concave lens made of a high refractive index and low dispersion material.

4. The rear-group focusing zoom system with large field of view and long back focus distance according to claim 1, characterized in that: The third lens group (3) comprises a third single lens (31) and a third cemented lens (32) corresponding to each other, wherein the third single lens (31) is a convex lens made of LAF series materials, and the first lens of the third cemented lens (32) is a convex lens made of HZBAF3_CDGM material, and the second lens is a concave lens made of ZF4_CHINA material.

5. The rear-group focusing zoom system with large field of view and long back focus distance according to claim 1, characterized in that: The fourth lens group (4) further comprises a fourth single lens (41), a fifth single lens (43) and a fourth cemented lens (44) which correspond to each other, wherein the fourth single lens (41) is a concave lens made of LAK series material, the focusing group (42) is a concave-convex lens made of HQK3L_CDGM material, the fifth single lens (43) is a convex lens made of HQK3L_CDGM material, and the first lens of the fourth cemented lens (44) is a convex lens made of HQK3L_CDGM material, and the second lens is a concave lens made of HZF6_CDGM material.

6. The rear-group focusing zoom system with large field of view and long back focus distance according to claim 5, characterized in that: The focusing group (42) is a single lens made of HQK3L material, with a focal length of 80 mm to 85 mm, a side close to the fourth single lens (41) is 8.2 mm to 10.2 mm away from the fourth single lens (41), and a side close to the fifth single lens (43) is 11.2 mm to 13.2 mm away from the fifth single lens (43).

7. The rear-group focusing zoom system with large field of view and long back focus distance according to claim 6, characterized in that: The length of the full target surface (5) is 20 mm to 25 mm, and the distance from the full target surface (5) to the fourth cemented mirror (44), i.e., the back intercept is ≥46.5 mm.

8. An optical zoom lens, characterized in that: The invention comprises the rear-group focusing large field of view long back focus zoom system as claimed in any one of claims 1 to 7, wherein the light beam reflected by the target object is imaged onto the full target surface (5) after passing through the rear-group focusing large field of view long back focus zoom system.

Images