A large field of view infrared lens

Abstract

This invention provides a wide field-of-view infrared lens, comprising a lens body, two front fixed groups disposed above the lens body, a fast-reflecting mirror group disposed within the lens body, and a relay group disposed to the right of the lens body; the relay group is horizontally positioned, the fast-reflecting mirror group is at an angle of 45° to the horizontal direction, the two front fixed groups are tilted at 20° relative to the vertical direction, and the angle between the two front fixed groups is 40°; this wide field-of-view infrared lens uses a 1280*1024@10μm mid-wave cooled detector, with a field of view ≥84.5°x54.2° and good imaging performance; the optical system has an F-number of 2.0, increasing the system's light transmission and improving sensitivity; distortion ≤1.0%; the lens is small in size and compact in structure, improving the lens assembly and adjustment accuracy; and it adopts an optical anechoic design to eliminate thermal and chromatic differences, achieving anechoicity within a temperature range of -40℃ to +70℃.

Description

Technical Field

[0001] This invention belongs to the field of infrared lens technology, specifically relating to a large field-of-view infrared lens. Background Technology

[0002] In recent years, infrared thermal imaging systems have been widely used in military and security fields, and related technologies have developed rapidly. Because mid-wave infrared thermal imagers have a high detection and recognition rate for characteristic targets, enabling all-weather real-time surveillance, the demand for their equipment in border defense, customs, airports, and other locations is constantly increasing.

[0003] Searching for and identifying characteristic targets requires a large field of view, long focal length, and large aperture. This is typically achieved by stitching together multiple thermal imagers or using a multi-field thermal imager with long focal length for identification and short focal length for search and detection. However, these two methods result in relatively large size and weight, which is not conducive to modular integration. This patent designs a large field of view infrared lens that quickly switches between the left and right optical paths using a fast-reflecting mirror assembly and uses a back-end processor for image stitching. This not only meets the requirements of a large field of view, long focal length, and large aperture but also reduces the structural size and weight. Summary of the Invention

[0004] The purpose of this invention is to design a large field-of-view infrared lens that employs a secondary imaging system to achieve 100% cold aperture matching, reduce system stray light, effectively reduce size and weight, design and control distortion, and improve the accuracy of outputting the position of the detected target.

[0005] To this end, the present invention provides a wide field-of-view infrared lens, comprising a lens body, two front fixed groups disposed above the lens body, a fast-reflecting mirror group disposed inside the lens body, and a relay group disposed to the right of the lens body; the relay group is horizontally disposed, the fast-reflecting mirror group is at an angle of 45° with the horizontal direction, the two front fixed groups are tilted at 20° with respect to the vertical direction, and the angle between the two front fixed groups is 40°.

[0006] Furthermore, the fast-reflecting mirror assembly uses a motor to rotate and drive the reflector to adjust its angle. The adjustment range of the fast-reflecting mirror assembly is -10° to 10°.

[0007] Furthermore, the front fixing group includes a first lens group, a second lens group, a third lens group, and a seventh retaining ring. The first lens group includes a first lens, a first lens frame, and a first retaining ring. The first lens is disposed within the first lens frame, and the first retaining ring is disposed above the first lens. The second lens group includes a second lens, a second lens frame, and a second retaining ring. The second lens is disposed within the second lens frame, and the second retaining ring is disposed above the second lens. The third lens group includes a third lens, a third lens frame, and a third retaining ring. The third lens is disposed within the third lens frame, and the third retaining ring is disposed above the third lens.

[0008] Furthermore, the relay group includes a fourth lens group, a fifth lens group, a sixth lens group, and an eighth retaining ring. The fourth lens group includes a fourth lens, a fourth lens frame, and a fourth retaining ring. The fourth lens is disposed within the fourth lens frame, and the fourth retaining ring is disposed above the fourth lens. The fifth lens group includes a fifth lens, a fifth lens frame, and a fifth retaining ring. The fifth lens is disposed within the fifth lens frame, and the fifth retaining ring is disposed above the fifth lens. The sixth lens group includes a sixth lens, a sixth lens frame, and a sixth retaining ring. The sixth lens is disposed within the sixth lens frame, and the sixth retaining ring is disposed above the sixth lens.

[0009] Furthermore, the right side of the relay group corresponds to the detector window, and a detector cold aperture is provided on the right side of the detector window.

[0010] This invention provides a wide field-of-view infrared lens using a 1280*1024@10μm mid-wave cooled detector with a field of view ≥84.5°x54.2°. It exhibits good imaging performance at the required 50 lp / mm. The optical system has an F-number of 2.0, increasing system light transmission and improving sensitivity. Distortion is ≤1.0%. The lens is small and compact. The lens design and assembly employ a centering process to improve lens assembly accuracy. An optical anechoic design eliminates thermal and chromatic aberrations, achieving anechoicity within a temperature range of -40℃ to +70℃.

[0011] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0012] Figure 1 A schematic diagram of the optical system implemented in this invention.

[0013] Figure 2 A schematic diagram of the structure of this invention.

[0014] Figure 3 A cross-sectional view of the structure of this invention.

[0015] Figure 4 A schematic diagram of the front fixing assembly structure of this invention.

[0016] Figure 5 A schematic diagram of the relay group structure implemented in this invention.

[0017] In the diagram: 1. Front fixed assembly; 1-1. First lens group; 1-2. Second lens group; 1-3. Third lens group; 1-4. First lens; 1-5. First retaining ring; 1-6. Second lens; 1-7. Second retaining ring; 1-8. Third lens; 1-9. Third retaining ring; 1-10. First lens frame; 1-11. Second lens frame; 1-12. Third lens frame; 2. Quick-reflecting mirror assembly; 2-1, 2-2. Reflecting mirror; 3. Relay assembly; 3-1. Fourth lens group 3-2, Fifth lens group; 3-3, Sixth lens group; 3-4, Fourth lens; 3-5, Fourth retaining ring; 3-6, Fifth lens; 3-7, Fifth retaining ring; 3-8, Sixth lens; 3-9, Sixth retaining ring; 3-10, Fourth lens frame; 3-11, Fifth lens frame; 3-12, Sixth lens frame; 4, Lens body; 5, Detector cold aperture; 6, Detector window; 7, Seventh retaining ring; 8, Eighth retaining ring; 9, First lens mount; 10, Second lens mount. Detailed Implementation

[0018] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the specific implementation methods, structural features and effects of the present invention are described in detail below with reference to the accompanying drawings and embodiments.

[0019] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] All features disclosed in this specification, or all steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps.

[0021] Any feature disclosed in this specification (including any appended claims, abstract, and drawings) may be replaced by other equivalent or similar features for a similar purpose, unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is merely one example of a series of equivalent or similar features.

[0022] Example 1

[0023] To design a wide field-of-view infrared lens, a secondary imaging system is adopted to achieve 100% cold aperture matching, reduce system stray light, effectively reduce size and weight, and design to control distortion, thereby improving the accuracy of outputting the position of the detected target.

[0024] This embodiment provides a method such as Figures 1-5The large field-of-view infrared lens shown is used in conjunction with a detector with a resolution of 1280*1024. The large field-of-view infrared lens includes a lens body 4, two front fixed groups 1 positioned above the lens body 4 (each with positive optical power), a fast-reflecting mirror group 2 positioned inside the lens body 4 (each with two high-frequency positioning adjustment functions), and a relay group 3 positioned to the right of the lens body 4 (also with positive optical power). The relay group 3 is horizontally positioned, the fast-reflecting mirror group 2 is at a 45° angle to the horizontal, the two front fixed groups 1 are tilted 20° relative to the vertical, and the angle between the two front fixed groups 1 is 40°. The intersection of the optical axes of the two front fixed groups 1 coincides with the center point of the reflectors 2-1 and 2-2 of the fast-reflecting mirror group 2, corresponding to two angular positions of the fast-reflecting mirror group 2, forming two optical paths that share a single relay group 3.

[0025] Furthermore, the fast-reflecting mirror assembly 2 adopts a GSM30 fast-reflecting mirror from Beijing Xunlai Optoelectronic Technology Co., Ltd. This assembly uses a motor to rotate and adjust the reflector's angle, with an adjustment range of -10° to 10°. The fast-reflecting mirror assembly 2 completes optical path folding and switching, reducing the length and volume of the optical system. The fast-reflecting mirror assembly 2, through motor rotation, drives the reflector to achieve high-frequency adjustment and positioning of two angles, primarily serving to fix the optical path before switching.

[0026] Furthermore, the front fixing group 1 includes a first lens group 1-1, a second lens group 1-2, a third lens group 1-3, and a seventh retaining ring 7. The first lens group 1-1, the second lens group 1-2, and the third lens group 1-3 are all disposed on the first lens mount 9 and fixed by the seventh retaining ring 7. The first lens group 1-1 includes a first lens 1-4, a first lens frame 1-10, and a first retaining ring 1-5. The first lens 1-4 is disposed within the first lens frame 1-10, and the first retaining ring 1-5 is disposed within the first lens mount 9. Above lens 1-4; the second lens group 1-2 includes a second lens 1-6, a second lens frame 1-11, and a second retaining ring 1-7, with the second lens 1-6 disposed within the second lens frame 1-11 and the second retaining ring 1-7 disposed above the second lens 1-6; the third lens group 1-3 includes a third lens 1-8, a third lens frame 1-12, and a third retaining ring 1-9, with the third lens 1-8 disposed within the third lens frame 1-12 and the third retaining ring 1-9 disposed above the third lens 1-8.

[0027] Furthermore, the relay group 3 includes a fourth lens group 3-1, a fifth lens group 3-2, a sixth lens group 3-3, and an eighth pressure ring 8. The fourth lens group 3-1, the fifth lens group 3-2, and the sixth lens group 3-3 are all mounted on the second lens mount 10. The fourth lens group 3-1 is fixed by an eighth retaining ring 8. It includes a fourth lens 3-4, a fourth lens frame 3-10, and a fourth retaining ring 3-5. The fourth lens 3-4 is disposed inside the fourth lens frame 3-10, and the fourth retaining ring 3-5 is disposed above the fourth lens 3-4. The fifth lens group 3-2 includes a fifth lens 3-6, a fifth lens frame 3-11, and a fifth retaining ring 3-7. The fifth lens 3-6 is disposed inside the fifth lens frame 3-11, and the fifth retaining ring 3-7 is disposed above the fifth lens 3-6. The sixth lens group 3-3 includes a sixth lens 3-8, a sixth lens frame 3-12, and a sixth retaining ring 3-9. The sixth lens 3-8 is disposed inside the sixth lens frame 3-12, and the sixth retaining ring 3-9 is disposed above the sixth lens 3-8.

[0028] Furthermore, the right side of the relay group 3 corresponds to the detector window 6, and a detector cold aperture 5 is provided on the right side of the detector window 6.

[0029] Furthermore, the first lens 1-4 is a meniscus germanium negative lens with its concave surface facing the object side;

[0030] Furthermore, the second lens 1-6 is a meniscus positive lens with its concave surface facing the object side, and the material is chalcogenide glass;

[0031] Furthermore, the third lens 1-8 is a biconvex silicon positive lens;

[0032] Furthermore, the fourth lens 3-4 is a meniscus positive lens with its convex surface facing the object side, and the material is chalcogenide glass;

[0033] Furthermore, the fifth lens 3-6 is a biconcave negative lens made of zinc sulfide;

[0034] Furthermore, the sixth lens 3-8 is a biconvex positive lens made of chalcogenide glass;

[0035] Furthermore, the fast-reflecting mirror group 2 is located between the third lens and the fourth lens, folding the optical path by 90°±20°;

[0036] Furthermore, in the working surfaces of the lens, the S1 surface of the first lens 1-4, the S4 surface of the second lens 1-6, the S5 surface of the third lens 1-8, the S8 surface of the fourth lens 2-4, the S10 surface of the fifth lens 3-6, and the S13 surface of the sixth lens 3-8 are aspherical surfaces, while the rest are spherical surfaces.

[0037] In the above lenses, the reflector is coated with a reflective film, and the remaining surfaces are coated with an anti-reflective film. Table 1 shows the optical structural parameters of the present invention.

[0038] Table 1 Optical Structure Parameters

[0039]

[0040] The aspherical surfaces mentioned in the lenses above are all even-order aspherical surfaces, and their expressions are as follows:

[0041] Where z is the distance vector from the vertex of the aspherical surface along the optical axis at a height of r, c represents the vertex curvature of the surface, which is equal to the reciprocal of the radius of curvature, c = 1 / r0, and k is the conic coefficient, k = 0. , , , , It represents the higher-order aspheric coefficient.

[0042] Table 2 shows the aspherical coefficients of surfaces S1, S4, S5, S8, S10, and S13:

[0043] Table 2 Aspherical Coefficients

[0044]

[0045] In summary, this wide field-of-view infrared lens, using a 1280*1024@10μm mid-wave cooled detector, has a field of view ≥84.5°x54.2° and exhibits good imaging performance at the required 50lp / mm. The optical system has an F-number of 2.0, increasing the system's light transmission and improving sensitivity. The distortion is ≤1.0%. The lens is small in size and compact in structure. The lens design and assembly employ a centering process to improve the lens's assembly accuracy. The use of an optical anechoic design eliminates thermal and chromatic differences, achieving anechoicity within a temperature range of -40℃ to +70℃.

[0046] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A wide field-of-view infrared lens, characterized in that: The system includes a lens body (4), two front fixed groups (1) disposed above the lens body (4), the front fixed groups (1) having positive optical power; a quick-reflecting mirror group (2) disposed inside the lens body (4), and a relay group (3) disposed to the right of the lens body (4), the relay group (3) also having positive optical power; the relay group (3) is horizontally disposed, the quick-reflecting mirror group (2) is at an angle of 45° to the horizontal direction, the two front fixed groups (1) are tilted at 20° relative to the vertical direction, and the angle between the two front fixed groups (1) is 40°; The fast-reflecting mirror assembly (2) uses a motor to rotate and drive the reflector to adjust the angle. The adjustment angle range of the fast-reflecting mirror assembly (2) is -10° to 10°. The front fixing group (1) includes a first lens group (1-1), a second lens group (1-2), a third lens group (1-3), and a seventh retaining ring (7). The first lens group (1-1) includes a first lens (1-4), a first lens frame (1-10), and a first retaining ring (1-5). The first lens (1-4) is disposed within the first lens frame (1-10), and the first retaining ring (1-5) is disposed above the first lens (1-4). The second lens group (1-2) includes a second lens (1-6). The third lens group (1-3) includes a second lens frame (1-11), a second retaining ring (1-7), a second lens (1-6) disposed within the second lens frame (1-11), and a second retaining ring (1-7) disposed above the second lens (1-6); the third lens group (1-3) includes a third lens (1-8), a third lens frame (1-12), and a third retaining ring (1-9), the third lens (1-8) disposed within the third lens frame (1-12), and the third retaining ring (1-9) disposed above the third lens (1-8); The relay group (3) includes a fourth lens group (3-1), a fifth lens group (3-2), a sixth lens group (3-3), and an eighth retaining ring (8). The fourth lens group (3-1) includes a fourth lens (3-4), a fourth lens frame (3-10), and a fourth retaining ring (3-5). The fourth lens (3-4) is disposed within the fourth lens frame (3-10), and the fourth retaining ring (3-5) is disposed above the fourth lens (3-4). The fifth lens group (3-2) includes a fifth lens (3-6). The fifth lens frame (3-11) and the fifth retaining ring (3-7) are provided. The fifth lens (3-6) is disposed within the fifth lens frame (3-11), and the fifth retaining ring (3-7) is disposed above the fifth lens (3-6). The sixth lens group (3-3) includes a sixth lens (3-8), a sixth lens frame (3-12), and a sixth retaining ring (3-9). The sixth lens (3-8) is disposed within the sixth lens frame (3-12), and the sixth retaining ring (3-9) is disposed above the sixth lens (3-8). The first lens (1-4) is a meniscus germanium negative lens with its concave surface facing the object side; The second lens (1-6) is a meniscus positive lens with its concave surface facing the object side, and the material is chalcogenide glass; The third lens (1-8) is a biconvex silicon positive lens; The fourth lens (3-4) is a meniscus positive lens with its convex surface facing the object side, and the material is chalcogenide glass; The fifth lens (3-6) is a biconcave negative lens made of zinc sulfide; The sixth lens (3-8) is a biconvex positive lens made of chalcogenide glass.

2. The wide field-of-view infrared lens as described in claim 1, characterized in that: The right side of the relay group (3) corresponds to the detector window (6), and a detector cold aperture (5) is provided on the right side of the detector window (6).

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