A wideband infrared optical system
By employing a combination of negative and positive optical power and an aspherical lens design in the infrared optical system, the focal length relationship was optimized, solving the problems of system aberration and chromatic aberration correction, and realizing panoramic imaging and low-cost infrared optical system applications.
Patent Information
- Application Number
- CN202521538116.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-23
- Publication Date
- 2026-07-03
- Estimated Expiration
- 2035-07-23
AI Technical Summary
Existing broadband infrared optical systems face challenges in correcting system aberrations and chromatic aberrations, resulting in complex designs and high costs.
The design employs a front optical structure with negative optical power and a rear optical structure with positive optical power. It combines aspherical and spherical lenses, optimizes the focal length relationship to achieve system correction, and selects specific lens materials and radii of curvature within a specific range. The overall optimization is performed using optical design software.
It realizes a wide-band infrared optical system with panoramic imaging, compact structure, easy color difference correction, and low manufacturing cost, and is suitable for infrared monitoring, early warning, key area security and situational awareness.
Smart Images
Figure CN224457126U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to optical systems, and more particularly to a wideband infrared optical system. Background Technology
[0002] Infrared thermal imaging systems offer numerous advantages, including good concealment, strong resistance to electronic interference, high precision, and excellent low-altitude detection performance. They also possess strong penetration capabilities, making them particularly suitable for target detection at night and under complex weather conditions. Multi-band detection, a key research area at present, can simultaneously acquire and process information from different bands, offering advantages such as compact structure and large information capacity. However, wide-band optical systems present design challenges, including difficulties in correcting system aberrations and chromatic aberration. Utility Model Content
[0003] To address the shortcomings of the aforementioned technologies, this invention provides a wideband infrared optical system.
[0004] To solve the above technical problems, the technical solution adopted by this utility model is: a wide-band infrared optical system, including a front optical structure and a rear optical structure;
[0005] The optical power of the front group optical structure is negative, and it includes a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4.
[0006] The optical power of the rear optical structure is positive, and it includes the fifth lens L5 and the sixth lens L6;
[0007] The surfaces S4 of the second lens L2, S5 of the third lens L3, and S11 of the sixth lens L6 are all aspherical.
[0008] Preferably, the surfaces S1, S2, S3, S4, S5, S6, S7, S8, and S12 of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L4, the fifth lens L5, and the sixth lens L6 are all spherical.
[0009] Preferably, the focal length of the entire optical system is set to f, and the focal length of the front optical group is f. 1-4 The focal length of the rear optical structure is f. 5-6 The focal length values satisfy the following:
[0010] 10 < |f1-4| / f < 11;
[0011] 0.5 < |f5-6| / f < 0.7.
[0012] Preferably, the focal length of the first lens L1 is set as f1, the focal length of the second lens L2 is f2, the focal length of the third lens L3 is f3, the focal length of the fourth lens L4 is f4, the focal length of the fifth lens L5 is f5, and the focal length of the sixth lens L6 is f6. Then the value ranges of each focal length are as follows:
[0013] 0.7 < f1 / |f2| < 0.8,
[0014] 15.5 < |f1 - 4| / f5 - 6 < 15.6,
[0015] 0.5 < f1 / f < 0.6,
[0016] 0.8 < |f2| / f < 0.9,
[0017] 1.4 < |f3| / f < 1.5,
[0018] 2.6 < |f4| / f < 2.7,
[0019] 28 < f5 / f < 29,
[0020] 1.7 < |f6| / f < 1.8.
[0021] Preferably, the radius of curvature of the surface S1 of the first lens L1 is: 40 mm < r < 50 mm, and the radius of curvature of the surface S2 is infinite.
[0022] Preferably, the radius of curvature of the surface S3 of the second lens L2 is: -140 mm < r < -130 mm, and the radius of curvature of the surface S4 is: 130 mm < r < 140 mm.
[0023] Preferably, the radius of curvature of the surface S5 of the third lens L3 is: -70 mm < r < -60 mm, and the radius of curvature of the surface S6 is: -150 mm < r < -140 mm.
[0024] Preferably, the radius of curvature of the surface S7 of the fourth lens L4 is: -120 mm < r < -110 mm, and the radius of curvature of the surface S8 is: 110 mm < r < 120 mm
[0025] Preferably, the radius of curvature of the surface S9 of the fifth lens L5 is: 60 mm < r < 70 mm, and the radius of curvature of the surface S10 is: -70 mm < r < -60 mm.
[0026] Preferably, the radius of curvature of the surface S11 of the fifth lens L5 is: 20 mm < r < 30 mm, and the radius of curvature of the surface S12 is: 10 mm < r < 20 mm.
[0027] This utility model discloses a wideband infrared optical system that can be applied to infrared monitoring, early warning, key area security, situational awareness and other fields. It has the technical advantages of panoramic imaging, compact structure, easy color difference correction and low manufacturing cost. Attached Figure Description
[0028] Figure 1 This is the initial structural diagram of the novel optical system.
[0029] Figure 2 This is a system diagram of the novel optical system.
[0030] Figure 3 This is the optical path diagram of the novel optical system.
[0031] Figure 4 The diagram shows the modulation transfer function (MTF) curve of this novel optical system.
[0032] Figure 5 This is a field distortion diagram of the novel optical system.
[0033] In the diagram: L1, first lens; L2, second lens; L3, third lens; L4, fourth lens; L5, fifth lens; L6, sixth lens. Detailed Implementation
[0034] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.
[0035] This novel design incorporates a wide-band infrared optical system based on a 1.0–9.0 μm cooled infrared detector with an array size of 640×512, suitable for applications such as infrared surveillance, early warning, key area security, and situational awareness.
[0036] First, the structure of the initial optical system is as follows: Figure 1 As shown, the optical system adopts a telephoto structure, which is divided into two groups in the overall structure. The first group has a negative optical power and the second group has a positive optical power. The optical power of the rear group is allocated according to the back intercept requirement. The front group is designed as a Galilean telescope structure, consisting of a positive lens and a negative lens structure.
[0037] Its infrared cooled detector's cold aperture is inside the Dewar. In order to achieve 100% cold aperture efficiency, the system needs to use the cooled detector's cold aperture as the system's aperture stop.
[0038] The system was optimized using optical design software. The optical design input parameters are shown in Table 1, and the design results are as follows. Figure 2 As shown, Figure 2 The corresponding optical system's system optical path diagram is as follows: Figure 3 As shown, Figure 2 The parameters of the corresponding optical system are shown in Table 2.
[0039] Table 1 Optical Design Input Parameters
[0040]
[0041] For example Figure 2 As shown, the novel wideband infrared optical system comprises six lenses, and the six transmission lens groups are the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, and the sixth lens L6.
[0042] Among them, the first lens L1 is made of zinc selenide, the second lens L2, the third lens L3, and the sixth lens L6 are made of IRG203, the fourth lens L4 is made of calcium fluoride (CAF2), and the fifth lens L5 is made of multispectral zinc sulfide (ZNS_BROAD).
[0043] Furthermore, Figure 2 In the diagram, W1 and W2 are detector windows, and W2 is the aperture stop of the optical system. FPA is the focal plane array. S1-S12 are the surfaces of each lens in the solar optical system, as shown in Table 2. The surface S4 of the second lens L2, the surface S5 of the third lens L3, and the surface S11 of the sixth lens L6 are aspherical, while the other surfaces are spherical.
[0044] Table 2 Optical System Data
[0045]
[0046] For aspherical surfaces, their surface shape must satisfy the following formula:
[0047] ,
[0048] In the formula, z represents the sag, which is the distance from a point on the surface along the optical axis (z-axis) to the vertex (origin); r represents the radial distance, which is the perpendicular distance from a point on the surface to the optical axis (z-axis); c represents the curvature of the lens surface, defined as the reciprocal of the spherical radius R; k is the conic coefficient; A2, A4, A6, A8, A 10 The coefficients of higher-order correction terms for aspherical surfaces are used to optimize the surface shape.
[0049] The coefficients of the higher-order correction terms for aspherical S4, S5, and S11 were finally determined, as shown in Table 3:
[0050] Table 3 Aspherical coefficients
[0051]
[0052] Furthermore, the focal length of the entire optical system is set to f, and the front group structure includes a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4, with a corresponding focal length of f. 1-4 The rear group structure includes a fifth lens L5 and a sixth lens L6, with a corresponding focal length of f. 5-6 Then the focal lengths of the front and rear groups satisfy the following:
[0053] 10 < |f1-4| / f < 11;
[0054] 0.5 < |f5-6| / f < 0.7.
[0055] Where L1 has a focal length of f1, L2 has a focal length of f2, L3 has a focal length of f3, L4 has a focal length of f4, L5 has a focal length of f5, and L6 has a focal length of f6, the ranges of each focal length are as follows:
[0056] 0.7 <f1 / |f2|<0.8,
[0057] 15.5 < |f1-4| / f5-6 < 15.6,
[0058] 0.5 <f1 / f<0.6,
[0059] 0.8 < |f²| / f < 0.9,
[0060] 1.4 < |f3| / f < 1.5,
[0061] 2.6 < |f4| / f < 2.7,
[0062] 28 <f5 / f<29,
[0063] 1.7 < |f6| / f < 1.8.
[0064] Furthermore, the imaging of the optical system is evaluated, and the MTF (Modulation Transfer Function) curves for different fields of view are shown below. Figure 4 As shown in the figure, TS represents the diffraction limit of the system, TS0.0000 represents the MTF of the central field of view, and TS6.1500 represents the edge field of view. The horizontal axis represents the number of line pairs per mm, and the vertical axis represents the normalized OTF coefficient. The central field of view transfer function in the figure is ≥0.55@30lp / mm, which is close to the diffraction limit, and the edge field of view transfer function is ≥0.45@30lp / mm.
[0065] The distortion of the system is caused by Distortion map representation, Distortion is caused by the height of the principal ray on the image plane in different fields of view. and Like Gao The difference is on get. Figure 5 After the system design is completed Distortion image, across the entire field of view Distortion <1%.
[0066] Therefore, the wideband infrared optical system disclosed in this utility model is designed based on a 640×512 cooled infrared detector array. It is applicable to cooled focal plane arrays with array sizes of 640×512, 1280×1024, and 2048×2048, a pixel size of 15μm, and a working wavelength of 1.0μm to 9μm. This meets the needs of its application in infrared monitoring, early warning, key area security, situational awareness, and other fields. It has technical advantages such as panoramic imaging, easy color difference correction, compact structure, and low manufacturing cost.
[0067] The above embodiments are not intended to limit the present utility model, nor is the present utility model limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the technical solution of the present utility model are also within the protection scope of the present utility model.
Claims
1. A wideband infrared optical system characterized by: It includes a front group optical structure and a rear group optical structure; The optical power of the front group optical structure is negative and includes a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4; The optical power of the rear group optical structure is positive and includes a fifth lens L5 and a sixth lens L6; The surface S4 of the second lens L2, the surface S5 of the third lens L3, and the surface S11 of the sixth lens L6 are all aspherical surfaces.
2. The wide waveband infrared optical system of claim 1, wherein: The surface S1 of the first lens L1, the surface S2 of the first lens L1, the surface S3 of the second lens L2, the surface S4 of the third lens L3, the surface S5 of the fourth lens L4, the surface S6 of the fourth lens L4, the surface S7 of the fifth lens L5, the surface S8 of the fifth lens L5, and the surface S12 of the sixth lens L6 are all spherical surfaces.
3. The wide waveband infrared optical system of claim 2, wherein: The focal length of the whole optical system is f, the focal length of the front optical structure is f 1-4 , the focal length of the rear optical structure is f 5-6 , and the focal length satisfies the following conditions: 10 < |f1-4| / f < 11; 0.5 < |f5-6| / f < 0.
7.
4. The broadband infrared optical system according to claim 3, characterized in that: Assume that the focal length of the first lens L1 is f1, the focal length of the second lens L2 is f2, the focal length of the third lens L3 is f3, the focal length of the fourth lens L4 is f4, the focal length of the fifth lens L5 is f5, and the focal length of the sixth lens L6 is f6. Then the value ranges of each focal length are as follows: 0.7 < f1 / |f2| < 0.8, 15.5 < |f1-4| / f5-6 < 15.6, 0.5 < f1 / f < 0.6, 0.8 < |f2| / f < 0.9, 1.4 < |f3| / f < 1.5, 2.6 < |f4| / f < 2.7, 28 < f5 / f < 29, 1.7 < |f6| / f < 1.
8.
5. The wide waveband infrared optical system of claim 4, wherein: The radius of curvature of the surface S1 of the first lens L1 is: 40mm < r < 50mm, and the radius of curvature of the surface S2 is infinite.
6. The wide waveband infrared optical system of claim 4, wherein: The radius of curvature of the surface S3 of the second lens L2 is: -140mm < r < -130mm, and the radius of curvature of the surface S4 is: 130mm < r < 140mm.
7. The wide waveband infrared optical system of claim 4, wherein: The radius of curvature of the surface S5 of the third lens L3 is: -70mm < r < -60mm, and the radius of curvature of the surface S6 is: -150mm < r < -140mm.
8. The wide waveband infrared optical system of claim 4, wherein: The radius of curvature of the surface S seventh of the fourth lens L4 is: -120mm < r < -110mm, and the radius of curvature of the surface S8 is: 110mm < r < 120mm.
9. The wide waveband infrared optical system of claim 4, wherein: The radius of curvature of the surface S9 of the fifth lens L5 is: 60mm < r < 70mm, and the radius of curvature of the surface S10 is: -70mm < r < -60mm.
10. The wide waveband infrared optical system of claim 4, wherein: The radius of curvature of the surface S11 of the fifth lens L5 is: 20mm < r < 30mm, and the radius of curvature of the surface S12 is: 10mm < r < 20mm.