Space debris detection optical system without vacuum preset focal plane

Abstract

The invention discloses a space debris detection optical system without a vacuum preset focal plane, and solves the problems that when the optical system is tested on the ground under normal pressure after the focal plane is preset, the preset optimal focal plane position needs to be frequently adjusted to the normal pressure position, the work is tedious, and time is consumed very much. The defocusing amount introduced by the working temperature change of the optical system and the defocusing amount caused by vacuum are mutually compensated, so that the optimal focal plane position of the optical system at normal temperature and normal pressure is the same as the optimal focal plane position during vacuum on-orbit working, the problem that the focal plane needs to be preset in vacuum when an existing optical system is used in orbit is solved, and meanwhile, the service life of the optical system is prolonged. When the working temperature of the on-orbit optical load is lower than the room temperature, the power consumption required by the satellite to maintain the working temperature of the optical load system can be reduced.

Description

Technical Field

[0001] The invention relates to a space optical system, in particular to a space debris detection optical system that does not require a vacuum preset focal plane. Background Art

[0002] Currently, when optical payloads are working in orbit, the optimal focal plane position of the optical system changes due to the change between the vacuum environment in orbit and the normal pressure environment of the ground laboratory, resulting in vacuum defocus (shift of the optimal focal plane), and the performance of the optical system is seriously degraded.

[0003] There are currently two solutions to the vacuum defocusing problem of on-orbit optical payloads:

[0004] 1. Design an optical system with large focal depth and small vacuum defocus to compensate for the effect of defocus on image quality;

[0005] 2. Use the focusing mechanism to adjust the optimal focal plane position in real time. For the space debris detection optical system, its F number is small (≤2), the focal depth (±0.02mm) is less than the vacuum focal plane preset (>0.05mm), and the system image quality is seriously degraded. Using the focusing mechanism to achieve focal plane preset requires increasing the system weight and motion mechanism, which greatly increases the system cost.

[0006] Usually, the actual optical system is assembled and adjusted under normal temperature and pressure on the ground. Before installing the satellite, the optimal focal plane of the test optical system assembled under normal pressure on the ground needs to be preset to optimize its on-orbit performance. After the focal plane is preset, when the optical system is tested under normal pressure on the ground, it is necessary to frequently adjust the preset optimal focal plane position to the normal pressure position, which is cumbersome and time-consuming. Summary of the invention

[0007] The purpose of the present invention is to provide an optical system for detecting space debris without vacuum preset focal plane, so as to solve the technical problem that after the focal plane is preset, the preset optimal focal plane position needs to be frequently adjusted to the normal pressure position when the optical system is tested at normal pressure on the ground, which is cumbersome and time-consuming.

[0008] The present invention utilizes the defocus amount introduced by the change of the working temperature of the optical system and the defocus amount caused by vacuum to compensate each other, so that the optimal focal plane position of the optical system at normal temperature and pressure is the same as the optimal focal plane position when the vacuum is working in orbit, thereby solving the problem that the existing optical system needs to preset the focal plane in vacuum when used in orbit. At the same time, when the working temperature of the on-orbit optical payload is lower than room temperature, the power consumption required by the satellite to maintain the working temperature of the optical payload system can be reduced.

[0009] In order to achieve the above purpose and complete the above invention concept, the present invention adopts the following technical solutions:

[0010] An optical system for detecting space debris without vacuum pre-setting focal plane, which is special in that it comprises a first positive lens, a first negative lens, a second positive lens, a third positive lens, a fourth positive lens and a second negative lens whose optical axes are located on the same straight line and are arranged in sequence from the object plane to the image plane;

[0011] The center of the rear surface of the first positive lens is 11 mm to 20 mm away from the center of the front surface of the first negative lens;

[0012] The center of the rear surface of the first negative lens is 0.2 mm to 4 mm away from the center of the front surface of the second positive lens;

[0013] The center of the rear surface of the second positive lens is 40 mm to 78 mm away from the center of the front surface of the third positive lens;

[0014] The center of the rear surface of the third positive lens is 0.3 mm to 6 mm away from the center of the front surface of the fourth positive lens;

[0015] The center of the rear surface of the fourth positive lens is 1 mm to 8 mm away from the center of the front surface of the second negative lens;

[0016] The rear surface of the second negative lens is 3 mm to 10 mm away from the image plane.

[0017] Further, the material of the first positive lens is SILICA;

[0018] The refractive index of the material of the first negative lens is 1.74 to 1.76;

[0019] The refractive index of the material of the second positive lens is 1.48 to 1.5;

[0020] The material refractive index of the third positive lens is 1.68-1.72;

[0021] The material refractive index of the fourth positive lens is 1.73-1.75;

[0022] The refractive index of the material of the second negative lens is 1.73-1.78.

[0023] Furthermore, the center thickness of the first positive lens is 7 mm to 13 mm;

[0024] The center thickness of the first negative lens is 3.5 mm to 6 mm;

[0025] The center thickness of the second positive lens is 6 mm to 10 mm;

[0026] The central thickness of the third positive lens is 4 mm to 8 mm;

[0027] The center thickness of the fourth positive lens is 3 mm to 9 mm;

[0028] The central thickness of the second negative lens is 3 mm to 8 mm.

[0029] Furthermore, the Abbe number of the first negative lens is 25 to 30;

[0030] The Abbe number of the second positive lens is 78 to 85;

[0031] The Abbe number of the third positive lens is 53 to 57;

[0032] The Abbe number of the fourth positive lens is 42 to 45;

[0033] The Abbe number of the second negative lens is 25 to 30.

[0034] Furthermore, the relationship between the focal length f1 of the first positive lens and the focal length f of the optical system is: 1.3f < f1 < 1.58f;

[0035] The relationship between the focal length f2 of the first negative lens and the focal length f of the optical system is: -1.65f < f2 < -1.48f;

[0036] The relationship between the focal length f3 of the second positive lens and the focal length f of the optical system is: 1.25f < f3 < 1.78f;

[0037] The relationship between the focal length f4 of the third positive lens and the focal length f of the optical system is: 0.6f < f4 < 1.4f;

[0038] The relationship between the focal length f5 of the fourth positive lens and the focal length f of the optical system is: 0.78f < f5 < 1.19f;

[0039] The relationship between the focal length f6 of the second negative lens and the focal length f of the optical system is: -0.45f < f6 < -0.25f.

[0040] Furthermore, the radius of curvature R1 and R2 of the front and rear surfaces of the first positive lens respectively satisfy: 0.95f < R1 < 1.37f and -1.65f < R2 < 1.5f;

[0041] The radius of curvature R3 and R4 of the front and rear surfaces of the first negative lens respectively satisfy: -1.19f < R3 < -0.79f and -7f < R4 < -5f;

[0042] The radius of curvature R5 and R6 of the front and rear surfaces of the second positive lens respectively satisfy: 0.5f < R5 < 0.85f and -60f < R6 < -40f;

[0043] The radius of curvature R7 and R8 of the front and rear surfaces of the third positive lens respectively satisfy: 0.45f < R7 < 0.9f and 20f < R8 < 40f;

[0044] The radii of curvature R9 and R of the front and rear surfaces of the fourth positive lens 10 respectively satisfy: 0.35f < R9 < 0.75f and 1.05f < R 10 < 2f;

[0045] The radii of curvature R 11 、R 12 of the front and rear surfaces of the second negative lens respectively satisfy: -1.3f < R 11 < -0.7f and 0.15f < R 12 < 0.72f.

[0046] Furthermore, the focal length of the first positive lens is 118.23 mm, the radii of curvature R1 and R2 of the front and rear surfaces are 90.36 mm and -129.42 mm respectively, and the central thickness is 10 mm;

[0047] The refractive index of the material of the first negative lens is 1.755, the Abbe number is 27.5, the focal length is -126.76 mm, the radii of curvature R3 and R4 of the front and rear surfaces are -79.8 mm and -517.7 mm respectively, and the central thickness is 5 mm; the front surface of the first negative lens is 17 mm away from the rear surface of the first positive lens;

[0048] The refractive index of the material of the second positive lens is 1.497, the Abbe number is 81.6, the focal length is 130.93 mm, the radii of curvature R5 and R6 of the front and rear surfaces are 65.7 mm and -4786 mm respectively, and the central thickness is 8 mm; the front surface of the second positive lens is 1 mm away from the rear surface of the first negative lens;

[0049] The refractive index of the material of the third positive lens is 1.697, the Abbe number is 55.5, the focal length is 733.46 mm, the radii of curvature R7 and R8 of the front and rear surfaces are 50.12 mm and 3020 mm respectively, and the central thickness is 5 mm; the front surface of the third positive lens is 62.4 mm away from the rear surface of the second positive lens;

[0050] The refractive index of the material of the fourth positive lens is 1.744, the Abbe number is 44.9, the focal length is 75.94 mm, the radii of curvature R9 and R 10 are 39.91 mm and 130.62 mm respectively, and the central thickness is 5 mm; the front surface of the fourth positive lens is 1 mm away from the rear surface of the third positive lens;

[0051] The refractive index of the material of the second negative lens is 1.755, the Abbe number is 27.5, the focal length is -28.53 mm, the radii of curvature R 11 、R 12They are -70.63mm and 31.5mm respectively, with a center thickness of 5mm. The front surface of the second negative lens is 4mm away from the back surface of the fourth positive lens, and the back of the second negative lens is 6.136mm away from the image plane.

[0052] Beneficial effects of the present invention:

[0053] 1. The space debris detection optical system provided by the present invention does not require a vacuum preset focal plane. At normal temperature and pressure, its optimal focal plane position coincides with the vacuum low-temperature optimal focal plane position, which improves the system assembly and testing efficiency and avoids frequent replacement of the optimal focal plane position.

[0054] 2. The space debris detection optical system provided by the present invention does not require a vacuum preset focal plane, and its focal plane increases as the temperature decreases (e.g. Figure 2 As shown in the figure, the increase in the optimal focal plane during low-temperature operation can compensate for the decrease in the vacuum optimal focal plane during vacuum operation, and the optimal focal plane position at room temperature and pressure coincides with the optimal focal plane position at vacuum and low temperature.

[0055] 3. When the space debris detection optical system provided by the present invention does not require a vacuum pre-set focal plane and the operating temperature is much lower than room temperature 20°C, the optical load can reduce the power consumption requirement. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a schematic structural diagram of an embodiment of a space debris detection optical system that does not require a vacuum pre-set focal plane according to the present invention;

[0057] Figure 2 is a curve fitting diagram of the change of the optimal focal plane of the optical system with temperature in an embodiment of the present invention;

[0058] Figure 3 is a graph of energy concentrations at 0°, 1.7°, 3°, 4° and 5.6° in an optical system at room temperature and pressure in an embodiment of the present invention;

[0059] Figure 4 80% energy circle diameter diagram of the optical system at room temperature and pressure in an embodiment of the present invention;

[0060] Figure 5 is a graph of energy concentrations at 0°, 1.7°, 3°, 4° and 5.6° in a vacuum-10°C optical system in an embodiment of the present invention;

[0061] Figure 6 It is a diagram of the 80% energy circle diameter of the optical system at -10°C in vacuum in an embodiment of the present invention.

[0062] Figure Number:

[0063] 1-first positive lens, 2-first negative lens, 3-second positive lens, 4-third positive lens, 5-fourth positive lens, 6-second negative lens. DETAILED DESCRIPTION

[0064] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than 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.

[0065] An embodiment of the present invention provides an optical system for detecting space debris without vacuum pre-setting focal plane. The system is an optical system for detecting small-scale space debris in a wide area.

[0066] like Figure 1 As shown, the space debris detection optical system includes a first positive lens 1, a first negative lens 2, a second positive lens 3, a third positive lens 4, a fourth positive lens 5 and a second negative lens 6, whose optical axes are located on the same straight line and are arranged in sequence from the object plane to the image plane. The lens barrel material of the optical system is metal aluminum.

[0067] The material of the first positive lens 1 is SILICA, which serves as the radiation protection window of the optical system and can also correct system aberrations. Its focal length is 118.23 mm, the curvature radii R1 and R2 of the front and rear surfaces are 90.36 mm and -129.42 mm respectively, and the center thickness is 10 mm.

[0068] The material refractive index of the first negative lens 2 is 1.755, the Abbe number is 27.5 (HZF6), the focal length is -126.76mm, the curvature radii R3 and R4 of the front and rear surfaces are -79.8mm and -517.7mm respectively, and the center thickness is 5mm; the interval from the front surface of the first negative lens 2 to the rear surface of the first positive lens 1 is 17mm.

[0069] The material refractive index of the second positive lens 3 is 1.497, the Abbe number is 81.6 (HFK61), the focal length is 130.93mm, the curvature radii R5 and R6 of the front and rear surfaces are 65.7mm and -4786mm respectively, and the thickness is 8mm; the interval from the front surface of the second positive lens 3 to the rear surface of the first negative lens 2 is 1mm.

[0070] The material refractive index of the third positive lens 4 is 1.697, and the Abbe number is 55.5 (HLAK51A). The focal length of the third positive lens 4 is 733.46 mm, and the curvature radii R7 and R8 of the front and rear surfaces are 50.12 mm and 3020 mm respectively, and the center thickness is 5 mm; the interval from the front surface of the third positive lens 4 to the rear surface of the second positive lens 3 is 62.4 mm.

[0071] The material refractive index of the fourth positive lens 5 is 1.744, the Abbe number is 44.9 (HLAF3B), the focal length is 75.94 mm, and the curvature radii of the front and rear surfaces are R9 and R 10 They are 39.91 mm and 130.62 mm respectively; the center thickness is 5 mm, and the distance from the front surface of the fourth positive lens 5 to the back surface of the third positive lens 4 is 1 mm.

[0072] The material refractive index of the second negative lens 6 is 1.755, the Abbe number is 27.5 (HZF6), and the focal length is -28.53 mm. The curvature radius R of the front and rear surfaces is 11 , R 12 They are: -70.63mm and 31.5mm respectively, the center thickness is 5mm, the distance from the front surface of the second negative lens 6 to the back surface of the fourth positive lens 5 is 4mm, and the distance from the back of the second negative lens 6 to the image plane (focal plane) is 6.136mm.

[0073] When the optical system is in vacuum at 20 degrees Celsius, the distance from the rear surface of the second negative lens 6 to the image plane (focal plane) is 6.08 mm.

[0074] It can be seen that the vacuum focal plane preset of the optical system is -0.055mm (relative to the normal temperature and pressure interval). When the working temperature of the optical system changes from room temperature 20℃ to -10℃, the optimal focal plane of the system is 6.192mm, and the increase is 0.053mm, which can fully compensate for the vacuum focal plane preset. The error (0.002mm) is much smaller than the focal depth of the system (±0.02mm). That is, the optical system can be assembled and tested at normal temperature (20℃) and normal pressure, and can work at vacuum -10℃ without vacuum focal plane preset. The optical performance of the two is close.

[0075] Figure 2 The curve of the best focal plane position of the optical system provided in the above embodiment changing with temperature shows that the best focal plane position increases by 0.0017 mm for every 1°C decrease in temperature;

[0076] like Figure 3 and Figure 4 As shown in FIG. 1 , the energy concentration curves of the optical system at 0°, 1.7°, 3°, 4° and 5.6° under normal temperature and pressure provided by this embodiment. Figure 4 It can be seen that 80% of the energy circle diameters of the system in the full field of view are less than 20μm, and the energy circle diameter range is controlled within 15μm-19μm.

[0077] like Figure 5 and Figure 6 As shown in FIG. 1 , the energy concentration curves of the optical system provided in this embodiment at 0°, 1.7°, 3°, 4° and 5.6° under vacuum conditions of -10°C. Figure 6It can be seen that 80% of the energy circle diameters of the system in the full field of view are less than 21μm, and the energy circle diameter range is controlled within 16μm-21μm.

[0078] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. An optical system for detecting space debris without vacuum pre-focusing, characterized in that: It comprises a first positive lens (1), a first negative lens (2), a second positive lens (3), a third positive lens (4), a fourth positive lens (5) and a second negative lens (6) whose optical axes are located on the same straight line and are arranged in sequence from the object plane to the image plane; The center of the rear surface of the first positive lens (1) is 11 mm to 20 mm away from the center of the front surface of the first negative lens (2); The distance between the center of the rear surface of the first negative lens (2) and the center of the front surface of the second positive lens (3) is 0.2 mm to 4 mm; The center of the rear surface of the second positive lens (3) is 40 mm to 78 mm away from the center of the front surface of the third positive lens (4); The distance between the center of the rear surface of the third positive lens (4) and the center of the front surface of the fourth positive lens (5) is 0.3 mm to 6 mm; The distance between the center of the rear surface of the fourth positive lens (5) and the center of the front surface of the second negative lens (6) is 1 mm to 8 mm; The rear surface of the second negative lens (6) is 3 mm to 10 mm away from the image plane.

2. The space debris detection optical system without vacuum pre-focusing according to claim 1, characterized in that: The material of the first positive lens (1) is SILICA; The material refractive index of the first negative lens (2) is 1.74 to 1.76; The material refractive index of the second positive lens (3) is 1.48 to 1.5; The material refractive index of the third positive lens (4) is 1.68 to 1.72; The material refractive index of the fourth positive lens (5) is 1.73-1.75; The refractive index of the material of the second negative lens (6) is 1.73-1.

78.

3. The space debris detection optical system without vacuum pre-focusing according to claim 2, characterized in that: The center thickness of the first positive lens (1) is 7 mm to 13 mm; The center thickness of the first negative lens (2) is 3.5 mm to 6 mm; The center thickness of the second positive lens (3) is 6 mm to 10 mm; The central thickness of the third positive lens (4) is 4 mm to 8 mm; The center thickness of the fourth positive lens (5) is 3 mm to 9 mm; The central thickness of the second negative lens (6) is 3 mm to 8 mm.

4. The space debris detection optical system without vacuum pre-focusing according to claim 3, characterized in that: The Abbe number of the first negative lens (2) is 25 to 30; The Abbe number of the second positive lens (3) is 78 to 85; The Abbe number of the third positive lens (4) is 53 to 57; The Abbe number of the fourth positive lens (5) is 42 to 45; The Abbe number of the second negative lens (6) is 25-30.

5. The space debris detection optical system without vacuum pre-focusing according to any one of claims 1 to 4, characterized in that: The relationship between the focal length f1 of the first positive lens (1) and the focal length f of the optical system is: 1.3f <f1<1.58f; The relationship between the focal length f2 of the first negative lens (2) and the focal length f of the optical system is: -1.65f <f2<-1.48f; The relationship between the focal length f3 of the second positive lens (3) and the focal length f of the optical system is: 1.25f < f3 < 1.78f; The relationship between the focal length f4 of the third positive lens (4) and the focal length f of the optical system is: 0.6f < f4 < 1.4f; The relationship between the focal length f5 of the fourth positive lens (5) and the focal length f of the optical system is: 0.78f < f5 < 1.19f; The relationship between the focal length f6 of the second negative lens (6) and the focal length f of the optical system is: -0.45f < f6 < -0.25f.

6. The space debris detection optical system without vacuum pre-focusing plane according to claim 5, characterized in that: The curvature radii R1 and R2 of the front and rear surfaces of the first positive lens (1) respectively satisfy: 0.95f < R1 < 1.37f and -1.65f < R2 < 1.5f; The curvature radii R3 and R4 of the front and rear surfaces of the first negative lens (2) respectively satisfy: -1.19f < R3 < -0.79f and -7f < R4 < -5f; The curvature radii R5 and R6 of the front and rear surfaces of the second positive lens (3) respectively satisfy: 0.5f < R5 < 0.85f and -60f < R6 < -40f; The curvature radii R7 and R8 of the front and rear surfaces of the third positive lens (4) respectively satisfy: 0.45f < R7 < 0.9f and 20f < R8 < 40f; The radii of curvature R9 and R of the front and rear surfaces of the fourth positive lens (5) 10 respectively satisfy: 0.35f < R9 < 0.75f and 1.05f < R 10 < 2f; The curvature radius R of the front and rear surfaces of the second negative lens (6) is 11 , R 12 Respectively satisfy: -1.3f <R 11 <-0.7f and 0.15f <R 12 <0.72f.

7. The space debris detection optical system without vacuum pre-focusing plane according to claim 5, characterized in that: The focal length of the first positive lens (1) is 118.23 mm, the curvature radii R1 and R2 of the front and rear surfaces are 90.36 mm and -129.42 mm respectively, and the central thickness is 10 mm; The material refractive index of the first negative lens (2) is 1.755, the Abbe number is 27.5, the focal length is -126.76 mm, the curvature radii R3 and R4 of the front and rear surfaces are -79.8 mm and -517.7 mm respectively, and the central thickness is 5 mm; the front surface of the first negative lens (2) is 17 mm away from the rear surface of the first positive lens (1); The material refractive index of the second positive lens (3) is 1.497, the Abbe number is 81.6, the focal length is 130.93 mm, the curvature radii R5 and R6 of the front and rear surfaces are 65.7 mm and -4786 mm respectively, and the central thickness is 8 mm; the front surface of the second positive lens (3) is 1 mm away from the rear surface of the first negative lens (2); The material refractive index of the third positive lens (4) is 1.697, the Abbe number is 55.5, the focal length is 733.46 mm, the curvature radii R7 and R8 of the front and rear surfaces are 50.12 mm and 3020 mm respectively, and the central thickness is 5 mm; the front surface of the third positive lens (4) is 62.4 mm away from the rear surface of the second positive lens (3); The material refractive index of the fourth positive lens (5) is 1.744, the Abbe number is 44.9, the focal length is 75.94 mm, and the curvature radii R9 and R 10 The front surface of the fourth positive lens (5) is 1 mm away from the rear surface of the third positive lens (4); The material refractive index of the second negative lens (6) is 1.755, the Abbe number is 27.5, the focal length is -28.53 mm, and the curvature radius R of the front and rear surfaces is 11 , R 12 They are -70.63mm and 31.5mm respectively, with a center thickness of 5mm. The front surface of the second negative lens (6) is 4mm away from the rear surface of the fourth positive lens (5), and the rear surface of the second negative lens (6) is 6.136mm away from the image plane.

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