Space debris detection optical system without vacuum pre-focusing surface

Abstract

The application discloses a space debris detection optical system without vacuum preset focal plane, and solves the problem that the preset optimal focal plane position needs to be frequently adjusted to the normal pressure position during the ground normal pressure test of the optical system after the focal plane is preset, the work is tedious, and a lot of time is consumed. The defocus amount caused by the change of the working temperature of the optical system and the defocus amount caused by the vacuum are mutually compensated, the optimal focal plane position of the optical system under the normal temperature and normal pressure is the same as the optimal focal plane position when the vacuum is used in orbit, the problem that the optical system needs to be preset in the vacuum when used in orbit is solved, and when the working temperature of the optical load in orbit is lower than the room temperature, the power consumption required for the satellite to keep the working temperature of the optical load system can be reduced.

Description

Technical Field

[0001] This invention relates to space optical systems, and more specifically to a space debris detection optical system that does not require a vacuum pre-set focal plane. Background Technology

[0002] Currently, when optical payloads are operating in orbit, the difference between the vacuum environment in orbit and the normal pressure environment in ground laboratories causes the optimal focal plane position of the optical system to change, resulting in vacuum defocusing (the optimal focal plane shifts forward), which severely degrades the performance of the optical system.

[0003] Currently, there are two solutions to the problem of vacuum defocusing of on-orbit optical payloads:

[0004] 1. Design an optical system with a large depth of focus and a small vacuum defocusing amount to compensate for the impact of defocusing on image quality;

[0005] 2. The optimal focal plane position is adjusted in real time via a focusing mechanism. For space debris detection optical systems, the F-number is relatively low (≤2), and the depth of focus (±0.02mm) is less than the vacuum focal plane preset amount (>0.05mm), resulting in severe image quality degradation. Achieving focal plane preset via a focusing mechanism requires increased system weight and motion mechanisms, significantly increasing system cost.

[0006] Typically, the assembly and adjustment of actual optical systems are carried out under normal temperature and pressure conditions on the ground. Before satellite installation, the optimal focal plane of the test optical system assembled under normal pressure on the ground needs to be preset to ensure its optimal on-orbit performance. After the focal plane is preset, the optical system needs to be frequently adjusted to the normal pressure position during testing on the ground, which is tedious and time-consuming. Summary of the Invention

[0007] The purpose of this invention is to provide a space debris detection optical system that does not require a vacuum-preset focal plane, in order to solve the technical problem that when the optical system with a preset focal plane is tested at atmospheric pressure on the ground, it is necessary to frequently adjust the preset optimal focal plane position to the atmospheric pressure position, which is cumbersome and time-consuming.

[0008] This invention utilizes the defocusing caused by the change in the operating temperature of the optical system to compensate for the defocusing caused by the vacuum, so that the optimal focal plane position of the optical system under normal temperature and pressure is the same as the optimal focal plane position when operating in orbit under vacuum. This solves the problem that existing optical systems require vacuum to pre-set the focal plane when used in orbit. At the same time, when the operating temperature of the optical payload in orbit is lower than room temperature, the power consumption required for the satellite to maintain the operating temperature of the optical payload system can be reduced.

[0009] To achieve the above objectives and complete the above inventive concept, the present invention adopts the following technical solution:

[0010] An optical system for detecting space debris without a vacuum preset focal plane is characterized by comprising 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 arranged sequentially from the object plane to the image plane, with the optical axes located on the same straight line.

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

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

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

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

[0015] The distance between the center of the rear surface of the fourth positive lens and the center of the front surface of the second negative lens is 1mm to 8mm.

[0016] The distance between the rear surface of the second negative lens and the image plane is 3mm to 10mm.

[0017] Furthermore, 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 refractive index of the material of the third positive lens is 1.68 to 1.72;

[0021] The fourth positive lens is made of a material with a refractive index of 1.73 to 1.75.

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

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

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

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

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

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

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

[0029] Further, 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] Further, 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] Further, the curvature radii 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 curvature radii 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 curvature radii 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 curvature radii 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 12The diameters are -70.63mm and 31.5mm respectively, with a center thickness of 5mm. The distance between the front surface of the second negative lens and the rear surface of the fourth positive lens is 4mm, and the distance between the rear surface of the second negative lens and the image plane is 6.136mm.

[0052] The beneficial effects of this invention are:

[0053] 1. The space debris detection optical system provided by this invention, which does not require a vacuum pre-set focal plane, has its optimal focal plane position coinciding with the optimal focal plane position under normal temperature and pressure, thereby improving the system's assembly, adjustment, and testing efficiency and avoiding frequent changes to the optimal focal plane position.

[0054] 2. The space debris detection optical system provided by this invention, which does not require a vacuum-preset focal plane, has a focal plane that 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 optimal focal plane during vacuum operation. The optimal focal plane position at room temperature and pressure coincides with the optimal focal plane position at low-temperature vacuum.

[0055] 3. The space debris detection optical system provided by this invention, which does not require a vacuum pre-set focal plane, can reduce the power consumption requirement of the optical payload when the operating temperature is much lower than the room temperature of 20°C. Attached Figure Description

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

[0057] Figure 2 This is a curve fitting diagram of the optimal focal plane of the optical system in the embodiment of the present invention as a function of temperature;

[0058] Figure 3 This is a graph showing the energy concentration at 0°, 1.7°, 3°, 4° and 5.6° in the optical system under normal temperature and pressure in an embodiment of the present invention.

[0059] Figure 4 This is a diagram showing the 80% energy circle diameter of the optical system under normal temperature and pressure in an embodiment of the present invention.

[0060] Figure 5 This is a graph showing the energy concentration at 0°, 1.7°, 3°, 4° and 5.6° in the vacuum-10°C optical system of this invention.

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

[0062] Icon labels:

[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 Implementation

[0064] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. 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.

[0065] The present invention provides a space debris detection optical system that does not require a vacuum pre-set focal plane. This system is a wide-area detection optical system for small-scale space debris.

[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 arranged sequentially from the object plane to the image plane with their optical axes on the same straight line. The lens barrel material of the optical system is aluminum.

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

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

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

[0070] The material of the third positive lens 4 has a refractive index of 1.697 and an Abbe number of 55.5 (HLAK51A). The focal length of the third positive lens 4 is 733.46 mm, and the radii of curvature of the front and rear surfaces, R7 and R8, are 50.12 mm and 3020 mm, respectively. The center thickness is 5 mm. The distance 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 fourth positive lens 5 is made of a material with a refractive index of 1.744, an Abbe number of 44.9 (HLAF3B), a focal length of 75.94 mm, and radii of curvature R9 and R on its front and rear surfaces. 10 The thicknesses are 39.91 mm and 130.62 mm respectively; the center thickness is 5 mm, and the distance between the front surface of the fourth positive lens 5 and the rear surface of the third positive lens 4 is 1 mm.

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

[0073] In this optical system, at a vacuum of 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 this optical system is -0.055mm (a decrease relative to the room temperature and pressure interval). When the operating temperature of this optical system changes from room temperature (20℃) to -10℃, the optimal focal plane of the system is 6.192mm, an increase of 0.053mm, which can completely compensate for the vacuum focal plane preset. The error (0.002mm) is much smaller than the system's depth of focus (±0.02mm). That is, this optical system can be assembled and tested at room temperature (20℃) and pressure, and can operate in a vacuum at -10℃ without vacuum focal plane preset, with similar optical performance.

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

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

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

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

Claims

1. A space debris detection optical system without vacuum pre-set focal plane, characterized in that: It is composed of 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) which are arranged in sequence from the object surface to the image surface with their optical axes on the same straight line; 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 material of the first positive lens (1) is SILICA, the center thickness is 7 mm to 13 mm, and the focal length f1 satisfies: 1.3f < f1 < 1.58f, and the curvature radii R1 and R2 of the front and rear surfaces respectively satisfy: 0.95f < R1 < 1.37f and -1.65f < R2 < 1.5f; where f is the focal length of the optical system; The center of the rear surface of the first negative lens (2) is 0.2 mm to 4 mm away from the center of the front surface of the second positive lens (3); the refractive index of the material of the first negative lens (2) is 1.74 to 1.76, the center thickness is 3.5 mm to 6 mm, the Abbe number is 25 to 30, and the focal length f2 satisfies: -1.65f < f2 < -1.48f, and the curvature radii R3 and R4 of the front and rear surfaces respectively satisfy: -1.19f < R3 < -0.79f and -7f < R4 < -5f; 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 refractive index of the material of the second positive lens (3) is 1.48 to 1.5, the center thickness is 6 mm to 10 mm, the Abbe number is 78 to 85, and the focal length f3 satisfies: 1.25f < f3 < 1.78f, and the curvature radii R5 and R6 of the front and rear surfaces respectively satisfy: 0.5f < R5 < 0.85f and -60f < R6 < -40f; The center of the rear surface of the third positive lens (4) is 0.3 mm to 6 mm away from the center of the front surface of the fourth positive lens (5); the refractive index of the material of the third positive lens (4) is 1.68 to 1.72, the center thickness is 4 mm to 8 mm, the Abbe number is 53 to 57, and the focal length f4 satisfies: 0.6f < f4 < 1.4f, and the curvature radii R7 and R8 of the front and rear surfaces respectively satisfy: 0.45f < R7 < 0.9f and 20f < R8 < 40f; The distance from the center of the rear surface of the fourth positive lens (5) to the center of the front surface of the second negative lens (6) is 1 mm to 8 mm; the refractive index of the material of the fourth positive lens (5) is 1.73 to 1.75, the central thickness is 3 mm to 9 mm, the Abbe number is 42 to 45, and the focal length f5 satisfies: 0.78f < f5 < 1.19f, and the radii of curvature R9 and R of the front and rear surfaces 10 respectively satisfy: 0.35f < R9 < 0.75f and 1.05f < R 10 <2f; The rear surface of the second negative lens (6) is 3 mm to 10 mm away from the image plane; the refractive index of the material of the second negative lens (6) is 1.73 to 1.78, the central thickness is 3 mm to 8 mm, the Abbe number is 25 to 30, and the focal length f6 satisfies: -0.45f < f6 < -0.25f, and the radii of curvature R 11 and R 12 respectively satisfy: -1.3f < R 11 < -0.7f and 0.15f < R 12 < 0.72f.

2. The space debris detection optical system without vacuum pre-set focal plane according to claim 1, 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 center thickness is 10 mm; The refractive index of the material 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 center 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 second positive lens (3) has a refractive index of 1.497, an Abbe number of 81.6, a focal length of 130.93 mm, and radii of curvature R5 and R6 of the front and rear surfaces of 65.7 mm and -4786 mm, respectively. The center 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 of the third positive lens (4) has a refractive index of 1.697, an Abbe number of 55.5, a focal length of 733.46 mm, and radii of curvature R7 and R8 of the front and rear surfaces of 50.12 mm and 3020 mm, respectively. The center thickness is 5 mm. The distance between the front surface of the third positive lens (4) and the rear surface of the second positive lens (3) is 62.4 mm. The fourth positive lens (5) has a refractive index of 1.744, an Abbe number of 44.9, a focal length of 75.94 mm, and radii of curvature R9 and R on its front and rear surfaces. 10 The diameters are 39.91 mm and 130.62 mm respectively, and the center thickness is 5 mm; the front surface of the fourth positive lens (5) is 1 mm away from the rear surface of the third positive lens (4); The second negative lens (6) has a refractive index of 1.755, an Abbe number of 27.5, a focal length of -28.53 mm, and radii of curvature R of its front and rear surfaces. 11 R 12 The diameters are -70.63mm and 31.5mm respectively, the center thickness is 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 of the second negative lens (6) is 6.136mm away from the image plane.

Images