Large-scale low-distortion space debris detection optical system

Abstract

The application relates to a large-scale low-distortion space debris detection optical system, which is used for solving the problem that the current optical system has a large field of view and a small entrance pupil diameter, and the system detection capability is limited. The application comprises a first positive lens, a second positive lens, a first negative lens, a system aperture diaphragm, a third positive lens, a fourth positive lens, a second negative lens, a third negative lens and a phase surface which are sequentially arranged on the same optical axis along the propagation direction of light; the first positive lens is used as an anti-radiation window of the whole system and corrects spherical aberration of the system; the second positive lens mainly corrects coma and astigmatism of the system; the first negative lens mainly corrects spherical aberration and astigmatism of the system; the third positive lens mainly corrects axial chromatic aberration; the fourth positive lens mainly corrects spherical aberration and distortion; the second negative lens mainly corrects spherical aberration, and the rear surface of the second negative lens is a high-order aspheric surface; and the third negative lens mainly corrects field curvature and distortion.

Description

Technical Field

[0001] This invention relates to a space optical system, specifically to a large-scale, low-distortion space debris detection optical system. Background Technology

[0002] Space debris refers to all man-made objects that are in orbit or re-entering Earth's dense atmosphere and are considered to be inoperable, including their fragments and components. Space debris poses a serious threat to the safety of spacecraft in orbit. If space debris collides with a spacecraft, it will directly alter the properties of the spacecraft's surface, causing surface damage and leading to spacecraft system failures.

[0003] In recent years, human space activities have become increasingly frequent, leading to a surge in space debris and a worsening space environment. Among the most worrying aspects of space debris research is the "Kessler Syndrome," which posits that collisions between pieces of space debris inevitably generate even more and smaller pieces, creating an avalanche-like effect where the number of fragments increases dramatically. Donald Kessler pointed out that if a series of collisions reaches a trigger point, it could trigger a chain reaction, further exacerbating the space debris problem.

[0004] To detect space debris, the aperture and spectral range of existing optical systems need to be increased. However, increasing the aperture and spectral range directly affects the spherical aberration, coma, distortion, field curvature, and transverse chromatic aberration of the optical system, significantly increasing the design complexity. Currently published optical systems suffer from limitations such as large field of view but small entrance pupil diameter, resulting in limited detection capabilities. Alternatively, they may contain an excessive number of optical components and aspherical surfaces, leading to high system costs and failing to meet the requirements for wide-area detection of space targets. Summary of the Invention

[0005] This invention provides a large-scale, low-distortion space debris detection optical system with excellent performance indicators, including an entrance pupil diameter exceeding 70 mm, a system F-number of less than 1.5, distortion of less than 0.1%, a spectral range of 450 nm to 850 nm, and an energy circle diameter of less than 8 μm in a 14° field of view. This system addresses the problems of current optical systems, such as a large field of view but a small entrance pupil diameter, resulting in limited system detection capabilities, as well as the high cost due to the excessive number of components and aspherical surfaces in existing optical systems.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A large-scale, low-distortion space debris detection optical system is characterized by comprising a first positive lens, a second positive lens, a first negative lens, a system aperture stop, a third positive lens, a fourth positive lens, a second negative lens, a third negative lens, and a phase plane, arranged sequentially on the same optical axis along the direction of light propagation.

[0008] The first positive lens is used as the radiation protection window of the system and corrects the spherical aberration of the system;

[0009] The second positive lens is used to correct the coma and astigmatism of the system;

[0010] The first negative lens is used to correct the spherical aberration and astigmatism of the system;

[0011] The third positive lens is used to correct the axial chromatic aberration;

[0012] The fourth positive lens is used to correct the spherical aberration and distortion;

[0013] The second negative lens is used to correct the spherical aberration, and the rear surface of the second negative lens is a high-order aspherical surface;

[0014] The third negative lens is used to correct the field curvature and distortion.

[0015] Furthermore, the thickness of the first positive lens satisfies 0.09f < t1 < 0.12f, and it is made of quartz material with a refractive index of 1.42 to 1.75;

[0016] The thickness of the second positive lens satisfies 0.13f < t2 < 0.17f, with a refractive index of 1.42 to 1.75 and an Abbe number of 81 to 95;

[0017] The thickness of the first negative lens satisfies 0.07f < t3 < 0.12f, with a refractive index of 1.43 to 1.65 and an Abbe number of 34 to 55;

[0018] The thickness of the third positive lens satisfies 0.1f < t4 < 0.3f, with a refractive index of 1.42 to 1.47 and an Abbe number of 77 to 90;

[0019] The thickness of the fourth positive lens satisfies 0.15f < t5 < 0.27f, with a refractive index of 1.4 to 1.5 and an Abbe number of 70 to 90;

[0020] The thickness of the second negative lens satisfies 0.075f < t6 < 0.15f, with a refractive index of 1.59 to 1.69 and an Abbe number of 38 to 40;

[0021] The thickness of the third negative lens satisfies 0.035f < t7 < 0.075f, with a refractive index of 1.69 to 1.89 and an Abbe number of 27 to 30;

[0022] Where f is the focal length of the system.

[0023] Furthermore, the distance between the front surface of the second positive lens and the rear surface of the first positive lens satisfies 0.08f < d1 < 0.12f;

[0024] The distance from the front surface of the first negative lens to the rear surface of the second positive lens is 0.05f < d2 < 0.09f;

[0025] The distance from the rear surface of the first negative lens to the system aperture stop is 0.045f < d3 < 0.097f;

[0026] The distance from the front surface of the third positive lens to the system aperture stop is 0.28f < d4 < 0.55f;

[0027] The distance from the front surface of the fourth positive lens to the rear surface of the third positive lens is 0.007f < d5 < 0.015f;

[0028] The distance from the front surface of the second negative lens to the rear surface of the fourth positive lens is 0.035f < d6 < 0.06f;

[0029] The distance between the front surface of the third negative lens and the rear surface of the second negative lens is 0.21f < d7 < 0.45f;

[0030] The distance from the rear surface of the third negative lens to the image plane is: 0.025f < d8 < 0.065f.

[0031] Furthermore, the radius of curvature R1 of the front surface of the first positive lens is: 0.98f < R1 < 1.24f, and the radius of curvature R2 of the rear surface of the first positive lens is: 3.3f < R2 < 4.3f;

[0032] The radius of curvature R3 of the front surface of the second positive lens is: 0.95f < R3 < 1.32f, and the radius of curvature R4 of the rear surface of the second positive lens is: -8.7f < R4 < -6.7f;

[0033] The radius of curvature R5 of the front surface of the first negative lens is: -1.73f < R5 < -1.21f, and the radius of curvature R6 of the rear surface of the first negative lens is: 1.25f < R6 < 1.75f;

[0034] The radius of curvature R7 of the front surface of the third positive lens is: 0.55f < R7 < 0.78f, and the radius of curvature R8 of the rear surface of the third positive lens is: -2.84f < R8 < -2.1f;

[0035] The radius of curvature R9 of the front surface of the fourth positive lens is: 0.4f < R9 < 0.65f, and the radius of curvature R10 of the rear surface of the fourth positive lens is: -2.1f < R10 < -1.5f;

[0036] The radius of curvature R11 of the front surface of the second negative lens is: -1.2f < R11 < -0.85f, and the radius of curvature R12 of the rear surface of the second negative lens is: -2.96f < R12 < -2.25f;

[0037] The radius of curvature R13 of the front surface of the third negative lens is: -0.5f < R13 < -0.25f, and the radius of curvature R14 of the rear surface of the third negative lens is: -4.96f < R14 < -2.25f.

[0038] Furthermore, the relationship between the focal length f1 of the first positive lens and the system focal length f is: 3.3f < f1 < 4.2f;

[0039] The relationship between the focal length f2 of the second positive lens and the system focal length f is: 2.01f < f2 < 2.45f;

[0040] The relationship between the focal length f3 of the first negative lens and the system focal length f is: -1.2f < f3 < -1.01f;

[0041] The relationship between the focal length f4 of the third positive lens and the system focal length f is: 1.15f < f4 < 1.32f;

[0042] The relationship between the focal length f5 of the fourth positive lens and the system focal length f is: 0.8f < f5 < 1.1f;

[0043] The relationship between the focal length f6 of the second negative lens and the system focal length f is: -3.2f < f6 < -1.85f;

[0044] The relationship between the focal length f7 of the third negative lens and the system focal length f is: -0.7f < f7 < -0.45f.

[0045] Furthermore, the expression of the rear surface of the second negative lens 6 is as follows:

[0046]

[0047] where K = -2 to 1.5, A = 2.2e-08 to 5.5e-04, B = -9.119e-07 to -5.29e-013, C = 0; z is the aspherical sag at different apertures, c is the aspherical curvature, r is the aspherical aperture, K is the conic coefficient, and A, B, and C are the coefficients of the high-order terms of the aspherical surface.

[0048] Furthermore, the system focal length f is 108 mm;

[0049] In the first positive lens, f1 is 393.15 mm, t1 is 11.7 mm, R1 is 123.55 mm, and R2 is 384.74 mm;

[0050] The second positive lens has a refractive index of 1.42, an Abbe number of 93, an f2 of 240.3 mm, an R3 of 118.94 mm, an R4 of -789.05 mm, a thickness of 16.3 mm, and a d1 of 10.87 mm.

[0051] The first negative lens has a refractive index of 1.64, an Abbe number of 45, an f3 of -123.24 mm, an R5 of -161.82 mm, an R6 of 154.49 mm, a d2 of 7.93 mm, and a d3 of 6.93 mm.

[0052] The third positive lens has a refractive index of 1.45, an Abbe number of 89, an f4 of 135.87 mm, an R7 of 73.85 mm, an R8 of -261.65 mm, an t4 of 22 mm, and a d4 of 41 mm.

[0053] The fourth positive lens has a refractive index of 1.42, an Abbe number of 87, an f5 of 102.88 mm, an R9 of 56.12 mm, an R10 of -189.29 mm, an t5 of 22 mm, and a d5 of 1 mm.

[0054] The second negative lens has a refractive index of 1.67, an Abbe number of 39, an f6 of -262.63 mm, an R11 of -101.41 mm, an R12 of -261.4 mm, an t6 of 11.7 mm, and a d6 of 5.08 mm.

[0055] The third negative lens has a refractive index of 1.75, an Abbe number of 29, an f7 of -63.41 mm, an R13 of -41.16 mm, an R14 of -329.73 mm, an t7 of 5.63 mm, an d7 of 31 mm, and an d8 of 6 mm.

[0056] Furthermore, the rear surface of the second negative lens is expressed as follows:

[0057]

[0058] Where K=0, A=3.7687e-007, B=-4.1219e-010, C=0, z is the aspherical sagitta for different apertures, c is the aspherical curvature, r is the aspherical aperture, K is the quadratic surface coefficient, and A, B, and C are the coefficients of higher-order terms of higher-order aspherical surfaces.

[0059] Furthermore, the focal length f is 80mm;

[0060] The focal length f1 of the first positive lens is 291.22 mm, R1 is 91.52 mm, R2 is 284.99 mm, and t1 is 8.67 mm.

[0061] The second positive lens has a refractive index of 1.49, an Abbe number of 81, an f2 of 177.96 mm, an R3 of 88.1 mm, an R4 of -584.48 mm, an t2 of 12.07 mm, and a d1 of 8.05 mm.

[0062] The first negative lens has a refractive index of 1.65, an Abbe number of 42, an f3 of -91.3 mm, an R5 of -119.87 mm, an R6 of 114.44 mm, an t3 of 7.33 mm, an d2 of 5.87 mm, and an d3 of 5.13 mm.

[0063] The third positive lens has a refractive index of 1.43, an Abbe number of 90, an f4 of 100.62 mm, an R7 of 54.7 mm, an R8 of -193.82 mm, an t4 of 16.3 mm, and a d4 of 30.82 mm.

[0064] The fourth positive lens has a refractive index of 1.45, an Abbe number of 89, an f5 of 76.2, an R9 of 41.57 mm, an R10 of -140.21 mm, an t5 of 16.3 mm, and a d5 of 0.74 mm.

[0065] The second negative lens has a refractive index of 1.65, an Abbe number of 40, an f6 of -194.55 mm, an R11 of -75.12 mm, an R12 of -193.63 mm, and a thickness t6 of 8.67 mm; the distance d6 from the front surface of the second negative lens 6 to the rear surface of the fourth positive lens 5 is 3.76 mm.

[0066] The third negative lens has a refractive index of 1.75, an Abbe number of 30, an f7 of -46.96 mm, an R13 of -30.48 mm, an R14 of -244.24 mm, an t7 of 4.17 mm, an d7 of 23.23 mm, and an d8 of 4.44 mm.

[0067] Furthermore, the rear surface of the second negative lens is a high-order aspherical surface, as expressed below:

[0068]

[0069] Where K=0, A=9.2724e-007, B=-1.8483e-09, C=0, z is the aspherical sagitta for different apertures, c is the aspherical curvature, r is the aspherical aperture, K is the quadratic surface coefficient, and A, B, and C are coefficients of higher-order terms of higher-order aspherical surfaces.

[0070] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0071] 1. The higher-order aspherical surface in this invention is located on the rear surface of the second negative lens and appears as a concave surface when viewed along the optical axis, which makes the processing and inspection less difficult.

[0072] 2. In the optical system of the present invention, the first positive lens, the second positive lens and the negative lens are considered as a whole, and the third positive lens, the fourth positive lens and the second negative lens are considered as a whole. The two wholes form a quasi-symmetrical structure with respect to the system aperture stop, so that the maximum distortion of the system across the entire field of view is less than 0.1%.

[0073] 3. In this invention, the entrance pupil diameter exceeds 80mm and the diameter of 80% of the circle of confusion within the 14° field of view is controlled within the range of 8μm through the cooperation of multiple lenses and the use of aspherical surfaces, resulting in a uniform diffusion spot across the entire field of view. Attached Figure Description

[0074] Figure 1 This is a schematic diagram of the structure of the large-scale, low-distortion space debris detection optical system of the present invention.

[0075] Figure 2 The energy concentration curves of the large-scale low-distortion space debris detection optical system in Embodiment 1 of the present invention at 1°, 3°, 5°, and 7° are shown.

[0076] Figure 3 The diameter of the 80% energy circle is obtained by the large-scale, low-distortion space debris detection optical system in Embodiment 1 of the present invention.

[0077] Figure 4 The image shows the aberration and distortion curves obtained by the large-scale low-distortion space debris detection optical system in Embodiment 1 of the present invention.

[0078] Figure 5 The energy concentration curves of the large-scale low-distortion space debris detection optical system in Embodiment 2 of the present invention at 1°, 3°, 5°, and 7° are shown.

[0079] Figure 6 The diameter of the 80% energy circle is obtained by the large-scale, low-distortion space debris detection optical system in Embodiment 2 of the present invention.

[0080] The accompanying figure is labeled as follows:

[0081] 1. First positive lens, 2. Second positive lens, 3. First negative lens, 4. Third positive lens, 5. Fourth positive lens, 6. Second negative lens, 7. Third negative lens, 8. System aperture stop, 9. Phase plane. Detailed Implementation

[0082] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0083] This invention provides a large-scale, low-distortion space debris detection optical system, such as... Figure 1As shown, along the light propagation direction, a first positive lens 1, a second positive lens 2, a first negative lens 3, a third positive lens 4, a fourth positive lens 5, a second negative lens 6, a third negative lens 7, and a phase surface 9 are sequentially arranged on the same optical axis. The system aperture stop 8 is located between the first negative lens 3 and the third positive lens 4, and the rear surface of the second negative lens 6 is a high-order aspheric surface.

[0084] The first positive lens 1 is made of quartz material and is used as the anti-radiation window of the overall system and to correct the spherical aberration of the system. The relationship between its focal length f1 and the system focal length f is: 3.3f < f1 < 4.2f. The curvature radii R1 and R2 of the front and rear surfaces are respectively: 0.98f < R1 < 1.24f and 3.3f < R2 < 4.3f, and the thickness is 0.09f < t1 < 0.12f.

[0085] The refractive index of the second positive lens 2 is 1.42 - 1.75, and the Abbe number is 81 - 95. It mainly corrects the coma and astigmatism of the system. Its focal length f2 is: 2.01f < f2 < 2.45f. The curvature radii R3 and R4 of the front and rear surfaces are respectively: 0.95f < R3 < 1.32f and -8.7f < R4 < -6.7f, and the thickness is 0.13f < t2 < 0.17f; the distance between the front surface of the second positive lens 2 and the rear surface of the first positive lens 1 is 0.08f < d1 < 0.12f.

[0086] The refractive index of the material of the first negative lens 3 is 1.43 - 1.65, and the Abbe number is 34 - 55. It mainly corrects the spherical aberration and astigmatism of the system. Its focal length f3 is: -1.2f < f3 < -1.01f. The curvature radii R5 and R6 of the front and rear surfaces are respectively: -1.73f < R5 < -1.21f and 1.25f < R6 < 1.75f, and the thickness is 0.07f < t3 < 0.12f; the distance between the front surface of the first negative lens 3 and the rear surface of the second positive lens 2 is 0.05f < d2 < 0.09f; the distance between the rear surface of the first negative lens 3 and the system aperture stop 8 is 0.045f < d3 < 0.097f.

[0087] The refractive index of the third positive lens 4 is 1.42 - 1.47, and the Abbe number is 77 - 90. It mainly corrects the axial chromatic aberration. Its focal length f4 is: 1.15f < f4 < 1.32f. The curvature radii R7 and R8 of the front and rear surfaces are respectively: 0.55f < R7 < 0.78f and -2.84f < R8 < -2.1f, and the thickness is 0.1f < t4 < 0.3f; the distance between the front surface of the third positive lens 4 and the system aperture stop 8 is 0.28f < d4 < 0.55f.

[0088] The refractive index of the fourth positive lens 5 is 1.4 to 1.5, and the Abbe number is 70 to 90. It is mainly used to correct spherical aberration and distortion. Its focal length f5 is: 0.8f < f5 < 1.1f. The curvature radii R9 and R10 of the front and rear surfaces are respectively: 0.4f < R9 < 0.65f and -2.1f < R10 < -1.5f, and the thickness is 0.15f < t5 < 0.27f; the distance from the front surface of the fourth positive lens 5 to the rear surface of the third positive lens 4 is 0.007f < d5 < 0.015f.

[0089] The second negative lens 6 is mainly used to correct spherical aberration. Its refractive index is 1.59 to 1.69, and the Abbe number is 38 to 40. The focal length f6 is: -3.2f < f6 < -1.85f. The curvature radii R11 and R12 of the front and rear surfaces are respectively: -1.2f < R11 < -0.85f and -2.96f < R12 < -2.25f, and the thickness is 0.075f < t6 < 0.15f; the distance from the front surface of the second negative lens 6 to the rear surface of the fourth positive lens 5 is 0.035f < d6 < 0.06f; the rear surface of the second negative lens 6 is a high-order aspheric surface, mainly used to correct the spherical aberration of the system, and the expression is as follows:

[0090]

[0091] where K = -2 to 1.5, A = 2.2e-08 to 5.5e-04, B = -9.119e-07 to -5.29e-013, C = 0. z is the aspheric sag at different apertures, c is the aspheric curvature, r is the aspheric aperture, K is the conic coefficient, and A, B, C are the coefficients of the high-order terms of the high-order aspheric surface.

[0092] The third negative lens 7 is mainly used to correct field curvature and distortion. Its refractive index is 1.69 to 1.89, and the Abbe number is 27 to 30. The focal length f7 is: -0.7f < f7 < -0.45f. The curvature radii R13 and R14 of the front and rear surfaces are respectively: -0.5f < R13 < -0.25f and -4.96f < R14 < -2.25f, and the thickness is 0.035f < t7 < 0.075f; the distance between the front surface of the third negative lens 7 and the rear surface of the second negative lens 6 is 0.21f < d7 < 0.45f; the distance from the rear surface of the third negative lens 7 to the image plane 9 is: 0.025f < d8 < 0.065f.

[0093] Example 1

[0094] In the optical system, the entrance pupil diameter is 80 mm; the design wavelength is 450 nm to 850 nm; the field angle is 22°, and it is a circular field; the system focal length f is 108 mm; the F number is 1.35, so that when the energy concentration is 80%, the energy is concentrated within a circle with a diameter of 8 μm, and the distortion is less than 0.1%.

[0095] The first positive lens 1 is made of quartz, which serves as a radiation shielding window for the optical system and also corrects system aberrations. The focal length f1 is 393.15 mm. The radii of curvature R1 and R2 of the front and rear surfaces are 123.55 mm and 384.74 mm, respectively, and the thickness t1 is 11.7 mm.

[0096] The second positive lens 2 has a refractive index of 1.42, an Abbe number of 93, and a focal length f2 of 240.3 mm. The radii of curvature R3 and R4 of the front and rear surfaces are 118.94 mm and -789.05 mm, respectively, and the thickness t2 is 16.3 mm. The distance d1 from the front surface of the second positive lens 2 to the rear surface of the first positive lens 1 is 10.87 mm.

[0097] The first negative lens 3 is mainly used to correct the chromatic aberration of the system. It has a refractive index of 1.64, an Abbe number of 45, and a focal length of f3 of -123.24 mm. The radii of curvature R5 and R6 of the front and rear surfaces are -161.82 mm and 154.49 mm, respectively, and the thickness t3 is 9.9 mm. The distance d2 from the front surface of the first negative lens 3 to the rear surface of the second positive lens 2 is 7.93 mm. The distance d3 from the rear surface of the first negative lens 3 to the system aperture stop 8 is 6.93 mm.

[0098] The third positive lens 4 has a refractive index of 1.45, an Abbe number of 89, and a focal length of f4 of 135.87 mm. The radii of curvature R7 and R8 of the front and rear surfaces are 73.85 mm and -261.65 mm, respectively, and the thickness t4 is 22 mm. The distance d4 from the front surface of the third positive lens 4 to the system aperture stop 8 is 41 mm.

[0099] The fourth positive lens 5 has a refractive index of 1.42, an Abbe number of 87, and a focal length of f5 of 102.88 mm. The radii of curvature R9 and R10 of the front and rear surfaces are 56.12 mm and -189.29 mm, respectively, and the thickness t5 is 22 mm. The distance d5 from the front surface of the fourth positive lens 5 to the rear surface of the third positive lens 4 is 1 mm.

[0100] The second negative lens 6 has a refractive index of 1.67, an Abbe number of 39, and a focal length of f6 of -262.63 mm. The radii of curvature R11 and R12 of its front and rear surfaces are -101.41 mm and -261.4 mm, respectively, and its thickness t6 is 11.7 mm. The distance d6 from the front surface of the second negative lens 6 to the rear surface of the fourth positive lens 5 is 5.08 mm. The rear surface is a high-order aspherical surface, mainly used to correct spherical aberration in the system, and its expression is as follows:

[0101]

[0102] Where K=0, A=3.7687e-007, B=-4.1219e-010, C=0.

[0103] In the above formula, z is the aspherical sagitta for different apertures, c is the aspherical curvature, r is the aspherical aperture, K is the quadratic surface coefficient, and A, B, and C are the coefficients of higher-order terms of higher-order aspherical surfaces.

[0104] The third negative lens 7 has a refractive index of 1.75, an Abbe number of 29, and a focal length of f7 of -63.41 mm. The radii of curvature R13 and R14 of the front and rear surfaces are -41.16 mm and -329.73 mm, respectively, and the thickness t7 is 5.63 mm. The distance d7 from the front surface of the third negative lens 7 to the rear surface of the second negative lens 6 is 31 mm; the distance d8 from the rear surface of the third negative lens 7 to the image plane 9 is 6 mm.

[0105] like Figure 2 The energy concentration curves of the optical system provided in the above embodiments at 1°, 3°, 5°, and 7° are shown below. Figure 3 As shown, 80% of the energy circle diameters within the entire field of view are less than 8 μm, and the energy circle diameter range is controlled within 7.73 μm-6.65 μm.

[0106] like Figure 4 The optical system distortion curves provided in the above embodiments show that the distortion is less than 0.1% across the entire field of view.

[0107] Example 2

[0108] If the system aperture, focal length, and field of view are reduced, the system's blur spot will also be reduced.

[0109] In this embodiment, the entrance pupil diameter of the optical system is 60mm; the design wavelength is 450nm~850nm; the field of view is 14° and is a circular field of view; the focal length f is 80mm; so that when the energy concentration is 80%, the energy is concentrated in a circle with a diameter of 6μm, and the distortion is less than 0.1%.

[0110] The first positive lens 1 is made of quartz material and can serve as a radiation shielding window for the system while also correcting system aberrations. The focal length f1 of the first positive lens 1 is 291.22 mm, the radii of curvature R1 and R2 of the front and rear surfaces are 91.52 mm and 284.99 mm, respectively, and the thickness t1 is 8.67 mm.

[0111] The second positive lens 2 has a refractive index of 1.49, an Abbe number of 81, a focal length of f2 of 177.96 mm, radii of curvature R3 and R4 of the front and rear surfaces of 88.1 mm and -584.48 mm, respectively, and a thickness of t2 of 12.07 mm. The distance d1 from the front surface of the second positive lens 2 to the rear surface of the first positive lens 1 is 8.05 mm.

[0112] The first negative lens 3 is mainly used to correct the chromatic aberration of the system. Its refractive index is 1.65, its Abbe number is 42, its focal length f3 is -91.3mm, its front and rear surface radii of curvature R5 and R6 are -119.87mm and 114.44mm respectively, and its thickness t3 is 7.33mm. The distance d2 from the front surface of the first negative lens 3 to the rear surface of the second positive lens 2 is 5.87mm. The distance d3 from the rear surface of the first negative lens 3 to the system aperture stop 8 is 5.13mm.

[0113] The third positive lens 4 has a refractive index of 1.43, an Abbe number of 90, a focal length of f4 of 100.62 mm, radii of curvature R7 and R8 of the front and rear surfaces of 54.7 mm and -193.82 mm, respectively, and a thickness of t4 of 16.3 mm. The distance d4 from the front surface of the third positive lens 4 to the system aperture stop 8 is 30.82 mm.

[0114] The fourth positive lens 5 has a refractive index of 1.45, an Abbe number of 89, a focal length of f5 of 76.2, and radii of curvature R9 and R10 of the front and rear surfaces of 41.57 mm and -140.21 mm, respectively. Its thickness t5 is 16.3 mm. The distance d5 from the front surface of the fourth positive lens 5 to the rear surface of the third positive lens 4 is 0.74 mm.

[0115] The second negative lens 6 has a refractive index of 1.65, an Abbe number of 40, a focal length of f6 of -194.55 mm, and radii of curvature R11 and R12 of its front and rear surfaces of -75.12 mm and -193.63 mm, respectively. Its thickness t6 is 8.67 mm. The distance d6 from the front surface of the second negative lens 6 to the rear surface of the fourth positive lens 5 is 3.76 mm. The rear surface of the second negative lens 6 is a high-order aspherical surface, primarily used to correct spherical aberration in the system, and its expression is as follows:

[0116]

[0117] Where K=0, A=9.2724e-007, B=-1.8483e-09, C=0.

[0118] In the above formula, z is the aspherical sagitta for different apertures, c is the aspherical curvature, r is the aspherical aperture, K is the quadratic surface coefficient, and A, B, and C are coefficients of higher-order terms of higher-order aspherical surfaces.

[0119] The third negative lens 7 has a refractive index of 1.75, an Abbe number of 30, a focal length of f7 of -46.96 mm, radii of curvature R13 and R14 of its front and rear surfaces of -30.48 mm and -244.24 mm, respectively, and a thickness of t7 of 4.17 mm. The distance d7 from the front surface of the third negative lens 7 to the rear surface of the second negative lens 6 is 23.23 mm. The distance d8 from the rear surface of the third negative lens 7 to the image plane 9 is 4.44 mm.

[0120] like Figure 5 The energy concentration curves of the optical system provided in the above embodiments at 1°, 3°, 5°, and 7° are shown below. Figure 6 As shown, 80% of the energy circle diameters within the entire field of view are less than 6 μm, and the energy circle diameter range is controlled within 5.73 μm-4.93 μm.

Claims

1. A large-scale, low-distortion space debris detection optical system, characterized in that: It includes a first positive lens (1), a second positive lens (2), a first negative lens (3), a system aperture stop (8), a third positive lens (4), a fourth positive lens (5), a second negative lens (6), a third negative lens (7) and an image plane (9) which are sequentially arranged on the same optical axis along the light propagation direction; The first positive lens (1) is a convex-concave positive lens, and the relationship between its focal length f1 and the system focal length f is: 3.3f < f1 < 4.2f, which is used as the anti-radiation window of the system and corrects the spherical aberration of the system; The second positive lens (2) is a biconvex positive lens, and the relationship between its focal length f2 and the system focal length f is: 2.01f < f2 < 2.45f, which is used to correct the coma and astigmatism of the system; The first negative lens (3) is a biconcave negative lens, and the relationship between its focal length f3 and the system focal length f is: -1.2f < f3 < -1.01f, which is used to correct the spherical aberration and astigmatism of the system; The third positive lens (4) is a biconvex positive lens, and the relationship between its focal length f4 and the system focal length f is: 1.15f < f4 < 1.32f, which is used to correct the axial chromatic aberration; The fourth positive lens (5) is a biconvex positive lens, and the relationship between its focal length f5 and the system focal length f is: 0.8f < f5 < 1.1f, which is used to correct the spherical aberration and distortion; The second negative lens (6) is a concave-convex negative lens, and the relationship between its focal length f6 and the system focal length f is: -3.2f < f6 < -1.85f, which is used to correct the spherical aberration, and the rear surface of the second negative lens (6) is a high-order aspheric surface; The third negative lens (7) is a concave-convex negative lens, and the relationship between its focal length f7 and the system focal length f is: -0.7f < f7 < -0.45f, which is used to correct the field curvature and distortion.

2. The large-scale low-distortion space debris detection optical system according to claim 1, wherein: The thickness of the first positive lens (1) is 0.09f < t1 < 0.12f, and it is made of quartz material with a refractive index of 1.42 - 1.75; The thickness of the second positive lens (2) is 0.13f < t2 < 0.17f, with a refractive index of 1.42 - 1.75 and an Abbe number of 81 - 95; The thickness of the first negative lens (3) is 0.07f < t3 < 0.12f, with a refractive index of 1.43 - 1.65 and an Abbe number of 34 - 55; The thickness of the third positive lens (4) is 0.1f < t4 < 0.3f, with a refractive index of 1.42 - 1.47 and an Abbe number of 77 - 90; The thickness of the fourth positive lens (5) is 0.15f < t5 < 0.27f, with a refractive index of 1.4 - 1.5 and an Abbe number of 70 - 90; The thickness of the second negative lens (6) is 0.075f < t6 < 0.15f, with a refractive index of 1.59 - 1.69 and an Abbe number of 38 - 40; The thickness of the third negative lens (7) is 0.035f < t7 < 0.075f, with a refractive index of 1.69 - 1.89 and an Abbe number of 27 - 30; Wherein, f is the system focal length.

3. The large-scale low-distortion space debris detection optical system according to claim 2, wherein: The distance between the front surface of the second positive lens (2) and the rear surface of the first positive lens (1) is 0.08f < d1 < 0.12f; The distance between the front surface of the first negative lens (3) and the rear surface of the second positive lens (2) is 0.05f < d2 < 0.09f; The distance between the rear surface of the first negative lens (3) and the system aperture stop (8) is 0.045f < d3 < 0.097f; The distance between the front surface of the third positive lens (4) and the system aperture stop (8) is 0.28f < d4 < 0.55f; The distance between the front surface of the fourth positive lens (5) and the rear surface of the third positive lens (4) is 0.007f < d5 < 0.015f; The distance between the front surface of the second negative lens (6) and the rear surface of the fourth positive lens (5) is 0.035f < d6 < 0.06f; The distance between the front surface of the third negative lens (7) and the rear surface of the second negative lens (6) is 0.21f < d7 < 0.45f; The distance between the rear surface of the third negative lens (7) and the phase surface (9) is: 0.025f < d8 < 0.065f.

4. The large-scale low-distortion space debris detection optical system according to claim 3, wherein: The radius of curvature R1 of the front surface of the first positive lens (1) is: 0.98f < R1 < 1.24f, and the radius of curvature R2 of the rear surface of the first positive lens (1) is: 3.3f < R2 < 4.3f; The radius of curvature R3 of the front surface of the second positive lens (2) is: 0.95f < R3 < 1.32f, and the radius of curvature R4 of the rear surface of the second positive lens (2) is: -8.7f < R4 < -6.7f; The radius of curvature R5 of the front surface of the first negative lens (3) is: -1.73f < R5 < -1.21f, and the radius of curvature R6 of the rear surface of the first negative lens (3) is: 1.25f < R6 < 1.75f; The radius of curvature R7 of the front surface of the third positive lens (4) is: 0.55f < R7 < 0.78f, and the radius of curvature R8 of the rear surface of the third positive lens (4) is: -2.84f < R8 < -2.1f; The radius of curvature R9 of the front surface of the fourth positive lens (5) is: 0.4f < R9 < 0.65f, and the radius of curvature R10 of the rear surface of the fourth positive lens (5) is: -2.1f < R10 < -1.5f; The radius of curvature R11 of the front surface of the second negative lens (6) is: -1.2f < R11 < -0.85f, and the radius of curvature R12 of the rear surface of the second negative lens (6) is: -2.96f < R12 < -2.25f; The radius of curvature R13 of the front surface of the third negative lens (7) is: -0.5f < R13 < -0.25f, and the radius of curvature R14 of the rear surface of the third negative lens (7) is: -4.96f < R14 < -2.25f.

5. The large-scale low-distortion space debris detection optical system according to claim 4, wherein: The expression of the rear surface of the second negative lens 6 is as follows: Where K = -2 to 1.5, A = 2.2e-08 to 5.5e-04, B = -9.119e-07 to -5.29e-013, C = 0; z is the aspherical sagitta for different apertures, c is the aspherical curvature, r is the aspherical aperture, K is the quadratic surface coefficient, and A, B, and C are the coefficients of higher-order terms of higher-order aspherical surfaces.

6. The large-scale, low-distortion space debris detection optical system according to claim 5, characterized in that: The system has a focal length f of 108mm; In the first positive lens (1), f1 is 393.15mm, t1 is 11.7mm, R1 is 123.55mm, and R2 is 384.74mm; The second positive lens (2) has a refractive index of 1.42, an Abbe number of 93, an f2 of 240.3 mm, an R3 of 118.94 mm, an R4 of -789.05 mm, a thickness of 16.3 mm, and a d1 of 10.87 mm. The first negative lens (3) has a refractive index of 1.64, an Abbe number of 45, an f3 of -123.24 mm, an R5 of -161.82 mm, an R6 of 154.49 mm, a d2 of 7.93 mm, and a d3 of 6.93 mm. The third positive lens (4) has a refractive index of 1.45, an Abbe number of 89, an f4 of 135.87 mm, an R7 of 73.85 mm, an R8 of -261.65 mm, an t4 of 22 mm, and a d4 of 41 mm. The fourth positive lens (5) has a refractive index of 1.42, an Abbe number of 87, f5 of 102.88 mm, R9 of 56.12 mm, R10 of -189.29 mm, t5 of 22 mm, and d5 of 1 mm. The second negative lens (6) has a refractive index of 1.67, an Abbe number of 39, an f6 of -262.63 mm, an R11 of -101.41 mm, an R12 of -261.4 mm, an t6 of 11.7 mm, and a d6 of 5.08 mm. The third negative lens (7) has a refractive index of 1.75, an Abbe number of 29, a f7 of -63.41 mm, a R13 of -41.16 mm, a R14 of -329.73 mm, a t7 of 5.63 mm, a d7 of 31 mm, and a d8 of 6 mm.

7. The large-scale, low-distortion space debris detection optical system according to claim 6, characterized in that: The rear surface of the second negative lens (6) is expressed as follows: Where K=0, A=3.7687e-007, B=-4.1219e-010, C=0, z is the aspherical sagitta for different apertures, c is the aspherical curvature, r is the aspherical aperture, K is the quadratic surface coefficient, and A, B, and C are the coefficients of higher-order terms of higher-order aspherical surfaces.

8. The large-scale, low-distortion space debris detection optical system according to claim 5, characterized in that: The focal length f is 80mm; The focal length f1 of the first positive lens (1) is 291.22 mm, R1 is 91.52 mm, R2 is 284.99 mm, and t1 is 8.67 mm; The second positive lens (2) has a refractive index of 1.49, an Abbe number of 81, a f2 of 177.96 mm, a R3 of 88.1 mm, a R4 of -584.48 mm, a t2 of 12.07 mm, and a d1 of 8.05 mm. The first negative lens (3) has a refractive index of 1.65, an Abbe number of 42, a f3 of -91.3 mm, a R5 of -119.87 mm, a R6 of 114.44 mm, a t3 of 7.33 mm, a d2 of 5.87 mm, and a d3 of 5.13 mm. The third positive lens (4) has a refractive index of 1.43, an Abbe number of 90, f4 of 100.62 mm, R7 of 54.7 mm, R8 of -193.82 mm, t4 of 16.3 mm, and d4 of 30.82 mm. The fourth positive lens (5) has a refractive index of 1.45, an Abbe number of 89, f5 of 76.2, R9 of 41.57 mm, R10 of -140.21 mm, t5 of 16.3 mm, and d5 of 0.74 mm. The second negative lens (6) has a refractive index of 1.65, an Abbe number of 40, an f6 of -194.55 mm, an R11 of -75.12 mm, an R12 of -193.63 mm, a thickness t6 of 8.67 mm, and a d6 of 3.76 mm. The third negative lens (7) has a refractive index of 1.75, an Abbe number of 30, an f7 of -46.96 mm, an R13 of -30.48 mm, an R14 of -244.24 mm, an t7 of 4.17 mm, an d7 of 23.23 mm, and an d8 of 4.44 mm.

9. The large-scale, low-distortion space debris detection optical system according to claim 8, characterized in that: The rear surface of the second negative lens (6) is a high-order aspherical surface, as expressed below: Where K=0, A=9.2724e-007, B=-1.8483e-09, C=0, z is the aspherical sagitta for different apertures, c is the aspherical curvature, r is the aspherical aperture, K is the quadratic surface coefficient, and A, B, and C are coefficients of higher-order terms of higher-order aspherical surfaces.

Images