Lens for short-wave imaging detector in all-day star sensor and design method thereof

Abstract

This invention relates to star sensors, specifically to lenses for shortwave imaging detectors in all-weather star sensors and their design methods. It addresses the problem that shortwave imaging detectors are not yet widely used in all-weather star sensors, resulting in a lack of suitable optical lenses. The invention comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens group, and a seventh lens arranged sequentially along the optical path. The sixth lens group is a cemented lens, including a first cemented lens and a second cemented lens arranged sequentially along the optical path. This six-lens-plus-one-cemented-lens configuration results in low lens distortion, uniform dispersion under a telecentric optical path, which is beneficial for centroid extraction and improves the lens's response in the near-infrared band, enabling all-weather detection.

Description

Technical Field

[0001] This invention relates to star sensors, and more specifically to lenses for shortwave imaging detectors in all-day star sensors and their design methods. Background Technology

[0002] With the development of aerospace technology, the requirements for aircraft navigation technology are becoming increasingly stringent. Star sensors, as an indispensable tool in integrated navigation, have been continuously evolving towards higher precision and stronger environmental adaptability. Most existing star sensors are visible light star sensors, which are easily affected by space background radiation during daytime operation. The main source of space background radiation is the sun, whose spectrum has the highest radiance in the visible light band. Therefore, it is necessary to attempt star detection in bands far from the visible light spectrum, leading to the development of near-infrared star sensors. However, near-infrared star sensors have low response and weak signal energy in the near-infrared band, making all-day detection impossible. Therefore, the best approach is to try using the short-wave infrared band as the primary operating band for near-infrared star sensors.

[0003] In recent years, shortwave imaging detectors capable of shortwave infrared detection have developed rapidly. In particular, Sony announced the IMX990 detector, which has a pixel count of 1296×1032, a pixel size of only 5 micrometers, a quantum efficiency of 0.7, and a full-well charge of 120,000 electrons. The development of similar detectors has made it possible to realize all-sky star sensors. However, shortwave imaging detectors are not yet widely used in all-sky star sensors, so there are almost no suitable optical lenses. Summary of the Invention

[0004] The purpose of this invention is to solve the technical problem that shortwave imaging detectors are not yet widely used in all-day star sensors, and therefore there are almost no suitable optical lenses. The invention provides a lens for shortwave imaging detectors in all-day star sensors and its design method.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] A lens for a shortwave imaging detector in an all-day star sensor is characterized by comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens group, and a seventh lens arranged sequentially along the optical path.

[0007] The first lens is a biconvex lens with positive optical power, the second lens is a biconcave lens with negative optical power, the third lens is a biconvex lens with positive optical power, the fourth lens is a biconcave lens with negative optical power, the fifth lens is a meniscus lens with positive optical power and its exit surface is concave, the sixth lens group is a cemented lens, including a first cemented lens and a second cemented lens arranged sequentially along the optical path, the first cemented lens is a biconvex lens with positive optical power, the second cemented lens is a biconcave lens with negative optical power, and the seventh lens is a plano-concave lens with negative optical power, its incident surface is concave and its exit surface is planar.

[0008] The distance on the optical axis of the light path between the center of the exit surface of the first lens and the center of the incident surface of the second lens is 4.5-5.5 mm; the distance on the optical axis of the light path between the center of the exit surface of the second lens and the center of the incident surface of the third lens is 0.3-0.4 mm; the distance on the optical axis of the light path between the center of the exit surface of the third lens and the center of the incident surface of the fourth lens is 0.1 mm; the distance on the optical axis of the light path between the center of the exit surface of the fourth lens and the center of the incident surface of the fifth lens is 1.4-1.6 mm; the distance on the optical axis of the light path between the center of the exit surface of the fifth lens and the center of the incident surface of the first cemented lens of the sixth lens group is 26-27 mm; and the distance on the optical axis of the light path between the center of the exit surface of the second cemented lens of the sixth lens group and the center of the incident surface of the seventh lens is 2-2.5 mm.

[0009] Furthermore, the center thickness of the first lens is 5mm-7mm;

[0010] The center thickness of the second lens is 1.5mm-3mm;

[0011] The center thickness of the third lens is 4mm-5mm;

[0012] The center thickness of the fourth lens is 1.5mm-3mm;

[0013] The center thickness of the fifth lens is 1.5mm-3mm;

[0014] The center thickness of the first cemented mirror is 3.5mm-4mm;

[0015] The center thickness of the second cemented mirror is 1.5mm-3mm;

[0016] The center thickness of the seventh lens is 1.5mm-3mm.

[0017] Furthermore, the incident surface radius of curvature R11 of the first lens satisfies: 30mm < R11 < 35mm, and the exit surface radius of curvature R12 satisfies: -155mm < R12 < -150mm.

[0018] The incident surface radius of curvature R21 of the second lens satisfies: -50mm < R21 < -45mm, and the exit surface radius of curvature R22 satisfies: 12mm < R22 < 17mm;

[0019] The incident surface curvature radius R31 of the third lens satisfies: 14mm < R31 < 16mm, and the exit surface curvature radius R32 satisfies: -165mm < R32 < -155mm.

[0020] The incident surface curvature radius R41 of the fourth lens satisfies: -200mm < R41 < -180mm, and the exit surface curvature radius R42 satisfies: 11mm < R42 < 15mm.

[0021] The incident surface curvature radius R51 of the fifth lens satisfies: 12mm < R51 < 15mm, and the exit surface curvature radius R52 satisfies: 20mm < R52 < 25mm.

[0022] The incident surface radius of curvature R61 of the first cemented mirror satisfies: 20mm < R61 < 25mm, and the exit surface radius of curvature R62 satisfies: -65mm < R62 < -50mm.

[0023] The incident surface radius of curvature R63 of the second cemented mirror satisfies: -65mm < R63 < -50mm, and the exit surface radius of curvature R64 satisfies: 35mm < R64 < 45mm;

[0024] The incident surface radius of curvature R71 of the seventh lens satisfies: -65mm < R71 < -50mm, and the exit surface radius of curvature R72 is infinite.

[0025] Furthermore, the refractive index n1 of the first lens satisfies: 1.75 < n1 < 1.85;

[0026] The refractive index n2 of the second lens satisfies: 1.45 < n2 < 1.55;

[0027] The refractive index n3 of the third lens satisfies: 1.85 < n3 < 1.95;

[0028] The refractive index n4 of the fourth lens satisfies: 1.85 < n4 < 1.95;

[0029] The refractive index n5 of the fifth lens satisfies: 1.75 < n5 < 1.85;

[0030] The refractive index n61 of the first cemented mirror satisfies: 1.85 < n61 < 1.95;

[0031] The refractive index n62 of the second cemented mirror satisfies: 1.45 < n62 < 1.55;

[0032] The refractive index n7 of the seventh lens satisfies: 1.45 < n7 < 1.55.

[0033] Furthermore, the Abbe number ν1 of the first lens satisfies: 40 < ν1 < 50;

[0034] The Abbe number ν2 of the second lens satisfies: 70 < ν2 < 85;

[0035] The Abbe number ν3 of the third lens satisfies: 30 < ν3 < 40;

[0036] The Abbe number ν4 of the fourth lens satisfies: 15 < ν4 < 20;

[0037] The Abbe number ν5 of the fifth lens satisfies: 45 < ν5 < 55;

[0038] The Abbe number ν61 of the first cemented mirror satisfies: 15 < ν61 < 55;

[0039] The Abbe number ν62 of the second cemented mirror satisfies: 75 < ν62 < 84;

[0040] The Abbe number ν7 of the seventh lens satisfies: 55 < ν7 < 75.

[0041] Furthermore, the distance on the optical axis of the first lens (exit surface center) and the second lens (incident surface center) is 5 mm; the distance on the optical axis of the second lens (exit surface center) and the third lens (incident surface center) is 0.34 mm; the distance on the optical axis of the fourth lens (exit surface center) and the fifth lens (incident surface center) is 1.56 mm; the distance on the optical axis of the fifth lens (exit surface center) and the first cemented lens (incident surface center) of the sixth lens group is 26.70 mm; and the distance on the optical axis of the optical axis of the seventh lens (incident surface center) and the second cemented lens (exit surface center) of the sixth lens group is 2.33 mm.

[0042] Furthermore, it also includes an aperture stop, which is disposed on the incident surface of the fourth lens.

[0043] Meanwhile, this invention also provides a design method for a lens used in a shortwave imaging detector in an all-day star sensor, which is characterized by including the following steps:

[0044] S1. The initial design is a three-element positive-negative-positive structure. The positive lens at the incident end is a biconvex lens with positive optical power. The positive lens at the exit end includes a cemented lens group and a plano-concave lens with negative optical power. The first cemented lens in the cemented lens group is a biconvex lens with positive optical power, and the second cemented lens in the cemented lens group is a biconcave lens with positive optical power. The middle negative lens adopts a structure of multiple lens combinations.

[0045] S2. Perform collimation and telecentrication on the positive lens at the exit end;

[0046] S3. The multiple lenses of the intermediate negative lens are split and combined to eliminate chromatic aberration and coma throughout the lens until good imaging of the short-wavelength broadband band is achieved.

[0047] Compared with the prior art, the beneficial effects of the present invention are:

[0048] (1) The lens for shortwave imaging detector in an all-day star sensor provided by the present invention adopts the form of six lenses plus a set of cemented mirrors. The lens distortion is small and the diffuse spot is uniform under the telecentric optical path, which is conducive to the extraction of the centroid of the spot and improves the response of the lens in the near-infrared band, and can perform all-day detection.

[0049] (2) The design method of the lens for the shortwave imaging detector in the all-day star sensor provided by the present invention evolves from the initial three-piece positive-negative-positive structure. The positive lens at the output end includes a cemented lens group and a plano-concave lens with negative optical power. The first cemented lens of the cemented lens group is a biconvex lens with positive optical power, and the second cemented lens of the cemented lens group is a biconcave lens with positive optical power. The middle negative lens adopts a structure of multiple lens combinations. The positive lens at the output end is collimated and telecentrically shaped, and the multiple lenses of the middle negative lens are split and combined to eliminate the chromatic aberration and coma of the entire lens, and finally achieve good imaging of the shortwave broadband band. Attached Figure Description

[0050] Figure 1 This is an optical path diagram of an embodiment of the lens used in the shortwave imaging detector of the all-day star sensor of the present invention;

[0051] Figure 2 This is a modulation transfer function diagram of an embodiment of the lens used in the shortwave imaging detector of the all-day star sensor of the present invention;

[0052] Figure 3 This is a distortion curve diagram of an embodiment of the lens used in the shortwave imaging detector of the all-day star sensor of the present invention;

[0053] Figure 4 This is a blur pattern at the focal plane of an embodiment of the lens used in the shortwave imaging detector of the all-day star sensor of the present invention;

[0054] Figure 5 This is a loop energy diagram at the focal plane of an embodiment of the lens used in the shortwave imaging detector of the all-day star sensor of the present invention;

[0055] Figure 6 This is a blur pattern at the defocus point in an embodiment of the lens used in the shortwave imaging detector of the all-day star sensor of the present invention;

[0056] Figure 7 This is a wraparound energy diagram at the defocus point of an embodiment of the lens used in the shortwave imaging detector of the all-day star sensor of the present invention.

[0057] The annotations in the attached figures are explained as follows:

[0058] 1-First lens, 2-Second lens, 3-Third lens, 4-Fourth lens, 5-Fifth lens, 6-Sixth lens group, 61-First cemented lens, 62-Second cemented lens; 7-Seventh lens, 8-Focal plane. Detailed Implementation

[0059] The present invention will be further described below with reference to the accompanying drawings and exemplary embodiments.

[0060] Reference Figures 1-7 The lens for the shortwave imaging detector in the all-weather star sensor of the present invention includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens group 6, and a seventh lens 7 arranged sequentially along the optical path. The sixth lens group 6 is a cemented lens, including a first cemented lens 61 and a second cemented lens 62 arranged sequentially along the optical path. An aperture is also provided on the incident surface of the fourth lens 4, and the light emitted from the seventh lens 7 is finally imaged on the focal plane 8.

[0061] The first lens 1 is a biconvex lens with positive optical power, made of HZLAF69_CDGM material; the second lens 2 is a biconcave lens with negative optical power, made of HFK61_CDGM material; the third lens 3 is a biconvex lens with positive optical power, made of HZLAF4LA_CDGM material; the fourth lens 4 is a biconcave lens with negative optical power, made of HZF88_CDGM material; the fifth lens 5 is a meniscus lens with positive optical power, its exit surface being concave, made of HLAK53A_CDGM material; the first cemented lens 61 is a biconvex lens with positive optical power, made of HZLAF4LA_CDGM material; the second cemented lens 62 is a biconcave lens with positive optical power, made of DFK61_CDGM material; and the seventh lens 7 is a plano-concave lens with negative optical power, its incident surface being concave and its exit surface being planar, made of HQK3L_CDGM material.

[0062] The distance on the optical axis between the center of the exit surface of the first lens 1 and the center of the incident surface of the second lens 2 is 4.5-5.5 mm; the distance on the optical axis between the center of the exit surface of the second lens 2 and the center of the incident surface of the third lens 3 is 0.3-0.4 mm; the distance on the optical axis between the center of the exit surface of the third lens 3 and the center of the incident surface of the fourth lens 4 is 0.1 mm; the distance on the optical axis between the center of the exit surface of the fourth lens 4 and the center of the incident surface of the fifth lens 5 is 1.4-1.6 mm; the distance on the optical axis between the center of the exit surface of the fifth lens 5 and the center of the incident surface of the first cemented lens 61 of the sixth lens group 6 is 26-27 mm; and the distance on the optical axis between the center of the exit surface of the second cemented lens 62 of the sixth lens group 6 and the center of the incident surface of the seventh lens 7 is 2-2.5 mm.

[0063] In this embodiment, the distance on the optical axis between the center of the exit surface of the first lens 1 and the center of the incident surface of the second lens 2 is 5 mm; the distance on the optical axis between the center of the exit surface of the second lens 2 and the center of the incident surface of the third lens 3 is 0.34 mm; the distance on the optical axis between the center of the exit surface of the fourth lens 4 and the center of the incident surface of the fifth lens 5 is 1.56 mm; the distance on the optical axis between the center of the exit surface of the fifth lens 5 and the center of the incident surface of the first cemented lens 61 of the sixth lens group 6 is 26.70 mm; and the distance on the optical axis between the center of the exit surface of the second cemented lens 62 of the sixth lens group 6 and the center of the incident surface of the seventh lens 7 is 2.33 mm.

[0064] The center thickness of the first lens 1 is 5mm-7mm, the center thickness of the second lens 2 is 1.5mm-3mm, the center thickness of the third lens 3 is 4mm-5mm, the center thickness of the fourth lens 4 is 1.5mm-3mm, the center thickness of the fifth lens 5 is 1.5mm-3mm, the center thickness of the first cemented lens 61 is 3.5mm-4mm, the center thickness of the second cemented lens 62 is 1.5mm-3mm, and the center thickness of the seventh lens 7 is 1.5mm-3mm.

[0065] The incident surface radius of curvature R11 of the first lens 1 satisfies: 30mm < R11 < 35mm, and the exit surface radius of curvature R12 satisfies: -155mm < R12 < -150mm; the incident surface radius of curvature R21 of the second lens 2 satisfies: -50mm < R21 < -45mm, and the exit surface radius of curvature R22 satisfies: 12mm < R22 < 17mm; the incident surface radius of curvature R31 of the third lens 3 satisfies: 14mm < R31 < 16mm, and the exit surface radius of curvature R32 satisfies: -165mm < R32 < -155mm; the incident surface radius of curvature R41 of the fourth lens 4 satisfies: -200mm < R41 < -180mm, and the exit surface radius of curvature R42 satisfies: 11mm < 35mm. R42 < 15mm; The incident surface radius of curvature R51 of the fifth lens 5 satisfies: 12mm < R51 < 15mm, and the exit surface radius of curvature R52 satisfies: 20mm < R52 < 25mm; The incident surface radius of curvature R61 of the first cemented lens 61 satisfies: 20mm < R61 < 25mm, and the exit surface radius of curvature R62 satisfies: -65mm < R62 < -50mm; The incident surface radius of curvature R63 of the second cemented lens 62 satisfies: -65mm < R63 < -50mm, and the exit surface radius of curvature R64 satisfies: 35mm < R64 < 45mm; The incident surface radius of curvature R71 of the seventh lens 7 satisfies: -65mm < R71 < -50mm, and the exit surface radius of curvature R72 is infinite.

[0066] The refractive index n1 of the first lens 1 satisfies: 1.75 < n1 < 1.85; the refractive index n2 of the second lens 2 satisfies: 1.45 < n2 < 1.55; the refractive index n3 of the third lens 3 satisfies: 1.85 < n3 < 1.95; the refractive index n4 of the fourth lens 4 satisfies: 1.85 < n4 < 1.95; the refractive index n5 of the fifth lens 5 satisfies: 1.75 < n5 < 1.85; the refractive index n61 of the first cemented mirror 61 satisfies: 1.85 < n61 < 1.95; the refractive index n62 of the second cemented mirror 62 satisfies: 1.45 < n62 < 1.55; and the refractive index n7 of the seventh lens 7 satisfies: 1.45 < n7 < 1.55.

[0067] The Abbe number ν1 of the first lens 1 satisfies: 40 < ν1 < 50; the Abbe number ν2 of the second lens 2 satisfies: 70 < ν2 < 85; the Abbe number ν3 of the third lens 3 satisfies: 30 < ν3 < 40; the Abbe number ν4 of the fourth lens 4 satisfies: 15 < ν4 < 20; the Abbe number ν5 of the fifth lens 5 satisfies: 45 < ν5 < 55; the Abbe number ν61 of the first cemented lens 61 satisfies: 15 < ν61 < 55; the Abbe number ν62 of the second cemented lens 62 satisfies: 75 < ν62 < 84; and the Abbe number ν7 of the seventh lens 7 satisfies: 55 < ν7 < 75.

[0068] In this embodiment, the specific parameters of each lens are shown in Table 1:

[0069] Table 1

[0070]

[0071] Note: In the description of the material properties (refractive index and Abbe number), for example, 8130.4353 means that the refractive index is 1.813020 and the Abbe number is 43.53.

[0072] The entire lens is suitable for shortwave imaging detectors smaller than 1 / 1.3 inch, with dimensions of Φ30mm×65mm, a focal length of 50mm, an estimated weight of no more than 50g, and an F-number of 2.

[0073] from Figure 2 As can be seen, at the focal plane, its full-field optical modulation transfer function is close to the diffraction limit, and the full-field optical modulation transfer function can reach 0.4@100lp / mm, which can achieve good imaging results; from Figure 3 It can be seen that the lens has good distortion control, with distortion across the entire field of view kept below 0.5%; from Figure 4 It can be seen that the lens has good convergence of the blur spots, with no obvious coma, astigmatism, or chromatic aberration; Figure 5 It can be seen that this lens can concentrate more than 70% of the energy within a 5-micrometer range at the focal plane, and more than 90% of the energy within a 10-micrometer range, exhibiting good light-gathering effect; Figure 6 It can be seen that the lens has good circularity of the blur spot, which is very beneficial for subsequent centroid extraction algorithms; Figure 7 It can be seen that the lens can concentrate more than 70% of the energy within a 30-micrometer range at the defocus point, and more than 90% of the energy within a 40-micrometer range, which has a good light-gathering effect.

[0074] The lens provided by this invention for a shortwave imaging detector in an all-weather star sensor employs a six-lens configuration plus a set of cemented mirrors. It can achieve high-quality point target imaging in the spectral range of 900nm to 1500nm, with minimal overall lens distortion (less than 0.5% across the entire field of view) and a telecentricity of no more than 2° across the entire field of view. The uniform dispersion pattern under the quasi-telecentric optical path facilitates the extraction of the spot centroid and improves the lens's response in the near-infrared band, enabling all-weather detection.

[0075] This invention also provides a design method for a lens used in a shortwave imaging detector in an all-weather star sensor, comprising the following steps:

[0076] S1. The initial design is a three-element positive-negative-positive structure, in which the positive lens at the incident end is a biconvex lens with positive optical power, and the positive lens at the exit end includes a cemented lens group and a plano-concave lens with negative optical power. The first cemented lens 61 of the cemented lens group is a biconvex lens with positive optical power, and the second cemented lens 62 of the cemented lens group is a biconcave lens with positive optical power. The middle negative lens adopts a structure of multiple lens combinations.

[0077] S2. Perform collimation and telecentrication on the positive lens at the exit end;

[0078] S3. The multiple lenses of the intermediate negative lens are split and combined to eliminate chromatic aberration and coma throughout the lens until good imaging of the short-wavelength broadband band is achieved.

[0079] The embodiments described above are merely illustrative of specific implementations of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A lens for a short-wave imaging detector in an all-weather star sensor, characterized in that: It includes a first lens (1), a second lens (2), a third lens (3), a fourth lens (4), a fifth lens (5), a sixth lens group (6), and a seventh lens (7) arranged sequentially along the optical path; The first lens (1) is a biconvex lens with positive optical power, the second lens (2) is a biconcave lens with negative optical power, the third lens (3) is a biconvex lens with positive optical power, the fourth lens (4) is a biconcave lens with negative optical power, the fifth lens (5) is a meniscus lens with positive optical power and its exit surface is concave, the sixth lens group (6) is a cemented lens, including a first cemented lens (61) and a second cemented lens (62) arranged sequentially along the optical path, the first cemented lens (61) is a biconvex lens with positive optical power, the second cemented lens (62) is a biconcave lens with negative optical power, and the seventh lens (7) is a plano-concave lens with negative optical power, its incident surface is concave and its exit surface is planar; The distance between the center of the exit surface of the first lens (1) and the center of the incident surface of the second lens (2) on the optical axis of the optical path is 4.5-5.5 mm. The distance between the center of the exit surface of the second lens (2) and the center of the incident surface of the third lens (3) on the optical axis of the optical path is 0.3-0.4 mm. The distance between the center of the exit surface of the third lens (3) and the center of the incident surface of the fourth lens (4) on the optical axis of the optical path is 0.1 mm. The distance between the center of the exit surface of the fourth lens (4) and the center of the incident surface of the fifth lens (5) on the optical axis of the optical path is 1.4-1.6 mm. The distance between the center of the exit surface of the fifth lens (5) and the center of the incident surface of the first cemented lens (61) of the sixth lens group (6) on the optical axis of the optical path is 26-27 mm. The distance between the center of the exit surface of the second cemented lens (62) of the sixth lens group (6) and the center of the incident surface of the seventh lens (7) on the optical axis of the optical path is 2-2.5 mm. The refractive index n1 of the first lens (1) satisfies: 1.75 < n1 < 1.85; the refractive index n2 of the second lens (2) satisfies: 1.45 < n2 < 1.55; the refractive index n3 of the third lens (3) satisfies: 1.85 < n3 < 1.95; the refractive index n4 of the fourth lens (4) satisfies: 1.85 < n4 < 1.95; the refractive index n5 of the fifth lens (5) satisfies: 1.75 < n5 < 1.85; the refractive index n61 of the first cemented mirror (61) satisfies: 1.85 < n61 < 1.95; the refractive index n62 of the second cemented mirror (62) satisfies: 1.45 < n62 < 1.55; the refractive index n7 of the seventh lens (7) satisfies: 1.45 < n7 < 1.55; The Abbe number ν1 of the first lens (1) satisfies: 40 < ν1 < 50; the Abbe number ν2 of the second lens (2) satisfies: 70 < ν2 < 85; the Abbe number ν3 of the third lens (3) satisfies: 30 < ν3 < 40; the Abbe number ν4 of the fourth lens (4) satisfies: 15 < ν4 < 20; the Abbe number ν5 of the fifth lens (5) satisfies: 45 < ν5 < 55; the Abbe number ν61 of the first cemented lens (61) satisfies: 15 < ν61 < 55; the Abbe number ν62 of the second cemented lens (62) satisfies: 75 < ν62 < 84; the Abbe number ν7 of the seventh lens (7) satisfies: 55 < ν7 < 75.

2. The lens for a shortwave imaging detector in an all-weather star sensor according to claim 1, characterized in that: The center thickness of the first lens (1) is 5mm-7mm; The center thickness of the second lens (2) is 1.5mm-3mm; The center thickness of the third lens (3) is 4mm-5mm; The center thickness of the fourth lens (4) is 1.5mm-3mm; The center thickness of the fifth lens (5) is 1.5mm-3mm; The center thickness of the first cemented mirror (61) is 3.5mm-4mm; The center thickness of the second cemented mirror (62) is 1.5mm-3mm; The center thickness of the seventh lens (7) is 1.5mm-3mm.

3. The lens for a shortwave imaging detector in an all-weather star sensor according to claim 2, characterized in that: The incident surface curvature radius R11 of the first lens (1) satisfies: 30mm < R11 < 35mm, and the exit surface curvature radius R12 satisfies: -155mm < R12 < -150mm; The incident surface radius of curvature R21 of the second lens (2) satisfies: -50mm < R21 < -45mm, and the exit surface radius of curvature R22 satisfies: 12mm < R22 < 17mm; The incident surface curvature radius R31 of the third lens (3) satisfies: 14mm < R31 < 16mm, and the exit surface curvature radius R32 satisfies: -165mm < R32 < -155mm; The incident surface curvature radius R41 of the fourth lens (4) satisfies: -200mm < R41 < -180mm, and the exit surface curvature radius R42 satisfies: 11mm < R42 < 15mm. The incident surface curvature radius R51 of the fifth lens (5) satisfies: 12mm < R51 < 15mm, and the exit surface curvature radius R52 satisfies: 20mm < R52 < 25mm. The incident surface curvature radius R61 of the first cemented mirror (61) satisfies: 20mm < R61 < 25mm, and the exit surface curvature radius R62 satisfies: -65mm < R62 < -50mm; The incident surface radius of curvature R63 of the second cemented mirror (62) satisfies: -65mm < R63 < -50mm, and the exit surface radius of curvature R64 satisfies: 35mm < R64 < 45mm; The incident surface curvature radius R71 of the seventh lens (7) satisfies: -65mm < R71 < -50mm, and the exit surface curvature radius R72 is infinite.

4. The lens for a shortwave imaging detector in an all-weather star sensor according to claim 1, characterized in that: The distance between the center of the exit surface of the first lens (1) and the center of the incident surface of the second lens (2) on the optical axis of the optical path is 5 mm. The distance between the center of the exit surface of the second lens (2) and the center of the incident surface of the third lens (3) on the optical axis of the optical path is 0.34 mm. The distance between the center of the exit surface of the fourth lens (4) and the center of the incident surface of the fifth lens (5) on the optical axis of the optical path is 1.56 mm. The distance between the center of the exit surface of the fifth lens (5) and the center of the incident surface of the first cemented lens (61) of the sixth lens group (6) on the optical axis of the optical path is 26.70 mm. The distance between the center of the exit surface of the second cemented lens (62) of the sixth lens group (6) and the center of the incident surface of the seventh lens (7) on the optical axis of the optical path is 2.33 mm.

5. The lens for a shortwave imaging detector in an all-weather star sensor according to claim 1, characterized in that: It also includes an aperture stop, which is disposed on the incident surface of the fourth lens (4).

6. A design method of a lens for a short-wave imaging detector in an all-weather star sensor based on the lens of claim 1, characterized in that, Includes the following steps: S1. The initial design is a three-element positive-negative-positive structure, wherein the positive lens at the incident end is a biconvex lens with positive optical power, and the positive lens at the exit end includes a cemented lens group and a plano-concave lens with negative optical power. The first cemented lens (61) of the cemented lens group is a biconvex lens with positive optical power, and the second cemented lens (62) of the cemented lens group is a biconcave lens with positive optical power. The middle negative lens adopts a structure of multiple lens combinations. S2. Perform collimation and telecentrication on the positive lens at the exit end; S3. The multiple lenses of the intermediate negative lens are split and combined to eliminate chromatic aberration and coma throughout the lens until good imaging of the short-wavelength broadband band is achieved.

Images