Refraction and reflection type optical system for infrared star sensor

Abstract

The catadioptric optical system for the infrared star sensor comprises an optical filter L12, a reflector group and a correction transmission lens group, the reflector group is composed of a first reflector L1 and a second reflector L2 which are coaxially arranged along the light propagation direction, a light passing opening is formed in the center of the second reflector L2, and the correction transmission lens group is connected with the first reflector L1 and the second reflector L2. The correction transmission lens group is composed of a first lens L3, a second lens L4, a third lens L5, a fourth lens L6, a fifth lens L7, a sixth lens L8, a seventh lens L9, an eighth lens L10 and a ninth lens L11 which are coaxially arranged in the light propagation direction, and the correction transmission lens group is arranged on the side, away from the first reflector L1, of the second reflector L2; and the optical filter L12 is arranged on one side, far away from the eighth lens L10, of the ninth lens L11, so that the distortion value of the catadioptric optical system can be effectively reduced, and the catadioptric optical system is high in detection capability and high in detection precision.

Description

[0001] The utility model relates to a folding-reflective optical system for an infrared star sensor. The present application claims priority. The application number of the prior application is: 202421510123.5, and the name is: A folding-reflective optical system for an infrared star sensor. The priority date is: 2024-6-28. Technical Field

[0002] The utility model relates to the technical field of optical systems, in particular to a catadioptric optical system used for an infrared star sensor. Background Art

[0003] A star sensor is a high-precision optical attitude sensor that uses stars as reference sources. It is currently the most accurate attitude measurement instrument. Generally speaking, traditional visible light star sensors are greatly affected by background stray light and can only be used for star measurement outside the atmosphere or at night. Moreover, the optical system is mostly transmissive. With the rapid development of navigation technology, the requirements for star sensors are getting higher and higher.

[0004] The optical system is an important part in the development of star sensors. However, the optical system of existing star sensors has large distortion, which leads to low detection accuracy of the optical system.

[0005] Therefore, the utility model is dedicated to providing a catadioptric optical system for an infrared star sensor to solve the above problems. Utility Model Content

[0006] The utility model aims to provide a catadioptric optical system for an infrared star sensor, which can effectively reduce the distortion value of the optical system when presenting an image by coaxially arranging a plurality of reflectors and lenses along the direction of light propagation, has strong detection capability and high precision, and ensures the imaging quality and observation effect of the star sensor.

[0007] The technical solution provided by the utility model is as follows:

[0008] A catadioptric optical system for an infrared star sensor comprises a filter L12, a reflector group and a correction transmission mirror group. The reflector group consists of a first reflector L1 and a second reflector L2 coaxially arranged at intervals along a light propagation direction, and a light aperture is provided at the center of the second reflector L2.

[0009] The correction transmission lens group consists of a first lens L3, a second lens L4, a third lens L5, a fourth lens L6, a fifth lens L7, a sixth lens L8, a seventh lens L9, an eighth lens L10 and a ninth lens L11 which are coaxially arranged at intervals along the light propagation direction, and the correction transmission lens group is arranged on a side of the second reflector L2 away from the first reflector L1.

[0010] The filter L12 is disposed on a side of the ninth lens L11 away from the eighth lens L10.

[0011] In some embodiments, the first lens L3, the second lens L4, the third lens L5, the fourth lens L6, the fifth lens L7, the sixth lens L8, the seventh lens L9, the eighth lens L10 and the ninth lens L11 meet the following conditions:

[0012] 10mm<d1<10.13mm, 3.8mm<d2<4.2mm, 8.5mm<d3<8.8mm, 8.2mm<d4<8.5mm;

[0013] 3.8mm<d5<4.1mm, 3.8mm<d6<4.1mm, 3.8mm<d7<4.1mm, 3.8mm<d8<4.1mm, 6.8mm<d9<7.1mm;

[0014] Wherein, d1 is the thickness of the first lens L3, d2 is the thickness of the second lens L4, d3 is the thickness of the third lens L5, d4 is the thickness of the fourth lens L6, d5 is the thickness of the fifth lens L7, d6 is the thickness of the sixth lens L8, d7 is the thickness of the seventh lens L9, d8 is the thickness of the eighth lens L10, and d9 is the thickness of the ninth lens L11.

[0015] In some embodiments, the first reflector L1 is convex toward a direction close to the second reflector L2, and a side of the second reflector L2 close to the first reflector L1 is concave.

[0016] The material of the first reflector L1 is N-FK5, and the material of the second reflector L2 is silicon carbide.

[0017] In some embodiments, the first lens L3, the fifth lens L7 and the sixth lens L8 are all negative meniscus lenses, and the third lens L5 and the fourth lens L6 are all biconvex lenses.

[0018] In some embodiments, the second lens L4, the seventh lens L9 and the eighth lens L10 are all biconcave lenses, and the ninth lens L11 is a plano-concave lens.

[0019] In some embodiments, the first lens L3, the fifth lens L7 and the sixth lens L8 are all made of ZNSE, the third lens L5 is made of ZNS, and the fourth lens L6 is made of N-PK52A.

[0020] In some embodiments, the second lens L4 and the eighth lens L10 are made of JGSI, the seventh lens L9 is made of ZNS, and the ninth lens L11 is made of ZNSE.

[0021] In some embodiments, the distance between the second reflector L2 and the first lens L3 is D2, 165mm<D2<165.3mm, the distance between the first lens L3 and the second lens L4 is D3, 4mm<D3<4.3mm, the distance between the second lens L4 and the third lens L5 is D4, 3mm<D4<3.3mm, the distance between the third lens L5 and the fourth lens L6 is D5, 117.5mm<D5<118mm, the distance between the fourth lens L6 and the fifth lens L7 is D8, 117.5mm<D8<118mm, the distance between the fourth lens L6 and the fifth lens L7 is D9, 118mm<D9<118mm, the distance between the fourth lens L6 and the fifth lens L7 is D10, 118mm<D10<118mm, the distance between the second lens L4 and the third lens L5 is D11, 118mm<D10<118mm, the distance between the third lens L5 and the fourth lens L6 is D12, 118mm<D10<118mm, the distance between the fourth lens L6 and the fifth lens L7 is D13, 118mm<D10<118mm, the distance between the second lens L4 and the third lens L5 is D14, 3mm<D4<3.3mm, the distance between the third lens L5 and the fourth lens L6 is D15, 117.5mm<D10<118mm, the distance between the fourth lens L6 and the fifth lens L7 is D15, 118mm<D10<118mm, the distance between the The distance between the fifth lens L7 and the sixth lens L8 is D6, 1.75mm<D6<2.05mm, the distance between the fifth lens L7 and the sixth lens L8 is D7, 0.1mm<D7<0.4mm, the distance between the sixth lens L8 and the seventh lens L9 is D8, 1.6mm<D8<1.9mm, the distance between the seventh lens L9 and the eighth lens L10 is D9, 3.5mm<D9<3.8mm, the distance between the eighth lens L10 and the ninth lens L11 is D10, 30.1mm<D10<30.4mm;

[0022] and / or

[0023] The distance between the first reflector L1 and the second reflector L2 is D1, 139.5 mm < D1 < 139.9 mm;

[0024] and / or

[0025] The diameter of the second reflector L2 is 140 mm.

[0026] In some embodiments, the curvature radii of the first lens L3, the second lens L4, the third lens L5, the fourth lens L6, the fifth lens L7, the sixth lens L8, the seventh lens L9, the eighth lens L10 and the ninth lens L11 satisfy the following conditions:

[0027] -30mm<R S1 <-20mm, -35mm<R S2 <-30mm;

[0028] -30mm<R S3 <-20mm, 100mm<R S4 <110mm;

[0029] 200mm<R S5 <252mm, -70mm<R S6<-60mm;

[0030] 20mm<R S7 <25mm, -80mm<R S8 <-70mm;

[0031] -70mm<R S9 <-66mm, -220mm<R S10 <-180mm;

[0032] 30mm<R S11 <35mm,15mm<R S12 <20mm;

[0033] 20mm<R S13 <25mm,250mm<R S14 <280mm;

[0034] -30mm<R S15 <-20mm, 15mm<R S16 <20mm;

[0035] 45mm<R S17 <50mm,230mm<R S18 <240mm;

[0036] Among them, R S1 and R S2 are the curvature radii of the front and rear surfaces of the first lens L3, R S3 and R S4 are the curvature radii of the front and rear surfaces of the second lens L4, R S5 and R S6 are the curvature radii of the front and rear surfaces of the third lens L5, R S7 and R S8 are the curvature radii of the front and rear surfaces of the fourth lens L6, R S9 and R S10 are the curvature radii of the front and rear surfaces of the fifth lens L7, R S11 and R S12 are the curvature radii of the front and rear surfaces of the sixth lens L8, R S13 and R S14 are the curvature radii of the front and rear surfaces of the seventh lens L9, R S15 and R S16 are the curvature radii of the front and rear surfaces of the eighth lens L10, R S17 and R S18 are the curvature radii of the front and back surfaces of the ninth lens L11 respectively.

[0037] In some embodiments, the distance between the filter L12 and the ninth lens L11 is 15.92 mm, and the thickness of the filter L12 is 1.1 mm.

[0038] The folding and reflecting optical system for an infrared star sensor provided by the utility model has the following beneficial effects:

[0039] 1. The utility model provides a catadioptric optical system for an infrared star sensor, which can significantly reduce relative distortion within the full field of view of a working band by arranging a first reflector, a second reflector, a first lens L3, a second lens L4, a third lens L5, a fourth lens L6, a fifth lens L7, a sixth lens L8, a seventh lens L9, an eighth lens L10, and a ninth lens L11 which are coaxially arranged in sequence along a light propagation direction. Compared with the optical system of a traditional star sensor, the utility model has smaller relative distortion and field of view, provides a more accurate imaging effect, significantly improves the detection accuracy of the star sensor, and meets the distortion requirements of the star sensor.

[0040] 2. The utility model provides a catadioptric optical system for an infrared star sensor, which has the characteristics of compact structure, short total optical length, etc., small distortion, so that the distortion value is less than 0.01%, and the telecentricity value of each field of view center wavelength is better than 0.5°. In addition, the catadioptric optical system has the characteristics of large aperture and small field of view. The large aperture can increase the target energy entering the catadioptric optical system, and the small field of view can reduce the adverse effect of the atmospheric background on stargazing, thereby meeting the detection of the star sensor under daytime conditions, and is conducive to multi-platform application, and can be applied to multiple fields such as infrared monitoring and situational awareness, and has a wider range of applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The preferred implementation scheme will be described below in a clear and understandable manner with reference to the accompanying drawings to further illustrate the above-mentioned characteristics, technical features, advantages and implementation methods of the present solution.

[0042] Figure 1 This is a schematic structural diagram of a catadioptric optical system for an infrared star sensor provided by the utility model;

[0043] Figure 2 The utility model provides a dispersion diagram of image points of each field of view of a catadioptric optical system for an infrared star sensor;

[0044] Figure 3 It is a distortion diagram of a catadioptric optical system for an infrared star sensor provided by the utility model;

[0045] Figure 4 It is a field curvature diagram of a catadioptric optical system for an infrared star sensor provided by the utility model;

[0046] Figure 5 This is an MTF resolution curve diagram of a catadioptric optical system for an infrared star sensor provided by the utility model;

[0047] Figure 6 It is a relative illumination diagram of a catadioptric optical system for an infrared star sensor provided by the utility model;

[0048] Figure 7 The utility model provides a light path diagram of a catadioptric optical system for an infrared star sensor.

[0049] Description of Figure Numbers:

[0050] A first reflector L1, a second reflector L2, a first lens L3, a second lens L4, a third lens L5,

[0051] Fourth lens L6, fifth lens L7, sixth lens L8, seventh lens L9, eighth lens L10, ninth lens L11, filter L12. DETAILED DESCRIPTION

[0052] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the specific implementation methods of the utility model will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings and other implementation methods can be obtained based on these drawings without creative work.

[0053] In order to simplify the drawings, only the parts related to the utility model are schematically shown in each figure, and they do not represent the actual structure of the product. In addition, in order to simplify the drawings and facilitate understanding, in some figures, only one of the parts with the same structure or function is schematically drawn or marked. In this article, "one" not only means "only one", but also means "more than one".

[0054] In this article, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this utility model can be understood according to specific circumstances.

[0055] In addition, in the description of the present application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0056] In one embodiment, a catadioptric optical system for an infrared star sensor is described, which effectively reduces the distortion value and field of view of the catadioptric optical system through the cooperation of a first reflector L1, a second reflector L2 and a plurality of lenses, thereby improving the detection capability of the star sensor, improving the detection imaging effect of the star sensor, and thereby improving the accuracy of the attitude data obtained by the star sensor.

[0057] Specifically, see the attached drawings of the specification Figure 1 , Figure 7 A catadioptric optical system for an infrared star sensor includes a reflector group, a correction transmission mirror group and a filter L12 which are sequentially arranged along a light propagation direction, wherein the reflector group includes a first reflector L1 and a second reflector L2, and the first reflector L1 and the second reflector L2 are coaxially arranged along the light propagation direction. Accordingly, the correction transmission mirror group includes a first lens L3, a second lens L4, a third lens L5, a fourth lens L6, a fifth lens L7, a sixth lens L8, a seventh lens L9, an eighth lens L10 and a ninth lens L11 which are coaxially arranged along the light propagation direction, and the first lens L3 is arranged on a side of the second reflector L2 away from the first reflector L1.

[0058] In addition, a light opening is arranged at the center of the second reflector L2. It can be understood that the reflector group and the correction transmission group are arranged coaxially in sequence along the propagation direction of the light, and the first lens L3 is arranged opposite to the light opening of the second reflector L2.

[0059] In this embodiment, see the accompanying drawings Figure 6 , the light irradiates the side of the second reflector L2 close to the first reflector L1, and then reflects to the side of the first reflector L1 close to the second reflector L2. After the light reflected on the first reflector L1 passes through the light opening of the second reflector L2, it passes through the first lens L3, the second lens L4, the third lens L5, the fourth lens L6, the fifth lens L7, the sixth lens L8, the seventh lens L9, the eighth lens L10, the ninth lens L11 and the filter L12 in sequence, and finally propagates to the star sensor, which can significantly reduce the distortion value and field of view of the catadioptric optical system. Compared with the prior art, the distortion value is significantly reduced, and a more accurate imaging effect can be provided, and the detection accuracy of the star sensor is significantly improved.

[0060] In one embodiment, based on the previous embodiment, this embodiment further describes the reflector assembly and the correction transmission mirror assembly, wherein the first reflector L1 is convex toward the direction close to the second reflector L2, and the side of the second reflector L2 close to the first reflector L1 is concave.

[0061] In addition, the materials of the first lens L3, the fifth lens L7, the sixth lens L8 and the ninth lens L11 are all ZNSE, the first lens L3, the sixth lens L8 and the fifth lens L7 are all negative meniscus lenses, and the ninth lens L11 is a plano-concave lens. The materials of the second lens L4 and the eighth lens L10 are all JGS1, and the second lens L4 and the eighth lens L10 are both biconcave lenses. The materials of the third lens L5 and the seventh lens L9 are all ZNS, the third lens L5 is a biconvex lens, and the seventh lens L9 is a biconcave lens. The material of the fourth lens L6 is N-PK52A, and the fourth lens L6 is a biconvex lens, the material of the first reflector L1 is N-FK5, and the material of the second reflector L2 is silicon carbide.

[0062] Furthermore, the distance between the first reflector L1 and the second reflector L2 is D1, 139.5 mm < D1 < 139.9 mm, the distance between the second reflector L2 and the first lens L3 is D2, 165 mm < D2 < 165.3 mm, the distance between the first lens L3 and the second lens L4 is D3, 4 mm < D3 < 4.3 mm, the distance between the second lens L4 and the third lens L5 is D4, 3 mm < D4 < 3.3 mm, and the distance between the third lens L5 and the fourth lens L6 is D5, 117.5 mm < D5 < 118 mm m, the distance between the fourth lens L6 and the fifth lens L7 is D6, 1.75 mm<D6<2.05 mm, the distance between the fifth lens L7 and the sixth lens L8 is D7, 0.1 mm<D7<0.4 mm, the distance between the sixth lens L8 and the seventh lens L9 is D8, 1.6 mm<D8<1.9 mm, the distance between the seventh lens L9 and the eighth lens L10 is D9, 3.5 mm<D9<3.8 mm, and the distance between the eighth lens L10 and the ninth lens L11 is D10, 30.1 mm<D10<30.4 mm.

[0063] Correspondingly, compared with the traditional transmissive optical system, the aperture of the second reflector L2 of the catadioptric optical system is 140 mm, which is larger and can further meet the needs of star exploration under strong background conditions during the day, enhance the target energy entering the optical system, and then collect more light, thereby improving the ability of the catadioptric optical system to extract starlight signals under a strong sky background.

[0064] Further, the distance between the first reflector L1 and the second reflector L2 is set to 139.85 mm, and accordingly, the distance between the second reflector L2 and the first lens is 165.04 mm, the distance between the first lens L3 and the second lens L4 is 4.11 mm, the distance between the second lens L4 and the third lens L5 is 3.24 mm, the distance between the third lens L5 and the fourth lens L6 is 117.91 mm, the distance between the fourth lens L6 and the fifth lens L7 is 1.95 mm, the distance between the fifth lens L7 and the sixth lens L8 is 0.28 mm, the distance between the sixth lens L8 to the seventh lens L9 is 1.88 mm, the distance between the seventh lens L9 and the eighth lens L10 is 3.73 mm, and the distance between the eighth lens L10 and the ninth lens L11 is 30.31 mm.

[0065] In one embodiment, based on the previous embodiment, this embodiment further describes the reflective lens group and the corrective transmission lens group. Among them, the thickness d1 of the first lens L3 is 10 mm < d1 < 10.13 mm, the thickness of the second lens L4 is 3.8 mm < d2 < 4.2 mm, the thickness of the third lens L5 is 8.5 mm < d3 < 8.8 mm, the thickness of the fourth lens L6 is 8.2 mm < d4 < 8.5 mm, the thickness of the fifth lens L7 is 3.8 mm < d5 < 4.1 mm, the thickness of the sixth lens L8 is 3.8 mm < d5 < 4.1 mm, the thickness of the seventh lens L9 is 3.8 mm < d5 < 4.1 mm, the thickness of the eighth lens L10 is 3.8 mm < d8 < 4.1 mm, and the thickness of the ninth lens L11 is 6.8 mm < d5 < 7.1 mm.

[0066] The thickness d1 of the first lens L3 is 10.12 mm, the thickness of the second lens L4 is 4 mm, the thickness of the third lens L5 is 8.75 mm, the thickness of the fourth lens L6 is 8.23 ​​mm, the thickness of the fifth lens L7 is 3.99 mm, the thickness of the sixth lens L8 is 3.99 mm, the thickness of the seventh lens L9 is 4 mm, the thickness of the eighth lens L10 is 3.99 mm, and the thickness of the ninth lens L11 is 7 mm.

[0067] Furthermore, based on the previous embodiment, the present embodiment further describes the correction transmission lens group. In which, along the light propagation direction, the first lens L3 is sequentially provided with a first surface S1 and a second surface S2, the second lens L4 is sequentially provided with a third surface S3 and a fourth surface S4, the third lens L5 is sequentially provided with a fifth surface S5 and a sixth surface S6, the fourth lens L6 is sequentially provided with a seventh surface S7 and an eighth surface S8, the fifth lens L7 is sequentially provided with a ninth surface S9 and a tenth surface S10, the sixth lens L8 is sequentially provided with an eleventh surface S11 and a twelfth surface S12, the seventh lens L9 is sequentially provided with a thirteenth surface S13 and a fourteenth surface S14, the eighth lens L10 is sequentially provided with a fifteenth surface S15 and a sixteenth surface S16, and the ninth lens L11 is sequentially provided with a seventeenth surface S17 and an eighteenth surface S18. Accordingly, the curvature radii of the first lens L3, the second lens L4, the third lens L5, the fourth lens L6, the fifth lens L7, the sixth lens L8, the seventh lens L9, the eighth lens L10 and the ninth lens L11 satisfy the following conditions:

[0068] -30mm<R S1 <-20mm, -35mm<R S2 <-30mm;

[0069] -30mm<R S3 <-20mm, 100mm<R S4 <110mm;

[0070] 200mm<R S5 <252mm, -70mm<R S6 <-60mm;

[0071] 20mm<R S7 <25mm, -80mm<R S8 <-70mm;

[0072] -70mm<R S9 <-66mm, -220mm<R S10 <-180mm;

[0073] 30mm<R S11 <35mm,15mm<R S12 <20mm;

[0074] 20mm<R S13 <25mm,250mm<R S14 <280mm;

[0075] -30mm<R S15 <-20mm, 15mm<R S16<20mm;

[0076] 45mm<R S17 <50mm,230mm<R S18 <240mm;

[0077] Among them, R S1 and R S2 are the curvature radii of the front and rear surfaces of the first lens L3, R S3 and R S4 are the curvature radii of the front and rear surfaces of the second lens L4, R S5 and R S6 are the curvature radii of the front and rear surfaces of the third lens L5, R S7 and R S8 are the curvature radii of the front and rear surfaces of the fourth lens L6, R S9 and R S10 are the curvature radii of the front and rear surfaces of the fifth lens L7, R S11 and R S12 are the curvature radii of the front and rear surfaces of the sixth lens L8, R S13 and R S14 are the curvature radii of the front and rear surfaces of the seventh lens L9, R S15 and R S16 are the curvature radii of the front and rear surfaces of the eighth lens L10, R S17 and R S18 are the curvature radii of the front and back surfaces of the ninth lens L11 respectively.

[0078] In addition, the optical data of the reflector group and the correction transmission group are as follows:

[0079] Table 1 Optical system data:

[0080]

[0081]

[0082] It can be understood that the first lens L3, the second lens L4, the third lens L5, the fourth lens L6, the fifth lens L7, the sixth lens L8, the seventh lens L9, the eighth lens L10 and the ninth lens L11 provided by the above-mentioned embodiment can significantly reduce the field of view of the present catadioptric optical system, thereby reducing the adverse effects of the external environment on the optical system. In this way, the present catadioptric optical system has the characteristics of a large aperture and a small field of view, and is less affected by background stray light. It can extract weak starlight signals under a strong sky background during daytime star measurement, meeting the needs of all-day star exploration. In addition, while increasing the aperture and reducing the field of view, the present catadioptric optical system also significantly reduces the distortion value, so that the present optical system can significantly improve the detection accuracy while meeting the needs of all-day star observation.

[0083] In one embodiment, referring to the accompanying drawings, Figure 1 , Figure 6 The filter L12 with a thickness of 1.1 mm is arranged on the side of the sixth lens L8 away from the fifth lens L7, and the distance between the filter L12 and the ninth lens L11 is 19.52 mm. The material of the filter L12 is SAPPHIRE sapphire.

[0084] In addition, a detector is arranged on the side of the filter L12 away from the ninth lens L11, and the distance between the filter L12 and the detector is 5.5 mm. The light passing through the reflective lens group and the corrective transmission lens group enters the detector after being acted upon by the filter L12.

[0085] As the preferred detector, a short-wave infrared InGaAs focal plane detector is selected, with a target size of 1280×1024 and a pixel size of 15×15μm2.

[0086] In one embodiment, this embodiment further describes the first reflector L1 and the second reflector L2. The surface of the first reflector L1 and the second reflector L2 are both hyperbolic surfaces, and the surface shapes satisfy the following formula:

[0087]

[0088] Wherein, z is the vector height of the first reflector L1 or the second reflector L2, c is the paraxial curvature, k is the coefficient of the quadratic term, and r is the radial variable. The coordinate data adopts the following right-hand coordinate system, with the horizontal rightward direction being the +Z axis, the vertical inward direction being the +X axis, and the upward direction being the +Y axis. The paraxial curvature of the first reflector L1 and the second reflector L2 is defined as follows: if the center of the sphere is on the left side of the mirror body, the paraxial curvature is negative; if the center of the sphere is on the right side of the mirror body, the paraxial curvature is positive.

[0089] The distortion degree of a catadioptric optical system for an infrared star sensor provided by the utility model is characterized to indicate the deformation between the actual image plane and the ideal image plane. Figure 3 As shown, the curve is the distortion value from zero degree to full field of view. Figure 3 The ordinate represents the field of view, and the abscissa represents the relative distortion percentage. The optical system of the utility model has the advantage of low distortion, wherein the central wavelength is 1.3 μm and the distortion is less than 0.01%. Therefore, the optical system provided by the utility model can significantly reduce the distortion value.

[0090] in addition, Figure 4 This is a field curvature diagram. Field curvature refers to the curvature of the image field. It means that after a plane object passes through an optical system, the image plane after all plane object points are focused does not coincide with the ideal image plane, but presents a curved image plane. Figure 4 The ordinate is the field of view, and the abscissa represents the field curvature, where the central wavelength is 1.3 μm and the field curvature is less than 0.2 mm.

[0091] The optical system provided by the utility model can be used in the atmosphere to realize all-day stargazing. Due to the influence of atmospheric scattering during the day, the influence in the short-wave 0.9-1.7um band is small, so this band is selected as the detection band. The dispersion diagram of each field image point of the optical system is as follows Figure 2 As shown, it serves as a reference for the system imaging quality. Figure 2 In the figure, OBG represents the field of view, IMA represents the image point dispersion diagram of the optical system, and the image point dispersion radius of each field of view is given in the figure. The maximum root mean square value of the image point dispersion radius of each field of view is 10.857μm (which can be obtained in the field of view of 2.828 or the half field of view of 1.414), and the diameter is 21.714μm, which is equivalent to the diagonal size of the detector pixel of 21.2μm, meeting the imaging requirements.

[0092] The relative illumination of the optical system provided by the utility model is characterized so as to accurately consider the influence of the exit pupil radiation and the solid angle, see the attached drawings of the specification Figure 6 It represents the ratio of the illumination at each field of view position on the image plane to the illumination at the central field of view. Figure 6 The ordinate represents the illumination value, and the abscissa represents the field of view. Figure 6 It can be seen that the illumination changes little in the entire field of view and the illumination is uniform.

[0093] The MTF value of the all-weather catadioptric optical system provided by the utility model is characterized, and the MTF resolution curve is shown as follows: Figure 5 As shown in the figure, the MTF (Modulation Transfer Function) of different fields of view, the horizontal axis of the MTF resolution curve in the figure represents the image height, and the vertical axis represents the contrast, which ranges from 0 to 1. Figure 5 It can be seen that an MTF better than 0.6 meets the imaging quality requirements.

[0094] It should be noted that the above embodiments can be freely combined as needed. The above is only a preferred implementation of the utility model. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the utility model, and these improvements and modifications should also be regarded as the protection scope of the utility model.

Claims

1. A catadioptric optical system for an infrared star sensor, characterized in that: It includes a filter L12, a reflector group and a correction transmission mirror group, wherein the reflector group is composed of a first reflector L1 and a second reflector L2 coaxially arranged in a spaced relationship along the light propagation direction, and a light opening is provided at the center of the second reflector L2; The correction transmission lens group is composed of a first lens L3, a second lens L4, a third lens L5, a fourth lens L6, a fifth lens L7, a sixth lens L8, a seventh lens L9, an eighth lens L10 and a ninth lens L11 which are coaxially arranged and spaced along the light propagation direction, and the correction transmission lens group is arranged on a side of the second reflector L2 away from the first reflector L1; The filter L12 is disposed on a side of the ninth lens L11 away from the eighth lens L10.

2. A catadioptric optical system for an infrared star sensor according to claim 1, characterized in that: The first lens L3, the second lens L4, the third lens L5, the fourth lens L6, the fifth lens L7, the sixth lens L8, the seventh lens L9, the eighth lens L10 and the ninth lens L11 meet the following conditions: 10mm<d1<10.13mm, 3.8mm<d2<4.2mm, 8.5mm<d3<8.8mm, 8.2mm<d4<8.5mm; 3.8mm<d5<4.1mm, 3.8mm<d6<4.1mm, 3.8mm<d7<4.1mm, 3.8mm<d8<4.1mm, 6.8mm<d9<7.1mm; Wherein, d1 is the thickness of the first lens L3, d2 is the thickness of the second lens L4, d3 is the thickness of the third lens L5, d4 is the thickness of the fourth lens L6, d5 is the thickness of the fifth lens L7, d6 is the thickness of the sixth lens L8, d7 is the thickness of the seventh lens L9, d8 is the thickness of the eighth lens L10, and d9 is the thickness of the ninth lens L11.

3. A catadioptric optical system for an infrared star sensor according to claim 2, characterized in that: The first reflector L1 is convex toward the direction close to the second reflector L2, and a side of the second reflector L2 close to the first reflector L1 is a concave surface; The material of the first reflector L1 is N-FK5, and the material of the second reflector L2 is silicon carbide.

4. A catadioptric optical system for an infrared star sensor according to claim 3, characterized in that: The first lens L3, the fifth lens L7 and the sixth lens L8 are all negative meniscus lenses, and the third lens L5 and the fourth lens L6 are all biconvex lenses.

5. A catadioptric optical system for an infrared star sensor according to claim 4, characterized in that: The second lens L4, the seventh lens L9 and the eighth lens L10 are all biconcave lenses, and the ninth lens L11 is a plano-concave lens.

6. The catadioptric optical system for an infrared star sensor according to claim 4, characterized in that: The material of the first lens L3, the fifth lens L7 and the sixth lens L8 are all ZNSE, the material of the third lens L5 is ZNS, and the material of the fourth lens L6 is N-PK52A.

7. The catadioptric optical system for an infrared star sensor according to claim 5, characterized in that: The materials of the second lens L4 and the eighth lens L10 are both JGSI, the material of the seventh lens L9 is ZNS, and the material of the ninth lens L11 is both ZNSE.

8. A catadioptric optical system for an infrared star sensor according to claim 6 or 7, characterized in that: The distance between the second reflector L2 and the first lens L3 is D2, 165mm<D2<165.3mm, the distance between the first lens L3 and the second lens L4 is D3, 4mm<D3<4.3mm, the distance between the second lens L4 and the third lens L5 is D4, 3mm<D4<3.3mm, the distance between the third lens L5 and the fourth lens L6 is D5, 117.5mm<D5<118mm, the distance between the fourth lens L6 and the fifth lens L7 ... is D6, 1.75mm<D6<2.05mm, the distance between the fifth lens L7 and the sixth lens L8 is D7, 0.1mm<D7<0.4mm, the distance between the sixth lens L8 and the seventh lens L9 is D8, 1.6mm<D8<1.9mm, the distance between the seventh lens L9 and the eighth lens L10 is D9, 3.5mm<D9<3.8mm, the distance between the eighth lens L10 and the ninth lens L11 is D10, 30.1mm<D10<30.4mm; and / or The distance between the first reflector L1 and the second reflector L2 is D1, 139.5 mm < D1 < 139.9 mm; and / or The diameter of the second reflector L2 is 140 mm.

9. A catadioptric optical system for an infrared star sensor according to claim 8, characterized in that: The curvature radii of the first lens L3, the second lens L4, the third lens L5, the fourth lens L6, the fifth lens L7, the sixth lens L8, the seventh lens L9, the eighth lens L10 and the ninth lens L11 meet the following conditions: -30mm<R S1 <-20mm,-35mm<R S2 <-30mm; -30mm<R S3 <-20mm,100mm<R S4 <110mm; 200mm<R S5 <252mm,-70mm<R S6 <-60mm; 20mm<R S7 <25mm,-80mm<R S8 <-70mm; -70mm<R S9 <-66mm,-220mm<R S10 <-180mm; 30mm<R S11 <35mm,15mm<R S12 <20mm; 20mm<R S13 <25mm,250mm<R S14 <280mm; -30mm<R S15 <-20mm,15mm<R S16 <20mm; 45mm<R S17 <50mm,230mm<R S18 <240mm; Among them, R S1 and R S2 are the curvature radii of the front and rear surfaces of the first lens L3, R S3 and R S4 are the curvature radii of the front and rear surfaces of the second lens L4, R S5 and R S6 are the curvature radii of the front and rear surfaces of the third lens L5, R S7 and R S8 are the curvature radii of the front and rear surfaces of the fourth lens L6, R S9 and R S10 are the curvature radii of the front and rear surfaces of the fifth lens L7, R S11 and R S12 are the curvature radii of the front and rear surfaces of the sixth lens L8, R S13 and R S14 are the curvature radii of the front and rear surfaces of the seventh lens L9, R S15 and R S16 are the curvature radii of the front and rear surfaces of the eighth lens L10, R S17 and R S18 are the curvature radii of the front and back surfaces of the ninth lens L11 respectively.

10. The catadioptric optical system for an infrared star sensor according to claim 1, characterized in that: The distance between the filter L12 and the ninth lens L11 is 15.92 mm, and the thickness of the filter L12 is 1.1 mm.

Images