Refraction-reflection type optical imaging system for infrared star sensor

Abstract

The catadioptric optical imaging system for the infrared star sensor comprises an optical filter L9, a reflector group and a correction transmission lens group, the reflector group comprises a first reflector L1 and a second reflector L2 which are coaxially and sequentially arranged along the light propagation direction, the center of the second reflector L2 is provided with a light passing port, and the light passing port is communicated with the correction transmission lens group. The correction transmission lens group comprises a first lens L3, a second lens L4, a third lens L5, a fourth lens L6, a fifth lens L7 and a sixth lens L8 which are coaxially and sequentially arranged along the light propagation direction, and the first lens L3 and the second lens L4 are arranged between the first reflecting mirror L1 and the second reflecting mirror L2; the third lens L5, the fourth lens L6, the fifth lens L7 and the sixth lens L8 are arranged on one side, far away from the first reflector L1, of the second reflector L2, and the optical filter L9 is arranged on one side, far away from the fifth lens L7, of the sixth lens L8, so that the distortion value of the star sensor optical system can be effectively reduced, and the measurement precision and the detection capability of a star sensor are further improved.

Description

[0001] The utility model relates to a catadioptric optical imaging system for an infrared star sensor. This application claims priority, the application number of the prior application is: 202421511239.0, the name is: A catadioptric optical imaging system for an infrared star sensor, and 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 imaging system used for infrared star sensors. 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 application environment requirements for star sensors are becoming increasingly higher.

[0004] The optical system is an important part in the development of star sensors. However, the existing optical systems of star sensors have large imaging distortion and poor authenticity, resulting in low detection accuracy of the optical system.

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

[0006] The utility model aims to provide a catadioptric optical imaging system for an infrared star sensor, which can effectively reduce the distortion value of the catadioptric optical imaging system by setting a reflector group and a correction transmission mirror group, thereby ensuring the imaging effect of the catadioptric optical imaging system of the star sensor and further ensuring the detection accuracy of the star sensor.

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

[0008] A catadioptric optical imaging system for an infrared star sensor, comprising a filter L9, a reflector group and a correction transmission mirror group, wherein the reflector group comprises a first reflector L1 and a second reflector L2 coaxially arranged in sequence along a light propagation direction, and a light opening is provided at the center of the second reflector L2;

[0009] The correction transmission lens group includes a first lens L3, a second lens L4, a third lens L5, a fourth lens L6, a fifth lens L7 and a sixth lens L8 which are coaxially arranged in sequence along the light propagation direction, the first lens L3 and the second lens L4 are arranged between the first reflector L1 and the second reflector L2, and the third lens L5, the fourth lens L6, the fifth lens L7 and the sixth lens L8 are arranged on a side of the second reflector L2 away from the first reflector L1;

[0010] The filter L9 is disposed on a side of the sixth lens L8 away from the fifth lens L7.

[0011] In some embodiments, the first lens L3, the second lens L4, the third lens L5, the fourth lens L6, the fifth lens L7 and the sixth lens L8 satisfy the following conditions:

[0012] 3.2mm<d1<3.6mm, 2.8mm<d2<3.1mm, 2.1mm<d3<2.4mm, 2.1mm<d4<2.4mm, 1.3mm<d5<1.6mm, 4.5mm<d6<4.7mm;

[0013] 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, and d6 is the thickness of the sixth lens L8.

[0014] In some embodiments, the first lens L3 and the third lens L5 are both negative meniscus lenses, and the second lens L4 is a positive meniscus lens.

[0015] In some embodiments, the sixth lens L8 is a plano-convex lens, and the fourth lens L6 and the fifth lens L7 are both biconcave lenses.

[0016] In some embodiments, the material of the first lens L3 is N-PK52A, the material of the third lens L5 is ZNSE, and the material of the second lens L4 is ZNS.

[0017] In some embodiments, the sixth lens L8 is made of ZNSE, the fourth lens L6 is made of ZNS, and the fifth lens L7 is made of JGS1.

[0018] In some embodiments, the distance between the second reflector L2 and the first lens L3 is D2, 95.8mm<D2<96.1mm, the distance between the first lens L3 and the second lens L4 is D3, 3.9mm<D3<4.2mm, the distance between the second lens L4 and the third lens L5 is D4, 16.1mm<D4<16.4mm, the distance between the third lens L5 and the fourth lens L6 is D5, 3.9mm<D5<4.2mm, the distance between the fourth lens L6 and the fifth lens L7 is D6, 1.5mm<D6<1.75mm, and the distance between the fifth lens L7 and the sixth lens L8 is D7, 36.5mm<D7<36.8mm;

[0019] and / or

[0020] The distance between the first reflector L1 and the second reflector L2 is D1, 112.5 mm < D1 ≤ 113 mm;

[0021] and / or

[0022] The diameter of the second reflector L2 is 105 mm.

[0023] In some embodiments, 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 concave;

[0024] The first reflector L1 is made of optical glass N-FK5, and the second reflector L2 is made of silicon carbide.

[0025] 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 and the sixth lens L8 satisfy the following conditions:

[0026] -15mm<R S1 <-10mm, -15mm<R S2 <-10mm;

[0027] 25mm<R S3 <30mm,550mm<R S4 <555mm;

[0028] -15mm<R S5 <-10mm, -25mm<R S6 <-20mm;

[0029] 10mm<R S7 <15mm, -50mm<R S8 <45mm;

[0030] -15mm<R S9 <-10mm, 5mm<R S10 <10mm;

[0031] 55mm<R S11 <60mm, R S12 =∞;

[0032] 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 respectively the curvature radii of the front and back surfaces of the sixth lens L8.

[0033] In some embodiments, the distance between the filter L9 and the sixth lens L8 is 15.92 mm, and the thickness of the filter L9 is 1.1 mm.

[0034] The folding-reflective optical imaging system for an infrared star sensor provided by the utility model has the following beneficial effects:

[0035] 1. The utility model provides a catadioptric optical imaging system for an infrared star sensor. By arranging a first reflector and a second reflector coaxially arranged in sequence along a light propagation direction, and arranging a first lens L3 and a second lens L4 between the first reflector L1 and the second reflector L2, and arranging a third lens L5, a fourth lens L6, a fifth lens L7 and a sixth lens L8 on a side of the second reflector L2 away from the first reflector L1, the catadioptric system is adopted, which can significantly reduce the relative distortion and field of view within the full field of view of the working band, and has smaller relative distortion and field of view than the optical system of a traditional star sensor, thereby improving the measurement accuracy of the star sensor.

[0036] 2. The utility model provides a catadioptric optical imaging system for infrared star sensors, with a distortion value of less than 0.005%, which reduces the total optical length, has a more compact structure, is conducive to multi-platform applications, and can be applied to multiple fields such as infrared monitoring and situational awareness, and has a wider range of applications. In addition, the aperture of the catadioptric optical system is large and the field of view is small. Increasing the aperture can increase the target energy entering the catadioptric optical system, improve the ability to extract light signals under strong backgrounds, and reducing the field of view can reduce the adverse effects of the atmospheric background on stargazing, thereby meeting the needs of optical systems for all-day star exploration. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] 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.

[0038] Figure 1 This is a schematic structural diagram of a catadioptric optical imaging system for an infrared star sensor provided by the utility model;

[0039] Figure 2 The utility model provides a dispersion diagram of image points in each field of view of a catadioptric optical imaging system for an infrared star sensor;

[0040] Figure 3 It is a distortion diagram of an optical system of a catadioptric optical imaging system for an infrared star sensor provided by the utility model;

[0041] Figure 4 It is a field curvature diagram of an optical system of a catadioptric optical imaging system for an infrared star sensor provided by the utility model;

[0042] Figure 5 This is an MTF resolution curve diagram of a catadioptric optical imaging system for an infrared star sensor provided by the utility model;

[0043] Figure 6 It is a relative illumination diagram of a catadioptric optical imaging system for an infrared star sensor provided by the utility model;

[0044] Figure 7 The utility model provides a light path diagram of a catadioptric optical imaging system for an infrared star sensor.

[0045] Description of Figure Numbers:

[0046] First reflecting mirror L1, second reflecting mirror L2, first lens L3, second lens L4, third lens L5, fourth lens L6, fifth lens L7, sixth lens L8, filter L9. DETAILED DESCRIPTION

[0047] 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.

[0048] 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".

[0049] 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.

[0050] 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.

[0051] In one embodiment, a catadioptric optical imaging system for an infrared star sensor is described, which significantly reduces the distortion value and field of view of the catadioptric optical imaging system by setting a reflective mirror group and a corrective transmission mirror group, thereby improving the detection accuracy of the star sensor and further improving the detection effect of the star sensor.

[0052] Specifically, see the attached drawings of the specification Figure 1 , Figure 7 A catadioptric optical imaging system for an infrared star sensor includes a filter L9, a reflector group and a correction transmission mirror group, the reflector group includes a first reflector L1 and a second reflector L2, the first reflector L1 and the second reflector L2 are coaxially arranged in sequence along the direction of light propagation, and a light opening is opened at the center of the second reflector L2, and the light opening of the second reflector L2 is coaxially arranged with the reflector group and the correction transmission mirror group. In addition, the distance between the first reflector L1 and the second reflector L2 is 113 mm.

[0053] Correspondingly, the correction transmission lens group includes a first lens L3, a second lens L4, a third lens L5, a fourth lens L6, a fifth lens L7 and a sixth lens L8, and the first lens L3, the second lens L4, the third lens L5, the fourth lens L6, the fifth lens L7 and the sixth lens L8 are arranged in sequence along the optical axis in the direction of light propagation. The first lens L3 and the second lens L4 are arranged between the first reflector L1 and the second reflector L2, and the second lens L4 is located on the side of the first lens L3 close to the second reflector L2. The third lens L5, the fourth lens L6, the fifth lens L7 and the sixth lens L8 are arranged on the side of the second reflector L2 away from the first reflector L1. The filter L9 is arranged on the side of the sixth lens L8 away from the fifth lens L7.

[0054] It can be understood that, referring to the accompanying drawings of the specification Figure 6 Through the arrangement of the reflective mirror group and the correction transmission mirror group, when the catadioptric optical imaging system is used, when the object imaging light enters the catadioptric optical imaging system, it is first irradiated onto the second reflective mirror L2. After being reflected on the second reflective mirror L2, the imaging light is irradiated onto the first reflective mirror L1, and then reflected on the first reflective mirror L1, enters the correction transmission mirror group, and passes through the first lens L3, the second lens L4, the third lens L5, the fourth lens L6, the fifth lens L7 and the sixth lens L8 in sequence.

[0055] In this embodiment, by setting up a reflective mirror group and a corrective transmission mirror group, the distortion value of the catadioptric optical imaging system can be significantly reduced. Compared with some optical systems used for star sensors in the prior art, the distortion value is significantly reduced, and the detection accuracy of the star sensor is significantly improved.

[0056] In addition, the distance between the second reflector L2 and the first lens is D2, 95.8mm<D2<96.1mm, the distance between the first lens L3 and the second lens L4 is D3, 3.9mm<D3<4.2mm, the distance between the second lens L4 and the third lens L5 is D4, 16.1mm<D4<16.4mm, the distance between the third lens L5 and the fourth lens L6 is D5, 3.9mm<D5<4.2mm, the distance between the fourth lens L6 and the fifth lens L7 is D6, 1.5mm<D6<1.75mm, and the distance between the fifth lens L7 and the sixth lens L8 is D7, 36.5mm<D7<36.8mm.

[0057] Correspondingly, the distance between the first reflector L1 and the second reflector L2 is D1, 112.5mm<D1≤113mm. In addition, compared with the traditional transmission optical system, the aperture of the second reflector L2 of the catadioptric optical system is 105mm, 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, making the image clearer and brighter, and improving the ability of the catadioptric optical system to extract starlight signals under a strong sky background.

[0058] Furthermore, the distance between the first reflector L1 and the second reflector L2 is 113 mm, and accordingly, the distance between the second reflector L2 and the first lens is 96 mm, the distance between the first lens L3 and the second lens L4 is 4 mm, the distance between the second lens L4 and the third lens L5 is 16.3 mm, the distance between the third lens L5 and the fourth lens L6 is 4 mm, the distance between the fourth lens L6 and the fifth lens L7 is 1.6 mm, and the distance between the fifth lens L7 and the sixth lens L8 is 36.56 mm.

[0059] In one embodiment, based on the previous embodiment, this 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, and the sixth lens L8 is sequentially provided with an eleventh surface S11 and a twelfth surface S12. 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 and the sixth lens L8 meet the following conditions:

[0060] -15mm<R S1 <-10mm, -15mm<R S2 <-10mm;

[0061] 25mm<R S3 <30mm,550mm<R S4 <555mm;

[0062] -15mm<R S5 <-10mm, -25mm<R S6 <-20mm;

[0063] 10mm<R S7 <15mm, -50mm<R S8 <45mm;

[0064] -15mm<R S9 <-10mm, 5mm<R S10 <10mm;

[0065] 55mm<R S11 <60mm, R S12 =∞;

[0066] R S1 and R S2 Respectively represent the curvature radius of the front and rear surfaces of the first lens L3, R S3 and R S4 Respectively represent the curvature radius of the front and rear surfaces of the second lens L4, R S5 and R S6 Respectively represent the curvature radius of the front and rear surfaces of the third lens L5, R S7 and R S8 Respectively represent the curvature radius of the front and rear surfaces of the fourth lens L6, R S9 and R S10 Respectively represent the curvature radius of the front and rear surfaces of the fifth lens L7, R S11 and R S12 They respectively represent the curvature radii of the front and back surfaces of the sixth lens L8.

[0067] Furthermore, based on the previous embodiment, the thicknesses of the first lens L3, the second lens L4, the third lens L5, the fourth lens L6, the fifth lens L7 and the sixth lens L8 satisfy the following conditions:

[0068] The thickness d1 of the first lens L3 is 3.2 mm<d1<3.6 mm, the thickness of the second lens L4 is 2.8 mm<d2<3.1 mm, the thickness of the third lens L5 is 2.1 mm<d3<2.4 mm, the thickness of the fourth lens L6 is 2.1 mm<d4<2.4 mm, the thickness of the fifth lens L7 is 1.3 mm<d5<1.6 mm, and the thickness of the sixth lens L8 is 4.5 mm<d5<4.7 mm.

[0069] The thickness d1 of the first lens L3 is 3.5 mm, the thickness d2 of the second lens L4 is 2.9 mm, the thickness d3 of the third lens L5 is 2.3 mm, the thickness d4 of the fourth lens L6 is 2.3 mm, the thickness d5 of the fifth lens L7 is 1.5 mm, and the thickness d6 of the sixth lens L8 is 4.6 mm.

[0070] In one embodiment, referring to the accompanying drawings, Figure 1 , Figure 6The filter L9 is arranged on the side of the sixth lens L8 away from the fifth lens L7, the thickness of the filter L9 is 1.1 mm, and the distance between the filter L9 and the sixth lens L8 is 15.92 mm. The material of the filter L9 is SAPPHIRE sapphire.

[0071] In addition, a detector is arranged on the side of the filter L9 away from the sixth lens L8, and the distance between the filter L9 and the detector is 5.5 mm. The light after being acted upon by the reflective mirror group and the corrective transmission mirror group enters the detector after being acted upon by the filter L9.

[0072] In one embodiment, the 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.

[0073] In addition, the material of the first lens L3 is N-PK52A material, and the first lens L3 is a negative meniscus lens. The second lens L4 and the fourth lens L6 are both ZNS materials, and the second lens L4 is a positive meniscus lens, and the fourth lens L6 is a double concave lens. The third lens L5 and the sixth lens L8 are both ZNSE materials, the third lens L5 is a negative meniscus lens, and the sixth lens L8 is a plano-convex lens. The fifth lens L7 is JGS1 material, and the fifth lens L7 is a double concave lens. The first reflector L1 is made of optical glass N-FK5 material, and the second reflector L2 is made of silicon carbide material. The total optical length of the reflector group and the correction transmission component is not more than 200 mm.

[0074] It is worth noting that the first lens L3 makes a great contribution to eliminating the system spherical aberration, the second lens L4 makes a great contribution to eliminating the system spherical aberration, the third lens L5 makes a great contribution to eliminating the system spherical aberration, the fourth lens L6 makes a great contribution to eliminating the system coma and astigmatism, the fifth lens L7 makes a great contribution to eliminating the system coma and astigmatism, and the sixth lens L8 makes a great contribution to eliminating the system field curvature and distortion.

[0075] In one embodiment, this embodiment further describes the first reflector L1 and the second reflector L2. The first reflector L1 and the second reflector L2 are both hyperbolic surfaces, and the surface shapes satisfy the following formula:

[0076]

[0077] 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.

[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 and the sixth lens L8 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, by designing the reflector group and the correction transmission lens group, the present catadioptric optical system has the characteristics of large aperture and small field of view, and the optical system is less affected by background stray light, and 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] The distortion degree of a catadioptric optical imaging 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, with a central wavelength of 1.5 μm and a distortion of less than 0.005%. Therefore, the optical system provided by the utility model can significantly reduce the distortion value.

[0084] 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, with a central wavelength of 1.5 μm and a field curvature of <0.2 mm.

[0085] 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. In the field of view of 1.838 (half field of view 0.919), the maximum root mean square value of the image point dispersion radius is 10.857μm, and the diameter is 21.714μm, which is equivalent to the diagonal size of the detector pixel of 21.2μm, meeting the imaging requirements.

[0086] 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.

[0087] The MTF value of the all-weather catadioptric optical imaging system provided by the present invention 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 0.3 meets the imaging quality requirements.

[0088] 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 imaging system for an infrared star sensor, characterized in that: It includes a filter L9, a reflector group and a correction transmission mirror group, wherein the reflector group includes a first reflector L1 and a second reflector L2 which are coaxially arranged in sequence along the light propagation direction, and a light opening is opened at the center of the second reflector L2; The correction transmission lens group includes a first lens L3, a second lens L4, a third lens L5, a fourth lens L6, a fifth lens L7 and a sixth lens L8 which are coaxially arranged in sequence along the light propagation direction, the first lens L3 and the second lens L4 are arranged between the first reflector L1 and the second reflector L2, and the third lens L5, the fourth lens L6, the fifth lens L7 and the sixth lens L8 are arranged on a side of the second reflector L2 away from the first reflector L1; The filter L9 is disposed on a side of the sixth lens L8 away from the fifth lens L7.

2. A catadioptric optical imaging 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 and the sixth lens L8 meet the following conditions: 3.2mm<d1<3.6mm, 2.8mm<d2<3.1mm, 2.1mm<d3<2.4mm, 2.1mm<d4<2.4mm, 1.3mm<d5<1.6mm, 4.5mm<d6<4.7mm; 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, and d6 is the thickness of the sixth lens L8.

3. A catadioptric optical imaging system for an infrared star sensor according to claim 2, characterized in that: The first lens L3 and the third lens L5 are both negative meniscus lenses, and the second lens L4 is a positive meniscus lens.

4. The catadioptric optical imaging system for an infrared star sensor according to claim 3, characterized in that: The sixth lens L8 is a plano-convex lens, and the fourth lens L6 and the fifth lens L7 are both biconcave lenses.

5. The catadioptric optical imaging system for an infrared star sensor according to claim 3, characterized in that: The material of the first lens L3 is N-PK52A, the material of the third lens L5 is ZNSE, and the material of the second lens L4 is ZNS.

6. The catadioptric optical imaging system for an infrared star sensor according to claim 4, characterized in that: The material of the sixth lens L8 is ZNSE, the material of the fourth lens L6 is ZNS, and the material of the fifth lens L7 is JGS1.

7. A catadioptric optical imaging system for an infrared star sensor according to any one of claims 1 to 6, characterized in that: The distance between the second reflector L2 and the first lens L3 is D2, 95.8mm<D2<96.1mm, the distance between the first lens L3 and the second lens L4 is D3, 3.9mm<D3<4.2mm, the distance between the second lens L4 and the third lens L5 is D4, 16.1mm<D4<16.4mm, the distance between the third lens L5 and the fourth lens L6 is D5, 3.9mm<D5<4.2mm, the distance between the fourth lens L6 and the fifth lens L7 is D6, 1.5mm<D6<1.75mm, the distance between the fifth lens L7 and the sixth lens L8 is D7, 36.5mm<D7<36.8mm; and / or The distance between the first reflector L1 and the second reflector L2 is D1, 112.5 mm < D1 ≤ 113 mm; and / or The diameter of the second reflector L2 is 105 mm.

8. The catadioptric optical imaging system for an infrared star sensor according to claim 7, 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 first reflector L1 is made of optical glass N-FK5, and the second reflector L2 is made of silicon carbide.

9. The catadioptric optical imaging 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 and the sixth lens L8 satisfy the following conditions: -15mm<R S1 <-10mm,-15mm<R S2 <-10mm; 25mm<R S3 <30mm,550mm<R S4 <555mm; -15mm<R S5 <-10mm,-25mm<R S6 <-20mm; 10mm<R S7 <15mm,-50mm<R S8 <45mm; -15mm<R S9 <-10mm,5mm<R S10 <10mm; 55mm<R S11 <60mm,R S12 =∞; 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 respectively the curvature radii of the front and back surfaces of the sixth lens L8.

10. The catadioptric optical imaging system for an infrared star sensor according to claim 1, characterized in that: The distance between the filter L9 and the sixth lens L8 is 15.92 mm, and the thickness of the filter L9 is 1.1 mm.

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