All-silicon carbide low-temperature lens, manufacturing method thereof and application of all-silicon carbide low-temperature lens to coaxial four-mirror optical infrared camera

Abstract

The invention relates to an all-silicon-carbide low-temperature lens, a manufacturing method and application of the all-silicon-carbide low-temperature lens to a coaxial four-mirror optical infrared camera. The all-silicon carbide low-temperature lens comprises a primary lens, a secondary lens, a third lens and a fourth lens. The primary mirror and the fourth mirror are arranged in a back-to-back manner and structurally form an integrated structure of the primary mirror and the fourth mirror, namely, the primary mirror and the fourth mirror; the main fourth mirror and the third mirror are respectively connected to two ends of a lens bearing cylinder, and the secondary mirror is connected with one end, provided with the main fourth mirror, of the lens bearing cylinder through a secondary mirror supporting rod assembly; the main fourth mirror, the secondary mirror, the third mirror, the secondary mirror supporting rod assembly and the lens bearing cylinder are made of silicon carbide materials. The whole silicon carbide lens structure shrinks integrally in a low-temperature environment, athermalization design of a lens light machine is achieved, and low-temperature stability and adaptability of the lens are improved. The lens bearing cylinder improves the structural rigidity and stability of the lens, serves as a low-temperature cold shield, inhibits external stray light, and improves the signal-to-noise ratio of the lens.

Description

Technical Field

[0001] The present invention relates to the technical field of low-temperature infrared cameras, in particular to a full silicon carbide low-temperature lens and a manufacturing method thereof, and application thereof in a coaxial four-mirror optical infrared camera. Background Art

[0002] With the continuous development of science and technology, there is an increasing demand for high-sensitivity infrared imaging in the fields of national defense, military, meteorological observation, commercial remote sensing, etc. In order to achieve high-sensitivity detection, reducing the temperature of the lens is one of the important technical means. In cryogenic lenses, the coaxial four-mirror optical system has the advantages of symmetrical structure, compact size, large field of view of the optical system, no chromatic aberration, refractive index influence, and many design parameters. The athermal design of cryogenic lenses can reduce the complexity of the system. Avoid adjusting the lens from room temperature, and avoid significant changes in system performance in low-temperature environments. In addition, the maturity of silicon carbide 3D printing technology provides support for the efficient manufacture of complex silicon carbide structures.

[0003] At present, the Chinese invention patent application disclosure (publication number: CN102338922A) discloses an all-aluminum low-temperature full-reflection mirror lens. In order to solve the problem of image quality degradation caused by the different environment during lens processing and adjustment and the working environment in low-temperature optics, the lens adopts a total reflection optical system, and the optical system and the support frame supporting the optical system adopt 6061 aluminum. As a lens reflector material, aluminum material has a small specific stiffness. In order to ensure the surface accuracy of the reflector and the rigidity of the lens structure, it is difficult to achieve high lightweight of the lens. Aluminum material is relatively soft, and it is difficult to achieve high-precision processing of large-diameter reflectors. As a structural material, its material rigidity is low, the thermal expansion coefficient is large, and the structural thermal deformation is large. In order to ensure the relative position of the reflector, it is difficult to achieve a high lightweight structure. The primary mirror, secondary mirror, third mirror and fourth mirror are connected to the primary support frame, the secondary mirror support frame and the third mirror support frame by bolts. This rigid connection has very high requirements on the flatness of the interface. The assembly stress generated by the dimensional accuracy and form and position tolerance of the installation interface is very likely to generate assembly stress, resulting in degradation of the surface accuracy of the reflector. The lens structure has very high requirements for temperature uniformity. The temperature difference of the lens will produce thermal stress, which will also cause the degradation of the surface accuracy of the reflector and the decline of the optical performance of the lens. Summary of the invention

[0004] The purpose of the present invention is to provide a full silicon carbide cryogenic lens and a manufacturing method and an application in a coaxial four-mirror optical infrared camera, mainly to solve the technical problems of low structural rigidity of the current low-temperature aluminum lens, difficulty in achieving high-precision large-aperture reflector surface shape, large structural deformation, high requirements for temperature uniformity and installation accuracy, and structure not suitable for batch processing.

[0005] In order to achieve the above object, the technical solution of the present invention is:

[0006] A full silicon carbide cryogenic lens comprises a primary mirror, a secondary mirror, a third mirror and a fourth mirror; the characteristic is that: the primary mirror and the fourth mirror are arranged back to back and structurally form a primary mirror and a fourth mirror structure, i.e., a primary four mirrors; the primary four mirrors and the third mirror are respectively connected to two ends of a lens bearing cylinder, and the secondary mirror is connected to one end of the lens bearing cylinder where the primary four mirrors are arranged through a secondary mirror support rod assembly; the primary four mirrors, the secondary mirror, the third mirror, the secondary mirror support rod assembly and the lens bearing cylinder are made of silicon carbide material.

[0007] The full silicon carbide cryogenic lens is characterized in that: the full silicon carbide cryogenic lens comprises

[0008] A main four-mirror assembly, the main four-mirror assembly comprising a main mirror, four mirrors, a main four-mirror common support ring, and a main four-mirror support member;

[0009] A secondary mirror assembly, the secondary mirror assembly comprising a secondary mirror, a secondary mirror support ring, and a secondary mirror adapter;

[0010] A three-mirror assembly, the three-mirror assembly comprising three mirrors and a three-mirror support ring;

[0011] A secondary mirror support rod assembly, the secondary mirror support rod assembly comprising a secondary mirror mounting flange, a secondary mirror support rod, and a support rod joint;

[0012] A lens bearing cylinder assembly, the lens bearing cylinder assembly comprising a lens bearing cylinder and a bearing cylinder support;

[0013] Among them, the primary mirror, secondary mirror, third mirror, fourth mirror, secondary mirror mounting flange, secondary mirror support rod, support rod joint, and lens load-bearing tube are all made of silicon carbide material, and each silicon carbide-made reflector and structural parts are lightweight; the main four-mirror common support ring, secondary mirror support ring, and third mirror support ring are made of Invar material that matches the thermal expansion coefficient of silicon carbide.

[0014] The all-silicon carbide cryogenic lens is characterized in that: the periphery of the main four mirrors is provided with a main four-mirror common supporting mirror surface for connection, and the three supporting mirror surfaces are evenly distributed at 120° around the periphery of the main four mirrors; the inner side of the main four-mirror common supporting ring is provided with a flexible supporting structure, and the three flexible supporting structures are evenly distributed at 120° on the inner side of the main four-mirror common supporting ring; the outer side of the main four-mirror common supporting ring has three mounting surfaces that are bolted to the main four-mirror support member, and the three mounting surfaces are evenly distributed at 120° on the outer side of the main four-mirror common supporting ring; the flexible supporting structure and the main four-mirror common supporting mirror surface are bonded with epoxy glue; the main four-mirror common supporting mounting surface is connected to the main four-mirror support member by bolts, and the angle between the main four-mirror common supporting ring mounting surface and the adjacent flexible supporting structure is 60°; the main four-mirror support member and the lens bearing tube are connected by bolts.

[0015] The all-silicon carbide cryogenic lens is characterized in that: a flexible support structure is provided on the inner side of the secondary mirror support ring in the secondary mirror assembly, and three flexible support structures are evenly distributed on the inner side of the secondary mirror support ring at an angle of 120°; three secondary mirror support ring mounting surfaces are provided on the upper surface of the secondary mirror support ring, which are bolted to the secondary mirror adapter, and the three secondary mirror support ring mounting surfaces are evenly distributed on the upper surface of the secondary mirror support ring at an angle of 120°; three adapter mounting surfaces are provided on the lower surface of the secondary mirror adapter, which are bolted to the secondary mirror support ring; the upper surface of the secondary mirror adapter is bolted to the secondary mirror mounting flange through a pressure block, and the pressure block is evenly distributed on the secondary mirror adapter at an angle of 120°; the secondary mirror mounting flange also includes a secondary mirror mounting flange bonding surface, and the secondary mirror mounting flange bonding surface is bonded to the upper end of the secondary mirror support rod with epoxy glue; the secondary mirror support ring flexible support structure is bonded to the secondary mirror with epoxy glue; the bolted parts in the secondary mirror assembly are all connected with bolts.

[0016] The all-silicon carbide cryogenic lens is characterized in that: the three support rod joints in the secondary mirror support rod assembly are evenly distributed on the lens bearing tube at 120°; the support rod joint includes a support rod joint mounting surface and a support rod joint bonding surface; the support rod joint mounting surface and the lens bearing tube are connected with bolts; the support rod joint bonding surface and the lower end of the secondary mirror support rod are bonded with epoxy glue.

[0017] The all-silicon carbide cryogenic lens is characterized in that: the three-mirror support ring includes three three-mirror support ring flexible support structures and three three-mirror support ring mounting surfaces; the three three-mirror support ring flexible support structures are evenly distributed on the inner side of the three-mirror support ring at 120°; the three three-mirror support ring mounting surfaces are evenly distributed on the outer side of the three-mirror support ring at 120°; the angle between the three-mirror support ring flexible support structure and the adjacent three-mirror support ring mounting surfaces is 60°; the three-mirror support ring flexible support structure is bonded to the three mirrors with epoxy glue; the three-mirror support ring mounting surface is bolted to the load-bearing cylinder mounting surface with bolts.

[0018] The full silicon carbide cryogenic lens is characterized in that: the lens bearing tube includes a first mounting surface connected to the main four-mirror support; a second mounting surface connected to the support rod joint; a third mounting surface connected to the three-mirror support ring; and a fourth mounting surface connected to the bearing tube support; the fourth mounting surface and the bearing tube support are connected by bolts.

[0019] A method for manufacturing a full silicon carbide cryogenic lens as described above, characterized in that: the main four mirrors, secondary mirror, triple mirror, secondary mirror support rod assembly, and lens bearing cylinder are manufactured by silicon carbide 3D printing.

[0020] The all-silicon carbide cryogenic lens as described above is applied to a coaxial four-mirror optical infrared camera.

[0021] In view of the above technical features, the present invention has the following advantages:

[0022] 1. The present invention adopts silicon carbide materials with low density, high modulus, low expansion coefficient and high thermal conductivity for both the reflector and the lens structure, which improves the rigidity and lightweight rate of the lens while realizing the athermalization of the optical system, reduces the thermal deformation of the structure and improves the temperature uniformity of the structure.

[0023] 2. The main four mirrors in the present invention adopt a double-sided co-body structure, and the main four mirrors are co-supported, which reduces the number of reflector supports, improves the compactness of the structure, and reduces the weight of the lens.

[0024] 3. In the present invention, the main four mirrors, the secondary mirrors, and the three mirrors are all supported circumferentially by support rings, which reduce the length dimension of the lens relative to the back support and improve the compactness of the structure. The support ring is designed with a flexible support structure, which reduces the influence of assembly stress and thermal stress on the surface shape of the reflector and improves the adaptability of the lens.

[0025] 4. In the present invention, epoxy glue is used to bond the reflector and the support ring, which reduces the requirements for installation plane accuracy between the reflector and the reflector support, improves assembly efficiency, and is suitable for mass assembly.

[0026] 6. In the present invention, the main bearing structure of the lens adopts a bearing cylinder configuration, which improves the stability and rigidity of the lens structure. At the same time, the bearing cylinder serves as a cold screen, and a stray light elimination structure can be designed inside to prevent stray light from entering the optical path through the third and fourth mirrors, and the stray light suppression effect is good.

[0027] 7. In the present invention, the lens silicon carbide structure is processed by 3D printing, and this process can adapt to more complex parts structure forms. It can achieve a higher lightweight rate and higher structural rigidity of the lens, and can improve production efficiency, which is suitable for mass processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the overall structure of the full silicon carbide cryogenic lens of the coaxial four-mirror optical infrared camera of the present invention.

[0029] Figure 2 It is a schematic diagram of the structure of the main four mirrors in the present invention.

[0030] Figure 3 It is a schematic diagram of the structure of the main four-mirror assembly in the present invention.

[0031] Figure 4 It is a structural schematic diagram of the secondary mirror assembly in the present invention.

[0032] Figure 5 It is a schematic diagram of the structure of the three-mirror assembly in the present invention.

[0033] Figure 6It is a schematic diagram of the connection structure of the lens bearing cylinder in the present invention.

[0034] Figure 7 The diagram is a schematic diagram of the optical path structure of the all-silicon carbide cryogenic lens of the coaxial four-mirror optical infrared camera of the present invention. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0036] See also Figure 1-7 The present invention discloses a preferred embodiment of a full silicon carbide cryogenic lens for a coaxial four-mirror optical infrared camera. As shown in the figure, it comprises:

[0037] A main four-mirror assembly, the main four-mirror assembly comprising a main mirror 1, four mirrors 4, a main four-mirror common supporting ring 5, and a main four-mirror supporting member 9;

[0038] A secondary mirror assembly, the secondary mirror assembly comprising a secondary mirror 2, a secondary mirror support ring 6, and a secondary mirror adapter 15;

[0039] A three-mirror assembly, the three-mirror assembly comprising three mirrors 3 and a three-mirror support ring 7;

[0040] A secondary mirror support rod assembly, the secondary mirror support rod assembly comprising a secondary mirror mounting flange 10, a secondary mirror support rod 11, and a support rod joint 12;

[0041] The lens bearing cylinder assembly comprises a lens bearing cylinder 8 and a bearing cylinder support 13 .

[0042] Among them, the primary mirror 1, the secondary mirror 2, the third mirror 3, the fourth mirror 4, the secondary mirror support rod assembly (i.e., the secondary mirror mounting flange 10, the secondary mirror support rod 11, the support rod joint 12), and the lens bearing tube 8 are all made of silicon carbide material, and each reflector and structural part made of silicon carbide is lightweight; each mirror body support ring (i.e., the main four-mirror common support ring 5, the secondary mirror support ring 6, and the third mirror support ring 7) is made of Invar material that matches the thermal expansion coefficient of silicon carbide.

[0043] As a further introduction to this embodiment, Figure 2 In the main four-mirror assembly, the main mirror 1 and the four-mirror 4 are arranged back-to-back, and are designed as a co-structured structure to form a main four-mirror 14; the periphery of the main four-mirror 14 is provided with a main four-mirror common supporting mirror surface 1401 for connection, and the three supporting mirror surfaces 1401 are evenly distributed at 120° around the periphery of the main four-mirror 14. Figure 3, the inner side of the main four-mirror common support ring 5 has a flexible support structure 501, and the three flexible support structures 501 are evenly distributed at 120° on the inner side of the main four-mirror common support ring 5; the outer side of the main four-mirror common support ring 5 has three mounting surfaces 502 that are bolted to the main four-mirror support member 9, and the three mounting surfaces 502 are evenly distributed at 120° on the outer side of the main four-mirror common support ring 5. The flexible support structure 501 and the main four-mirror common support mirror surface 1401 are bonded with epoxy glue, and the thickness of the epoxy glue is 0.15mm. The main four-mirror common support mounting surface 502 is connected to the main four-mirror support member 9 with M5 bolts, and the angle between the main four-mirror common support ring mounting surface 502 and the adjacent flexible support structure 501 is 60°. The main four-mirror support member 9 is connected to the lens bearing cylinder 801 with 4 M5 bolts.

[0044] As a further introduction to this embodiment, Figure 4 In the secondary mirror assembly, a flexible support structure 601 is provided inside the secondary mirror support ring 6, and three flexible support structures 601 are evenly distributed at 120° on the inside of the secondary mirror support ring 6. The upper surface of the secondary mirror support ring 6 has three secondary mirror support ring mounting surfaces 602 that are bolted to the secondary mirror adapter 15, and the three secondary mirror support ring mounting surfaces 602 are evenly distributed at 120° on the upper surface of the secondary mirror support ring 6. The lower surface of the secondary mirror adapter 15 has three adapter mounting surfaces 1502 that are bolted to the secondary mirror support ring 6; the upper surface of the secondary mirror adapter 15 is bolted to the secondary mirror mounting flange 10 through a pressing block 1501, and the pressing block 1501 is evenly distributed at 120° on the secondary mirror adapter 15. The secondary mirror mounting flange 10 also includes a secondary mirror mounting flange bonding surface 1001, and the secondary mirror mounting flange bonding surface 1001 is bonded to the upper end of the secondary mirror support rod 11 using epoxy glue. The secondary mirror support ring flexible support structure 601 and the secondary mirror 2 are bonded with epoxy glue, and the thickness of the epoxy glue is 0.15 mm; the bolt connection parts in the secondary mirror assembly are all connected with M4 bolts.

[0045] As a further introduction to this embodiment, Figure 1 The three support rod joints 12 in the secondary mirror support rod assembly are evenly distributed on the lens bearing tube 8 at 120 degrees; the support rod joint 12 includes a support rod joint installation surface 1201 and a support rod joint bonding surface 1202. The support rod joint installation surface 1201 is connected to the lens bearing tube 8 by two M5 bolts; the support rod joint bonding surface 1202 is bonded to the lower end of the secondary mirror support rod by epoxy glue.

[0046] As a further introduction to this embodiment, Figure 5 The three-mirror support ring 7 includes three three-mirror support ring flexible support structures 701 and three three-mirror support ring mounting surfaces 702.

[0047] The three three-mirror support ring flexible support structures 701 are evenly distributed on the inner side of the three-mirror support ring 7 at an angle of 120°; the three three-mirror support ring mounting surfaces 702 are evenly distributed on the outer side of the three-mirror support ring at an angle of 120°; the angle between the support structure 701 and the adjacent mounting surface 702 is 60°;

[0048] The three-mirror support ring flexible support structure 701 is bonded to the three mirrors 3 using epoxy glue; the thickness of the epoxy glue is 0.15 mm; the three-mirror support ring mounting surface 702 is bolted to the bearing cylinder mounting surface 803 using M5 bolts.

[0049] As a further introduction to this embodiment, Figure 6 The lens bearing cylinder 8 includes a first mounting surface 801 connected to the main four-mirror support member 9; a second mounting surface 802 connected to the support rod joint 12; a third mounting surface 803 connected to the three-mirror support ring 7; and a fourth mounting surface 804 connected to the bearing cylinder support member 13; the fourth mounting surface 804 is connected to the bearing cylinder support member 13 using four M5 bolts;

[0050] In the above technical solution, the present invention provides an athermalized all-silicon carbide cryogenic lens for a coaxial four-mirror optical infrared camera, which has the following beneficial effects:

[0051] The full silicon carbide lens structure can shrink as a whole in a low-temperature environment, realizing the athermal design of the lens optical machine and improving the low-temperature stability and adaptability of the lens. In a 150K environment, the RMS value of the deformation of each mirror surface is better than 6nm.

[0052] The low-temperature lens of the present invention, the reflector of the lens, the secondary mirror support rod assembly for controlling the distance between the reflectors, and the lens bearing tube assembly are all made of light, low expansion coefficient, high rigidity, and high thermal conductivity silicon carbide materials. Each silicon carbide structure is made by silicon carbide 3D printing, which reduces the difficulty of manufacturing complex structures, improves production efficiency, and is suitable for mass production. A higher structural rigidity and lightweight rate, better temperature uniformity, and larger-caliber lens reflector surface shape accuracy are achieved. The support ring is designed with a flexible support structure, which reduces the influence of assembly stress and thermal stress on the reflector surface shape, improves the adaptability of the lens, and under gravity conditions, the deformation RMS of each mirror surface in the radial and axial directions is better than 3nm. Compared with commonly used aluminum materials, the full silicon carbide lens can achieve higher structural rigidity and lightweight rate, better temperature uniformity, and larger-caliber lens reflector surface shape accuracy. The full silicon carbide lens structure shrinks as a whole in a low-temperature environment, realizes the athermal design of the lens optical machine, and improves the low-temperature stability and adaptability of the lens. The lens bearing tube improves the rigidity and stability of the lens structure, and acts as a low-temperature cold screen to suppress external stray light and improve the lens signal-to-noise ratio.

[0053] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A full silicon carbide cryogenic lens, comprising a primary mirror, a secondary mirror, a third mirror, and a fourth mirror; characterized in that: The primary mirror and the fourth mirror are arranged back to back and structurally form a common structure of the primary mirror and the fourth mirror, i.e., the primary four mirrors; the primary four mirrors and the third mirror are respectively connected to the two ends of a lens bearing cylinder, and the secondary mirror is connected to one end of the lens bearing cylinder on which the primary four mirrors are arranged through a secondary mirror support rod assembly; the primary four mirrors, the secondary mirror, the third mirror, the secondary mirror support rod assembly, and the lens bearing cylinder are made of silicon carbide material.

2. The all-silicon carbide cryogenic lens according to claim 1, characterized in that: The all-silicon carbide cryogenic lens includes A main four-mirror assembly, the main four-mirror assembly comprising a main mirror, four mirrors, a main four-mirror common support ring, and a main four-mirror support member; A secondary mirror assembly, the secondary mirror assembly comprising a secondary mirror, a secondary mirror support ring, and a secondary mirror adapter; A three-mirror assembly, the three-mirror assembly comprising three mirrors and a three-mirror support ring; A secondary mirror support rod assembly, the secondary mirror support rod assembly comprising a secondary mirror mounting flange, a secondary mirror support rod, and a support rod joint; A lens bearing cylinder assembly, the lens bearing cylinder assembly comprising a lens bearing cylinder and a bearing cylinder support; Among them, the primary mirror, secondary mirror, third mirror, fourth mirror, secondary mirror mounting flange, secondary mirror support rod, support rod joint, and lens load-bearing tube are all made of silicon carbide material, and each silicon carbide-made reflector and structural parts are lightweight; the main four-mirror common support ring, secondary mirror support ring, and third mirror support ring are made of Invar material that matches the thermal expansion coefficient of silicon carbide.

3. The all-silicon carbide cryogenic lens according to claim 2, characterized in that: The periphery of the main four mirrors is provided with a main four mirror common support mirror surface for connection, and the three support mirror surfaces are evenly distributed at 120° around the periphery of the main four mirrors; the inner side of the main four mirror common support ring is provided with a flexible support structure, and the three flexible support structures are evenly distributed at 120° on the inner side of the main four mirror common support ring; the outer side of the main four mirror common support ring is provided with three mounting surfaces that are bolted to the main four mirror support member, and the three mounting surfaces are evenly distributed at 120° on the outer side of the main four mirror common support ring; the flexible support structure and the main four mirror common support mirror surface are bonded with epoxy glue; The main four-mirror common support mounting surface is connected to the main four-mirror support member by bolts, and the angle between the main four-mirror common support ring mounting surface and the adjacent flexible support structure is 60°; the main four-mirror support member is connected to the lens bearing cylinder by bolts.

4. The all-silicon carbide cryogenic lens according to claim 2, characterized in that: In the secondary mirror assembly, a flexible support structure is provided on the inner side of the secondary mirror support ring, and three flexible support structures are evenly distributed on the inner side of the secondary mirror support ring at an angle of 120°; the upper surface of the secondary mirror support ring has three secondary mirror support ring mounting surfaces that are bolted to the secondary mirror adapter, and the three secondary mirror support ring mounting surfaces are evenly distributed on the upper surface of the secondary mirror support ring at an angle of 120°; the lower surface of the secondary mirror adapter has three adapter mounting surfaces that are bolted to the secondary mirror support ring; the upper surface of the secondary mirror adapter is bolted to the secondary mirror mounting flange through a pressure block, and the pressure block is evenly distributed on the secondary mirror adapter at an angle of 120°; the secondary mirror mounting flange also includes a secondary mirror mounting flange bonding surface, and the secondary mirror mounting flange bonding surface is bonded to the upper end of the secondary mirror support rod with epoxy glue; the secondary mirror support ring flexible support structure is bonded to the secondary mirror with epoxy glue; the bolted parts in the secondary mirror assembly are all connected with bolts.

5. The all-silicon carbide cryogenic lens according to claim 2, characterized in that: The three support rod joints in the secondary mirror support rod assembly are evenly distributed at 120° on the lens bearing tube; the support rod joint includes a support rod joint installation surface and a support rod joint bonding surface; the support rod joint installation surface and the lens bearing tube are connected with bolts; the support rod joint bonding surface and the lower end of the secondary mirror support rod are bonded with epoxy glue.

6. The all-silicon carbide cryogenic lens according to claim 2, characterized in that: The three-mirror support ring includes three three-mirror support ring flexible support structures and three three-mirror support ring mounting surfaces; the three three-mirror support ring flexible support structures are evenly distributed at 120° on the inner side of the three-mirror support ring; the three three-mirror support ring mounting surfaces are evenly distributed at 120° on the outer side of the three-mirror support ring; the angle between the three-mirror support ring flexible support structure and the adjacent three-mirror support ring mounting surfaces is 60°; the three-mirror support ring flexible support structure is bonded to the three mirrors with epoxy glue; the three-mirror support ring mounting surface is bolted to the load-bearing cylinder mounting surface with bolts.

7. The all-silicon carbide cryogenic lens according to claim 2, characterized in that: The lens bearing cylinder comprises a first mounting surface connected to the main four-mirror support member; a second mounting surface connected to the support rod joint; and a third mounting surface connected to the three-mirror support ring; A fourth mounting surface connected to the load-bearing cylinder support member; the fourth mounting surface and the load-bearing cylinder support member are connected by bolts.

8. A method for manufacturing a full silicon carbide cryogenic lens as claimed in claim 1 or 2 or 3 or 4 or 5 or 6 or 7, characterized in that: The main four mirrors, secondary mirror, third mirror, secondary mirror support rod assembly, and lens bearing cylinder are made by silicon carbide 3D printing.

9. A full silicon carbide cryogenic lens as claimed in claim 1 or 2 or 3 or 4 or 5 or 6 or 7 applied to a coaxial four-mirror optical infrared camera.

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