Large-aperture off-axis telescopic system adopting spherical adjusting structure and adjusting method thereof

Abstract

The invention discloses a large-aperture off-axis telescopic system adopting a spherical adjusting structure and an adjusting method thereof, and belongs to the technical field of high-precision optical element supporting and adjusting mechanisms. Comprising a supporting frame, a primary mirror and a secondary mirror, the primary mirror and the secondary mirror are installed on the supporting frame, the primary mirror is installed on the supporting frame through a primary mirror positioning module, and the secondary mirror is installed on the supporting frame through a secondary mirror positioning module and a fine adjustment module; and the fine adjustment module can dynamically adjust the secondary mirror to realize six-degree-of-freedom adjustment of the secondary mirror. According to the invention, the problem of position offset generated when three position degrees of freedom and three angle degrees of freedom of the secondary mirror are adjusted in place and then assembled by using six-degree-of-freedom auxiliary adjustment equipment at present is solved, the adjustment process of the secondary mirror of the large-aperture off-axis telescopic system is simplified, and the adjustment efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of high-precision optical element support and adjustment mechanisms, and in particular relates to a large-aperture off-axis telescope system using a spherical adjustment structure and an adjustment method thereof. Background Art

[0002] In large-aperture off-axis telescope systems, secondary mirrors are often used to fold the optical path to reduce the size and volume of the system. They are widely used, and their surface quality has a great impact on the imaging quality of the optoelectronic system. The commonly used secondary mirrors of telescope systems often use an integrated installation structure. The secondary mirror needs to ensure the surface quality while completing the adjustment of the angle and position freedom, which is difficult. Therefore, through reasonable adjustment structure design, while meeting the surface accuracy indicators of the optical system, optimizing the angle and position freedom adjustment links, and effectively reducing the impact of the installation stress on the surface, it is of great significance to improve assembly efficiency and reduce costs.

[0003] At present, in the assembly and adjustment of large-aperture off-axis telescope systems, the commonly used method is to first fix the secondary mirror in the auxiliary assembly and adjustment equipment, use the six-degree-of-freedom auxiliary assembly and adjustment equipment to adjust the three position degrees of freedom and three angle degrees of freedom of the secondary mirror, and then fix the secondary mirror to its fixed mirror mount by peripheral bonding. However, this method has the following disadvantages:

[0004] 1. Because the fixed state of the secondary mirror adjusted by the auxiliary adjustment equipment is inconsistent with the fixed state of the secondary mirror of the final telescope system, the secondary mirror needs to be fixed again during the conversion from the assembly state to the final product state. The change of the fixed state will inevitably affect the state of the secondary mirror, causing repeated adjustment process;

[0005] 2. After the secondary mirror is adjusted into place, there is a lack of auxiliary support when it is fixed by gluing. After the angle is adjusted, the thickness of the glue layer fixing the secondary mirror is uneven around the periphery. The shrinkage stress of the glue layer during curing will cause the angle of the secondary mirror to shift. Repeated disassembly and adjustment are often required, which is inefficient. Summary of the invention

[0006] Technical issues to be solved:

[0007] In order to avoid the shortcomings of the prior art, the present invention provides a large-aperture off-axis telescope system using a spherical adjustment structure and an adjustment method thereof, wherein the secondary mirror is directly assembled in the optical system through the cooperation of a positioning module and a fine-tuning module, thereby solving the problem of positional deviation caused by adjusting the three positional degrees of freedom and the three angular degrees of freedom of the secondary mirror into place and then assembling the secondary mirror using a six-degree-of-freedom auxiliary assembly and adjustment device, simplifying the secondary mirror adjustment process of the large-aperture off-axis telescope system and improving the assembly and adjustment efficiency.

[0008] The technical solution of the present invention is: a large-aperture off-axis telescope system using a spherical adjustment structure, including a support frame and a primary mirror and a secondary mirror installed thereon, the primary mirror being installed on the support frame through a primary mirror positioning module, and the secondary mirror being installed on the support frame through a secondary mirror positioning module and a fine-tuning module; the fine-tuning module can dynamically adjust the secondary mirror to achieve 6-degree-of-freedom adjustment of the secondary mirror.

[0009] A further technical solution of the present invention is: the main mirror is a non-uniform thickness structure, and a plurality of positioning grooves are evenly distributed on its circumferential surface along the circumferential direction, which cooperate with the main mirror positioning module to complete the positioning and installation of the main mirror on the support frame.

[0010] A further technical solution of the present invention is: the main mirror positioning module includes a main mirror frame and a plurality of elastic pressure plates arranged along the circumferential direction, the main mirror frame is an annular frame structure with light transmittance at both ends, and the main mirror is embedded therein; the plurality of elastic pressure plates are evenly distributed on the mounting annular surface of the main mirror frame along the circumferential direction, corresponding one by one to the positioning grooves on the circumferential surface of the main mirror; the fixed end of the elastic pressure plate is installed on the main mirror frame, and the free end thereof is inserted into the main mirror positioning groove to limit the main mirror axially.

[0011] A further technical solution of the present invention is: the elastic pressing plate is an annular pressing plate made of elastic material, and lugs are provided on both sides of the elastic pressing plate. The lugs on both sides are fixed to corresponding positions of the main mirror frame by fasteners, and axial elastic pressure is applied to the main mirror, which can ensure the axial positioning of the main mirror while avoiding damage caused by excessive stress.

[0012] A further technical solution of the present invention is: the secondary mirror positioning module includes a secondary mirror frame and a plurality of leaf springs circumferentially arranged on it, the secondary mirror frame is an annular frame structure with light transmittance at both ends, and the secondary mirror is embedded therein; the secondary mirror frame is fastened after being adjusted into place by bolts installed on the leaf springs.

[0013] A further technical solution of the present invention is: the fine-tuning module includes an adjustment seat, a height adjustment pad and a spherical structure on the secondary mirror frame; the adjustment seat is a flange structure, and the annular boss on one side thereof is consistent with the inner diameter of the mounting hole of the support frame, is coaxially sleeved in the mounting hole of the support frame, and its radial position is adjusted by the height adjustment pad, that is, the radial position of the secondary mirror frame is limited; the annular boss on the other side serves as the mounting hole of the secondary mirror frame, and its inner root is a ring surface with a convergent structure, which is used to limit the axial position of the secondary mirror frame, and the generatrix of the convergent ring surface is a straight line; a plurality of through holes are opened on the outer edge end surface of the flange structure along the circumferential direction, which are used to install fasteners for fixing the adjustment seat to the support frame and fasteners for installing the secondary mirror frame on the adjustment seat;

[0014] The annular surface on the secondary mirror frame adjacent to the secondary mirror reflective surface is a spherical structure, which is coaxially installed relative to the convergent annular surface of the adjustment seat. Through the tangential cooperation between the spherical surface and the inclined surface, the secondary mirror can be adjusted in three directions while constraining the axial and radial positions of the secondary mirror.

[0015] A further technical solution of the present invention is that the rotation center of the spherical structure on the secondary mirror frame is located on the folding axis of the secondary mirror.

[0016] A further technical solution of the present invention is that the primary mirror and the secondary mirror are both fixed by bonding with silicone rubber after being positioned.

[0017] A further technical solution of the present invention is: the telephoto magnification of the large-aperture off-axis system is 4 times, the working band is 3.5-5 μm, the primary mirror aperture is 210 mm, the primary mirror off-axis amount is 200 mm, the secondary mirror off-axis amount is 50 mm, and the overall size of the telephoto system is 343.5 mm long * 264 mm wide * 283.5 mm high; the spherical structure rotation radius of the secondary mirror frame is 46 mm, which is the same as the diameter of the secondary mirror.

[0018] A method for adjusting a large-aperture off-axis telescope system using a spherical adjustment structure, the specific steps are as follows:

[0019] Step 1: Install the primary mirror on the support frame through the primary mirror frame, which serves as the installation reference for the telescope system;

[0020] Step 2: With the primary mirror as a reference, adjust the position of the adjustment seat through the height adjustment pad, and pre-position the secondary mirror frame with the secondary mirror in the adjustment seat;

[0021] Step 3: With the primary mirror as a reference, the secondary mirror frame is rotated around the center of the spherical structure in the adjustment seat, and the two angular degrees of freedom of the secondary mirror in the direction perpendicular to its folding axis are adjusted into place;

[0022] Step 4: With the primary mirror as a reference, the secondary mirror frame is rotated in the adjustment seat around the secondary mirror folding axis, and the angular freedom of the secondary mirror around its folding axis is adjusted to the desired position;

[0023] Step 5: Repeat steps 2 to 4 to make the position and angle of the secondary mirror meet the requirements of the telescope system;

[0024] Step 6: After confirming that the adjustment is in place, use screws to secure the adjustment seat to the support frame, and use silicone rubber to bond and fix the adjustment gap between the secondary frame and the adjustment seat, as well as the joint surface between the leaf spring and the secondary frame.

[0025] Beneficial Effects

[0026] The beneficial effects of the present invention are as follows: the large-aperture off-axis telescope system and its adjustment method using a spherical adjustment structure of the present invention can achieve one-time adjustment to meet the requirements of the telescope system spacing, angle and surface shape in actual adjustment, and the changes of the above indicators after high and low temperature and process vibration are all within the permitted range, which improves the success rate of one-time adjustment. Compared with the conventional method, which is prone to repeated adjustment due to changes in surface shape and angle, the adjustment process of the telescope system is effectively simplified, and has the advantages of high connection stiffness, good stability, and easy adjustment. The specific advantages are as follows:

[0027] 1. Both the primary mirror and the secondary mirror are bonded to the main mirror frame by silicone rubber. While bonding and fixing the mirrors, the silicone rubber uses its flexibility to isolate the installation stress caused by the installation structure;

[0028] 2. The spherical structure is used as the mounting structure of the secondary mirror. The rotation around the center of the spherical structure or the secondary mirror folding axis can realize the three degrees of freedom adjustment of the secondary mirror installed thereon. The spherical adjustment structure and the secondary mirror fixing structure are independent in function, avoiding the influence of the adjustment process on the secondary mirror surface. After the adjustment, the secondary mirror seat can be directly fixed by injecting glue to maintain the consistency between the installation and the actual use state, avoiding repeated installation and adjustment. The spherical adjustment structure and the fixing structure of the secondary mirror are independent in function, and the existence of the glue layer avoids the influence of the angle adjustment process on the secondary mirror surface, fundamentally ensuring the surface accuracy of the secondary mirror.

[0029] 3. The secondary mirror adjustment structure of the present invention can be applied to various off-axis telescope systems in mid- and long-wave infrared optical systems, as well as other occasions with high requirements on the mirror group surface shape and angle adjustment.

[0030] 4. The spherical adjustment structure of the present invention is independent of the primary and secondary mirrors, which facilitates mass assembly and improves assembly efficiency.

[0031] The present invention simplifies the adjustment structure and adjustment method of the primary and secondary mirrors while ensuring the surface accuracy of the primary and secondary mirrors, thereby improving the installation and adjustment efficiency of the off-axis telescope system. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic diagram of a large-aperture off-axis telescope system in the present invention;

[0033] Figure 2 It is a composition diagram of the large-aperture off-axis telephoto system of the present invention;

[0034] Figure 3 is a cross-sectional view of a large-aperture off-axis telescope system in the present invention;

[0035] Figure 4 This is a schematic diagram of the design of the main mirror group of the large-aperture off-axis telescope system in the present invention;

[0036] Figure 5is a cross-sectional view of the main mirror assembly of the large-aperture off-axis telescope system of the present invention;

[0037] Figure 6 It is a schematic diagram of the design of the secondary lens group of the large-aperture off-axis telescope system in the present invention;

[0038] Figure 7 It is a cross-sectional view of the secondary lens group of the large-aperture off-axis telescope system in the present invention.

[0039] Explanation of the reference numerals: 1—primary mirror; 2—primary mirror frame; 3—secondary mirror; 4—secondary mirror frame; 5—adjustment seat; 6—support frame; 7—elastic pressure plate; 8—height adjustment pad; 9—leaf spring; 10—spherical structure; 11—inclined structure. DETAILED DESCRIPTION

[0040] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0041] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0042] Based on the problems of inconsistency between the installation and use status of existing large-aperture off-axis telescope systems and poor stability of the installation and adjustment results, the present invention adopts a spherical adjustment structure for medium- and long-wave infrared optical and mechanical systems with large-aperture requirements, and provides a more convenient and more stable large-aperture off-axis telescope system and its adjustment method, which reduces the difficulty of installation and adjustment of the telescope system and improves assembly efficiency. The large-aperture off-axis telescope system includes a support frame and a primary mirror and a secondary mirror mounted thereon, wherein the primary mirror is mounted on the support frame through a primary mirror positioning module, and the secondary mirror is mounted on the support frame through a secondary mirror positioning module and a fine-tuning module; the fine-tuning module can dynamically adjust the secondary mirror to achieve 6-degree-of-freedom adjustment of the secondary mirror.

[0043] Specifically, the main mirror is a non-uniform thickness structure, and a plurality of positioning grooves are evenly distributed on its circumferential surface in the circumferential direction, which cooperate with the main mirror positioning module to complete the positioning and installation of the main mirror on the support frame.

[0044] Specifically, the main mirror positioning module includes a main mirror frame and a plurality of elastic pressure plates arranged along the circumferential direction. The main mirror frame is an annular frame structure with light transmittance at both ends, and the main mirror is embedded therein; the plurality of elastic pressure plates are evenly distributed on the mounting annular surface of the main mirror frame along the circumferential direction, corresponding one by one to the positioning grooves on the circumferential surface of the main mirror; the fixed end of the elastic pressure plate is installed on the main mirror frame, and the free end thereof is inserted into the main mirror positioning groove to limit the main mirror axially.

[0045] Specifically, the elastic pressing piece is an elastic material annular pressing piece, with lugs on both sides, and the lugs on both sides are fixed to the corresponding positions of the main mirror frame by fasteners, so as to apply axial elastic pressure to the main mirror, thereby ensuring the axial positioning of the main mirror while avoiding damage caused by excessive stress. While reducing the size of the telescope system in the off-axis direction, the dynamic stability of the telescope system installation reference is guaranteed.

[0046] Specifically, the secondary mirror positioning module includes a secondary mirror frame and a plurality of leaf springs arranged circumferentially thereon. The secondary mirror frame is an annular frame structure with light-transmitting ends, and the secondary mirror is embedded therein. The secondary mirror frame is fastened after being adjusted into place by bolts installed on the leaf springs.

[0047] Specifically, the fine-tuning module includes an adjustment seat, a height adjustment pad and a spherical structure on the secondary mirror frame; the adjustment seat is a flange structure, and its annular boss on one side is consistent with the inner diameter of the mounting hole of the support frame, is coaxially sleeved in the mounting hole of the support frame, and its radial position is adjusted by the height adjustment pad, that is, the radial position of the secondary mirror frame is limited; the annular boss on the other side serves as the mounting hole of the secondary mirror frame, and its inner root is a ring surface with a convergent structure, which is used to limit the axial position of the secondary mirror frame, and the generatrix of the convergent ring surface is a straight line; a plurality of through holes are opened in the circumferential direction on the upper edge end surface of the flange structure, which are used to install fasteners that fix the adjustment seat to the support frame and fasteners that install the secondary mirror frame on the adjustment seat; the ring surface on the side of the secondary mirror frame adjacent to the secondary mirror reflection surface is a spherical structure, which is coaxially installed relative to the convergent ring surface of the adjustment seat, and through the tangent cooperation between the spherical surface and the inclined surface, it is achieved that the secondary mirror can be adjusted with three degrees of freedom while constraining the axial and radial positions of the secondary mirror.

[0048] Specifically, the rotation center of the spherical structure on the secondary mirror frame is located on the folding axis of the secondary mirror.

[0049] Specifically, after the secondary mirror is adjusted into place, the leaf spring is glued and fixed to the secondary mirror adjustment seat by silicone rubber, and 3M glue is applied around the contact surface between the fastener and the leaf spring to ensure angle stability in high and low temperature and vibration environments.

[0050] Specifically, since each component of the spherical adjustment structure has good processability, the processing precision can be reduced, the processing cycle can be shortened, and the processing cost can be reduced.

[0051] After the primary mirror is fixed as the adjustment reference of the telescope system, the angle adjustment of the secondary mirror is achieved by rotating the secondary mirror frame in a small range relative to the adjustment seat. Among them, the primary mirror and the secondary mirror are both bonded to the main mirror frame by silicone rubber. While the silicone rubber is bonded and fixed to the mirror, it uses its flexibility to isolate the installation stress brought by the installation structure; the spherical structure is used as the installation structure of the secondary mirror, and the three degrees of freedom of the angle of the secondary mirror installed thereon are adjusted by rotating around the center of the spherical structure or the folding axis of the secondary mirror; and the spherical adjustment structure and the secondary mirror fixing structure are independent in function, avoiding the influence of the adjustment process on the secondary mirror surface shape. After the adjustment is completed, the secondary mirror seat can be directly fixed by glue injection to maintain the consistency of the adjustment with the actual use state, avoiding repeated adjustment. The secondary mirror adjustment structure of the present invention can be applied to various off-axis telescope systems of medium and long-wave infrared optical machine systems, as well as other occasions with high requirements for the mirror group surface shape and angle adjustment.

[0052] The spherical adjustment structure is composed of a spherical structure on one end face of the secondary mirror frame, an inclined surface structure on the inner end face of the adjustment seat, and a leaf spring installed on the adjustment seat. The secondary mirror frame is used as the installation structure of the secondary mirror, and is installed on the inclined surface structure of the adjustment seat. The angle adjustment of the secondary mirror is achieved by using a small angle deviation around the center of the circle of the spherical structure or the center of rotation of the rotation axis, and the gap between the spherical structure and the inclined surface structure is injected with glue and solidified after adjustment. The plane spring is used to maintain the position of the secondary mirror frame during angle adjustment, and to assist in fixing the adjusted secondary mirror frame to prevent the secondary mirror from deflecting under the action of the overturning moment or the curing stress of the glue layer.

[0053] The above technical solution is further described below with reference to the accompanying drawings and examples:

[0054] Reference Figure 1-Figure 3 As shown, the present embodiment adopts a large-aperture off-axis telescope system with a spherical adjustment structure, comprising a primary mirror 1, a primary mirror frame 2, a secondary mirror 3, a secondary mirror frame 4, an adjustment seat 5, a support frame 6, an elastic pressure plate 7, a height adjustment pad 8, a leaf spring 9, and a spherical structure 10 and an inclined surface structure 11 (i.e., a convergent annulus) for angle adjustment; wherein the spherical structure 10 is arranged on one side end surface of the secondary mirror frame 4, and the inclined surface structure 11 is arranged on the inner end surface of the adjustment seat 5. The primary mirror 1 is fixed in the primary mirror frame 2 as the adjustment reference of the telescope system, and the elastic pressure plate 7 is bonded to the primary mirror 1 through silicone rubber and fixed to the primary mirror frame 2 with screws. The secondary mirror 3 is fixed in the secondary mirror frame 4. The spherical structure 10 on one side end face of the secondary mirror frame 4 is tangent to the inclined structure 11 on the adjustment seat 5. The secondary mirror frame 4 is pressed into the adjustment seat 5 by the leaf spring 9. A gap is reserved between the radial direction of the secondary mirror frame 4 and the adjustment seat 5 for rotation angle adjustment. The gap is selected according to the adjustment angle requirements and generally should not exceed the allowable thickness of the glue selected for fixing later.

[0055] The primary mirror 1 and the secondary mirror 3 are respectively bonded to the mirror frame by silicone rubber to ensure the optical surface accuracy, and a spherical adjustment structure is arranged between the primary mirror frame 2 and the secondary mirror frame 4 to adjust the angle and position freedom of the secondary mirror 3.

[0056] Reference Figure 4 and Figure 5 As shown, the large-diameter primary mirror 1 adopts a non-uniform thickness design, and a weight-reducing groove is designed on its back. It is bonded to the primary mirror frame 2 through a radial silicone rubber ring, and is pressed against the primary mirror frame 2 by an elastic pressure plate 7 on the side of the primary mirror 1. The anti-impact design of the primary mirror 1 adopts an elastic pressure plate 7, which is pressed into the embedded groove on the side of the primary mirror 1. While reducing the diameter of the primary mirror 1, it avoids light blocking caused by pressing on the working end face of the primary mirror.

[0057] Reference Figure 6 and Figure 7 As shown, the angle adjustment of the secondary mirror 3 is achieved by adopting a spherical adjustment structure, which includes a spherical structure 10 on one end face of the secondary mirror frame 4 and a slope structure 11 on the inner end face of the adjustment seat 5. The angle adjustment of the secondary mirror 3 is achieved by rotating the spherical structure 10 on the tangent slope structure 11.

[0058] The end surface of the secondary mirror frame 4 adopts a spherical structure 10, and by using it in conjunction with the inclined surface structure 11 on the adjustment seat 5, the secondary mirror 3 can be rotated around the center of the spherical structure 10 to achieve angle adjustment of the secondary mirror 3. The gyration radius of the spherical structure 10 is generally selected in combination with the size of the secondary mirror 3 and the adjustment angle requirement to select a suitable gyration radius of the spherical structure, which not only meets the angle adjustment requirements, but also minimizes the influence of the angle adjustment on the axial position of the secondary mirror 3. When adjusting at a small angle, the size of the secondary mirror can be referenced for selection.

[0059] Reference Figure 6 As shown, the end surface of the adjustment seat 5 that is tangent to the spherical structure 10 on the secondary mirror frame 4 adopts a slope structure 11, and the mounting hole where the adjustment seat 5 and the support frame 6 are connected adopts a rough fit, and a gap is reserved to achieve radial position adjustment of the secondary mirror 3.

[0060] Reference Figure 6 As shown, the leaf spring 9 arranged on the end face of the secondary mirror frame 4 presses the secondary mirror frame 4 against the adjustment seat 5 by utilizing the preload generated when it is deformed, so as to prevent the position and angle displacement of the secondary mirror 3 under the action of the overturning moment. Finally, after the telephoto system is adjusted into place, the contact surfaces of the leaf spring 9, the secondary mirror frame 4, the adjustment seat 5 and the fixing fasteners are all glued and fixed to improve the support stiffness under vibration conditions.

[0061] Reference Figure 7As shown, the spherical structure 10 is the core component of the spherical adjustment structure, which cooperates with the inclined surface structure 11 on the adjustment seat 5, and the angle adjustment of the secondary mirror 3 is achieved through the rotation movement of the spherical structure 10 in the inclined surface structure 11. When designing the spherical structure 10, it is necessary to set the rotation center of the spherical structure on the folding axis of the secondary mirror 3, so that the adjustment of the rotational freedom of the secondary mirror 3 around its folding axis does not affect the adjustment of the angle freedom of the secondary mirror 3 around its spherical adjustment structure; it is also necessary to ensure that the angle adjustment amount required by the spherical structure 10 is adapted to the glue gap between the secondary mirror frame 4 and the adjustment seat 5, and when the small angle is generally not more than ±6', it will not cause a significant change in the glue gap between the secondary mirror frame 4 and the adjustment seat 5, and then cause the peripheral glue layer to shrink due to different thicknesses, causing the angle of the secondary mirror frame 4 and the secondary mirror 3 thereon to deviate, resulting in repeated assembly process. Due to the existence of this associated feature, the present invention solves the problems of poor stability of the existing installation and adjustment technology and easy repetition of angle adjustment.

[0062] Example:

[0063] This embodiment adopts a large-aperture off-axis telescope system with a spherical adjustment structure. The telescope magnification of the system is 4 times, and the working band is 3.5-5 μm. The primary mirror has an aperture of 210 mm, the primary mirror is 200 mm off-axis, and the secondary mirror is 50 mm off-axis. The overall size of the telescope system is 343.5 mm long * 264 mm wide * 283.5 mm high. The primary mirror 1 and the secondary mirror 3 are both made of fused quartz material and are bonded to their respective frames using silicone rubber. The primary mirror frame 2, the secondary mirror frame 4, and the elastic pressure plate 7 are all made of titanium alloy material. The operating temperature of the telescope system is -20°C to +60°C.

[0064] In this embodiment, the main mirror adopts a lightweight design on the back, and adopts an upper and lower two-stage layered bonding method along the side wall of the mirror body to provide firm support while minimizing the curing stress of the glue layer; in addition, 5 anti-impact grooves are opened on the side wall of the mirror body, and the position of the grooves avoids the thinnest part of the mirror body after the off-axis design, so as to maintain the optical position of the main mirror 1 in a dynamic environment to meet the system requirements.

[0065] In this embodiment, the secondary mirror frame 4 uses a spherical structure 10, which is pressed against the inclined surface structure 11 in the adjustment seat 5 through a leaf spring 9. The three-degree-of-freedom angle adjustment of the secondary mirror installed thereon is achieved by rotating the spherical structure 10 around the center of the sphere or the folding axis. The secondary mirror 3 is fixed with silicone rubber, and the outer spherical structure will not have an adverse effect on the surface shape of the secondary mirror 3 when adjusting the angle. After the adjustment is completed, the secondary mirror seat can be fixed by directly injecting glue, so that the installation and adjustment are consistent with the actual use state, avoiding repeated installation and adjustment.

[0066] In order to maximize the angle adjustment of the secondary mirror in the present solution and avoid light blocking by the system due to the excessive size of the secondary mirror adjustment structure, the secondary mirror frame 4 uses a spherical structure 10 with a rotation radius of 46 mm, which is the same as the diameter of the secondary mirror, and the gap between the secondary mirror frame 4 and the adjustment seat 5 is selected to be 0.6 mm to ensure that the RTV silicone rubber used for fixing has sufficient bonding strength; while achieving the angle adjustment of the secondary mirror within the range of ±6′, the change in the gap between the secondary mirror frame 4 and the adjustment seat 5 does not exceed 0.12 mm, and the change in the gap between the glue layer caused by the angle adjustment does not exceed 20%, which effectively avoids the angle deflection caused by the uneven thickness of the glue layer during the shrinkage stress of the glue layer curing.

[0067] In this embodiment, the adjustment seat 5 is docked with the support frame 6 through the screw mounting hole, and a rough fit is adopted. The diameter of the mounting hole is about 0.8mm larger than the diameter of the mounting screw. The reserved gap can realize the adjustment of the two radial position freedoms perpendicular to the folding axis of the secondary mirror 3 by ±0.4mm each. The screw mounting hole can be changed into a waist-shaped hole to realize a wide range of position adjustment in a specific direction. A height adjustment pad 8 is used under the adjustment seat 5 to adjust the overall axial position of the secondary mirror 3 and its secondary mirror frame 4 installed in the adjustment seat 5. The selected height adjustment pad 8 is a series of gaskets with a minimum adjustment range of 0.01mm and a maximum adjustment range of 1mm. The maximum adjustment amount can be reduced or expanded by selecting the theoretical thickness of the height adjustment pad 8 during design.

[0068] In this embodiment, a leaf spring 9 is arranged on the end surface of the adjustment seat 5, and the leaf spring 9 is deformed to generate preload by adjusting the installation height, so that the secondary mirror frame 4 is pressed against the inclined surface structure 11 of the adjustment seat 5. The leaf spring material is a tin bronze strip, and the thickness is divided into 0.1mm and 0.2mm. When installing and adjusting, it is selected according to the direction and size of the angle adjustment amount of the secondary mirror 3. After the angle of the secondary mirror 3 is adjusted in place, a proper amount of silicone rubber is applied on the contact surface between the leaf spring 9 and the secondary mirror frame 4 for bonding, and a proper amount of 3M is applied on the contact surface between the leaf spring 9 and the adjustment seat 5 for curing, so as to prevent the secondary mirror frame 4 from possible angle deflection under the curing stress of the surrounding adhesive layer.

[0069] The specific adjustment method of the telescopic system in this embodiment is:

[0070] Step 1: Taking the primary mirror 1 as a reference, the overall translation adjustment seat 5 or selecting a suitable height adjustment pad 8 to adjust the position of the secondary mirror 3 to the correct position;

[0071] Step 2: With the primary mirror 1 as a reference, the secondary mirror frame 4 is rotated in the adjustment seat 5 around the center of the spherical structure 10 or its folding axis to adjust the angle of the secondary mirror 3 to the desired position;

[0072] Step 3: If necessary, repeat steps 1 and 2 to make the position and angle of the secondary mirror 3 meet the requirements of the telescope system;

[0073] Step 4: After confirming that the adjustment is in place, use screws to fix the adjustment seat 5 to the support frame 6, and use silicone rubber to bond and fix in the adjustment gap between the secondary frame 4 and the adjustment seat 5, and on the joint surface of the leaf spring 9 and the secondary frame 4.

[0074] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A large-aperture off-axis telescope system using a spherical adjustment structure, characterized in that: It includes a supporting frame and a primary mirror and a secondary mirror installed thereon, wherein the primary mirror is installed on the supporting frame through a primary mirror positioning module, and the secondary mirror is installed on the supporting frame through a secondary mirror positioning module and a fine-tuning module; the fine-tuning module can dynamically adjust the secondary mirror to achieve 6-degree-of-freedom adjustment of the secondary mirror.

2. According to claim 1, a large-aperture off-axis telephoto system using a spherical adjustment structure, characterized in that: The primary mirror is a non-uniform thickness structure, and a plurality of positioning grooves are evenly distributed along the circumferential direction on the circumference of the circumference, which cooperate with the primary mirror positioning module to complete the positioning and installation of the primary mirror on the support frame.

3. According to claim 2, a large-aperture off-axis telephoto system using a spherical adjustment structure is characterized in that: The main mirror positioning module includes a main mirror frame and a plurality of elastic pressing plates arranged along the circumferential direction. The main mirror frame is an annular frame structure with light transmittance at both ends, and the main mirror is embedded therein; the plurality of elastic pressing plates are evenly distributed on the mounting annular surface of the main mirror frame along the circumferential direction, corresponding one by one to the positioning grooves on the circumferential surface of the main mirror; the fixed end of the elastic pressing plate is installed on the main mirror frame, and the free end thereof is inserted into the main mirror positioning groove to axially limit the main mirror.

4. The large-aperture off-axis telephoto system using a spherical adjustment structure according to claim 3, characterized in that: The elastic pressing plate is an annular pressing plate made of elastic material, and lugs are provided on both sides of the elastic pressing plate. The lugs on both sides are fixed to corresponding positions of the main mirror frame by fasteners, and axial elastic pressure is applied to the main mirror, which can ensure the axial positioning of the main mirror while avoiding damage caused by excessive stress.

5. The large-aperture off-axis telephoto system using a spherical adjustment structure according to claim 4, characterized in that: The secondary mirror positioning module includes a secondary mirror frame and a plurality of leaf springs arranged circumferentially thereon. The secondary mirror frame is an annular frame structure with light-transmitting ends, and the secondary mirror is embedded therein. The secondary mirror frame is fastened after being adjusted into place by bolts installed on the leaf springs.

6. The large-aperture off-axis telephoto system using a spherical adjustment structure according to claim 5, characterized in that: The fine-tuning module comprises an adjustment seat, a height adjustment pad and a spherical structure on the secondary mirror frame; the adjustment seat is a flange structure, and the annular boss on one side thereof is consistent with the inner diameter of the mounting hole of the support frame, is coaxially sleeved in the mounting hole of the support frame, and its radial position is adjusted by the height adjustment pad, that is, the radial position of the secondary mirror frame is limited; the annular boss on the other side serves as the mounting hole of the secondary mirror frame, and its inner root is a ring surface with a convergent structure, which is used to limit the axial position of the secondary mirror frame, and the generatrix of the convergent ring surface is a straight line; a plurality of through holes are opened on the outer edge end surface of the flange structure along the circumferential direction, which are used to install fasteners for fixing the adjustment seat to the support frame and fasteners for installing the secondary mirror frame on the adjustment seat; The annular surface on the secondary mirror frame adjacent to the secondary mirror reflective surface is a spherical structure, which is coaxially installed relative to the convergent annular surface of the adjustment seat. Through the tangential cooperation between the spherical surface and the inclined surface, the secondary mirror can be adjusted in three directions while constraining the axial and radial positions of the secondary mirror.

7. A large-aperture off-axis telescopic system using a spherical adjustment structure according to claim 6, characterized in that: The rotation center of the spherical structure on the secondary mirror frame is located on the folding axis of the secondary mirror.

8. The large-aperture off-axis telescopic system using a spherical adjustment structure according to claim 7, characterized in that: After being positioned, the primary mirror and the secondary mirror are both fixed by bonding with silicone rubber.

9. A large-aperture off-axis telescopic system using a spherical adjustment structure according to claim 8, characterized in that: The large-aperture off-axis system has a telephoto magnification of 4 times and an operating band of 3.5 to 5 μm. The primary mirror has an aperture of 210 mm, an off-axis amount of the primary mirror is 200 mm, and an off-axis amount of the secondary mirror is 50 mm. The overall size of the telephoto system is 343.5 mm long * 264 mm wide * 283.5 mm high; the spherical structure rotation radius of the secondary mirror frame is 46 mm, which is the same as the diameter of the secondary mirror.

10. An adjustment method for a large-aperture off-axis telescope system using a spherical adjustment structure according to any one of claims 1 to 9, characterized in that The specific steps are as follows: Step 1: Install the primary mirror on the support frame through the primary mirror frame, which serves as the installation reference for the telescope system; Step 2: With the primary mirror as a reference, adjust the position of the adjustment seat through the height adjustment pad, and pre-position the secondary mirror frame with the secondary mirror in the adjustment seat; Step 3: With the primary mirror as a reference, the secondary mirror frame is rotated around the center of the spherical structure in the adjustment seat, and the two angular degrees of freedom of the secondary mirror in the direction perpendicular to its folding axis are adjusted into place; Step 4: With the primary mirror as a reference, the secondary mirror frame is rotated in the adjustment seat around the secondary mirror folding axis, and the angular freedom of the secondary mirror around its folding axis is adjusted to the desired position; Step 5: Repeat steps 2 to 4 to make the position and angle of the secondary mirror meet the requirements of the telescope system; Step 6: After confirming that the adjustment is in place, use screws to secure the adjustment seat to the support frame, and use silicone rubber to bond and fix the adjustment gap between the secondary frame and the adjustment seat, as well as the joint surface between the leaf spring and the secondary frame.

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