A large-aperture off-axis telescopic system using a spherical adjustment structure and an adjustment method thereof

Abstract

The present invention relates to a large-aperture off-axis telescope system employing a spherical adjustment structure and its adjustment method, belonging to the technical field of high-precision optical element support and adjustment mechanisms. The system comprises a support frame and a primary mirror and a secondary mirror mounted thereon. The primary mirror is mounted on the support frame via a primary mirror positioning module, and the secondary mirror is mounted on the support frame via a secondary mirror positioning module and a fine-tuning module. The fine-tuning module is capable of dynamically adjusting the secondary mirror to achieve six degrees of freedom (DOF) of the secondary mirror. This invention solves the problem of positional offset that occurs during reassembly after the three positional and three angular degrees of freedom of the secondary mirror are adjusted using six-DOF auxiliary assembly and adjustment equipment. This simplifies the secondary mirror adjustment process for large-aperture off-axis telescope systems and improves assembly and adjustment efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-precision optical element support and adjustment mechanisms, and particularly 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 system size and volume. While widely used, their surface quality significantly impacts the imaging quality of the optoelectronic system. Commonly used secondary mirrors in telescope systems often utilize integrated mounting structures, requiring them to maintain surface quality while simultaneously adjusting both the angular and positional degrees of freedom, a significant challenge. Therefore, through the design of a rational adjustment structure, while meeting the optical system's surface accuracy specifications, optimizing the angular and positional degree of freedom adjustment process and effectively reducing the impact of adjustment stress on surface shape are crucial for improving assembly efficiency and reducing costs.

[0003] Currently, the common method for assembling large-aperture off-axis telescope systems is to first secure the secondary mirror in an auxiliary assembly and adjustment device, then use the six-degree-of-freedom auxiliary assembly and adjustment device to adjust the secondary mirror's three positional degrees of freedom and three angular degrees of freedom into place. The secondary mirror is then secured to its fixed mount by peripheral bonding. However, this method has the following disadvantages:

[0004] 1. Because the fixed state of the secondary mirror adjusted using the auxiliary assembly and adjustment equipment is inconsistent with the fixed state of the secondary mirror in 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 in the fixed state inevitably affects the state of the secondary mirror, causing repeated assembly and adjustment processes.

[0005] 2. After the secondary mirror is adjusted into place and fixed by gluing, there is a lack of auxiliary support means. After the angle is adjusted, the thickness of the adhesive layer fixing the secondary mirror is uneven around the periphery. The shrinkage stress of the adhesive 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 existing technology, the present invention provides a large-aperture off-axis telescope system using a spherical adjustment structure and an adjustment method thereof. The secondary mirror is directly assembled in the optical system through the cooperation of a positioning module and a fine-tuning module. This solves the problem of positional offset caused by adjusting the three positional degrees of freedom and three angular degrees of freedom of the secondary mirror into place after currently using six-degree-of-freedom auxiliary assembly and adjustment equipment, simplifies the secondary mirror adjustment process of the large-aperture off-axis telescope system, and improves 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 via a primary mirror positioning module, and the secondary mirror being installed on the support frame via 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 along the circumference on its circumference, 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 multiple elastic pressure plates arranged along the circumferential direction, the main mirror frame is an annular frame structure with light-transmitting ends, and the main mirror is embedded therein; multiple elastic pressure plates are evenly distributed on the mounting annular surface of the main mirror frame along the circumferential direction, corresponding one-to-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 its free end 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 the corresponding positions of the main mirror frame by fasteners, applying axial elastic pressure 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 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.

[0013] A further technical solution of the present invention is as follows: 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 along the circumferential direction on the outer edge end surface of the flange structure for installing 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 large-aperture off-axis system has a telephoto magnification of 4 times and an operating band of 3.5 to 5 μm, wherein the primary mirror has an aperture of 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 onto the support frame through the main mirror frame, which serves as the reference for the telescope system.

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

[0021] Step 3: Using the primary mirror as a reference, rotate the secondary mirror frame around the center of the spherical structure in the adjustment seat to adjust the two angular degrees of freedom of the secondary mirror in the direction perpendicular to its folding axis;

[0022] Step 4: Using the primary mirror as a reference, rotate the secondary mirror frame in the adjustment seat around the secondary mirror folding axis to adjust the angular freedom of the secondary mirror around its folding axis.

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

[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 achieves a single adjustment to meet the telescope system spacing, angle, and surface requirements in actual adjustment, and the changes in these indicators after high and low temperature and process vibration are all within the permitted range, thereby improving the success rate of single-step adjustment. Compared with conventional methods that are prone to repeated adjustment due to changes in surface shape and angle, the telescope system adjustment process is effectively simplified, and has the advantages of high connection rigidity, good stability, and easy adjustment. The specific advantages are as follows:

[0027] 1. Both the primary and secondary mirrors are bonded to the main mirror frame with silicone rubber. While the silicone rubber secures the mirrors, it also uses its flexibility to isolate the installation stress caused by the mounting structure.

[0028] 2. The spherical structure serves as the mounting structure for the secondary mirror. Its rotation around the spherical structure's center or the secondary mirror's folding axis enables adjustment of the three degrees of freedom of angle of the secondary mirror mounted thereon. Furthermore, the spherical adjustment structure and the secondary mirror's fixed structure function independently, preventing the adjustment process from affecting the secondary mirror's surface shape. After adjustment, the secondary mirror mount can be directly fixed with glue, maintaining consistency between the installation and actual use, and avoiding repeated installation and adjustment. The spherical adjustment structure and the secondary mirror's fixed structure are functionally independent, and the presence of the glue layer prevents the angle adjustment process from affecting the secondary mirror's surface shape, fundamentally guaranteeing the secondary mirror's surface accuracy.

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

[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 This is a diagram showing the composition of the large-aperture off-axis telescope system of the present invention;

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

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

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

[0037] Figure 6 This 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 accompanying drawings: 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 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 to 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 device or element referred to 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] To address the issues of inconsistencies between the setup and use of existing large-aperture off-axis telescopes and the poor stability of the setup results, the present invention, specifically for medium- and long-wave infrared optical and mechanical systems requiring large apertures, employs a spherical adjustment structure to provide a more convenient and stable large-aperture off-axis telescope system and its adjustment method, thereby reducing the difficulty of telescope system setup and improving assembly efficiency. The large-aperture off-axis telescope system comprises a support frame and a primary mirror and a secondary mirror mounted thereon. The primary mirror is mounted on the support frame via a primary mirror positioning module, and the secondary mirror is mounted on the support frame via a secondary mirror positioning module and a fine-tuning module. The fine-tuning module enables dynamic adjustment of the secondary mirror, achieving six degrees 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 along the circumference on its circumference, 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 multiple elastic pressure plates arranged along the circumferential direction. The main mirror frame is an annular frame structure with light-transmitting ends, and the main mirror is embedded in it; multiple elastic pressure plates are evenly distributed on the mounting ring 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 its free end is inserted into the main mirror positioning groove to limit the main mirror axially.

[0045] Specifically, the elastic pressure plate is an annular plate made of elastic material, with lugs on either side. Fasteners secure the lugs to corresponding positions on the main mirror frame, applying axial elastic pressure to the primary mirror. This ensures axial positioning of the primary mirror while preventing damage due to excessive stress. This reduces the off-axis dimensions of the telescope system while ensuring the dynamic stability of the telescope's assembly and adjustment datum.

[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 position 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, limiting the radial position of the secondary mirror frame; 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 convergent ring surface generatrix is ​​a straight line; a plurality of through holes are opened along the circumferential direction on the outer edge end surface of the flange structure for installing fasteners for fixing the adjustment seat to the support frame and fasteners for installing 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 in 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 all components of the spherical adjustment structure have good machinability, the machining accuracy can be reduced, the machining cycle can be shortened, and the machining 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. The primary mirror and the secondary mirror are both bonded to the main mirror frame by silicone rubber. While the silicone rubber is bonding and fixing the mirrors, it also uses its flexibility to isolate the installation stress caused by the installation structure. The spherical structure serves as the installation structure of the secondary mirror. The three degrees of freedom of angle adjustment of the secondary mirror installed thereon are achieved by rotating around the center of the spherical structure or the secondary mirror folding axis. 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 surface shape and angle adjustment of the mirror group.

[0052] The spherical adjustment structure consists 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 mounted on the adjustment seat. The secondary mirror frame, serving as the mounting structure for the secondary mirror, is mounted on the inclined surface structure of the adjustment seat. The angle of the secondary mirror is adjusted by utilizing a slight angular offset around the center of the spherical structure or the center of rotation of the rotation axis. Once adjusted, glue is injected and cured into the gap between the spherical structure and the inclined surface structure. The flat spring is used to both maintain the position of the secondary mirror frame during angle adjustment and to assist in securing the adjusted secondary mirror frame, preventing the secondary mirror from deflecting due to overturning torque or 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, this embodiment employs 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. The spherical structure 10 is disposed on a side end surface of the secondary mirror frame 4, and the inclined surface structure 11 is disposed on the inner end surface of the adjustment seat 5. The primary mirror 1, serving as the adjustment reference for the telescope system, is fixed to the primary mirror frame 2. The elastic pressure plate 7 is bonded to the primary mirror 1 via 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 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 subsequent selected fixing glue.

[0055] The primary mirror 1 and the secondary mirror 3 are each bonded to the frame by silicone rubber to ensure optical surface accuracy, and a spherical adjustment structure is provided between the primary frame 2 and the secondary 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, with a weight-reducing groove on its back. It is bonded to the primary mirror frame 2 via 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 impact-resistant design of the primary mirror 1 uses an elastic pressure plate 7, which is pressed into an embedded groove on the side of the primary mirror 1. This reduces the diameter of the primary mirror 1 while avoiding 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 the end face of one side 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 secondary mirror frame 4 has a spherical structure 10 on its end surface. This structure, in conjunction with the inclined surface 11 on the adjustment base 5, allows the secondary mirror 3 to rotate about the center of the spherical structure 10, thereby adjusting the angle of the secondary mirror 3. The spherical structure 10's gyration radius is typically selected based on the size of the secondary mirror 3 and the required adjustment angle. This ensures that the required angle adjustment is met while minimizing the impact of the angle adjustment on the axial position of the secondary mirror 3. For small angle adjustments, the secondary mirror size can be used as a reference 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 connects with the support frame 6 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 provided 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, thereby preventing the position and angle displacement of the secondary mirror 3 under the action of the overturning moment. Finally, after the telescope 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 coated with glue 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. It 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 rotational 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 angular freedom of the secondary mirror 3 around its spherical adjustment structure; it is also necessary to ensure that the angle adjustment required by the spherical structure 10 is consistent with the glue gap between the secondary mirror frame 4 and the adjustment seat 5. When adjusting at a small angle generally not exceeding ±6', it will not cause a significant change in the glue gap between the secondary mirror frame 4 and the adjustment seat 5, thereby causing the angle of the secondary mirror frame 4 and the secondary mirror 3 thereon to shift when the peripheral glue layer solidifies and shrinks due to different thicknesses, resulting in repeated assembly processes. Due to the existence of this associated feature, the present invention solves the problems of poor stability and easy repetition of angle adjustment in existing assembly and adjustment technologies.

[0062] Example:

[0063] This embodiment utilizes a large-aperture off-axis telescope system with a spherical adjustment structure. The system boasts a 4x telephoto magnification and operates in the 3.5-5μm wavelength range. The primary mirror has a 210mm aperture, a 200mm off-axis offset, and a 50mm off-axis offset for the secondary mirror. The overall dimensions of the telescope system are 343.5mm long, 264mm wide, and 283.5mm high. Both the primary mirror 1 and the secondary mirror 3 are made of fused quartz and bonded to their respective frames with silicone rubber. The primary and secondary frames 2 and 4, as well as the elastic pressure plate 7, are all made of titanium alloy. The operating temperature range of the telescope system is -20°C to +60°C.

[0064] In this embodiment, the main mirror adopts a lightweight back design, 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 to meet the system requirements in a dynamic environment.

[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 by 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. The outer spherical structure will not have an adverse effect on the surface shape of the secondary mirror 3 when the angle is adjusted. 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 usage state, avoiding repeated installation and adjustment.

[0066] In this solution, in order to maximize the angle adjustment range of the secondary mirror and avoid the system blocking light 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 46mm, which is the same as the diameter of the secondary mirror. The gap between the secondary mirror frame 4 and the adjustment seat 5 is selected to be 0.6mm 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 0.12mm, and the change in the glue layer gap caused by the angle adjustment does not exceed 20%, effectively avoiding the angle deflection caused by the uneven thickness of the glue layer during the shrinkage stress of the glue layer during curing.

[0067] In this embodiment, the adjustment base 5 is docked with the support frame 6 via screw mounting holes, employing a coarse fit. The diameter of the mounting holes is approximately 0.8 mm larger than the diameter of the mounting screws. This reserved clearance allows for ±0.4 mm adjustment of the two radial degrees of freedom perpendicular to the pivot axis of the secondary mirror 3. The screw mounting holes can be modified to waist-shaped holes to enable a wide range of position adjustment in a specific direction. A height adjustment pad 8 is used beneath the adjustment base 5 to adjust the overall axial position of the secondary mirror 3 and its secondary mirror frame 4 mounted within the adjustment base 5. The selected height adjustment pad 8 is a series of shims with an adjustment range of a minimum of 0.01 mm and a maximum of 1 mm. The maximum adjustment range can be reduced or increased by selecting the theoretical thickness of the height adjustment pad 8 during design.

[0068] In this embodiment, a leaf spring 9 is installed on the end face of the adjustment seat 5. Adjusting the installation height causes it to deform and generate a preload, pressing the secondary mirror frame 4 against the inclined surface structure 11 of the adjustment seat 5. The leaf spring is made of tin bronze strip with thicknesses of 0.1mm or 0.2mm. The selected thickness depends on the direction and magnitude of the angle adjustment of the secondary mirror 3 during installation. After the angle of the secondary mirror 3 is adjusted, an appropriate amount of silicone rubber is applied to the contact surface between the leaf spring 9 and the secondary mirror frame 4 for bonding. An appropriate amount of 3M curing agent is also applied to the contact surface between the leaf spring 9 and the adjustment seat 5 to prevent possible angular deflection of the secondary mirror frame 4 due to the curing stress of the surrounding adhesive layer.

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

[0070] Step 1: Using the primary mirror 1 as a reference, adjust the entire base 5 or select a suitable height adjustment pad 8 to adjust the position of the secondary mirror 3 to the desired position.

[0071] Step 2: Using the primary mirror 1 as a reference, rotate the secondary mirror frame 4 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 the adjustment gap between the secondary frame 4 and the adjustment seat 5, as well as 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 will be understood that the above embodiments are illustrative 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 purpose of the present invention.

Claims

1. A large-aperture off-axis telescope system using a spherical adjustment structure, characterized by: The system comprises a support frame and a primary mirror and a secondary mirror mounted thereon, wherein the primary mirror is mounted on the support frame via a primary mirror positioning module, and the secondary mirror is mounted on the support frame via 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; The fine-tuning module includes an adjustment seat, a height adjustment pad and a spherical structure on the secondary 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 frame is limited; the annular boss on the other side serves as the mounting hole of the secondary frame, and its inner root is a ring surface with a convergent structure, which is used to limit the axial position of the secondary frame, and the generatrix of the convergent ring surface is a straight line; a plurality of through holes are opened along the circumferential direction on the outer edge end surface of the flange structure, for installing fasteners for fixing the adjustment seat to the support frame and fasteners for installing the secondary 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.

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

3. The large-aperture off-axis telescope system using a spherical adjustment structure according to claim 2, characterized in that: The main mirror positioning module includes a main mirror frame and multiple elastic pressure plates arranged along the circumferential direction. The main mirror frame is an annular frame structure with light-transmitting ends, and the main mirror is embedded in it; multiple elastic pressure plates are evenly distributed along the circumferential direction on the mounting ring surface of the main mirror frame, 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 its free end is inserted into the main mirror positioning groove to limit the main mirror axially.

4. The large-aperture off-axis telescope 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 has lugs on both sides. The lugs on both sides are fixed to corresponding positions of the main mirror frame by fasteners, applying axial elastic pressure to the main mirror, which can ensure the axial positioning of the main mirror while avoiding damage due to excessive stress.

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

6. The large-aperture off-axis telescopic system using a spherical adjustment structure according to claim 5, 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.

7. The large-aperture off-axis telescopic system using a spherical adjustment structure according to claim 6, characterized in that: After being positioned, the primary mirror and the secondary mirror are both fixed by bonding with silicone rubber.

8. The large-aperture off-axis telescopic system using a spherical adjustment structure according to claim 7, 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 distance of 200 mm, and a secondary mirror has an off-axis distance of 50 mm. The overall dimensions of the telephoto system are 343.5 mm long, 264 mm wide, and 283.5 mm high. The spherical structure of the secondary mirror frame has a rotation radius of 46 mm, which is the same as the diameter of the secondary mirror.

9. A method for adjusting a large-aperture off-axis telescope system using a spherical adjustment structure according to any one of claims 1 to 8, characterized in that The specific steps are as follows: Step 1: Install the primary mirror onto the support frame through the main mirror frame, which serves as the reference for the telescope system. Step 2: Using the primary mirror as a reference, adjust the position of the adjustment seat using the height adjustment pads, and pre-position the secondary mirror frame with the secondary mirror in the adjustment seat; Step 3: Using the primary mirror as a reference, rotate the secondary mirror frame around the center of the spherical structure in the adjustment seat to adjust the two angular degrees of freedom of the secondary mirror in the direction perpendicular to its folding axis; Step 4: Using the primary mirror as a reference, rotate the secondary mirror frame in the adjustment seat around the secondary mirror folding axis to adjust the angular freedom of the secondary mirror around its folding axis. Step 5: Repeat steps 2 to 4 to adjust the position and angle of the secondary mirror to meet the telescope system requirements. 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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