An ultra-lightweight curvature radius adjustable segmented mirror and an integrated method thereof

Abstract

The application provides an integrated method and integrated structure of an ultra-light curvature radius adjustable segmented mirror, and relates to the technical field of space optical remote sensors. The curvature radius adjustable segmented mirror provided by the application can adjust the vertex curvature radius in a wide range through an integrated surface shape actuator and ensure the surface shape precision after adjustment, can meet the mode reconstruction imaging requirement of splicing a large aperture optical mirror, and because the curvature radius of the segmented mirror is adjustable, the design of each segmented mirror is the same, which greatly improves the development efficiency. The integrated structure of the application comprises a rigid connection structure integrated with the ultra-light segmented mirror and a flexible surface shape actuator integrated structure; the rigid structure comprises a small nest and a nest connecting piece; the flexible surface shape actuator integrated structure comprises a surface shape actuator, a fixed end flexible joint, a moving end flexible joint, a flexible joint connecting piece and a locking nut. In addition, the application further provides an integrated process of the ultra-light curvature radius adjustable segmented mirror.

Description

Technical Field

[0001] This invention relates to the field of space optical remote sensing technology, specifically to an integration method and structure for an ultra-lightweight, adjustable radius of curvature modular mirror. Background Technology

[0002] To meet the higher performance requirements of human Earth observation and space exploration, the aperture of space optical remote sensor mirrors has increased from the meter level to the tens of meters level, showing a continuous increasing trend. The use of modular mirror designs for folding and unfolding or on-orbit assembly has become the main technical means to achieve imaging technology for large-aperture space optical remote sensors. Traditional modular mirrors all adopt a rigid design with a fixed radius of curvature. Depending on the size of the modular mirror aperture, traditional support methods are used for fixation to ensure good surface accuracy and positioning accuracy of the modular mirror assembly on the ground, thereby ensuring the imaging quality of the large-aperture space optical remote sensor formed after on-orbit unfolding or assembly. Assembled large-aperture space optical remote sensors can only complete predetermined imaging tasks, and each segment mirror has a specific position, resulting in long processing time and poor maintainability. This can no longer meet the multi-mode imaging requirements of reconnaissance and surveillance systems for ultra-large-aperture remote sensors. Using segment mirrors with adjustable curvature radius to assemble large-aperture space optical remote sensors will become a development trend for ultra-large-aperture reconnaissance and detection systems. Moreover, the curvature radius of the segment mirrors is adjustable over a wide range, making each mirror replaceable, which greatly improves assembly efficiency and on-orbit maintainability. Therefore, the integration of surface actuators and ultra-lightweight segment mirrors has become a key technology that must be mastered for segment mirrors with adjustable curvature radius. Summary of the Invention

[0003] The technical problem to be solved by this invention is to provide a surface actuator and an ultra-lightweight modular mirror and their integration method, so as to achieve adjustable and controllable curvature radius of the ultra-lightweight modular mirror.

[0004] The surface actuator selected in this invention is a cylindrical piezoelectric ceramic actuator, with an external thread connection on one side and an internal thread connection on the other side. Since the surface actuator can only withstand tensile and compressive forces, the integrated structure of the surface actuator should include at least two components.

[0005] The modular mirror used in this invention is an ultra-lightweight hexagonal optical mirror with semi-rigid and semi-flexible characteristics and made of SiC. Therefore, it should include at least one rigid connection structure for the integration of the modular mirror and the surface actuator.

[0006] To address the aforementioned problems, the present invention employs the following technical solution:

[0007] A modular mirror includes an optical mirror and a plurality of surface actuators, wherein the surface actuators are mounted on the back of the optical mirror and the vertex curvature radius and surface accuracy of the optical mirror are adjusted by the surface actuators.

[0008] Preferably, the surface actuator is mounted to the optical mirror via a rigid connection structure integrated on the back of the optical mirror; the rigid connection structure includes a nest and a nested connector; the back of the optical mirror has a precision-machined annular groove, the nest is glued in the annular groove, and the nested connector is mounted on top of the annular groove via the nest, thereby connecting to the surface actuator via the nested connector.

[0009] Preferably, the nested connector is a disc-shaped structure with a central connecting hole. The disc is evenly distributed with integrated structure fixing holes for connecting with the surface actuator. Between the fixing holes is a fan-shaped plane formed by reinforcing ribs. The fan-shaped plane is provided with mounting holes for fixing with the external support structure. The central connecting hole is used for fixing with the nest.

[0010] Preferably, all the nested upper surfaces glued into the annular groove are coplanar and coplanar with the upper surface of the annular groove.

[0011] Preferably, the circumferentially distributed integrated structure fixing holes on the nested connector are collinearly arranged along the direction of the optical mirror reinforcing rib, and the surface actuators are collinearly installed.

[0012] Preferably, the surface actuator is integrated using at least two flexible links, first forming a flexible surface actuator integrated structure, and then fixed to the segmented mirror rigid connection structure.

[0013] Preferably, the flexible surface actuator integrated structure includes a surface actuator, a fixed end flexible joint, a moving end flexible joint, a flexible joint connector, and a locking nut;

[0014] The fixed end flexible joint is fixed to the fixed end of the surface actuator, and the moving end flexible joint is connected to the moving end of the surface actuator. The moving end flexible joint and the surface actuator are fixed with locking nuts while ensuring that the mounting surface of the wing-shaped flange of the moving end flexible joint and the semi-circular panel mounting surface of the fixed end flexible joint are perpendicular. The flexible joint connector is fixed to the moving end flexible joint through the flange structure.

[0015] Preferably, the surface actuator is a cylindrical piezoelectric ceramic actuator.

[0016] Preferably, the flexibility of both the fixed end flexible joint and the moving end flexible joint is provided by two sets of orthogonally distributed flexible grooves. Each set of flexible grooves consists of symmetrically distributed "Ω"-shaped flexible grooves, and anti-crack holes are machined at the starting and ending ends of the "Ω"-shaped flexible grooves.

[0017] A method for integrating ultra-lightweight modular mirrors with adjustable radius of curvature includes:

[0018] The mirror blank was precision machined to the point that the installation accuracy of the annular groove on the back meets the design requirements;

[0019] Small nests are bonded using epoxy adhesive;

[0020] After the epoxy adhesive cures, the nested connectors are fixed in place.

[0021] Optical processing, inspection, and surface treatment of segmented mirrors with rigid connection structures; simultaneously, integration of flexible structures for surface actuators;

[0022] Integrate a flexible surface actuator integrated structure with a segmented mirror with a rigid connection structure;

[0023] After integration, the optical processing and testing of the split-lens camera are carried out.

[0024] After integration, the individual mirrors are coated and inspected.

[0025] The beneficial results of this invention are as follows: The adjustable curvature radius segmented mirror provided by this invention can adjust the vertex curvature radius over a wide range through an integrated surface actuator while ensuring the accuracy of the adjusted surface shape. This can meet the pattern reconstruction imaging requirements of stitched large-aperture optical mirrors. At the same time, because the curvature radius of the segmented mirror is adjustable, the design of each segmented mirror can be made the same, which greatly improves the development efficiency and lays the foundation for the development of multi-mission imaging stitched large-aperture space optical remote sensors. Attached Figure Description

[0026] Figure 1 This is a flowchart of the integration method for the ultra-lightweight segmented mirror with adjustable curvature radius of the present invention.

[0027] Figure 2 This is a schematic diagram of the overall structure of the ultra-lightweight, adjustable radius of curvature segmented mirror of the present invention.

[0028] Figure 3 This is a cross-sectional view of the rigid connection structure of the segmented mirror of the present invention.

[0029] Figure 4 This is a schematic diagram of the structure of the nested connector for the invention.

[0030] Figure 5 This is a schematic diagram of the flexible integrated structure of the surface actuator of the present invention.

[0031] Figure label:

[0032] 1. Ultra-lightweight segmented mirror; 2. Small nest; 3. Nested connector; 4. Surface actuator; 5. Fixed end flexible joint; 6. Moving end flexible joint; 7. Flexible joint connector; 8. Locking nut; 9. Epoxy adhesive; 201. Injection hole; 202. Center connection hole of small nest; 301. Fixing hole of flexible surface actuator structure; 401. Fixed end of surface actuator; 402. Moving end of surface actuator; 501. Semi-circular panel mounting surface; 502. First set of flexible grooves; 503. Second set of flexible grooves; 601. Wing-shaped flange mounting surface; 602. First flexible groove; 603. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to the accompanying drawings.

[0034] This invention provides a segmented mirror with a number of surface actuators integrated on its back. The vertex curvature radius and surface accuracy of the ultra-lightweight segmented mirror can be adjusted through these surface actuators. The segmented mirror is integrated through a rigid connection structure and a flexible surface actuator integration structure. The rigid connection structure is fixedly connected to the ultra-lightweight segmented mirror, and the two ends of the flexible surface actuator integration structure are fixed to the rigid connection structure.

[0035] The rigid connection structure includes a small nest and a nested connector. The small nest is glued to the ultra-lightweight segmented mirror, and the nested connector is screwed to the small nest.

[0036] like Figure 3 As shown, the rigid connection structure of the ultra-lightweight segmented mirror 1 of the present invention includes a small nest 2 and a nested connector 3. The nested connector and the small nest are connected by screws. The outer wall of the small nest 2 is bonded to the annular groove of the segmented mirror 1 by epoxy adhesive 9. To increase the reliability of the connection, the small nest and the ultra-lightweight segmented mirror are bonded to a full area. Specifically, N injection holes are provided on the small nest structure, N≥3. The small nest is uniformly bonded to the annular groove of the segmented mirror through the injection holes. In this example, the material of the segmented mirror 1 is SiC, and the material of the small nest 2 is TC4. The three injection holes 201 evenly distributed around the circumference of the small nest 2 ensure full-area bonding between the small nest 2 and the segmented mirror 1. The adhesive layer thickness is 0.1mm, the adhesive layer is evenly distributed, and the bonding is reliable by the injection tool. It is also ensured that the upper surfaces of all small nests 2 are coplanar and coplanar with the annular groove of the segmented mirror.

[0037] The nested connector is a multifunctional connection structure. Its lower end face is a fan-shaped plane with 60° circumference distribution, and it has connection holes for fixing to the integrated structure of the flexible surface actuator. Its upper end face is a small fan-shaped plane with 60° circumference distribution formed by reinforcing ribs, and it has mounting holes for fixing to the external support structure. A connection hole is located in the center for fixing to the small nested connector. Figure 3 , Figure 4 As shown, the nested connector 3 is fixed to the small nest 2 through the central connecting hole; the lower end face of the nested connector 3 has six fan-shaped, circumferentially distributed flexible surface actuator integrated structure fixing holes 301; in order to ensure the installation accuracy of the flexible surface actuator structure and prevent it from bearing external forces, when installing the nested connector 3, it is necessary to ensure that the 60° circumferentially distributed integrated structure fixing holes 301 are collinearly arranged along the direction of the optical mirror reinforcing rib, so as to ensure that the surface actuator is installed collinearly and does not generate additional bending and torsional forces. Figure 5As shown, the integrated structure of the flexible surface actuator includes a surface actuator 4, a fixed-end flexible joint 5, a moving-end flexible joint 6, a flexible joint connector 7, and a locking nut 8. The surface actuator is a low-voltage cylindrical piezoelectric ceramic actuator. The moving end of the actuator has an external thread connection, and the fixed end has an internal thread connection. The fixed-end flexible joint has an external thread at one end, connecting to the fixed end of the surface actuator; the other end has a semi-circular panel structure with a connection hole for fixing to the nested connector. The middle section is a cylindrical flexible structure. The specific integration steps are as follows:

[0038] Step 1: Fix the fixed end flexible joint 5 to the fixed end 401 of the surface actuator;

[0039] Step 2: Connect the moving end 402 of the face actuator to the moving end flexible joint 6, but do not fix it. Adjust the orientation of the moving end flexible joint 6 to ensure that the wing-shaped flange mounting surface 601 of the moving end flexible joint 6 is perpendicular to the semi-circular panel mounting surface 501 of the fixed end flexible joint 5. In this state, use the locking nut 8 to fix the moving end flexible joint 6 to the face actuator 4.

[0040] Step 3: Secure the flexible connector 7 to the moving end flexible joint via the flange structure.

[0041] This completes the integrated structure of the flexible surface actuator.

[0042] To ensure the flexibility of the fixed end joint, two sets of flexible grooves are set along the longitudinal direction on the cylindrical surface. The first set of flexible grooves and the second set of flexible grooves are arranged orthogonally. Each set of flexible grooves consists of two symmetrically distributed "Ω"-shaped flexible grooves. At the same time, anti-crack holes are machined at the starting and ending ends of the "Ω"-shaped flexible grooves.

[0043] The movable end flexible joint has an end face with a mounting hole at one end, which connects to the movable end of the surface actuator and is fixed by a locking nut; the other end is provided with a wing-shaped mounting flange for fixing to the flexible joint connector. The middle end is a columnar flexible structure.

[0044] To ensure the flexibility of the mobile end joint, two sets of flexible grooves are arranged longitudinally on the cylindrical surface, with the first set of flexible grooves and the second set of flexible grooves arranged orthogonally. Each set of flexible grooves consists of two symmetrically distributed "Ω"-shaped flexible grooves, and anti-crack holes are machined at the starting and ending ends of the "Ω"-shaped flexible grooves.

[0045] The locking nut is mainly used to fix the moving end flexible joint and the surface actuator after they are adjusted to the required positions.

[0046] The flexible connector has a wing-shaped flange at one end, which is fixedly connected to the flexible joint at the moving end, and a semi-circular panel structure with mounting holes at the other end, which is used to fix it to the nested connector.

[0047] like Figure 2 As shown, the flexible surface actuator integrated structure is fixed to the rigid connection structure of the segmented mirror. In this invention, a total of 90 surface actuators are integrated for adjusting the curvature radius and surface accuracy of the ultra-lightweight segmented mirror.

[0048] The present invention also provides an integration method for an ultra-lightweight segmented mirror with adjustable curvature radius, comprising: after the annular groove on the back of the ultra-lightweight segmented mirror is precision machined, firstly, rigid structure integration of the segmented mirror is performed; then, subsequent grinding and polishing, flexible structure integration of the surface actuator, and coating are performed, and finally, the segmented mirror with adjustable curvature radius provided by the present invention is obtained.

[0049] In one implementation example, the rigid structure integration of the segmented mirror and the flexible structure integration of the surface actuator include:

[0050] Step 1: The mirror blank is precision machined until the installation accuracy of the annular groove on the back meets the design requirements;

[0051] Step 2: Attach small nested parts;

[0052] Step 3: After the epoxy adhesive has cured, fix the nested connectors in place;

[0053] Step 4: Optical processing, inspection, and surface treatment of the segmented mirrors (with rigid connectors); simultaneously, integration of the flexible structure of the surface actuator;

[0054] Step 5: Integration of the flexible surface actuator integrated structure with the segmented (with rigid connector) mirror;

[0055] Step 6: Post-integration split-lens optical processing and testing;

[0056] Step 7: After integration, the individual mirrors are coated and inspected.

[0057] In one specific embodiment, the ultra-lightweight modular mirror integration method with adjustable curvature radius proposed in this invention is applied to the design of the primary mirror of a demonstration and verification system for a ground-based reconfigurable imaging mode. The edge-to-edge distance of this modular mirror is 500mm, and the initial vertex curvature radius is 9100mm. A schematic diagram of the integrated structure is shown below. Figure 2 As shown, the density of the integrated segmented mirror surface is 30 kg / m². 2 When the surface actuator is powered on according to certain requirements, the surface shape of the reconstructed segmented mirror after the radius of curvature of the segmented mirror changes meets the required accuracy.

[0058] Based on the design results of the ultra-lightweight adjustable curvature radius modular mirror above, it can be seen that, compared with the traditional rigid modular mirror with a fixed curvature radius, the design method proposed in this invention can enable the spliced ​​large-aperture optical mirror to be reconstructed into multiple modes for imaging. This is of great significance for the spliced ​​large-aperture space optical remote sensor to perform multi-functional imaging tasks.

[0059] The above are merely embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent parts or equivalent process transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A segmented mirror, characterized in that, It includes an optical mirror and several surface actuators, which are mounted on the back of the optical mirror and are used to adjust the vertex curvature radius and surface accuracy of the optical mirror. The surface actuator is mounted to the optical mirror via a rigid connection structure integrated on the back of the optical mirror; the rigid connection structure includes a nest and a nest connector; the back of the optical mirror has a precision-machined annular groove, the nest is glued in the annular groove, and the nest connector is mounted on the top of the annular groove through the nest, thereby connecting to the surface actuator through the nest connector; The surface actuator is integrated using at least two flexible links, first forming a flexible surface actuator integrated structure, and then fixed to the rigid connection structure of the segmented mirror. The flexible surface actuator integrated structure includes a surface actuator, a fixed end flexible joint, a moving end flexible joint, a flexible joint connector, and a locking nut; The fixed end flexible joint is fixed to the fixed end of the surface actuator, and the moving end flexible joint is connected to the moving end of the surface actuator. The moving end flexible joint and the surface actuator are fixed with locking nuts while ensuring that the mounting surface of the wing-shaped flange of the moving end flexible joint and the semi-circular panel mounting surface of the fixed end flexible joint are perpendicular. The flexible joint connector is fixed to the moving end flexible joint through the flange structure.

2. The segmented mirror according to claim 1, characterized in that, The nested connector is a disc-shaped structure with a central connecting hole. The disc is evenly distributed with integrated structure fixing holes for connecting with the surface actuator. Between the fixing holes are fan-shaped planes formed by reinforcing ribs. Mounting holes are provided on the fan-shaped planes for fixing with the external support structure. The central connecting hole is used for fixing with the nest.

3. The segmented mirror according to claim 2, characterized in that, All the nested upper surfaces glued into the annular groove are coplanar and coplanar with the upper surface of the annular groove.

4. The segmented mirror according to claim 2, characterized in that, The circumferentially distributed fixing holes on the nested connector are collinearly arranged along the direction of the optical mirror reinforcing rib, and the surface actuators are installed collinearly.

5. The segmented mirror according to claim 1, characterized in that, The surface actuator is a cylindrical piezoelectric ceramic actuator.

6. The segmented mirror according to claim 1, characterized in that, The flexibility of both the fixed-end flexible joint and the moving-end flexible joint is provided by two sets of orthogonally distributed flexible grooves. Each set of flexible grooves consists of symmetrically distributed "Ω"-shaped flexible grooves, and anti-crack holes are machined at the starting and ending ends of the "Ω"-shaped flexible grooves.

7. A method for integrating ultra-lightweight modular mirrors with adjustable curvature radius based on the modular mirror implementation described in claim 1, characterized in that... include: The mirror blank was precision machined to the point that the installation accuracy of the annular groove on the back meets the design requirements; Small nests are bonded using epoxy adhesive; After the epoxy adhesive cures, the nested connectors are fixed in place. Optical processing, inspection, and surface treatment of segmented mirrors with rigid connection structures; simultaneously, integration of flexible structures for surface actuators; Integrate a flexible surface actuator integrated structure with a segmented mirror with a rigid connection structure; After integration, the optical processing and testing of the split-lens camera are carried out. After integration, the individual mirrors are coated and inspected.

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