Flexible supporting structure for reducing deformation of mirror surface of ultralight oscillating mirror

Abstract

The invention discloses a flexible support structure for reducing deformation of a mirror surface of an ultra-light oscillating mirror, and the structure comprises a plurality of connection substrates which serve as the installation basis of the flexible support structure and are used for being connected with an oscillating mirror movement mechanism. The flexible hole is configured as an auxiliary structure for stress buffering; the outer-layer flexible groove and the inner-layer flexible groove jointly serve as a core stress buffer structure; the oscillating mirror bonding surface is used for bonding and fixing with an oscillating mirror; and the flexible substrate is positioned on the outer side of the connecting substrate. According to the invention, the stress blocking effect is remarkable, through the combined design of double-layer 120-degree uniformly distributed flexible grooves and flexible holes, the elastic deformation characteristic of a flexible structure is utilized, axial force and radial force generated during screw connection can be effectively absorbed, and the transmission of stress to the oscillating mirror is blocked; due to the coplanar design of the three connecting substrates and the screw connection technology of layer-by-layer reinforcement, additional stress in the installation process is further reduced, and it is ensured that the mirror surface of the oscillating mirror always keeps high precision.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of space remote sensing technology, and in particular to a flexible support structure for reducing mirror surface deformation of an ultra-light pendulum mirror. BACKGROUND

[0002] In the field of aerospace, space optical remote sensors are the core equipment for obtaining key data such as earth observation and deep space exploration. With the increasing requirements of space missions for observation range and data accuracy, space optical remote sensors are rapidly developing towards large field of view and high resolution, which puts extremely strict requirements on the performance of their image stabilization systems.

[0003] In the actual imaging process of space optical remote sensors, the satellite platform is inevitably affected by various factors such as orbital perturbation, attitude control system error, and instrument operation vibration, resulting in small but continuous jitter. This jitter directly leads to imaging light path deviation, causing image blurring and distortion, and seriously affecting the usability of remote sensing data. To solve this problem, image stabilization systems have emerged. Image stabilization systems compensate for image deviation caused by satellite platform jitter in real time through rapid and small-angle attitude adjustment, thereby ensuring the stability of imaging quality. The realization of its core function relies on the internal pendulum mirror assembly. As a key executive element of the image stabilization system, the surface accuracy of the pendulum mirror directly determines the imaging quality of the optical remote sensor. To meet the rapid response and lightweight design requirements of the image stabilization system, modern pendulum mirrors generally adopt ultra-light and ultra-thin structural design, usually made of lightweight and high-strength optical materials such as silicon carbide. However, this ultra-light and ultra-thin structure makes the pendulum mirror surface extremely sensitive to external stress, temperature changes, and other factors. Small external actions can cause significant changes in the mirror surface accuracy, thereby affecting the imaging effect of the optical system. Therefore, how to reduce the influence of external factors on the mirror surface accuracy of the pendulum mirror through reasonable support structure design has become a key technical problem in the design of space optical remote sensors.

[0004] To address this challenge, the industry generally uses flexible support structures as the connection method between the pendulum mirror and other components. The flexible support structure absorbs and buffers external stress and displacement through its elastic deformation, avoiding the direct transmission of stress from rigid connection to the pendulum mirror, thereby protecting the mirror surface accuracy of the pendulum mirror.

[0005] Currently, there are some flexible support structure design schemes for pendulum mirrors in related fields, among which the most representative is patent CN115542512B, which discloses a flexible support structure for reducing pendulum mirror bonding deformation, mainly including a base mounting hole, a flexible support seat, and a pendulum mirror bonding boss. By setting six arc-shaped flexible grooves on the flexible support seat, the elastic deformation capability of the arc-shaped flexible grooves is utilized to reduce the rigid displacement of the pendulum mirror caused by gravity load and temperature changes, thereby reducing the deformation impact generated during the bonding process of the pendulum mirror.

[0006] In addition, several academic papers have also studied the flexible support technology of the pendulum mirror: "Research on Design and Servo Control Technology of Two-Dimensional Swing Mirror for Space Remote Sensing Camera": This paper focuses on the structural design and servo control algorithm of two-dimensional swing mirrors, and proposes a support scheme based on flexible hinges. The attitude adjustment of the swing mirror is achieved through the small deformation of the flexible hinges, while taking into account the support stiffness and stress buffering capacity. "Design and Simulation of Spatial Image Stabilization System Swing Mirror": The mechanical properties of different flexible support structures were compared through simulation analysis, and the effectiveness of the flexible groove structure in reducing the deformation of the swing mirror was verified. However, no optimization design was carried out for the special needs of ultra-light and ultra-thin swing mirrors. "Flexible Support Design and Analysis of Spatial Image Stabilization System Swing Mirror": The paper analyzes the material selection and structural parameters of the flexible support structure and proposes a design principle based on stiffness matching, but does not solve the stress transfer problem generated during the screw connection process.

[0007] With the continuous advancement of space optical remote sensing technology, the design requirements for mirror assemblies are becoming increasingly stringent. Modern ultralight and ultrathin mirrors have significantly reduced weight and thickness compared to traditional mirrors, and their surface accuracy is exponentially more sensitive to external stress. Existing technical solutions suffer from the following key drawbacks: Firstly, the combined stress generated by screw connections is not considered: existing flexible support structures commonly use standard screws for fixing when connected to the tilting mirror mechanism. Standard screws have a 60° thread angle. During tightening, the engagement of the screw with the threaded hole generates axial preload and radial compressive force, creating combined stress. This combined stress is directly transmitted to the tilting mirror through the support structure, causing micro-deformation of the ultralight and ultrathin tilting mirror surface, severely affecting its surface accuracy. Secondly, the structural adaptability is insufficient: the design of the number, distribution, and size parameters of the flexible grooves in the existing flexible support structure is mainly aimed at the stiffness characteristics of traditional pendulum mirrors, without fully considering the low stiffness characteristics of ultra-light and ultra-thin pendulum mirrors, resulting in limited stress buffering effect. Based on the above-mentioned technical problems, those skilled in the art urgently need to develop a flexible support structure that can effectively block the transmission of axial and radial forces generated during screw connection to the swing mirror, and prevent the swing mirror surface from undergoing surface distortion due to connection stress, thereby reducing the deformation of the ultralight swing mirror surface. Summary of the Invention

[0008] The purpose of this invention is to provide a flexible support structure that reduces the deformation of the ultralight swing mirror. By optimizing the structural layout, dimensional parameters, processing technology and material selection, it can effectively block the stress of screw connection and temperature stress, and protect the surface shape accuracy of the ultralight and ultrathin swing mirror.

[0009] To achieve the above objectives, the present invention provides the following technical solution: The present invention provides a flexible support structure for reducing the deformation of an ultralight pendulum mirror surface, the flexible support structure comprising: Multiple connecting base plates, which serve as the mounting base for the flexible support structure and are used for screw connection with the tilting mirror movement mechanism; Flexible holes, which are configured as auxiliary structures for stress buffering; The flexible support structure also includes: The outer flexible groove and the inner flexible groove together serve as the core stress buffer structure; The bonding surface of the swing mirror is used for bonding and fixing to the swing mirror; A flexible substrate located outside the connecting substrate, the flexible substrate being configured as a load-bearing base for a flexible structure.

[0010] Preferably, each of the connecting substrates is provided with a boss with a height of 0.3mm, and the boss has a connecting hole at its center, which is coaxial with the connecting substrate; The flexible support structure also includes flexible groove process holes, which provide process references for the processing of flexible grooves.

[0011] Preferably, both the outer flexible groove and the inner flexible groove are coaxial with the connecting hole and are evenly distributed in a 120° circle, corresponding to the distribution pattern of the connecting substrate.

[0012] Preferably, the grooving arc of both the outer flexible groove and the inner flexible groove is 90°, and the groove width is 0.25mm.

[0013] Preferably, the flexible hole is a circular through hole with a diameter of 3 mm, and is evenly distributed on the inner side of the inner flexible groove.

[0014] Preferably, the surface roughness of the bonding surface of the swing mirror is in the range of Ra0.8-Ra1.6μm.

[0015] In the above technical solution, the flexible support structure for reducing the deformation of an ultralight tilting mirror provided by the present invention has the following beneficial effects: This invention discloses a flexible support structure for reducing the deformation of an ultralight oscillating mirror, which has a significant stress-blocking effect and high surface accuracy and stability. Through the combined design of "double-layer 120° evenly distributed flexible grooves + flexible holes", the elastic deformation characteristics of the flexible structure can effectively absorb the axial and radial forces generated during screw connection, blocking the transmission of stress to the oscillating mirror. The coplanar design of the three connecting base plates and the screw connection process with progressively increasing force further reduce the additional stress during installation, ensuring that the oscillating mirror surface always maintains high accuracy.

[0016] Adapting to the low stiffness characteristics of ultra-light and ultra-thin oscillating mirrors: Addressing the extreme sensitivity of ultra-light and ultra-thin oscillating mirrors to external stress, this invention optimizes the curvature (90°), width (0.25mm), and distribution (120° uniform distribution) of the flexible groove. Simultaneously, the thickness of the flexible substrate is designed to be 1mm. This maximizes structural flexibility while ensuring structural stiffness, achieving precise adaptation to low-stiffness oscillating mirrors and solving the problem of poor support performance for ultra-light and ultra-thin oscillating mirrors in existing technologies.

[0017] Strong thermal stress control capability: Invar steel is selected as the manufacturing material for the support structure. Its coefficient of thermal expansion is consistent with that of the mirror material, which avoids thermal stress caused by the difference in deformation between the two when the temperature changes. This effectively reduces the impact of temperature fluctuations in the space environment on the surface accuracy of the mirror.

[0018] The processing and assembly process is standardized and highly reliable: This invention clarifies the "drilling + wire cutting" processing flow, surface treatment requirements, and key process parameters such as roughening treatment of the bonding surface and epoxy curing time for the flexible groove, effectively reducing residual stress and additional stress introduced during processing and assembly; the height design (≥5mm) and surface roughening treatment of the bonding surface of the swing mirror improve the bonding strength and stability, avoiding the connection failure problem caused by insufficient bonding in the prior art.

[0019] With a wide range of applications and strong practicality, the flexible support structure of this invention is not only suitable for ultra-light and ultra-thin mirrors, but also allows for adjustment of structural parameters (such as the size of the flexible groove and the specifications of the connecting holes) according to actual needs, adapting to mirror components of different sizes and weights; moreover, the structural design is simple, the processing technology is mature, the materials are easy to obtain, the production cost is controllable, and it is convenient for engineering applications and mass production. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0021] Figure 1 This is a front view of a flexible support structure for reducing the deformation of an ultralight pendulum mirror, provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of the reverse side of a flexible support structure for reducing the deformation of an ultralight pendulum mirror, provided in an embodiment of the present invention. Figure 3 This is a schematic diagram of the structure after the flexible support structure for reducing the deformation of the ultralight oscillating mirror is bonded to the oscillating mirror, as provided in an embodiment of the present invention. Figure 4This is the test result of the surface shape accuracy of the pendulum mirror in the embodiment of the present invention.

[0022] Explanation of reference numerals in the attached figures: 1. Connecting substrate; 2. Connecting hole; 3. Flexible hole; 4. Flexible groove process hole; 5. Outer flexible groove; 6. Inner flexible groove; 7. Mirror bonding surface; 8. Flexible substrate. Detailed Implementation

[0023] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0024] See Figures 1-4 As shown; This invention discloses a flexible support structure for reducing the deformation of an ultralight tilting mirror. The flexible support structure is manufactured entirely from Invar steel. After a specific formulation, the Invar steel has the same coefficient of thermal expansion as silicon carbide, a commonly used material for ultralight tilting mirrors, thus avoiding thermal stress caused by the difference in deformation between the two materials during temperature changes. The flexible support structure includes: Multiple connecting base plates 1, which serve as the mounting base for the flexible support structure and are used for screw connection with the mirror movement mechanism; Flexible hole 3, which is configured as an auxiliary structure for stress buffering; The flexible support structure also includes: The outer flexible groove 5 and the inner flexible groove 6 together serve as the core stress buffer structure; The bonding surface 7 of the swing mirror is used for bonding and fixing to the swing mirror; The flexible substrate 8 is located outside the connecting substrate 1 and is configured as the load-bearing foundation of the flexible structure.

[0025] As a preferred technical solution in this embodiment, each of the connecting substrates 1 is provided with a boss with a height of 0.3mm, and a connecting hole 2 is provided in the center of the boss, which is coaxial with the connecting substrate 1; the thickness of the connecting substrate 1 must meet two requirements: first, to ensure that the thread connection depth of the connecting hole 2 conforms to the installation specifications of the mirror movement mechanism (usually the effective thread depth is not less than 1.5 times the screw diameter); second, to have sufficient structural strength to avoid deformation of the substrate itself during the connection process. Before assembly, ensure that the coplanarity error of the top surfaces of the three bosses is no more than 0.005mm to minimize additional stress caused by uneven mounting surfaces.

[0026] The flexible support structure also includes a flexible groove process hole 4, which provides a process reference for the processing of the flexible groove.

[0027] As a preferred technical solution in this embodiment, the outer flexible groove 5 and the inner flexible groove 6 are both coaxial with the connecting hole 2 and are evenly distributed in a 120° circle, corresponding to the distribution pattern of the connecting substrate 1, to ensure the symmetry of stress buffering.

[0028] As a preferred technical solution in this embodiment, the grooving arc of both the outer flexible groove 5 and the inner flexible groove 6 is 90°, and the groove width is 0.25mm. This parameter is the optimal value determined after comprehensively considering space installation limitations, structural stiffness requirements, and stress buffering effect: if the groove width is too large, it will lead to insufficient structural stiffness and affect the dynamic response performance of the pendulum mirror; if the groove width is too small, effective elastic deformation cannot be achieved, and the stress buffering effect is poor. The processing technology for flexible grooves is as follows: Processing sequence: First process the flexible groove process hole 4, then process the outer flexible groove 5 and the inner flexible groove 6; Process hole parameters: The flexible groove process hole 4 is a circular through hole with a diameter of not less than Φ1mm. It is drilled using a drill bit. This process hole is used to provide a wire threading channel for wire EDM and avoid stress concentration at the starting end of wire EDM. Wire EDM machining: The outer flexible groove 5 and the inner flexible groove 6 are machined using slow wire EDM technology, with the cutting speed controlled at 10-15 mm / min and the machining accuracy controlled within ±0.003 mm. Surface treatment: After wire cutting, the walls of the flexible groove need to be polished to remove burrs and machining marks. The surface roughness should be controlled below Ra0.8μm to avoid stress concentration.

[0029] As a preferred technical solution in this embodiment, the flexible hole 3 is a circular through hole with a diameter of Φ3mm (which can be adjusted according to the actual structural size). It is evenly distributed on the inner side of the inner flexible groove. By increasing the perforation rate of the structure, the overall flexibility is improved, and the flexible groove is assisted in absorbing stress.

[0030] As a preferred technical solution in this embodiment, the surface roughness of the bonding surface 7 of the tilting mirror is in the range of Ra0.8-Ra1.6μm. Surface roughening treatment (such as sandblasting or grinding) is required before bonding to increase the contact area and adhesion between the bonding surface and the epoxy adhesive, and to reduce stress concentration at the bonding interface. The height of the bonding surface is not less than 5mm. This height design is to ensure the bonding area and thickness of the optical epoxy adhesive, and to improve the bonding strength and stability.

[0031] As a further introduction to this embodiment, the flexible substrate 8, as the load-bearing foundation, needs to minimize its thickness while meeting the overall structural rigidity requirements, so as to improve the flexible deformation capability of the structure. Through mechanical simulation and experimental verification, the thickness of the flexible substrate 8 is designed to be 1mm. This thickness can ensure the stability of the support structure during the movement of the mirror, and also provide sufficient space for the deformation of the flexible groove.

[0032] The assembly process and requirements for a flexible support structure for reducing the deformation of an ultralight pendulum mirror according to the present invention are as follows: Bonding process: (1) Adhesive material: Optical epoxy adhesive that generates low stress during curing is selected. This type of epoxy adhesive has low shrinkage (curing shrinkage <0.5%), high bonding strength (shear strength ≥15MPa) and good environmental resistance. (2) Bonding process: Align and bond the mirror with the bonding surface 7 of the mirror, and control the thickness of the epoxy adhesive to 0.1-0.2mm to ensure that the bonding surface is completely covered and free of air bubbles; (3) Curing treatment: After bonding, the components are placed in a constant temperature and humidity environment (temperature 25℃±2℃, humidity 50%±5%) for curing. The curing time is not less than 15 days to ensure that the epoxy adhesive is fully cured and the bonding strength meets the design requirements, while also allowing the internal stress generated during the bonding process to be completely released.

[0033] Screw connection process: (1) Screw selection: High-strength titanium alloy fine-thread screws with a thread accuracy grade of 6H / 6g are selected to reduce stress fluctuations caused by thread meshing clearance; (2) Connection method: The screws are tightened by increasing the torque layer by layer. The specific steps are as follows: First, pre-tighten all screws with 30% of the design torque and let stand for 10 minutes; then tighten all screws with 70% of the design torque and let stand for 15 minutes; finally tighten all screws with the design torque. (3) Anti-loosening treatment: After tightening, a small amount of thread-locking adhesive can be applied between the screw head and the connecting base plate boss to prevent the screw from loosening due to vibration in the space environment.

[0034] As a further introduction to this embodiment, the flexible groove structure can be replaced by a U-shaped groove or a V-shaped groove structure. The groove width remains at 0.25 mm, and the groove curvature is adjusted to 80°-100°. The optimal parameters are determined through simulation optimization, which can also achieve the stress buffering effect. Replacement of the number of connecting substrates 1: The three connecting substrates 1 can be adjusted to four or six (circumferentially distributed), which is suitable for scenarios with higher requirements for connection stability. The distribution of flexible grooves and flexible holes is adjusted synchronously to ensure uniform force. Alternative bonding method: For some special mirrors, threaded holes can be set on the bonding surface (7) of the mirror, and a "bonding + screw" composite fixing method of low stress set screw and epoxy glue can be used to further improve the connection reliability without affecting the stress blocking effect.

[0035] In addition to the image stabilization system of space optical remote sensors, the flexible support structure of the present invention can also be applied to equipment that requires high-precision tilting mirrors, such as aerial photography cameras and ground high-precision optical measuring instruments, to protect the surface shape accuracy of the tilting mirror. It can be extended to the support and fixation of other ultra-thin precision components that are sensitive to external stress (such as miniature mirrors, precision optical lenses, etc.), providing them with a low-stress, high-precision installation solution.

[0036] To verify the feasibility and effectiveness of the technical solution of this invention, targeted experimental verification was conducted, as follows: Experimental subject: A pendulum mirror assembly formed by bonding using the flexible support structure of the present invention.

[0037] Experimental equipment: High-precision surface shape measuring instrument (Zygo GPI XPC interferometer), measurement accuracy ≤0.001λ (λ=632.8nm); torque wrench (accuracy ±0.01N・m); constant temperature and humidity test chamber (temperature control range 20-30℃, humidity control range 40%-60%).

[0038] Experimental procedure: The mirror assembly that has been bonded and cured (curing time 15 days) was placed in a constant temperature and humidity test chamber and left to stand for 2 hours to allow the component temperature to match the ambient temperature. The initial surface shape accuracy of the pendulum mirror (before connecting to the motion mechanism) was measured using a high-precision surface shape measuring instrument, and the RMS value was recorded. With torques of 0.36 N·m (1 T) and 0.65 N·m (1.8 T) respectively, the mirror assembly is connected to the simulated motion mechanism via the connecting hole using screws according to the layer-by-layer force-increasing method specified in this invention. After the connection is completed, place the components back in the constant temperature and humidity test chamber for 2 hours to eliminate the instantaneous stress generated during the connection process. Using the same measuring instrument and method, the surface accuracy of the pendulum mirror after connection under two different torques was measured, and the RMS value was recorded.

[0039] like Figure 4 As shown, experimental verification shows that under two commonly used torques of 0.36 N·m (1 T) and 0.65 N·m (1.8 T), the RMS value (λ=632.8 nm) of the connecting front and rear pendulum mirrors changes from 1 / 27.7λ to 1 / 26.3λ and 1 / 27λ, respectively, with almost no change in surface accuracy, which is far superior to the stress buffering effect of the existing technology; Considering the impact of slight fluctuations in ambient temperature and humidity on the measurement results during the experiment, it can be assumed that the surface accuracy of the pendulum mirror is almost unchanged before and after the connecting screw, proving that the flexible support structure of the present invention can effectively block the influence of connecting stress on the pendulum mirror surface. No problems such as adhesive failure or support structure deformation occurred during the experiment, which verified the connection strength and structural reliability of the present invention.

[0040] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A flexible support structure for reducing the deformation of an ultralight pendulum mirror surface, characterized in that, The flexible support structure includes: Multiple connecting substrates (1), the connecting substrates (1) serve as the mounting base for the flexible support structure and are used to connect with the swing mirror movement mechanism by screws; Flexible holes (3) are configured as auxiliary structures for stress buffering; The flexible support structure also includes: The outer flexible groove (5) and the inner flexible groove (6) together serve as the core stress buffer structure; The bonding surface (7) of the swing mirror is used for bonding and fixing with the swing mirror; A flexible substrate (8) located outside the connecting substrate (1) is configured as a load-bearing base for a flexible structure.

2. The flexible support structure for reducing the deformation of an ultralight pendulum mirror according to claim 1, characterized in that, Each of the connecting substrates (1) is provided with a boss with a height of 0.3 mm, and a connecting hole (2) is provided in the center of the boss, which is coaxial with the connecting substrate (1); The flexible support structure also includes a flexible groove process hole (4) to provide a process reference for the processing of the flexible groove.

3. The flexible support structure for reducing the deformation of an ultralight pendulum mirror according to claim 2, characterized in that, The outer flexible groove (5) and the inner flexible groove (6) are both coaxial with the connecting hole (2) and are evenly distributed in a 120° circle, corresponding to the distribution pattern of the connecting substrate (1).

4. The flexible support structure for reducing the deformation of an ultralight pendulum mirror according to claim 1, characterized in that, The outer flexible groove (5) and the inner flexible groove (6) both have a grooving radius of 90° and a groove width of 0.25 mm.

5. The flexible support structure for reducing the deformation of an ultralight pendulum mirror according to claim 1, characterized in that, The flexible hole (3) is a circular through hole with a diameter of 3 mm, and is evenly distributed inside the inner flexible groove (6).

6. The flexible support structure for reducing the deformation of an ultralight pendulum mirror according to claim 1, characterized in that, The surface roughness of the bonding surface (7) of the swing mirror is in the range of Ra0.8-Ra1.6μm.

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