A large aperture MEMS piezoelectric fast mirror double-axis gimbal direct drive structure

Abstract

The application discloses a kind of large aperture MEMS piezoelectric fast mirror's double-shaft universal joint direct drive structure, it is related to optical MEMS device technical field, including substrate, outer ring driving structure, inner ring driving structure, universal joint structure, center mirror and mirror support structure, inner and outer ring driving structure is concentric orthogonal arrangement, through universal joint realizes double-shaft orthogonal support and motion complete decoupling, piezoelectric driving unit directly drives without amplification mechanism, transmission chain is short, response is fast, precision is high, center mirror is millimeter level large aperture structure, mirror back is equipped with radial plus annular rib plate reinforcing rib, stiffness is high, deformation is small, resonance frequency is high.The large aperture MEMS piezoelectric fast mirror's double-shaft universal joint direct drive structure can realize large aperture mirror double-shaft quasi-static stable deflection under low voltage, with large light aperture, high rigidity, high frequency, high precision and high stability, suitable for optical communication, target tracking, beam stabilization and other high-precision optical system.

Description

Technical Field

[0001] This invention relates to the field of optical MEMS device technology, specifically to a dual-axis gimbal direct-drive structure for a large-aperture MEMS piezoelectric fast-reflecting mirror. Background Technology

[0002] MEMS fast reflectors enable precise control of beam direction and are widely used in free-space optical communication, target tracking, beam stabilization, and other fields. Compared with traditional mechanical fast reflectors, MEMS fast reflectors have advantages such as small size, light weight, easy integration, and easy mass production. With the development of high-precision beam control applications, the system has put forward higher requirements for MEMS fast reflectors. Not only are large apertures (mirror size greater than 10mm) and dual-axis deflection capabilities required, but they are also required to achieve quasi-static stable rotation under low driving voltage. Therefore, the structural design of MEMS piezoelectric fast reflectors with large aperture, dual-axis, and quasi-static drive has become an important research direction.

[0003] In the prior art, such as the MEMS piezoelectric micromirror for quasi-static rotation and non-resonant scanning with application number 202311097780.1, the technical solution includes: a fixed substrate and a fixed frame disposed thereon, a piezoelectric actuator located within the fixed frame, and a reflective mirror located within the piezoelectric actuator. The two ends of the reflective mirror are connected to the fixed frame through support beams. The piezoelectric actuators are symmetrically distributed on both sides of the reflective mirror about the support beams. The piezoelectric actuators are connected to the reflective mirror through elastic connecting folding beams and to the fixed frame through anchor points. However, this solution is mainly a single-axis structure with a small mirror size, which is difficult to meet the requirements of large-aperture biaxial fast-reflection mirrors.

[0004] Additionally, the technical solution of the two-dimensional biaxial piezoelectric MEMS micromirror, such as application number 202311067233.9, is as follows: the MEMS micromirror includes a silicon wafer substrate, a reflective mirror surface etched on the silicon wafer substrate, and N cantilever beams, where N is 2 or 4. The N cantilever beams are symmetrically arranged around the reflective mirror surface. The fixed ends of the N cantilever beams are integrally connected to the silicon wafer substrate, and the free ends are integrally connected to the reflective mirror surface. The fixed ends are evenly distributed on the silicon wafer substrate, and the free ends are evenly distributed on the reflective mirror surface. Each cantilever beam is provided with a piezoelectric driving block. After power-on, the piezoelectric driving block drives the cantilever beam to bend, and the bending of the cantilever beam drives the reflective mirror surface to flip. However, this solution does not belong to the universal joint support structure, and the biaxial decoupling and structural stability are relatively limited. It is also more inclined towards a large-angle scanning micromirror than a large-aperture quasi-static fast-reflecting mirror.

[0005] In summary, existing piezoelectric MEMS micromirror solutions for quasi-static rotation cannot meet the precise requirements of fast-reflecting mirrors for biaxial deflection and two-dimensional pointing control. Many designs focus on small-size scanning micromirrors with small mirror apertures, favoring large-angle scanning applications. This makes it difficult to simultaneously achieve the quasi-static stable deflection, structural rigidity, and engineering applicability required by large-aperture fast-reflecting mirrors. Some existing solutions introduce complex transmission structures to increase output displacement, which can lead to complex structural paths and reduced overall rigidity, hindering the static actuation of large-aperture fast-reflecting mirrors. The lower stiffness of the shaft results in poor shock resistance, making it difficult to meet the high-frequency requirements of fast-reflecting mirrors. For MEMS fast-reflecting mirrors, not only are large mirror sizes and a certain deflection angle required, but also high structural frequencies are needed to meet rapid response requirements. This places higher demands on device rigidity and support structures. Existing technologies struggle to simultaneously achieve large aperture, high frequency, and effective rotation angle output.

[0006] In view of this, in-depth research was conducted on the above issues, which led to the creation of this case.

[0007] To address the aforementioned issues, an innovative design was developed based on the existing MEMS piezoelectric micromirrors. Summary of the Invention

[0008] The purpose of this invention is to provide a dual-axis universal joint direct-drive structure for a large-aperture MEMS piezoelectric fast-reflection mirror, so as to solve the problems mentioned in the background art, such as the inability to accommodate large apertures, lack of universal support structure, and insufficient quasi-static stability.

[0009] To achieve the above objectives, the present invention provides the following technical solution: A dual-axis gimbal direct-drive structure for a large-aperture MEMS piezoelectric fast-reflecting mirror includes: The substrate serves as a fixed part of the MEMS piezoelectric fast reflector and is used to support the entire driving structure and provide boundary constraints. An outer ring driving structure is disposed above the substrate and located in the peripheral active area of ​​the MEMS piezoelectric fast reflector. The outer ring driving structure is generally arranged in a circular shape and has an arc-shaped driving area arranged opposite to each other. An inner ring drive structure is provided inside the outer ring drive structure, and the inner ring drive structure is distributed in a circular shape. The inner ring drive structure and the outer ring drive structure are arranged concentrically and orthogonally. The universal joint structure is located between the outer ring drive structure and the inner ring drive structure, and the universal joint structure constitutes the core support unit for dual-axis deflection. A central reflecting mirror is disposed in the central region of the MEMS piezoelectric fast reflecting mirror, and the central reflecting mirror is surrounded by an inner ring driving structure, which is connected to the outer ring driving structure through a universal joint structure. A mirror support structure is provided on the back of the central reflecting mirror, and the mirror support structure is used to improve the rigidity and flatness of the mirror.

[0010] Preferably, the base has a square plate frame structure, and the middle of the base is hollowed out to form a circular mounting area.

[0011] The above technical solution uses a square plate frame with a circular mounting area hollowed out in the middle, which can provide uniform and symmetrical boundary constraints for the outer ring drive structure and the inner ring drive structure, ensuring a balanced stress distribution in the overall structure and avoiding deflection deviation caused by uneven stiffness at the fixed end. The circular hollowing out has a high degree of matching with the ring drive structure and sufficient space for movement, which can effectively improve the smoothness of dual-axis deflection.

[0012] Preferably, the substrate is made of silicon-based material and is composed of at least one of the following structures formed by combining a device layer, a buried oxide layer, a substrate layer, and a silicon substrate in an SOI wafer with a surface thin film process.

[0013] Using the above technical solution, the substrate is made of silicon-based material and fabricated based on SOI wafer structure. It can make full use of the advantages of silicon material, such as high rigidity, low density and easy micromachining. Combined with the device layer, buried oxide layer and substrate layer combination structure, it can accurately control the structural thickness and mechanical properties, and ensure high resonant frequency and low deformation of the device.

[0014] Preferably, the outer ring drive structure has a circular annular symmetrical structure, and the ring body of the outer ring drive structure has a piezoelectric drive unit arrangement area distributed on it, and the outer ring drive structure is provided with a flexible arm connected to the universal joint structure.

[0015] The above technical solution adopts a circular symmetrical layout for the inner and outer ring drive structure. The piezoelectric drive units are evenly arranged, and the force and deformation are symmetrical, which can avoid the mirror tilt caused by the off-center load. The four quadrant flexible arms are connected to the universal joint structure, the support points are reasonably distributed, and the deformation transmission is stable. It can efficiently and smoothly convert piezoelectric strain into rotational torque and improve the dual-axis deflection accuracy.

[0016] Preferably, the outer ring drive structure is fixed to the base on the outside, and the inner side of the outer ring drive structure is connected to the inner ring drive structure through a universal joint structure. The outer ring drive structure provides Y-axis drive and deflection support for the inner ring and the central mirror.

[0017] Using the above technical solution, the outer ring drive structure is fixed to the base on the outside, and the inner ring drive structure is connected to the inner ring drive structure through a universal joint structure, forming a stable double-layer support transmission chain. The dual-axis deflection transmission path is short and the rigidity is high. There are no redundant flexible links, and the response speed is fast and the angle is precise and controllable.

[0018] Preferably, piezoelectric driving units are respectively provided on the outer ring driving structure and the inner ring driving structure, and the piezoelectric driving unit is formed by stacking a lower electrode layer, a piezoelectric material layer and an upper electrode layer in sequence, and the piezoelectric material is at least one of PZT, AlN and AlScN, and the upper and lower electrode layers are at least one of Pt and Au.

[0019] The above technical solution is adopted. Both the outer ring drive structure and the inner ring drive structure are equipped with a three-layer piezoelectric drive unit consisting of a lower electrode, a piezoelectric layer and an upper electrode. It can provide stable and controllable micro-deformation output. High-efficiency piezoelectric materials such as PZT, AlN and ScAlN are selected. The drive voltage is low and the strain is large, which meets the low-voltage quasi-static drive requirements of large-diameter mirrors.

[0020] Preferably, the universal joint structure includes two sets of mutually orthogonal flexible connecting shafts. One set is used to realize the deflection of the central reflective mirror surface relative to the Y-axis of the inner ring drive structure, and the other set is used to realize the deflection of the inner ring drive structure relative to the X-axis of the outer ring drive structure. The two axes are perpendicular to each other and realize motion decoupling.

[0021] Using the above technical solution, the universal joint structure adopts two sets of orthogonal flexible connecting shafts. One set realizes the Y-axis deflection of the central reflecting mirror relative to the inner ring drive structure, and the other set realizes the X-axis deflection of the inner ring drive structure relative to the outer ring drive structure. The two axes are vertically independent and their motion is completely decoupled, which completely eliminates the coupling interference between the axes. The orthogonal support has balanced rigidity and smooth rotation. The support path is compact, which can realize free rotation of the two axes in a limited space, ensuring that the support rigidity and deflection accuracy of the large-diameter mirror are met at the same time.

[0022] Preferably, the central reflecting mirror is a circular mirror, and the diameter of the central reflecting mirror is at least on the order of millimeters, and the size of the central reflecting mirror is larger than that of a typical scanning MEMS micromirror.

[0023] The above technical solution adopts a circular large-aperture structure with a diameter in the millimeter range, which is much larger than that of ordinary MEMS scanning micromirrors. It has a large light transmission capacity and high optical energy utilization rate, which can meet the requirements of optical communication, target tracking and other systems for large light transmission diameter. The circular mirror has uniform stress distribution and small deformation. With the support of a universal joint, it can achieve stable quasi-static deflection, which solves the problem that traditional small-aperture micromirrors cannot meet the requirements of high-precision and high-power optical systems, and expands the application range.

[0024] Preferably, the mirror support structure is a reinforced structure formed by a combination of radial stiffeners and annular stiffeners, with the radial stiffeners extending from the center of the mirror to the outer periphery, and the annular stiffeners connected to each radial stiffener, thereby forming a support network with high rigidity.

[0025] The above technical solution employs a combination network of radial and annular stiffeners in the mirror support structure, which can significantly improve the overall stiffness of the central reflecting mirror, suppress warping and deformation of the large-aperture mirror during deflection and vibration, ensure the flatness and optical accuracy of the mirror surface, and improve the stiffener layout without significantly increasing the mass while improving the stiffness. This is beneficial for improving the device's resonant frequency and dynamic response speed, enhancing its impact resistance, and enabling the large-aperture mirror to maintain a high-precision optical surface shape even under rapid deflection and complex environments.

[0026] Compared with the prior art, the beneficial effects of the present invention are: the dual-axis gimbal direct-drive structure of this large-aperture MEMS piezoelectric fast-reflection mirror, 1. It features a nested dual-axis universal joint support, which offers motion decoupling, high integration, and high control precision. By combining an outer ring drive structure, an inner ring drive structure, and a universal joint structure in a nested support scheme, dual-axis deflection of the central reflective mirror is achieved. This scheme fully utilizes the motion decoupling characteristics of the universal joint to separate the two rotational degrees of freedom, ensuring that the deflection actions of the mirror in two orthogonal directions do not interfere with each other. This effectively reduces inter-axis coupling interference at the structural level and avoids control errors and angle drift caused by motion cross-coupling. The nested layout structure is compact and has high space utilization, which is conducive to completing dual-degree-of-freedom integration within a limited chip area, significantly improving the structural compactness and space utilization of the device. 2. Equipped with a piezoelectric direct-drive mechanism without amplification, the deformation generated by the piezoelectric drive unit directly acts on the ring drive structure and is smoothly transmitted to the central reflecting mirror, eliminating the need for complex mechanical amplification mechanisms such as levers or bridges. This direct-drive mode significantly simplifies the overall structural design, reduces stress concentration, hysteresis deformation, and energy loss caused by intermediate flexible links, and significantly improves drive efficiency and energy utilization. Simultaneously, the simplified structure reduces processing difficulty and assembly errors, improves device consistency and reliability, and results in higher structural rigidity and stronger anti-interference capabilities.

[0027] 3. A mirror support structure is provided to enhance rigidity. By setting a mirror support structure in the central reflecting mirror, the overall rigidity of the large-aperture mirror can be significantly improved, effectively reducing the dynamic deformation and surface distortion of the mirror under high-speed deflection, vibration and external impact, ensuring the high precision and flatness of the optical surface. The support structure enhances rigidity without excessively increasing mass, enabling the device to achieve a large light-passing aperture while taking into account high modal frequency and fast dynamic response capability, meeting the needs of fast beam adjustment and high-precision optical systems. 4. Adaptable to large-aperture, dual-axis, quasi-static scenarios, meeting the requirements of low voltage, miniaturization, and high stability. Specifically optimized for large-aperture, dual-axis, quasi-static control MEMS piezoelectric fast-reflecting mirrors, it effectively meets the stringent requirements of high-end applications such as beam stabilization and laser pointing control for low-voltage drive, miniaturization, and high stability. The device employs a millimeter-scale large-aperture central reflecting mirror to enhance light transmission and optical system performance. The dual-axis gimbal structure enables precise two-dimensional angle control, and the piezoelectric direct-drive mode achieves stable deflection at a relatively low drive voltage, reducing the complexity and power consumption of the drive module. The overall structure is compact, small in size, and easy to integrate, perfectly adapting to miniaturized optical systems. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall frontal planar structure of the present invention; Figure 2 This is a schematic diagram of the overall back planar structure of the present invention; Figure 3 This is a schematic diagram of the overall three-dimensional structure of the present invention; Figure 4 This is a schematic diagram of the substrate structure of the present invention; Figure 5 This is a schematic diagram of the universal joint structure of the present invention; Figure 6 This is a schematic diagram of the mirror support structure of the present invention.

[0029] In the diagram: 1. Base; 2. Outer ring drive structure; 3. Inner ring drive structure; 4. Universal joint structure; 5. Central reflecting mirror; 6. Mirror support structure. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Please see Figure 1-6 The present invention provides a technical solution: A dual-axis gimbal direct-drive structure for a large-aperture MEMS piezoelectric fast-reflecting mirror includes: Substrate 1 serves as the fixed part of the MEMS piezoelectric fast reflector and is used to support the entire driving structure and provide boundary constraints. The outer ring drive structure 2 is disposed above the substrate 1 and is located in the outer active area of ​​the MEMS piezoelectric fast reflector. The outer ring drive structure 2 is distributed in a circular shape and has an arc-shaped drive area arranged opposite to it. The inner ring drive structure 3 is located inside the outer ring drive structure 2, and the inner ring drive structure 3 is arranged in a circular shape. The inner ring drive structure 3 and the outer ring drive structure 2 are arranged concentrically and orthogonally. Universal joint structure 4 is located between outer ring drive structure 2 and inner ring drive structure 3, and universal joint structure 4 constitutes the core support unit for dual-axis deflection. The central reflecting mirror 5 is located in the central region of the MEMS piezoelectric fast reflecting mirror, and the central reflecting mirror 5 is surrounded by the inner ring driving structure 3. The inner ring driving structure 3 is connected to the outer ring driving structure 2 through the universal joint structure 4. The mirror support structure 6 is located on the back of the central reflecting mirror 5 and is used to improve the rigidity and flatness of the mirror.

[0032] The substrate 1 has a square frame structure with a circular mounting area formed by a hollow center. The substrate 1 is made of silicon-based material and consists of at least one of the following structures formed by SOI wafers: device layer, buried oxide layer, substrate layer, and silicon substrate, combined with surface thin film technology. The square frame structure with a circular mounting area provides uniform and symmetrical boundary constraints for the outer ring drive structure 2 and the inner ring drive structure 3, ensuring a balanced stress distribution in the overall structure and avoiding deflection deviation caused by uneven stiffness at the fixed end. The circular hollow center has a high degree of matching with the ring drive structure and provides ample space for movement, effectively improving the smoothness of dual-axis deflection. The substrate 1 is made of silicon-based material and based on the SOI wafer structure, which can fully utilize the advantages of silicon material such as high stiffness, low density, and easy micromachining. Combined with the device layer, buried oxide layer, and substrate layer combination structure, it can precisely control the structural thickness and mechanical properties, ensuring high resonant frequency and low deformation of the device.

[0033] The outer ring drive structure 2 has a circular symmetrical structure, and the ring body of the outer ring drive structure 2 has an area for arranging piezoelectric drive units. The outer ring drive structure 2 also has flexible arms connected to the universal joint structure 4 in four quadrants. The outer side of the outer ring drive structure 2 is fixed to the base 1, and the inner side of the outer ring drive structure 2 is connected to the inner ring drive structure 3 through the universal joint structure 4. The outer ring drive structure 2 provides Y-axis drive and deflection support for the inner ring and the central mirror. The outer ring drive structure 2 adopts a circular symmetrical layout, and the piezoelectric drive units... The components are evenly arranged, and the force and deformation are symmetrical, which can avoid the mirror tilt caused by the off-center load. The four quadrant flexible arms are connected to the universal joint structure 4. The support points are reasonably distributed, and the deformation transmission is stable. It can efficiently and smoothly convert piezoelectric strain into rotational torque, improve the dual-axis deflection accuracy. The outer ring drive structure 2 is fixed to the base 1 on the outside and connected to the inner ring drive structure 3 on the inside through the universal joint structure 4, forming a stable double-layer support transmission chain. The dual-axis deflection transmission path is short, the rigidity is high, there are no redundant flexible links, the response speed is fast, and the angle is precise and controllable.

[0034] Piezoelectric driving units are respectively set on the outer ring driving structure 2 and the inner ring driving structure 3. The piezoelectric driving unit is formed by stacking a lower electrode layer, a piezoelectric material layer and an upper electrode layer in sequence. The piezoelectric material is at least one of PZT, AlN and AlScN. Both the outer ring driving structure 2 and the inner ring driving structure 3 are equipped with a three-layer piezoelectric driving unit consisting of a lower electrode, a piezoelectric layer and an upper electrode. This can provide stable and controllable micro-deformation output. The selection of high-efficiency piezoelectric materials such as PZT, AlN and AlScN results in low driving voltage and large strain, which meets the low-voltage quasi-static driving requirements of large-diameter mirrors.

[0035] The universal joint structure 4 includes two sets of orthogonal flexible connecting shafts. One set is used to achieve the Y-axis deflection of the central reflecting mirror 5 relative to the inner ring drive structure 3, and the other set is used to achieve the X-axis deflection of the inner ring drive structure 3 relative to the outer ring drive structure 2. The two axes are perpendicular to each other and achieve motion decoupling. The universal joint structure 4 uses two sets of orthogonal flexible connecting shafts. One set achieves the Y-axis deflection of the central reflecting mirror 5 relative to the inner ring drive structure 3, and the other set achieves the X-axis deflection of the inner ring drive structure 3 relative to the outer ring drive structure 2. The two axes are vertical and independent, and the motion is completely decoupled, which completely eliminates the coupling interference between axes. The orthogonal support has balanced rigidity and smooth rotation. The support path is compact and can achieve free rotation of the two axes in a limited space, ensuring that the support rigidity and deflection accuracy of the large-diameter mirror are met at the same time.

[0036] The central reflecting mirror 5 is a circular mirror with a minimum aperture on the order of millimeters. Furthermore, the size of the central reflecting mirror 5 is larger than that of ordinary scanning MEMS micromirrors. The central reflecting mirror 5 adopts a large-aperture circular structure, with an aperture on the order of millimeters, far exceeding that of ordinary scanning MEMS micromirrors. This results in high light transmission and high optical energy utilization, meeting the requirements of systems such as optical communication and target tracking for large light transmission apertures. The circular mirror has uniform stress distribution and minimal deformation. Combined with a universal joint support, it can achieve stable quasi-static deflection, solving the problem that traditional small-aperture micromirrors cannot meet the needs of high-precision, high-power optical systems, thus expanding its application range.

[0037] The mirror support structure 6 is a reinforced structure formed by a combination of radial stiffeners and annular stiffeners. The radial stiffeners extend from the center of the mirror to the outer periphery, and the annular stiffeners are connected to each radial stiffener, thus forming a support network with high rigidity. The combination of radial stiffeners and annular stiffeners in the mirror support structure 6 can significantly improve the overall rigidity of the central reflecting mirror 5, suppress the warping and deformation of the large-aperture mirror during deflection and vibration, and ensure the flatness and optical accuracy of the mirror surface. The stiffener layout improves rigidity without significantly increasing mass, which is beneficial to improving the device's resonant frequency and dynamic response speed, enhancing impact resistance, and enabling the large-aperture mirror to maintain a high-precision optical surface shape even under rapid deflection and complex environments. Example 1:

[0038] In this embodiment, piezoelectric driving units are respectively provided on the outer ring driving structure 2 and the inner ring driving structure 3. The piezoelectric driving unit can be formed by stacking a lower electrode layer, a piezoelectric material layer and an upper electrode layer in sequence. The piezoelectric material is preferably a PZT thin film, but it can also be a piezoelectric material suitable for MEMS devices such as AlN and AlScN.

[0039] Wherein: the piezoelectric drive unit set on the outer ring drive structure 2 is used to drive the outer ring direction deflection; the piezoelectric drive unit set on the inner ring drive structure 3 is used to drive the inner ring direction deflection.

[0040] When a driving voltage is applied to the corresponding piezoelectric driving unit, the piezoelectric material generates strain, which causes the corresponding ring driving structure to deform. This deformation is then converted into a driving torque around the corresponding axis through the universal joint structure 4, thereby driving the central reflecting mirror 5 to deflect.

[0041] This embodiment adopts a piezoelectric direct drive method, that is, the deformation generated by the piezoelectric unit does not pass through complex flexible amplification mechanisms such as bridge amplifiers and lever amplifiers, but directly acts on the ring drive structure and universal joint support structure. This design helps to shorten the mechanical transmission path and reduce the stiffness loss introduced by the intermediate flexible structure, thereby improving the stability and engineering feasibility of the device. Example 2:

[0042] The overall dimensions of the device are on the order of millimeters. (Instruction manual attached.) Figure 1 The medium scale is 10mm. The diameter of the central reflecting mirror 5 is set according to specific application requirements, preferably in the range of 5mm-10mm. The outer ring drive structure 2 and the inner ring drive structure 3 are arranged symmetrically around the central mirror to improve the force balance of the device.

[0043] In one test embodiment, when the driving voltage is approximately 20V, the device can achieve biaxial quasi-static deflection, with a mechanical deflection angle of approximately 1.5mrad in one direction and approximately 4mrad in the other direction. This result indicates that this embodiment can achieve biaxial stable driving of a large-aperture MEMS fast-reflection mirror at a relatively low driving voltage. The actual device performance can be further adjusted by optimizing six parameters: piezoelectric film thickness, driving region size, gimbal structure size, and mirror support structure. Example 3:

[0044] The MEMS piezoelectric fast-reflecting mirror in this embodiment can be fabricated using MEMS micro / nano fabrication technology based on SOI wafers, specifically including the following steps: An SOI wafer is provided as substrate 1, and the SOI wafer includes a device layer, a buried oxide layer and a substrate layer; A bottom electrode layer and a piezoelectric thin film layer are sequentially deposited on the surface of the device layer, wherein the piezoelectric thin film is preferably a PZT thin film. The piezoelectric thin film layer is patterned and etched so that it remains in the driving regions corresponding to the outer ring driving structure 2 and the inner ring driving structure 3. The bottom electrode layer is patterned to form a lower electrode structure corresponding to the piezoelectric drive region; An upper electrode layer is formed on the piezoelectric thin film layer, and corresponding lead and pad structures are fabricated. An insulating protective layer is deposited on the device surface, and through-holes are opened at the lead connection locations; The SOI device layer is patterned by deep reactive ion etching process to form an outer ring driving structure 2, an inner ring driving structure 3, a universal joint structure 4, a central reflective mirror 5, and a mirror support structure 6. The back side of the wafer is etched and the sacrificial layer below the active area is removed to release the outer ring driving structure 2, the inner ring driving structure 3 and the central reflective mirror 5, making them movable structures. A reflective layer is formed on the surface of the central reflecting mirror 5; Finally, the chip is cut, packaged, and electrically connected to obtain a complete MEMS piezoelectric fast reflector device.

[0045] This embodiment employs a process combining piezoelectric thin film fabrication and SOI microstructure processing to fabricate a large-aperture MEMS piezoelectric fast-reflecting mirror device with a biaxial gimbal support structure and a ring-shaped drive structure. The above process route can be adjusted according to the specific material system and processing platform; for example, thin-film PZT technology, AlN sputtering technology, or other MEMS-compatible piezoelectric thin film fabrication processes can be used.

[0046] Working principle: 1. Y-direction deflection When a driving voltage is applied only to the piezoelectric driving unit on the outer ring driving structure 2, the outer ring driving structure 2 undergoes a slight deformation, which, through the universal joint structure 4, drives the inner ring driving structure 3 and the central reflecting mirror 5 to deflect around the Y-axis as a whole. At this time, the central reflecting mirror 5 achieves quasi-static angle adjustment in the Y direction.

[0047] II. X-direction deflection When a driving voltage is applied only to the piezoelectric driving unit on the inner ring driving structure 3, the inner ring driving structure 3 undergoes a slight deformation, causing the central reflecting mirror 5 to deflect around the X-axis. At this time, the central reflecting mirror 5 achieves quasi-static angle adjustment in the X direction.

[0048] III. Dual-axis compound deflection When driving voltage is applied to the piezoelectric driving units on the outer ring driving structure 2 and the inner ring driving structure 3 at the same time, the central reflecting mirror 5 can be synchronously deflected in two orthogonal directions to achieve two-dimensional pointing control. The device mainly operates in quasi-static mode, that is, the central reflecting mirror 5 is stably deflected to the target angle and maintained by DC voltage or low-frequency control voltage. This operating mode is suitable for the application requirements of fast reflectors in beam stabilization, beam pointing correction and precision control.

[0049] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

[0050] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A dual-axis gimbal direct-drive structure for a large-aperture MEMS piezoelectric fast-reflecting mirror, characterized in that: include: The substrate (1) serves as a fixed part of the MEMS piezoelectric fast reflector and is used to support the entire driving structure and provide boundary constraints. The outer ring drive structure (2) is disposed above the substrate (1) and is located in the peripheral active area of ​​the MEMS piezoelectric fast reflector. The outer ring drive structure (2) is distributed in a circular shape and has an arc-shaped drive area arranged opposite to each other. The inner ring drive structure (3) is located inside the outer ring drive structure (2), and the inner ring drive structure (3) is arranged in a circular shape. The inner ring drive structure (3) and the outer ring drive structure (2) are arranged concentrically and orthogonally. Universal joint structure (4), the universal joint structure (4) is disposed between the outer ring drive structure (2) and the inner ring drive structure (3), and the universal joint structure (4) constitutes the core support unit for dual-axis deflection; The central reflecting mirror (5) is located in the central region of the MEMS piezoelectric fast reflector, and the central reflecting mirror (5) is surrounded by the inner ring drive structure (3), and the inner ring drive structure (3) is connected to the outer ring drive structure (2) through the universal joint structure (4). A mirror support structure (6) is provided on the back of the central reflecting mirror (5), and the mirror support structure (6) is used to improve the rigidity and flatness of the mirror.

2. The dual-axis gimbal direct-drive structure for a large-aperture MEMS piezoelectric fast-reflecting mirror according to claim 1, characterized in that: The base (1) has a square plate frame structure, and the middle of the base (1) is hollowed out to form a circular installation area.

3. The dual-axis gimbal direct-drive structure for a large-aperture MEMS piezoelectric fast-reflecting mirror according to claim 2, characterized in that: The substrate (1) is made of silicon-based material and is composed of at least one of the following structures formed by the device layer, buried oxide layer, substrate layer and silicon substrate in SOI wafer with surface thin film process.

4. The dual-axis gimbal direct-drive structure for a large-aperture MEMS piezoelectric fast-reflecting mirror according to claim 1, characterized in that: The outer ring drive structure (2) has a circular symmetrical structure, and the outer ring drive structure (2) has a piezoelectric drive unit arrangement area distributed on the ring body, and the outer ring drive structure (2) has flexible arms connected to the universal joint structure (4) in four quadrant positions.

5. The dual-axis gimbal direct-drive structure for a large-aperture MEMS piezoelectric fast-reflecting mirror according to claim 4, characterized in that: The outer ring drive structure (2) is fixed to the base (1) on the outside, and the inner side of the outer ring drive structure (2) is connected to the inner ring drive structure (3) through the universal joint structure (4). The outer ring drive structure (2) provides Y-axis drive and deflection support for the inner ring and the central mirror.

6. The dual-axis gimbal direct-drive structure for a large-aperture MEMS piezoelectric fast-reflecting mirror according to claim 5, characterized in that: The outer ring drive structure (2) and the inner ring drive structure (3) are respectively provided with piezoelectric drive units, and the piezoelectric drive units are formed by stacking a lower electrode layer, a piezoelectric material layer and an upper electrode layer in sequence. The piezoelectric material is at least one of PZT, AlN and AlScN, and the upper and lower electrode layers are at least one of Pt and Au.

7. The dual-axis gimbal direct-drive structure for a large-aperture MEMS piezoelectric fast-reflecting mirror according to claim 1, characterized in that: The universal joint structure (4) includes two sets of mutually orthogonal flexible connecting shafts. One set is used to realize the Y-axis deflection of the central reflective mirror (5) relative to the inner ring drive structure (3), and the other set is used to realize the X-axis deflection of the inner ring drive structure (3) relative to the outer ring drive structure (2). The two axes are perpendicular to each other and realize motion decoupling.

8. The dual-axis gimbal direct-drive structure for a large-aperture MEMS piezoelectric fast-reflecting mirror according to claim 1, characterized in that: The central reflecting mirror (5) is a circular mirror, and the diameter of the central reflecting mirror (5) is at least on the order of millimeters. Furthermore, the size of the central reflecting mirror (5) is larger than that of a typical scanning MEMS micromirror.

9. The dual-axis gimbal direct-drive structure for a large-aperture MEMS piezoelectric fast-reflecting mirror according to claim 1, characterized in that: The mirror support structure (6) is a reinforced structure formed by a combination of radial stiffeners and annular stiffeners. The radial stiffeners extend from the center of the mirror to the outer periphery, and the annular stiffeners are connected to each radial stiffener, thereby forming a support network with high rigidity.

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