Quartz mems accelerometer based on optical detection and method of manufacturing the same

Abstract

The application discloses a quartz MEMS accelerometer based on optical detection and a manufacturing method thereof, relates to the fields of micro-electro-mechanical system technology and micro-inertial instruments, and the accelerometer comprises a body, a base and an optical detection system; the body is integrally processed from a quartz material through a MEMS process and comprises an anchor point, an isolation frame and a mass block suspended in the isolation frame through a flexible hinge; the anchor point is fixed on the base; the optical detection system is integrated in the body and comprises an incident optical fiber, a detection optical fiber, a beam splitter arranged on the mass block and a mirror arranged on the second anchor point; the optical detection system divides incident light into a reference light beam and a sensing light beam; when there is an acceleration input from the outside world, the mass block generates displacement and causes optical intensity drift; and the intensity change of the output interference light signal can be accurately calculated to obtain the acceleration. The application can convert a small mechanical displacement into a change of an optical intensity signal and has high displacement detection sensitivity.

Description

Technical Field

[0001] This application relates to the fields of microelectromechanical systems (MEMS) technology and micro-inertial instruments, and in particular to a quartz MEMS accelerometer based on optical detection and its manufacturing method. Background Technology

[0002] Accelerometers, as core inertial sensors for measuring the motion state of objects, play a crucial role in inertial navigation, earthquake monitoring, aerospace attitude control, and consumer electronics. With the evolution of micro-electro-mechanical systems (MEMS) technology, devices are rapidly developing towards miniaturization, integration, and high precision.

[0003] However, existing MEMS accelerometers face severe challenges in complex electromagnetic environments. First, traditional electrical detection mechanisms, such as capacitance, piezoelectricity, and piezoresistive methods, have inherent limitations. Thermal noise and parasitic effects of electronic components set physical detection limits, making it difficult to meet the demands of sub-micro-g level high-precision measurements. Second, although quartz materials are preferred for high-precision sensors due to their excellent thermal stability, current mainstream quartz MEMS still rely on electrical detection methods, failing to fundamentally solve the problem of high-frequency signal parasitics. Summary of the Invention

[0004] The purpose of this application is to provide a quartz MEMS accelerometer based on optical detection and its manufacturing method, which can convert minute mechanical displacements into changes in light intensity signals and has high displacement detection sensitivity.

[0005] To achieve the above objectives, this application provides the following solution: In a first aspect, this application provides a quartz MEMS accelerometer based on optical detection, comprising: The body, integrally formed from quartz material using MEMS technology, includes anchor points, an isolation frame supported by the anchor points, and a mass block suspended within the isolation frame by a flexible hinge; the isolation frame is located inside the anchor points; the anchor points include a first anchor point and a second anchor point. The base, wherein the anchor point is fixed on the base; An optical detection system, integrated inside the main body, includes an incident optical fiber, a detection optical fiber, a first beam splitter and a second beam splitter disposed on the mass block, and a first reflector and a second reflector disposed on the second anchor point; the first beam splitter and the first reflector are arranged opposite to and parallel to each other, and the second beam splitter and the second reflector are arranged opposite to and parallel to each other. An incident light beam is emitted from the incident optical fiber and split into a reference beam and a sensing beam by the first beam splitter. The reference beam is transmitted into the interior of the mass block and transmitted. The sensing beam is reflected to the first reflector and then transmitted to the second reflector. After being reflected again by the second reflector, it merges with the reference beam at the second beam splitter to form an interference light signal. When an external acceleration is applied to the quartz MEMS accelerometer, the mass block is displaced relative to the isolation frame to change the optical path of the sensing beam, thereby modulating the intensity of the interference light signal, and the acceleration value is calculated based on the intensity change of the interference light signal.

[0006] Secondly, this application provides a method for manufacturing a quartz MEMS accelerometer based on optical detection, including: fabricating a body, fabricating a substrate, and assembling and installing optical fibers; The process of creating the main body includes: Clean and prepare the first quartz block; A first metal mask and a second metal mask are sputtered on the upper and lower surfaces of the first quartz block, respectively. The pattern window of the first metal mask is opened by photolithography and etching processes, the front side of the first quartz block is etched to form a flexible hinge, and then the first metal mask is removed. A third metal mask is sputtered on the upper surface of the first quartz block. The pattern windows of the second and third metal masks are opened simultaneously through photolithography and etching processes. The first quartz block is etched on both sides to form the isolation beam, mass block, first anchor point, second anchor point and isolation frame. Then the second and third metal masks are removed. A first shadow mask with a first graphic window is mounted upside down on a first quartz block, and over-plating is performed to form a first beam splitter and a second beam splitter, and then the first shadow mask is removed. A second shadow mask with a second graphic window is mounted on the first quartz block, and over-plating is performed to form a first reflector and a second reflector. The second shadow mask is then removed to obtain the main body. The process of creating the base includes: Clean and prepare the second quartz block; A fourth metal mask and a fifth metal mask are sputtered onto the upper and lower surfaces of the second quartz block, respectively. The pattern window of the fourth metal mask is opened by photolithography and etching processes, and the front side of the second quartz block is etched to form a cavity. Then the fourth and fifth metal masks are removed to obtain the substrate. The process of assembling and installing optical fibers includes: The body and the substrate are bonded together, and an incident fiber and a detection fiber are installed to obtain a quartz MEMS accelerometer based on optical detection.

[0007] According to the specific embodiments provided in this application, this application has the following technical effects: (1) This application utilizes the high light transmittance of quartz material, combined with the beam splitter and reflector structure set on the mass block and the isolation frame, to construct a miniaturized three-dimensional Mach-Zehnder interferometer inside the main body. It can convert the small displacement of the mass block caused by acceleration into changes in optical path and optical phase inside the quartz, and then realize acceleration detection through interference optical signals. Compared with traditional pure fiber or waveguide optical accelerometers, this application has higher detection sensitivity and more prominent potential for miniaturization and integration. Compared with traditional electrical detection methods such as capacitance, piezoelectricity, and piezoresistive, it uses optical signal transmission and detection throughout the process, without electrical parasitic effects and electromagnetic interference problems, and significantly improves the ability to resist complex electromagnetic interference. (2) This application uses a one-piece quartz material for molding and an isolation frame structure inside the anchor point, which can effectively isolate the influence of thermal stress and encapsulation stress on the sensitive structure. In addition, the low thermal expansion coefficient of quartz material itself greatly improves the output stability and ultra-low frequency measurement stability of the accelerometer under temperature change environment. Combining this quartz mechanical structure with the optical detection system can give full play to the integration and high precision advantages of optical MEMS technology, while taking into account the excellent thermal stability of quartz material, fundamentally improving the high-frequency parasitic and accuracy-limited problems caused by the use of electrical detection in traditional quartz MEMS. (3) This application integrates mechanical structures such as anchor points, isolation frames, and mass blocks with an optical detection system consisting of incident optical fiber, detection optical fiber, beam splitter, and reflector on a quartz body using MEMS technology. This solves the problem of the large size of traditional quartz sensors and realizes the integration of optical components with semiconductor substrates, further improving the miniaturization and integration of the optical detection system, which is more in line with the application requirements of MEMS devices to develop towards miniaturization, integration, and high precision. Attached Figure Description

[0008] 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 of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 This is a front view of a quartz MEMS accelerometer based on optical detection provided in Embodiment 1 of this application; Figure 2A side cross-sectional view of a quartz MEMS accelerometer based on optical detection provided in Embodiment 1 of this application; Figure 3 A top view of the upper structure of the quartz MEMS accelerometer based on optical detection provided in Embodiment 1 of this application; Figure 4 A top view of the lower-level mechanism of the quartz MEMS accelerometer based on optical detection provided in Embodiment 1 of this application; Figure 5 This is a static structural diagram of the optical detection system provided in Embodiment 1 of this application; Figure 6 This is a dynamic schematic diagram of acceleration detection provided in Embodiment 1 of this application; Figure 7 This is a process flow diagram of the fabrication of a quartz MEMS accelerometer based on optical detection provided in Embodiment 2 of this application.

[0010] Reference numerals in the attached figures: 1-First anchor point; 2-Second anchor point; 3-1-First isolation beam; 3-2-Second isolation beam; 3-3-Third isolation beam; 4-Isolation frame; 5-1-First flexible hinge; 5-2-Second flexible hinge; 6-Mass block; 7-1-First beam splitter; 7-2-Second beam splitter; 8-1-First reflector; 8-2-Second reflector; 9-Incident fiber; 10-Detection fiber; 11-Substrate; 12-Cavity. Detailed Implementation

[0011] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0012] In the following description, specific details such as target system architecture and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of this application with unnecessary detail.

[0013] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0014] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0015] Furthermore, in the description of this application and the appended claims, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0016] References to "one embodiment" or "some embodiments" in this specification mean that one or more embodiments of this application include the target features, structures, or characteristics described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized.

[0017] Example 1: like Figures 1-4 As shown, this embodiment provides a quartz MEMS accelerometer based on optical detection, including a body, a substrate 11, and an optical detection system. The body and the optical detection system constitute the upper structure of the quartz MEMS accelerometer, and the substrate 11 is the lower structure of the quartz MEMS accelerometer. The following is a detailed description of each part.

[0018] (1) Ontology.

[0019] The body is integrally formed from quartz material using MEMS technology, and includes anchor points, an isolation frame 4 supported by the anchor points, and a mass block 6 suspended within the isolation frame 4 by a flexible hinge; the isolation frame 4 is located inside the anchor points; the anchor points include a first anchor point 1 and a second anchor point 2.

[0020] (2) Base 11.

[0021] The base 11, and the anchor point is fixed on the base 11.

[0022] A cavity 12 is provided on the base 11, and the anchor point is fixed to a solid area on the base 11 outside the cavity 12; the mass block 6 is located above the cavity 12.

[0023] (3) Optical detection system.

[0024] An optical detection system, integrated inside the main body, includes an incident optical fiber 9, a detection optical fiber 10, a first beam splitter 7-1 and a second beam splitter 7-2 disposed on the mass block 6, and a first reflector 8-1 and a second reflector 8-2 disposed on the second anchor point 2; the first beam splitter 7-1 and the first reflector 8-1 are arranged opposite to and parallel to each other, and the second beam splitter 7-2 and the second reflector 8-2 are arranged opposite to and parallel to each other.

[0025] An incident light beam exits from the incident optical fiber 9 and is split into a reference beam and a sensing beam by the first beam splitter 7-1. The reference beam is transmitted through the interior of the mass block 6, while the sensing beam is reflected to the first reflector 8-1. After reflection by the first reflector 8-1, it is transmitted to the second reflector 8-2, and after being reflected again by the second reflector 8-2, it merges with the reference beam at the second beam splitter 7-2, forming an interference light signal. When an external acceleration is applied to the quartz MEMS accelerometer, the mass block 6 is displaced relative to the isolation frame 4 to change the optical path of the sensing beam, thereby modulating the intensity of the interference light signal. The acceleration value is calculated based on the intensity change of the interference light signal.

[0026] Furthermore, the optical detection system constitutes a miniature three-dimensional Mach–Zehnder interferometer (MZI).

[0027] Furthermore, an optical fiber channel for placing the incident optical fiber 9 and the detection optical fiber 10 is provided between the first anchor point 1 and the second anchor point 2.

[0028] Furthermore, the first anchor point 1 is connected to the isolation frame 4 by multiple isolation beams.

[0029] The first anchor point 1 and the second anchor point 2 serve as fixed support ends of the structure and are respectively arranged on both sides of the periphery of the accelerometer structure; the isolation frame 4 is located inside the anchor point and is connected to the first anchor point 1 through the first isolation beam 3-1, the second isolation beam 3-2 and the third isolation beam 3-3 to form a stress isolation structure.

[0030] The first isolation beam 3-1, the second isolation beam 3-2, and the third isolation beam 3-3 are slender beam structures connected between the first anchor point 1 and the frame isolation frame 4. They are used to release the encapsulation stress and the thermal stress generated by temperature changes, and to block the transmission of external stress to the internal sensitive structure.

[0031] Furthermore, the flexible hinge includes a first flexible hinge 5-1 and a second flexible hinge 5-2, the first flexible hinge 5-1 and the second flexible hinge 5-2 being symmetrically arranged at both ends of the mass block 6; the thickness of the first flexible hinge 5-1 and the second flexible hinge 5-2 is less than the thickness of the mass block.

[0032] The first flexible hinge 5-1 and the second flexible hinge 5-2 are symmetrically arranged at both ends of the mass block 6 about the horizontal central axis of the mass block 6. The thickness of the first flexible hinge 5-1 and the second flexible hinge 5-2 is significantly smaller than the thickness of the mass block 6 to enhance its mechanical sensitivity. One end of the first flexible hinge 5-1 and the second flexible hinge 5-2 is connected to the inner wall of the isolation frame 4, and the other end is connected to the mass block 6. When there is an acceleration input along the sensitive axis (x-axis in Figure 1), the mass block 6 overcomes the elastic restoring force of the flexible hinge and generates linear displacement.

[0033] Furthermore, a cavity 12 is provided on the substrate 11, and the first anchor point 1 and the second anchor point 2 are fixed to a solid area on the substrate 11 located outside the cavity 12; the mass block 6 is located above the cavity 12. The substrate 11 is only bonded to the first anchor point 1 and the second anchor point 2, and the rest of the substrate does not need to be in contact.

[0034] The outer periphery of the base 11 is bonded to the anchor point of the upper mechanism, and the base 11 has a cavity 12 inside. The cavity 12 is a hexagonal prism, located at the center of the lower mechanism, with its geometric center located directly below the center of the mass block 6, and the six sides of the cavity 12 are slightly longer than the six sides of the mass block 6, thus surrounding the mass block 6 as a whole.

[0035] Mass 6 is located above cavity 12 and is suspended and supported on isolation frame 4 by first flexible hinge 5-1 and second flexible hinge 5-2, allowing mass 6 to move along the sensitive axis. An optical detection system is constructed within the cavity formed by anchor point, mass 6, and substrate 11. It senses the change in the propagation distance of the light beam within mass 6 caused by the displacement of mass 6 relative to second anchor point 2. Due to the difference in refractive index between quartz and air, the optical path difference changes, ultimately leading to a change in the intensity of the interference light signal, thereby achieving high-precision acceleration detection.

[0036] Furthermore, such as Figures 2-3 As shown, the isolation frame 4 has a semi-enclosed structure.

[0037] Furthermore, the mass block 6 can be a polygonal structure, but it needs to meet the requirements of the first beam splitter 7-1, the second beam splitter 7-2, the first reflector 8-1, and the second reflector 8-2. In this embodiment, the mass block 6 is designed as an octagonal structure.

[0038] Furthermore, the incident fiber 9 and the detection fiber 10 are coaxially arranged and located on the same optical axis. The first beam splitter 7-1 and the first reflector 8-1 are both at a 45-degree angle to the sensitive axis of the mass block 6; the second beam splitter 7-2 and the second reflector 8-2 are both at a 45-degree angle to the sensitive axis of the mass block 6; and both the incident fiber 9 and the detection fiber 10 are perpendicular to the sensitive axis of the mass block 6.

[0039] like Figure 5 As shown, the optical path layout of the optical detection system is as follows: the incident fiber 9 and the detection fiber 10 are respectively fixedly installed in the fiber optic channel reserved between the first anchor point 1 and the second anchor point 2, and are arranged coaxially in the vertical direction and located on the same optical axis. The first beam splitter 7-1 is fixed on the inclined side of the incident side of the optical path of the mass block 6 and moves synchronously with the mass block 6; the second beam splitter 7-2 is fixed on the inclined side of the exit side of the optical path of the mass block 6 and moves synchronously with the mass block 6. The first reflector 8-1 is fixed on the inner side of the frame near the incident direction of the second anchor point 2, and the second reflector 8-2 is fixed on the inner side of the frame near the exit direction of the second anchor point 2. The first beam splitter 7-1 is parallel to the first reflector 8-1, and the second beam splitter 7-2 is parallel to the second reflector 8-2. The first beam splitter 7-1 and the first reflector 8-1 both make an angle of 45 degrees with the x-axis; the second beam splitter 7-2 and the second reflector 8-2 both make an angle of 45 degrees with the x-axis.

[0040] The optical detection system is a miniature Mach-Zehnder interferometer. This quartz MEMS accelerometer utilizes the Mach-Zehnder interferometer to convert changes in light intensity into acceleration measurement signals. For example... Figure 6 As shown, the specific optical path is as follows: The incident beam enters from the incident fiber 9 and is split into a reference beam and a sensing beam by the first beam splitter 7-1 located on the mass block 6: the reference beam is transmitted into the mass block 6, which is made of quartz, and its direction remains unchanged; the sensing beam is reflected to the first reflector 8-1.

[0041] The sensing beam is directed toward the first reflector 8-1 fixed on the second anchor point 2. After reflection, the beam changes direction and becomes parallel to the incident direction, then is directed toward the second reflector 8-2. After being reflected again by the second reflector 8-2, the beam changes direction and becomes perpendicular to the incident direction, then is directed toward the second beam splitter 7-2 on the exit side of the mass block 6.

[0042] At this point, the reference beam and the sensing beam converge and interfere at the second beam splitter 7-2. After being coupled and split by the second beam splitter 7-2, one interference beam is emitted along the direction of the initial incident beam toward the detection fiber 10, carrying information about the change in light intensity and entering the detection fiber 10 for detection; the other beam is dissipated inside the mass block 6, which is not considered.

[0043] When there is no external acceleration input, the mass block 6 is in a balanced position, and the two interference arms of the optical detection system maintain the initial optical path difference, outputting a constant light intensity. When there is external acceleration along the sensitive axis, the mass block 6 causes the first beam splitter 7-1 and the second beam splitter 7-2 fixed on it to undergo relative displacement with respect to the first reflector 8-1 and the second reflector 8-2 fixed on the second anchor point 2, resulting in a change in the optical path of the sensing beam, thereby changing the phase difference between the two beams and producing modulation of the interference intensity. By demodulating the intensity change of the interference light signal output by the detection fiber 10, the acceleration value can be accurately calculated.

[0044] This application utilizes the Mach-Zehnder interferometry principle. The core of the Mach-Zehnder interferometer lies in reflecting the change of physical quantities by measuring the phase difference between two beams of light.

[0045] Intensity of the interference light signal Depends on the phase difference between the reference beam and the sensing beam Assume the intensity of the incident light beam is... , The calculation formula is: When the accelerometer is subjected to the acceleration to be measured When in action, the mass block Generates inertial force This force overcomes the flexible hinge (elastic modulus is ). The resistance of the mass block causes it to undergo mechanical displacement in the sensitive direction. .

[0046] According to Newton's second law and Hooke's law, the following relationship exists: Combining the above two equations, we obtain the mechanical displacement and acceleration. The relationship is: During geometry and optical path modulation, the physical distance between the reference beam and the sensing beam changes as acceleration occurs, as follows: in, The physical distance to the reference beam; The physical distance to the sensing beam; The physical distance after the mass block is displaced by x; Let x be the physical distance after the mass block is displaced.

[0047] Optical path difference between the optical path of the reference beam and the optical path of the sensing beam for: in, The refractive index of quartz is... is the refractive index of air.

[0048] Phase synthesis is based on the principles of wave optics. The amount of dynamic phase change caused by acceleration for: In the formula, λ is the wavelength of the incident light beam.

[0049] Finally, combining the light intensity formula, the complete input-output equation of the system is: This application provides a quartz MEMS accelerometer designed to address the problems of traditional electrical sensing MEMS accelerometers, such as weak anti-interference capability against high-frequency signals, poor thermal stability, and limited resolution due to thermal noise. The main structure of this quartz MEMS accelerometer is made of single-crystal quartz material and fabricated using MEMS technology. It includes anchor points, a semi-enclosed isolation frame, flexible hinges, and an octagonal mass block located in the central cavity. An optical detection system is integrated within the main body, using incident and detection optical fibers to introduce and output optical signals. A miniature Mach-Zehnder interferometer is constructed using beam splitters and mirrors positioned on the mass block and a second anchor point. This optical detection system splits the incident beam into a reference beam and a sensing beam. When there is an external acceleration input, the displacement of the mass block further causes optical intensity drift. The acceleration can be accurately calculated by demodulating the intensity change of the output interference optical signal. This application employs an optical signal transmission and detection scheme, combined with the thermal stability of quartz material and the Mach-Zehnder interferometer, demonstrating excellent performance in high-frequency signal environments.

[0050] Example 2: like Figure 7 As shown, this embodiment provides a method for manufacturing a quartz MEMS accelerometer based on optical detection, including: fabricating a body, fabricating a substrate, and assembling and installing optical fibers.

[0051] The process of creating the main body includes: S1-1: Clean and prepare the first quartz block; S1-1: A first metal mask and a second metal mask are sputtered on the upper and lower surfaces of the first quartz block, respectively; S1-3: Open the graphic window of the first metal mask through photolithography and etching processes; S1-4: The first quartz block is etched on the front to form a flexible hinge; S1-5: Remove the first metal mask; S1-6: A third metal mask is sputtered onto the upper surface of the first quartz block; S1-7: Simultaneously open the graphic windows of the second and third metal masks through photolithography and etching processes; S1-8: The first quartz block is etched on both sides to form the isolation beam, mass block, first anchor point, second anchor point and isolation frame; S1-9: Remove the second and third metal mask plates; S1-10: Reverse-mount a first shadow mask with a first graphics window onto the first quartz block; S1-11: Perform plating to form the first beam splitter and the second beam splitter; S1-12: Remove the first shadow mask; S1-13: Reverse mount a second shadow mask with a second graphics window onto the first quartz block; S1-14: Perform plating to form the first and second reflectors; S1-15: Remove the second shadow mask to obtain the complete body.

[0052] The process of creating the base includes: S2-1: Clean and prepare the second quartz block; S2-2: A fourth metal mask and a fifth metal mask are sputtered on the upper and lower surfaces of the second quartz block, respectively; S2-3: Open the pattern window of the fourth metal mask through photolithography and etching processes; S2-4: Etch the front side of the second quartz block to form a cavity; S2-5: Remove the fourth and fifth metal mask plates to obtain the substrate.

[0053] The process of assembling and installing optical fibers includes: S3-1: Bond the body to the substrate and assemble them; S3-2: Install the incident fiber and the detection fiber in the fiber optic channel to obtain a complete quartz MEMS accelerometer based on optical detection.

[0054] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0055] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A quartz MEMS accelerometer based on optical detection, characterized in that, include: The body, integrally formed from quartz material using MEMS technology, includes anchor points, an isolation frame supported by the anchor points, and a mass block suspended within the isolation frame by a flexible hinge; the isolation frame is located inside the anchor points; the anchor points include a first anchor point and a second anchor point. The base, wherein the anchor point is fixed on the base; An optical detection system, integrated inside the main body, includes an incident optical fiber, a detection optical fiber, a first beam splitter and a second beam splitter disposed on the mass block, and a first reflector and a second reflector disposed on the second anchor point; the first beam splitter and the first reflector are arranged opposite to and parallel to each other, and the second beam splitter and the second reflector are arranged opposite to and parallel to each other. An incident light beam is emitted from the incident optical fiber and split into a reference beam and a sensing beam by the first beam splitter. The reference beam is transmitted into the interior of the mass block and transmitted. The sensing beam is reflected to the first reflector and then transmitted to the second reflector. After being reflected again by the second reflector, it merges with the reference beam at the second beam splitter to form an interference light signal. When an external acceleration is applied to the quartz MEMS accelerometer, the mass block is displaced relative to the isolation frame to change the optical path of the sensing beam, thereby modulating the intensity of the interference light signal, and the acceleration value is calculated based on the intensity change of the interference light signal.

2. The quartz MEMS accelerometer based on optical detection according to claim 1, characterized in that, The optical detection system constitutes a Mach-Zehnder interferometer.

3. The quartz MEMS accelerometer based on optical detection according to claim 1, characterized in that, An optical fiber channel for placing the incident optical fiber and the detection optical fiber is provided between the first anchor point and the second anchor point.

4. The quartz MEMS accelerometer based on optical detection according to claim 3, characterized in that, The first anchor point is connected to the isolation frame by multiple isolation beams.

5. The quartz MEMS accelerometer based on optical detection according to claim 3, characterized in that, The substrate has a cavity, and the first anchor point and the second anchor point are fixed to a solid area on the substrate outside the cavity; the mass block is located above the cavity.

6. The quartz MEMS accelerometer based on optical detection according to claim 1, characterized in that, The flexible hinge includes a first flexible hinge and a second flexible hinge, which are symmetrically arranged at both ends of the mass block; the thickness of the first flexible hinge and the second flexible hinge is less than the thickness of the mass block.

7. The quartz MEMS accelerometer based on optical detection according to claim 1, characterized in that, The incident optical fiber and the detection optical fiber are arranged coaxially and located on the same optical axis.

8. The quartz MEMS accelerometer based on optical detection according to claim 1, characterized in that, The first beam splitter and the first reflector are both at a 45-degree angle to the sensitive axis of the mass block; the second beam splitter and the second reflector are both at a 45-degree angle to the sensitive axis of the mass block; the incident optical fiber and the detection optical fiber are both perpendicular to the sensitive axis of the mass block.

9. The quartz MEMS accelerometer based on optical detection according to claim 1, characterized in that, The isolation frame has a semi-enclosed structure.

10. A method for manufacturing a quartz MEMS accelerometer based on optical detection as described in any one of claims 1-9, characterized in that, include: Fabrication of the main body, fabrication of the base, and assembly and installation of optical fibers; The process of creating the main body includes: Clean and prepare the first quartz block; A first metal mask and a second metal mask are sputtered on the upper and lower surfaces of the first quartz block, respectively. The pattern window of the first metal mask is opened by photolithography and etching processes, the front side of the first quartz block is etched to form a flexible hinge, and then the first metal mask is removed. A third metal mask is sputtered on the upper surface of the first quartz block. The pattern windows of the second and third metal masks are opened simultaneously through photolithography and etching processes. The first quartz block is etched on both sides to form the isolation beam, mass block, first anchor point, second anchor point and isolation frame. Then the second and third metal masks are removed. A first shadow mask with a first graphic window is mounted upside down on a first quartz block, and over-plating is performed to form a first beam splitter and a second beam splitter, and then the first shadow mask is removed. A second shadow mask with a second graphic window is mounted on the first quartz block, and over-plating is performed to form a first reflector and a second reflector. The second shadow mask is then removed to obtain the main body. The process of creating the base includes: Clean and prepare the second quartz block; A fourth metal mask and a fifth metal mask are sputtered onto the upper and lower surfaces of the second quartz block, respectively. The pattern window of the fourth metal mask is opened by photolithography and etching processes, and the front side of the second quartz block is etched to form a cavity. Then the fourth and fifth metal masks are removed to obtain the substrate. The process of assembling and installing optical fibers includes: The body and the substrate are bonded together, and an incident fiber and a detection fiber are installed to obtain a quartz MEMS accelerometer based on optical detection.

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