Micro-surface external speed sensor for detecting micro-vibration and acceleration detection method

Abstract

The invention relates to the technical field of vibration detection, and provides a miniature surface external speed sensor for detecting micro vibration and an acceleration detection method. The acceleration sensor comprises an optical fiber and an elastic assembly oppositely arranged at one end of the optical fiber; the elastic assembly comprises a frame, a central mass block, four edge mass blocks, four first cantilever beams and four second cantilever beams. The edge mass blocks are distributed around the center mass block in a surrounding mode and are in 90-degree rotational symmetry. One end of the first long edge of each edge mass block is connected with one vertex of the center mass block through a first cantilever beam, and the other end of the first long edge of each edge mass block is connected with the inner edge of the frame through a second cantilever beam. According to the invention, by arranging the edge mass block, the first cantilever beam and the second cantilever beam, a U-shaped connection structure is formed, so that the sensitivity and the impact resistance are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of vibration detection, and in particular to a miniature out-of-plane acceleration sensor for detecting micro-vibrations and an acceleration detection method. Background Art

[0002] Acceleration measurement plays a vital role in modern industry and technology. In aerospace, monitoring the vibration acceleration of key aircraft components enables real-time assessment of structural health, preventing mechanical failures, and ensuring flight safety. In intelligent manufacturing, high-precision accelerometers can detect minute abnormal vibrations in equipment such as machine tools and robots, enabling predictive maintenance and improving production efficiency. In the new energy vehicle sector, as usage environments become increasingly diverse and complex, accelerometers are evolving towards miniaturization and high sensitivity to meet the increasingly complex needs of engineering monitoring. Compared to electrical accelerometers, optical accelerometers are small, lightweight, highly sensitive, resistant to electromagnetic interference, and have low installation costs. They can achieve long-distance signal transmission and are easy to network and reuse on a large scale, making them suitable for large-scale application in harsh environmental conditions. Currently, fiber optic accelerometers offer a variety of acceleration transducers, including elastic cylinder structures, elastic disk structures, and fiber-optic direct-connect structures. However, their size is limited by processing technology and optical path structures, especially sensors processed by metal machining, which struggle to meet the miniaturization requirements of sensors. Cantilever beam mass blocks, on the other hand, have a compact structure that can be easily formed into a two-dimensional planar distribution and integrated on a substrate through silicon micromachining. They offer the advantages of small size and light weight, but some existing cantilever beam mass block structures often use a four-beam inertial mass beam sensitive structure, comprising four beams and a mass block. The mass block's side near the frame is directly connected to the frame via a beam. This structure often has poor impact resistance and is easily damaged, making it unsuitable for application in harsh environments.

[0003] In view of this, overcoming the defects of the prior art is an urgent problem to be solved in this technical field. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a miniature out-of-plane acceleration sensor for detecting micro-vibrations, so as to solve the problem of poor impact resistance of acceleration sensors in the prior art.

[0005] The present invention adopts the following technical solutions: In a first aspect, the present invention provides a miniature out-of-plane acceleration sensor for detecting micro-vibrations, comprising an optical fiber 1 and an elastic component 2 disposed oppositely at one end of the optical fiber 1; The elastic component 2 includes a frame 21 etched from a block material, a central mass block 22, four edge mass blocks 23, four first cantilever beams 24 and four second cantilever beams 25; The edge masses 23 are distributed around the central mass 22 and are 90° rotationally symmetrical. One end of the first long side 231 of each edge mass block 23 is connected to a vertex of the central mass block 22 through a first cantilever beam 24, and the other end of the first long side 231 of each edge mass block 23 is connected to the inner side of the frame 21 through a second cantilever beam 25; wherein, the first long side 231 is the long side of the edge mass block 23 close to the frame 21.

[0006] Preferably, the frame 21 is further provided with four connecting portions 211 extending from respective inner corners of the frame 21; wherein the connecting portion 211 extends toward the inner corners on the opposite side to approach the edge mass block 23 perpendicular to its extension direction, so that the ends of the connecting portions 211 are connected to the corresponding second cantilever beams 25; The other end of the first long side 231 of each edge mass block 23 is connected to the inner edge of the frame 21 through the second cantilever beam 25 , which is manifested as: the other end of the first long side 231 is connected to the end of the connecting portion 211 through the second cantilever beam 25 .

[0007] Preferably, the first cantilever beam 24 includes a first cantilever 241 and a second cantilever 242 that are perpendicular to each other; The first cantilever 241 is located on the extension line of one side of the central mass block 22 and is connected to the vertex of the side; The second cantilever 242 is located on the extension line of the first long side 231 of the edge mass 23 and is connected to the vertex of the first long side 231 .

[0008] Preferably, the second cantilever beam 25 includes a third cantilever 251 and a fourth cantilever 252 that are perpendicular to each other; The third cantilever 251 is located on the extension line of the first long side 231 of the edge mass 23 and is connected to the vertex of the first long side 231; The fourth cantilever 252 is parallel to the short side of the edge mass 23 and is connected to the inner side of the frame 21 .

[0009] Preferably, the first short side 232 of each edge mass block 23 is aligned with the first long side 231 of another edge mass block 23 on the side where the first short side 232 is located; wherein the first short side 232 is the short side of the edge mass block 23 close to the second cantilever beam 25 to which it is connected.

[0010] Preferably, the bulk material is beryllium copper alloy.

[0011] Preferably, it also includes a groove base 3; A through hole 31 is provided at the bottom of the groove base 3, and the frame 21 of the elastic component 2 is installed on the top of the groove base 3; The optical fiber 1 passes through the through hole 31 to be aligned with the center of the elastic component 2 .

[0012] In a second aspect, the present invention further provides an acceleration detection method, using any of the micro-vibration detection micro-plane acceleration sensors described in the first aspect to measure the acceleration in a direction perpendicular to the elastic component 2, the method comprising: Collect the interference light signal of the optical fiber 1 in the micro out-of-plane acceleration sensor, the spectral function of the interference light signal ; The spectral function of the interference light signal Perform Fourier transform and extract the peak of its spatial spectrum ,in is the spatial frequency point of the peak; According to the peak , calculate the phase angle ;in, , ; According to the phase angle Corresponding relationship with acceleration , calculate the acceleration; in, is the free spectral range of the interference light signal, is the resonant frequency of the sensor, a is the acceleration, λ is the central wavelength of the spectrum, represents the extraction of the real part, represents the extraction of the imaginary part, represents the complex modulus value, n is the refractive index of the medium in the FP cavity, and is the preset coefficient.

[0013] In a third aspect, the present invention further provides a miniature out-of-plane acceleration sensor for detecting micro-vibrations, comprising a first sensor, a second sensor, and a third sensor; the first sensor, the second sensor, and the third sensor are all miniature out-of-plane acceleration sensors for detecting micro-vibrations described in any one of the first aspects; The first elastic component 51, the second elastic component 52 and the third elastic component 53 are perpendicular to each other, and the cavity lengths of the first sensor, the second sensor and the third sensor are different; The first elastic component 51 is the elastic component of the first sensor, the second elastic component 52 is the elastic component of the second sensor, and the third elastic component 53 is the elastic component of the third sensor.

[0014] Preferably, the present invention provides an acceleration detection method, using the miniature out-of-plane acceleration sensor for detecting micro-vibrations described in the third aspect to measure accelerations in three perpendicular directions, the method comprising: Collecting the composite signal formed by superposition of three interference light signals in the micro out-of-plane acceleration sensor ; The composite signal Perform Fourier transform and extract the i-th peak of the spatial spectrum ; According to the i-th peak , calculate the phase angle of the i-th interference light signal in the composite signal ;in, , ; According to the phase angle of the i-th interference light signal The corresponding relationship between the acceleration in the i-th direction , calculate the acceleration in the i-th direction; in, is the free spectral range of the i-th interference light signal, is the resonant frequency of the sensor, is the acceleration in the i-th direction, λ is the central wavelength of the spectrum, represents the extraction of the real part, represents the extraction of the imaginary part, represents the complex modulus value, i is an integer greater than 0 and less than or equal to 3, n is the refractive index of the medium in the FP cavity, 、 、 and is the preset coefficient.

[0015] The present invention provides an edge mass 23, a first cantilever beam 24, and a second cantilever beam 25, so that the central mass 22 is connected to the frame 21 sequentially through the first cantilever beam 24, the first long side 231 of the edge mass 23, and the second cantilever beam 25, thereby forming a "U"-shaped connection structure. Compared with the single beam in the prior art, the "U"-shaped connection structure has a longer connection path, so when subjected to force, it can provide a larger displacement space, thereby improving its sensitivity. At the same time, the central mass 22 is connected to the frame 21 through four "U"-shaped connection structures, so that the four "U"-shaped connection structures form an equivalent spring structure capable of torsional deformation. Its sensitivity is not sensitive to the thickness of the cantilever beams, thereby improving its impact resistance. The edge mass 23 not only serves as a connection between the first cantilever beam 24 and the second cantilever beam 25, but also improves the stability of the "U"-shaped connection structure while increasing the overall mass of the mass within a limited space, thereby improving detection sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0017] Figure 1 1 is a schematic structural diagram of a miniature out-of-plane acceleration sensor for detecting micro-vibrations provided by an embodiment of the present invention; Figure 2 1 is a schematic structural diagram of an elastic component in a miniature out-of-plane acceleration sensor for detecting micro-vibrations provided by an embodiment of the present invention; Figure 3 1 is a schematic structural diagram of an elastic component in a miniature out-of-plane acceleration sensor for detecting micro-vibrations provided by an embodiment of the present invention; Figure 4 1 is a schematic structural diagram of a miniature out-of-plane acceleration sensor for detecting micro-vibrations provided by an embodiment of the present invention; Figure 5 This is a schematic structural diagram of a groove base in a miniature out-of-plane acceleration sensor for detecting micro-vibrations provided by an embodiment of the present invention; Figure 6 1 is a schematic structural diagram of an elastic component in a miniature out-of-plane acceleration sensor for detecting micro-vibrations provided by an embodiment of the present invention; Figure 7 1 is a schematic structural diagram of an elastic component in a miniature out-of-plane acceleration sensor for detecting micro-vibrations provided by an embodiment of the present invention; Figure 8 1 is a schematic structural diagram of an elastic component in a miniature out-of-plane acceleration sensor for detecting micro-vibrations provided by an embodiment of the present invention; Figure 9 1 is a schematic cross-sectional view of a miniature out-of-plane acceleration sensor for detecting micro-vibrations provided by an embodiment of the present invention; Figure 10 This is a schematic structural diagram of a groove base in a miniature out-of-plane acceleration sensor for detecting micro-vibrations provided by an embodiment of the present invention; Figure 11 1 is a schematic diagram of the architecture of an acceleration detection system provided by an embodiment of the present invention; Figure 12 1 is a flow chart of an acceleration detection method provided by an embodiment of the present invention; Figure 13 1 is a schematic structural diagram of a miniature out-of-plane acceleration sensor for detecting micro-vibrations provided by an embodiment of the present invention; Figure 14 1 is a schematic structural diagram of a mounting base in a miniature out-of-plane acceleration sensor for detecting micro-vibrations provided by an embodiment of the present invention; Figure 15 1 is a schematic structural diagram of a mounting base in a miniature out-of-plane acceleration sensor for detecting micro-vibrations provided by an embodiment of the present invention; Figure 16 1 is a schematic structural diagram of a miniature out-of-plane acceleration sensor for detecting micro-vibrations provided by an embodiment of the present invention; Figure 17 1 is a schematic diagram of the structure before assembly of a miniature out-of-plane acceleration sensor for detecting micro-vibrations provided by an embodiment of the present invention; Figure 18 1 is a schematic diagram of the structure before assembly of a miniature out-of-plane acceleration sensor for detecting micro-vibrations provided by an embodiment of the present invention; Figure 19 1 is a schematic diagram of the architecture of an acceleration detection system provided by an embodiment of the present invention; Figure 20 It is a schematic diagram of a composite signal collected by a miniature out-of-plane acceleration sensor for detecting micro-vibrations provided by an embodiment of the present invention.

[0018] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1. Optical fiber; 2. Elastic component; 21. Frame; 211. Connecting part; 22. Center mass block; 23. Edge mass block; 231. First long side; 232. First short side; 24. First cantilever beam; 241. First cantilever; 242. Second cantilever; 25. Second cantilever beam; 251. Third cantilever; 252. Fourth cantilever; 3. Grooved base; 31. Through hole; 32. Table; 33. Channel; 4. Ceramic ferrule; 51. First Elastic component; 52, second elastic component; 53, third elastic component; 61, first optical fiber; 62, second optical fiber; 63, third optical fiber; 7, mounting seat; 71, first groove; 711, first through hole; 72, second groove; 721, second through hole; 73, third groove; 731, third through hole; 74, first opening; 75, second opening; 76, third opening; 8, packaging shell; 81, first shell; 82, second shell. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0020] Unless the context requires otherwise, throughout the specification and claims, the term "including" is to be interpreted as meaning open inclusion, that is, "including, but not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiments", "example", "specific example" or "some examples" and the like are intended to indicate that the specific features, structures, materials or characteristics associated with the embodiment or example are included in at least one embodiment or example of the present disclosure. The schematic representation of the above terms does not necessarily refer to the same embodiment or example. In addition, the specific features, structures, materials or characteristics may be included in any one or more embodiments or examples in any appropriate manner, that is, although they may be carried in the embodiments or examples of the above terms due to reasons such as the order and position of appearance, it is not limited to that they can be carried in combination by one embodiment or example.

[0021] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present disclosure.

[0022] In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, unless otherwise specified, "multiple" means two or more. In addition, for example, the description may also use the method of adding "A" and "B" at the end to describe the same type of nouns as two independent individuals. In this case, the corresponding features defined as "A" and "B" are only used to distinguish the description purposes of the same type of individuals, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated.

[0023] When describing some embodiments, the expressions “coupled”, “coupled” and “connected” and their derivatives may be used. For example, when describing some embodiments, the term “connected” may be used to indicate that two or more components are in direct physical or electrical contact with each other. For another example, when describing some embodiments, the term “coupled” may be used to indicate that two or more components are in direct physical or electrical contact. However, the term “connected” or “coupled” may also mean that two or more components are not in direct contact with each other, but still cooperate or interact with each other, such as “optical coupling”, “wireless connection”, etc. The embodiments disclosed herein are not necessarily limited to the contents of the present invention.

[0024] In the description of the present invention, the expression "A and / or B" (where A and B are used to formally represent specific characteristic contents) is involved, and the corresponding expressions include the following three combinations: only A, only B, and a combination of A and B.

[0025] As used herein, "about," "substantially," or "approximately" includes the stated value and an average value that is within an acceptable range of deviation from the particular value as determined by one of ordinary skill in the art taking into account the measurements in question and errors associated with measurement of the particular quantity (i.e., limitations of the measurement system).

[0026] In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0027] Embodiment 1: Since the cantilever beam mass block structure in the prior art often adopts a four-beam inertial mass beam sensitive structure, that is, it includes four beams and a mass block, and the side of the mass block close to the frame is directly connected to the frame through a single beam. In this way, since the weight of the mass block and the length and thickness of the beam determine the sensitivity of the acceleration sensor, in order to ensure the sensitivity, the length of the single beam is relatively long and the thickness is relatively thin, and the mass block is large, so that its impact resistance is weak. In order to solve this problem, embodiment 1 of the present invention provides a miniature out-of-plane acceleration sensor for detecting micro-vibrations, such as Figure 1 、 Figure 2 and Figure 3 As shown, it includes an optical fiber 1 and an elastic component 2 arranged opposite to one end of the optical fiber 1; The elastic component 2 includes a frame 21 etched on a block material, a central mass block 22, four edge mass blocks 23, four first cantilever beams 24 for connecting the central mass block 22 and the edge mass blocks 23, and four second cantilever beams 25 for connecting the edge mass blocks 23 and the frame 21; the edge mass blocks 23 are distributed around the central mass block 22 and are rotationally symmetrical at 90° (the specific positions are rotationally symmetrical at 90° about the center of the central mass block 22); one end of the first long side 231 of each edge mass block 23 is connected to a vertex of the central mass block 22 through the first cantilever beam 24, and the other end of the first long side 231 of each edge mass block 23 is connected to the inner side of the frame 21 through the second cantilever beam 25; wherein, the first long side 231 is the long side of the edge mass block 23 close to the frame 21.

[0028] The side of the central mass block 22 facing the optical fiber 1 is a light reflecting surface, and the light reflecting surface is perpendicular to the optical fiber 1. The optical fiber 1 is aligned with the center of the elastic component 2 and there is a certain distance between the optical fiber 1 and the elastic component 2 to form a Fabry-Perot cavity. In actual use, the optical fiber 1 remains fixed, and the frame 21 of the elastic component 2 is rigidly fixed to the object to be measured in a certain way. A detection light signal is input into the optical fiber 1 from the other end, and the detection light signal is injected into the Fabry-Perot cavity (Fabry-Pérot, abbreviated as: FP) through the optical fiber 1. ) cavity, an FP interference light signal is formed between the end face of the optical fiber 1 and the light reflecting surface; when the object to be measured generates micro-vibration, it drives the elastic component 2 to vibrate, causing the first cantilever beam 24, the second cantilever beam 25, the edge mass block 23 and the central mass block 22 to move. At this time, the central mass block 22 will lag in motion due to inertia, thereby causing the cavity length of the Fabry-Perot cavity formed by the end face of the optical fiber 1 and the central mass block 22 to change, resulting in a change in the FP interference light signal, so that the acceleration in the direction perpendicular to the light reflecting surface of the elastic component 2 can be measured through the change in the interference light signal.

[0029] The bulk material is beryllium copper alloy or silicon. Since beryllium copper alloy has higher toughness than silicon and other materials, in a preferred embodiment, the bulk material is beryllium copper alloy.

[0030] For the central mass block 22 , except for the connection position between the central mass block 22 and the first cantilever beam 24 , other parts around the central mass block 22 are etched away to form a gap.

[0031] Similarly, for the edge mass 23, except for the connection between the first cantilever beam 24 and the edge mass 23, and the connection between the edge mass 23 and the second cantilever beam 25, the rest of the periphery of the edge mass 23 is etched away, forming a gap. For the first cantilever beam 24, except for the connection between the first cantilever beam 24 and the edge mass 23, and the connection between the central mass 22 and the first cantilever beam 24, the rest of the periphery of the first cantilever beam 24 is etched away, forming a gap. For the second cantilever beam 25, except for the connection between the second cantilever beam 25 and the edge mass 23, and the connection between the second cantilever beam 25 and the frame 21, the rest of the periphery of the second cantilever beam 25 is etched away, forming a gap.

[0032] It should be noted that in order to distinguish between the solid part (ie, the unetched part) and the etched part of the elastic component 2, Figure 2 、 Figure 3 The subsequent drawings involving the specific structure of the elastic component 2 are all presented using grayscale images, wherein the grayscale part is the solid part and the white part is the etched part.

[0033] In this embodiment, an edge mass block 23, a first cantilever beam 24 and a second cantilever beam 25 are provided so that the central mass block 22 is connected to the frame 21 in sequence through the first cantilever beam 24, the first long side 231 of the edge mass block 23 and the second cantilever beam 25, thereby forming a "U"-shaped connection structure. Compared with the single beam in the prior art, the "U"-shaped connection structure has a longer connection path length, so when subjected to force, it can provide a larger displacement space and improve its sensitivity.

[0034] At the same time, the central mass block 22 is connected to the frame 21 through four "U"-shaped connecting structures, so that the four "U"-shaped connecting structures form an equivalent spring structure that can torsionally deform. Its sensitivity is not sensitive to the thickness of the cantilever beam, further improving its impact resistance. The setting of the edge mass block 23, on the one hand, plays a connecting role between the first cantilever beam 24 and the second cantilever beam 25. While improving the stability of the "U"-shaped connecting structure, it also increases the overall mass of the mass block within a limited space, thereby improving the detection sensitivity.

[0035] In fact, it is deduced that the displacement of the central mass block 22 is ; Wherein, δ is the displacement of the central mass block 22; F is the magnitude of the concentrated force; L1 is the length of the first cantilever beam 24; L2 is the length of the edge mass block 23; L3 is the length of the second cantilever beam 25; E is the Young's modulus of the block material; I1 is the section moment of inertia of the first cantilever beam 24; I2 is the section moment of inertia of the edge mass block 23; I3 is the section moment of inertia of the second cantilever beam 25; G is the shear modulus of the block material; J1 is the torsional constant of the first cantilever beam 24.

[0036] In a preferred embodiment, the width of the first cantilever beam is less than or equal to its own thickness, the width of the second cantilever beam is less than or equal to its own thickness, the width of the edge mass block is greater than twice its own thickness, and the length of the edge mass block (i.e., the length of the first side length) is greater than the side length of the center mass block.

[0037] In some optional embodiments, when there is no installation space inside the object to be measured, the elastic component 2 can be directly built into the cavity of the corresponding object to be measured, so that the frame 21 of the elastic component 2 remains fixed to the object to be measured, and the center mass block 22, the edge mass block 23, the first cantilever beam 24 and the second cantilever beam 25 can move in the cavity.

[0038] When there is no installation space inside the object to be measured, there is another optional implementation method: the acceleration sensor described in this embodiment further includes a groove base 3; Figure 4 and Figure 5 As shown, the bottom of the groove base 3 is provided with a through hole 31, and the frame 21 of the elastic component 2 is mounted on the top of the groove base 3. The optical fiber 1 passes through the through hole 31 to align with the center of the elastic component 2. The side wall of the groove base 3 can be adhered and fixed to the object to be measured, thereby achieving the installation of the acceleration sensor.

[0039] In actual application scenarios, such as Figure 6 As shown, the frame 21 is further provided with four connecting portions 211 extending from respective inner corners of the frame 21; wherein the connecting portion 211 extends toward the inner corner on the opposite side to approach the edge mass block 23 perpendicular to its extension direction (the edge mass block 23 is located in the extension direction of the connecting portion 211), so that the distal end of the connecting portion 211 is connected to the corresponding second cantilever beam 25 (specifically: the second cantilever beam 25 connected to the extended edge mass block 23); The other end of the first long side 231 of each edge mass block 23 is connected to the inner edge of the frame 21 through the second cantilever beam 25 , which is manifested as: the other end of the first long side 231 is connected to the end of the connecting portion 211 through the second cantilever beam 25 .

[0040] by Figure 6Taking the bottom connecting portion 211 as an example, the connecting portion 211 is formed by the inner top corner position of the lower right corner of the frame 21 (i.e. Figure 6 The edge mass block 23 perpendicular to the direction is the edge mass block 23 at the lower left corner. The end of the connecting portion 211 (i.e. Figure 6 The position b marked in the figure is connected to the edge mass block 23 in the lower left corner through the second cantilever beam 25.

[0041] The connecting portion 211 is intended to reduce the loss of structural stability caused by the excessive length of the second cantilever 242. That is, by providing the connecting portion 211, the length of the second cantilever 242 can be reduced. In actual use, the length of the second cantilever 242 and the length of the connecting portion 211 are determined by technicians in this field based on demand analysis.

[0042] In some specific application scenarios, such as Figure 7 As shown, the first cantilever beam 24 includes a first cantilever 241 and a second cantilever 242, which are perpendicular to each other. The first cantilever 241 is located on the extension line of one side of the central mass 22 and is connected to the vertex of the side. The second cantilever 242 is located on the extension line of the first long side 231 of the edge mass 23 and is connected to the vertex of the first long side 231. The second cantilever beam 25 includes a third cantilever 251 and a fourth cantilever 252, which are perpendicular to each other. The third cantilever 251 is located on the extension line of the first long side 231 of the edge mass 23 and is connected to the vertex of the first long side 231. The fourth cantilever 252 is parallel to the short side of the edge mass 23 and is connected to the inner side of the frame 21.

[0043] And, as Figure 8 As shown, the first short side 232 of each edge mass 23 is aligned with the first long side 231 of another edge mass 23 on the side of the first short side 232 to avoid large etched areas and ensure the impact resistance of the structure.

[0044] In actual use, such as Figure 9 and Figure 10 As shown, the acceleration sensor further includes a ceramic ferrule 4, which is inserted into the through hole 31, and the outer periphery of the ceramic ferrule 4 is adhered and fixed to the inner wall of the through hole 31 using adhesive (such as AB glue). The optical fiber 1 passes through the through hole 31 as follows: the optical fiber 1 passes through the ceramic ferrule 4 and is aligned with the center of the elastic component 2.

[0045] like Figure 10As shown, the side wall of the groove base 3 is designed to be stepped, and the frame 21 of the elastic component 2 is installed on the top of the groove base 3, which is manifested as: the frame 21 of the elastic component 2 is pasted on the table 32 of the step.

[0046] A channel 33 is also designed at the top corner of the table 32 to which the frame 21 is pasted. The channel 33 is connected to the table 32 from the top surface of the groove base 3. In an optional embodiment, the channel 33 is a cylindrical channel 33, and the height of the cylindrical channel 33 is perpendicular to the bottom surface of the groove base 3.

[0047] In this embodiment, the displacement of the central mass is primarily a result of the combined bending deformation of each segment and the torsional deformation unique to the U-shaped connection structure. Compared to a simple straight beam structure, the cantilever beam is extended, increasing the displacement sensitivity caused by bending deformation. Furthermore, the introduction of torsional deformation further increases the displacement of the central mass.

[0048] In a preferred embodiment, the width of the first cantilever beam of the "U"-shaped connecting structure is less than or equal to its own thickness, so as to reduce the torsion constant and improve sensitivity; the width of the edge mass block in the "U"-shaped structure is greater than twice its own thickness, which improves the lateral stiffness of the structure and reduces the crosstalk of the structure, and the length of its edge mass block is greater than the side length of the central mass block, which has the benefit of converting the torsion angle of the "U"-shaped first cantilever beam into the displacement of the central mass block, thereby improving sensitivity; the width of the second cantilever beam in the "U" shape is less than or equal to its own thickness, which has the benefit of compensating for the torsion angle of the "U"-shaped first cantilever beam, so that the central mass block maintains linear motion.

[0049] The displacement of the central mass is primarily due to the torsional deformation unique to the U-shaped connection structure, which is insensitive to the thickness of the cantilever beam. Compared to existing methods that require the cantilever beam to be much thinner than the mass, which improves sensitivity by reducing the cantilever beam thickness and increasing the mass thickness, the U-shaped cantilever beam and mass thickness are consistent, overcoming this manufacturing challenge.

[0050] In a specific application scenario, the acceleration sensor described in this embodiment, together with the circulator, the wide-spectrum light source, the spectrum real-time acquisition module and the signal demodulation module, constitutes an acceleration detection system; Figure 11 As shown, the broadband light source is used to output a probe light signal. The circulator inputs the probe light signal into optical fiber 1 until it reaches the light-reflecting surface of elastic component 2, generating an interference light signal. This interference light signal returns along optical fiber 1. The circulator transmits this interference light signal to the real-time spectrum acquisition module. The real-time spectrum acquisition module acquires the spectrum of the interference light signal. The signal demodulation module processes the spectrum of the interference light signal to obtain acceleration.

[0051] Based on the above acceleration sensor and acceleration detection system, this embodiment also provides an acceleration detection method, which uses the above-mentioned micro-out-of-plane acceleration sensor for detecting micro-vibration to measure the acceleration in the direction perpendicular to the elastic component 2, such as Figure 12 As shown, the method includes: In step 201, the interference light signal of the optical fiber 1 in the acceleration sensor is collected, and the spectrum function of the interference light signal is .

[0052] In step 202, the spectral function of the interference light signal is Perform Fourier transform and extract the peak of its spatial spectrum ,in In actual use, step 202 can be understood as: performing Fourier transform on the spectrum function of the signal at each moment to obtain the spatial spectrum, and extracting the peak value from the spatial spectrum. .

[0053] In step 203, according to the peak , calculate the phase angle ;in, , .

[0054] In step 204, according to the phase angle Corresponding relationship with acceleration , calculate the acceleration.

[0055] in, is the free spectral range of the interference light signal, , n is the refractive index of the medium in the FP cavity (usually air), L is the cavity length of the FP cavity, is the resonant frequency of the sensor, a is the acceleration, λ is the central wavelength of the spectrum, represents the extraction of the real part, represents the extraction of the imaginary part, Represents the complex modulus value, and is the preset coefficient.

[0056] Example 2: like Figure 4 As shown, the embodiment of the present invention provides a miniature out-of-plane acceleration sensor for detecting micro-vibration, comprising an elastic component 2, a groove base 3, a ceramic ferrule 4 and an optical fiber 1. Figure 2As shown, the elastic assembly 2 includes a central mass 22, four edge masses 23, and eight cantilever beams (including four first cantilever beams 24 and four second cantilever beams 25). The cantilever beams and edge masses 23 are evenly and symmetrically distributed around the central mass 22. A "U"-shaped connection structure is formed by first cantilever beam 24, edge mass 23, and second cantilever beam 25, with one end connected to the frame 21 and the other end connected to the central mass 22.

[0057] The eight elastic cantilever beams act as equivalent springs mainly based on torsional deformation. The "U"-shaped connection structure is different from the traditional straight beam based on bending deformation and tensile deformation. It has a more compact structure and can achieve higher acceleration sensitivity at the same size.

[0058] The edge mass block 23 converts the torsion angle of the elastic cantilever beam into the displacement outside the plane of the central mass block 22. The purpose of adding the edge mass block 23 is to increase the mass of the mass block within a limited space, thereby improving the detection sensitivity.

[0059] In this embodiment of the present invention, the elastic cantilever beam, central mass 22, and edge mass 23 are made of beryllium copper. This material's high toughness makes the sensing structure highly impact-resistant, making it suitable for use in harsh environments. Furthermore, beryllium copper, the second reflective surface in the FP cavity, has a high reflectivity, enabling it to reduce energy loss from optical signal reflections without a reflective coating, thereby improving the interference contrast of the detection light.

[0060] Specifically, the elastic component 2 adopts a metal wet etching process. After applying photosensitive resin, ultraviolet light exposure, development and other steps, the sensing structure outline designed on the film mask is transferred to the photoresist. The solution is then configured to completely penetrate the metal substrate through wet etching, releasing the central mass block 22, the edge mass block 23 and the elastic cantilever beam, and finally obtaining the sensing structure.

[0061] In the embodiment of the present invention, the elastic cantilever beam is integrally formed with the central mass block 22 and the edge mass block 23, thereby avoiding adhesive bonding, welding, screw fastening and other combined processes, simplifying the assembly steps, avoiding problems such as aging and rusting of solder joints and fragile adhesive structures, and achieving stable working performance. In this embodiment of the present invention, a through hole 31 is formed at the center of the bottom of the groove base 3. The ceramic ferrule 4 passes through this central through hole 31 and is bonded to the groove base 3 using AB glue. The optical fiber 1 forms an FP interference microcavity with the bottom surface of the central mass 22 through the ceramic ferrule 4.

[0062] In the example of the present invention, the groove base 3 of the acceleration sensor is fully bonded and fixed to the object to be measured by hot melt adhesive, so that the groove base 3 moves synchronously with the object to be measured. The inertial hysteresis motion of the central mass block 22 in the elastic component 2 generates a relative displacement with the groove base 3, which modulates the detection light signal in the FP interference microcavity, thereby realizing acceleration sensing.

[0063] like Figure 11 As shown, an embodiment of the present invention provides an optical sensing system for detecting micro-vibrations, including a broadband light source, a circulator, an acceleration sensor, a real-time spectrum acquisition module and a signal demodulation module, wherein the acceleration sensor is the miniature out-of-plane acceleration optical sensor in Example 1.

[0064] The broadband light source is used to output the original detection optical signal. The wavelength range used in the present embodiment is the communication band, 1526-1563 nm. In other embodiments, the broadband light source can be kept flat within a certain wavelength range. The circulator is used to ensure unidirectional transmission of the optical signal in the optical path, from the broadband light source to the acceleration sensor and to the real-time spectrum acquisition module. The acceleration sensor is used to detect micro-vibrations of an object rigidly fixed to it. It uses the relative displacement between the central mass block 22 and the groove base 3 generated by the inertial hysteresis motion to modulate the original detection wide-spectrum optical signal to form FP interference light with phase change.

[0065] Specifically, the end face of the optical fiber 1 and the bottom surface of the central mass block 22 form a Fabry-Perot cavity. After the original detection light signal is injected into the FP interference microcavity through the optical fiber 1, the reflected light at the two end faces forms an FP interference light signal; when the platform rigidly fixed to the acceleration sensor generates micro-vibration, it will drive the groove base 3 of the acceleration sensor to vibrate, and then cause the cantilever beam mass block structure to move. At this time, the central mass block 22 in the elastic component 2 will lag in motion due to inertia. The relative displacement between the central mass block 22 and the groove base 3 is the relative change in the cavity length of the FP microcavity 35, which in turn causes the spectral phase of the FP interference light signal of the reflected light at both ends of the cavity length to change.

[0066] The spectrum real-time acquisition module is used to collect in real time the phase change of the reflection interference spectrum corresponding to the change of the cavity length; in the embodiment of the present invention, the spectrum real-time acquisition module is a high-speed spectrum detector.

[0067] The signal demodulation module is used to perform FFT operation on the interference spectrum and calculate the real and imaginary parts of the spatial spectrum at the spatial frequency to obtain its Fourier phase change, which corresponds to the micro-vibration to be measured, and the micro-vibration information can be obtained.

[0068] The optical sensing system of the present invention converts the micro-vibration signal to be measured into the phase change of the FP interference spectrum and demodulates the phase information instead of the light intensity signal to effectively reduce the interference of light source noise and environmental noise, thereby ensuring the purity and accuracy of the detection signal.

[0069] The optical sensing system of the present invention has a fully passive structure and can operate under strong electromagnetic interference conditions. It has excellent performance and a small size. At the same time, the system can be integrated into various devices and environments, greatly improving its application flexibility and adaptability.

[0070] The optical sensing system for detecting micro-vibrations of the present invention only includes a wide-spectrum light source module, a circulator, a miniature out-of-plane acceleration sensor, a real-time spectrum acquisition module, and a signal demodulation module. It involves fewer devices and a simple detection device, and can accurately measure micro-vibrations.

[0071] In the embodiment of the present invention, a small-sized micro out-of-plane acceleration sensing structure is prepared by using a metal etching process.

[0072] An embodiment of the present invention further provides an acceleration signal detection method, which uses the above-mentioned optical sensing system to perform acceleration detection.

[0073] Specifically, the acceleration signal detection method includes the following steps: Step S1: The original detection light signal generated by the broadband light source is first passed through a circulator and into the acceleration sensor. Inside the sensor, the light signal is injected into the sensor's FP interference microcavity via optical fiber 1. The reflected light at the end face of optical fiber 1 and the bottom surface of the central mass 22 forms an FP interference light signal. When the platform rigidly fixed to the acceleration sensor generates microvibrations, this drives the sensor's groove base 3 to vibrate, further causing the cantilever beam mass structure to move. At this time, the central mass 22 in the sensing structure lags due to inertia, causing the length of the Fabry-Perot cavity formed by the end face of optical fiber 1 and the bottom surface of the central mass 22 to change, resulting in a phase shift in the interference spectrum formed by the light reflected from the two end faces.

[0074] Step S2: collecting spectrum information of the interference light signal corresponding to the change in the detection cavity length in real time.

[0075] Step S3: Since the low-fineness FP interference can be approximated as double-beam interference, the spectrum of the interference light signal is approximately a sine function, which is expressed as:

[0076] Where FSR is the free spectral range of the spectrum. The spectral function is Fourier transformed and its spatial spectrum is There will be a corresponding characteristic frequency peak. By extracting the real and imaginary parts at the peak and performing an inverse tangent operation, the phase information of the interference spectrum can be obtained:

[0077]

[0078]

[0079] The phase change corresponds to the acceleration to be measured:

[0080] in is the resonant frequency of the sensor, a is the acceleration to be measured, and λ is the central wavelength of the spectrum. Thus, the information of the acceleration to be measured is obtained.

[0081] Example 3: Based on the first and second embodiments, this embodiment further provides a sensor capable of measuring three-dimensional acceleration, such as Figure 13 As shown, the present embodiment provides a miniature out-of-plane acceleration sensor for detecting micro-vibrations, comprising a first sensor, a second sensor, and a third sensor; the first sensor, the second sensor, and the third sensor are all the miniature out-of-plane acceleration sensors for detecting micro-vibrations described in Example 1; the first elastic component 51, the second elastic component 52, and the third elastic component 53 are mutually perpendicular, and the cavity lengths of the first sensor, the second sensor, and the third sensor are different; wherein the first elastic component 51 is the elastic component of the first sensor, the second elastic component 52 is the elastic component of the second sensor, and the third elastic component 53 is the elastic component of the third sensor. The term "mutually perpendicular" refers to the light-reflecting surfaces of the first elastic component 51, the second elastic component 52, and the third elastic component 53 being perpendicular to each other.

[0082] In an actual application scenario, the cavity length of the first sensor may be 400 um, the cavity length of the second sensor may be 240 um, and the cavity length of the second sensor may be 150 um.

[0083] This embodiment is capable of measuring acceleration in three orthogonal directions by providing three sensors with mutually perpendicular light reflecting surfaces and by providing the three sensors with different cavity lengths. The different cavity lengths of the sensors ensure that when the interfering light signals of the sensors are combined for transmission and reception, information for calculating acceleration in each direction can be separated from the combined signal.

[0084] In a preferred embodiment, Figure 13 、 Figure 14 and Figure 15As shown, the acceleration sensor described in this embodiment also includes a mounting base 7; the mounting base 7 is a hollow cubic structure, and the first surface of the mounting base 7 is designed with a first groove 71 with a notch facing outward, and the bottom of the first groove 71 is provided with a first through hole 711; the second surface of the mounting base 7 is designed with a second groove 72 with a notch facing outward, and the bottom of the second groove 72 is provided with a second through hole 721; the third surface of the mounting base 7 is designed with a third groove 73 with a notch facing outward, and the bottom of the third groove 73 is provided with a third through hole 731.

[0085] like Figure 16 As shown, the mounting seat 7 is designed with a first opening 74 on the fourth surface opposite to the first surface, the mounting seat 7 is designed with a second opening 75 on the fifth surface opposite to the second surface, and the mounting seat 7 is designed with a third opening 76 on the sixth surface opposite to the third surface.

[0086] The frame 21 of the first elastic component 51 is installed on the top of the first groove 71, and the first optical fiber 61 passes through the first opening 74 and the first through hole 711 and is aligned with the center of the first elastic component 51; the frame 21 of the second elastic component 52 is installed on the top of the second groove 72, and the second optical fiber 62 passes through the second opening 75 and the second through hole 721 and is aligned with the center of the second elastic component 52; the frame 21 of the third elastic component 53 is installed on the top of the third groove 73, and the third optical fiber 63 passes through the third opening 76 and the third through hole 731 and is aligned with the center of the third elastic component 53.

[0087] The first optical fiber 61 is an optical fiber of a first sensor, the second optical fiber 62 is an optical fiber of a second sensor, and the third optical fiber 63 is an optical fiber of a third sensor.

[0088] In an optional embodiment, the first opening 74, the second opening 75 and the third opening 76 can be through holes punched directly on the corresponding surfaces. However, in order to facilitate the installation of the first optical fiber 61, the second optical fiber 62 and the third optical fiber 63, as shown in FIG. Figure 17 As shown, one or more of the first opening 74, the second opening 75 and the third opening 76 can be directly hollowed out from the corresponding surface and matched with a cover body that matches the hollowed position. The cover body can be embedded in the hollowed position and fixed by adhering the outer wall of the cover body to the inner wall of the hollowed position. In addition, a through hole is provided on the cover body, and the corresponding optical fiber passes through the through hole position to reach the inside of the mounting seat 7, and passes through the through hole on the opposite side groove (that is, the first through hole 711, the second through hole 721 or the third through hole 731) to align with the light reflecting surface of the corresponding elastic component.

[0089] The first, second, and third grooves 71, 72, and 73 are implemented based on the same concept as the groove base 3 in Example 1. For example, the sidewalls of the first groove 71 are designed to be stepped, and the frame of the corresponding elastic component is attached to the stepped surface. A channel is also designed at the top corner of the surface to which the frame is attached. The channel connects the top surface of the first groove to the surface. In an optional embodiment, the channel is a cylindrical channel, the height of which is perpendicular to the bottom surface of the first groove.

[0090] In actual use, the first optical fiber 61 passes through the first through-hole 711, the second optical fiber 62 passes through the second through-hole 721, and the third optical fiber 63 passes through the third through-hole 731 by bonding a ceramic ferrule 4 to the inner wall of the corresponding through-hole, and then the optical fiber 1 passes through the ceramic ferrule. If the first ceramic ferrule is inserted into the first through-hole 711 and the outer periphery of the first ceramic ferrule is bonded to the inner wall of the first through-hole 711 using adhesive (such as AB adhesive), the first optical fiber 61 passes through the first ceramic ferrule and is aligned with the center of the first elastic component 51.

[0091] In a specific application scenario, such as Figure 14 As shown, the centers of the first groove 71, the second groove 72 and the third groove 73 are relatively offset by a preset distance, as shown in FIG. Figure 17 As shown, the first optical fiber 61, the second optical fiber 62 and the third optical fiber 63 are staggered with each other inside the mounting base 7. The preset distance is obtained by those skilled in the art based on empirical analysis.

[0092] In actual use, this embodiment also has an application scenario, that is, detecting the three-dimensional acceleration of the underwater sound field. In this case, the acceleration sensor described in this embodiment further includes a packaging shell 8, such as Figure 18 As shown, the packaging shell 8 is spherical and is used to withstand hydrostatic pressure and protect the internal structure from being damaged. The packaging shell 8 includes a first shell 81 and a second shell 82. The first shell 81 and the second shell 82 can be installed and fixed in conjunction with each other, so as to encapsulate other components of the acceleration sensor inside the packaging shell.

[0093] The encapsulation shell 8 has eight symmetrical cylinders evenly distributed on the first shell 81 and the second shell 82 (wherein, four cylinders are located on the outer surface of the first shell 81 and the other four cylinders are located on the outer surface of the second shell 82), which are used for underwater external suspension, and a threaded cylinder with an opening on the top (i.e., leading to the interior of the encapsulation shell) is provided in the center of the first shell 81 for leading out the optical fiber.

[0094] The inner wall of the first shell 81 is also provided with four columns, and the inner wall of the second shell 82 is also provided with four columns. These columns are used to connect the columns of the first shell 81 with the columns of the second shell 82, thereby enhancing the stability of the internal structure of the package shell. The edges of the first shell 81 and the edges of the second shell 82 are also provided with screw holes, which are used for corresponding screws to pass through the screw holes of the first shell 81 and the screw holes of the second shell 82, and then install nuts at the other ends to achieve the installation and fixation of the first shell 81 and the second shell 82.

[0095] In an optional embodiment, the packaging shell 8 is made of aluminum alloy 7075, with an outer diameter of 40 mm and an inner diameter of 36 mm, and can withstand a hydrostatic pressure of 20 MPa. The mounting base 7 allows the three miniature out-of-plane acceleration sensors to be compactly placed in a limited space, and the symmetrical structure is conducive to stable operation underwater. When the first shell 81 and the second shell 82 are assembled, an O-ring is used for sealing. The sealing material is fluororubber, that is, a sealing ring is added at the position where the first shell 81 and the second shell 82 are fixed relative to each other. Its overall density is similar to that of water, and it can be regarded as a point mass to collect acceleration information in the underwater sound field.

[0096] Based on the above acceleration sensor, this embodiment further provides an acceleration detection system, which includes a circulator, a coupler, a broadband light source, a spectrum real-time acquisition module and a signal demodulation module; Figure 19 As shown, the broadband light source is used to output a detection light signal; the circulator inputs the detection light signal into a coupler, which is used to equally split the detection light signal into a first detection light signal, a second detection light signal, and a third detection light signal. Each detection light signal is transmitted through its corresponding optical fiber to the light reflecting surface of the corresponding elastic component, generating interference light signals (i.e., the first interference light signal, the second interference light signal, and the third interference light signal). Each interference light signal returns along its corresponding optical fiber and is combined into an interference light signal by the coupler. The circulator transmits the interference light signal to the real-time spectrum acquisition module. The real-time spectrum acquisition module acquires the spectrum of the interference light signal. The signal demodulation module processes the spectrum of the interference light signal to obtain three-dimensional acceleration.

[0097] In the application scenario of the acceleration detection system, this embodiment further provides an acceleration detection method, which uses the above-mentioned miniature out-of-plane acceleration sensor for detecting micro-vibrations to measure accelerations in three perpendicular directions, and the method includes: Collecting the composite signal formed by superposition of three interference light signals in the micro out-of-plane acceleration sensor ; For the composite signal Perform Fourier transform and extract the i-th peak of the spatial spectrum , that is, the spectrum function of the signal at each moment is Fourier transformed to obtain the spatial spectrum, and each peak is extracted from the spatial spectrum; according to the i-th peak , calculate the phase angle of the i-th interference light signal in the composite signal ;in, , ; According to the phase angle of the i-th interference light signal The corresponding relationship between the acceleration in the i-th direction , calculate the acceleration in the i-th direction; where, is the free spectral range of the i-th interference light signal, is the resonant frequency of the sensor, is the acceleration in the i-th direction, λ is the central wavelength of the spectrum, represents the extraction of the real part, represents the extraction of the imaginary part, Represents the complex modulus value, i is an integer, i is greater than 0 and less than or equal to 3, 、 、 and is the preset coefficient.

[0098] In a specific application scenario, when the cavity length of the first sensor is 400 um, When the cavity length of the second sensor is 240 um, is 5 nm; when the cavity length of the second sensor is 150 um, is 8 nm.

[0099] Embodiment 4: In conjunction with the aforementioned figures, the present invention provides a three-dimensional acceleration information detection system for underwater sound fields. The system primarily comprises a housing 8, a mounting base 7, an acceleration sensor, a circulator, a coupler, a broadband light source, a real-time spectrum acquisition module, and a signal demodulation module. The acceleration sensor is the miniature out-of-plane optical acceleration sensor described in Example 1.

[0100] The encapsulating housing 8 is designed to withstand hydrostatic pressure, protecting the internal structure from damage. It also features evenly distributed small cylinders that connect to springs or rubber bands to form an underwater suspension system, maintaining stability during underwater use. Mounting base 7 integrates three accelerometers, enabling them to detect acceleration information in all three directions.

[0101] Specifically, the encapsulating shell 8 is made of 7075 aluminum alloy, with an outer diameter of 40 mm and an inner diameter of 36 mm, capable of withstanding a hydrostatic pressure of 20 MPa. The mounting base 7 allows for compact placement of the three acceleration sensors within a limited space, and its symmetrical structure facilitates greater stability during underwater use. The upper and lower hemispherical shells are assembled using O-rings made of fluororubber for sealing. With an overall density similar to that of water, the sensor can be treated as a point mass to collect acceleration information in the underwater sound field.

[0102] Specifically, three acceleration sensors are placed on three surfaces of the mounting base 7, forming Figure 13 The structure is in the middle, and the centers of the elastic components are staggered to prevent the optical fibers from interfering with each other. A threaded cylindrical hole is located above the spherical package housing 8. The optical fibers of the three accelerometers are led out through this hole and connected to a 1×3 coupler. This combines the three interference beams, which then enter the circulator and the real-time spectrum acquisition module, capturing the superimposed spectrum of the three beams.

[0103] The embodiment of the present invention uses three acceleration sensors to simultaneously detect accelerations in three directions of a three-dimensional space and simultaneously demodulates the information.

[0104] Specifically, the FP cavity lengths of the three sensors are adjusted to be different so that the natural spatial frequencies corresponding to their interference are separated in the aliased spectrum. The cavity length of the sensor in the X-axis direction is set to 400 um. The cavity length of the sensor in the Y-axis direction is set to 240 um. The cavity length of the sensor in the Z-axis direction is set to 150 um. is 8 nm, and three different interference spectra are superimposed to form a composite spectrum, such as Figure 20 As shown in (a) in the figure, its expression is:

[0105] in is the free spectral range of the i-th interference light signal. The above spectral function is Fourier transformed, and its spatial spectrum is There will be corresponding characteristic frequency peaks, such as Figure 20 As shown in (b), the positions are , , Therefore, the different cavity lengths can be used to separate the phase information collected by the three acceleration sensors. , , .

[0106] Furthermore, by extracting the real and imaginary parts of the three characteristic frequency peaks and performing inverse tangent operations, the corresponding phase information can be obtained:

[0107]

[0108]

[0109] The change in their respective phase information corresponds to the acceleration in their respective detection directions:

[0110] in is the resonant frequency of the sensor, is the acceleration to be measured in the three directions, λ is the center wavelength of the spectrum, and n is the refractive index of the medium in the FP cavity. Therefore, by setting the FP cavity lengths of the acceleration sensors in the three directions to different values, simultaneous detection and demodulation can be achieved to obtain the measured acceleration information.

[0111] In general, the above technical solution proposed in this embodiment has the following beneficial effects compared with the prior art: (1) The micro out-of-plane acceleration sensor is composed of an elastic component 2, a frame 21, a ceramic ferrule 4 and an optical fiber 1. The elastic component 2 includes a central mass block 22, four edge mass blocks 23 and eight cantilever beams. The cantilever beams and edge mass blocks 23 are evenly distributed around the central mass block 22 in a symmetrical manner. A "U"-shaped connection structure is formed according to the first cantilever beam 24-edge mass block 23-second cantilever beam 25, one end of which is connected to the frame 21 and the other end is connected to the central mass block 22. The displacement of the central mass block 22 is mostly contributed by the torsional deformation unique to the "U"-shaped connection structure. It is not sensitive to the thickness of the cantilever beam. Unlike traditional straight beams based on bending deformation and tensile deformation, it can obtain higher acceleration sensitivity under the same size. In addition, adding the edge mass block 23 between the two cantilever beams can effectively utilize the limited space to increase the mass block mass, thereby improving the acceleration sensitivity.

[0112] (2) The acceleration sensor is made of beryllium copper, a metal material that has a high toughness compared to materials such as silicon and silicon nitride used in other etching processes. This makes the sensor highly impact-resistant and more suitable for practical environments. Furthermore, the metal material, serving as the second reflective surface in the FP cavity, has a high reflectivity, which reduces energy loss from optical signal reflection without the need for a reflective film, thereby improving the interference contrast of the detection light.

[0113] (3) The miniature out-of-plane acceleration sensor has both small size and high sensitivity. The metal etching process is used to achieve the integrated processing of the cantilever beam mass block, which simplifies the sensor splicing and packaging process, improves the sensor's working stability, and reduces crosstalk between axes. Taking advantage of the mature metal etching processing technology, short cycle time, and low testing cost, the sensor is low-cost, has good consistency, and can be mass-produced. The process cost is much lower than that of MEMS silicon micromachining process.

[0114] (4) The optical sensing system for detecting micro-vibrations provided by the present invention only includes a broadband light source, an optical circulator, a miniature out-of-plane acceleration sensor, a real-time spectrum acquisition module, and a signal demodulation module. The number of devices involved is relatively small, and the detection device is simple.

[0115] (5) The method for detecting three-dimensional acceleration information of an underwater sound field provided by the present invention utilizes a spherical housing (i.e., housing 8) to achieve underwater high-pressure operation. A mounting base 7 is used to compactly arrange three miniature out-of-plane acceleration sensors within a limited space, forming a symmetrical structure. The three miniature out-of-plane acceleration sensors are used to simultaneously detect the acceleration of the sound field in three directions of three-dimensional space, and simultaneously demodulate the acceleration information in the three directions.

[0116] Those skilled in the art will understand that all or part of the steps in the various methods of the embodiments can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium, which may include: read-only memory (ROM), random access memory (RAM), a disk or an optical disk, etc.

[0117] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A miniature out-of-plane acceleration sensor for detecting micro-vibrations, characterized in that: It comprises an optical fiber (1) and an elastic component (2) arranged relative to one end of the optical fiber (1); The elastic component (2) comprises a frame (21) etched on a block material, a central mass block (22), four edge mass blocks (23), four first cantilever beams (24) and four second cantilever beams (25); The edge mass blocks (23) are distributed around the central mass block (22) and are 90° rotationally symmetrical; One end of a first long side (231) of each edge mass block (23) is connected to a vertex of the central mass block (22) via a first cantilever beam (24), and the other end of the first long side (231) of each edge mass block (23) is connected to an inner side of the frame (21) via a second cantilever beam (25); wherein the first long side (231) is the long side of the edge mass block (23) close to the frame (21).

2. The micro out-of-plane acceleration sensor for detecting micro-vibrations according to claim 1, characterized in that: The frame (21) is further provided with four connecting portions (211) extending from respective inner top corners of the frame (21); wherein the connecting portion (211) extends toward the inner top corner on the opposite side to approach the edge mass block (23) perpendicular to its extension direction, so that the end of the connecting portion (211) is connected to the corresponding second cantilever beam (25); The other end of the first long side (231) of each edge mass block (23) is connected to the inner side of the frame (21) via the second cantilever beam (25), as shown in the following: the other end of the first long side (231) is connected to the end of the connecting portion (211) via the second cantilever beam (25).

3. The micro out-of-plane acceleration sensor for detecting micro-vibrations according to claim 1, characterized in that: The first cantilever beam (24) comprises a first cantilever (241) and a second cantilever (242) that are perpendicular to each other; The first cantilever (241) is located on an extension line of an edge of the central mass block (22) and is connected to a vertex of the edge; The second cantilever (242) is located on an extension line of the first long side (231) of the edge mass block (23) and is connected to the vertex of the first long side (231).

4. The micro out-of-plane acceleration sensor for detecting micro-vibrations according to claim 1, characterized in that: The second cantilever beam (25) comprises a third cantilever (251) and a fourth cantilever (252) perpendicular to each other; The third cantilever (251) is located on the extension line of the first long side (231) of the edge mass block (23) and is connected to the vertex of the first long side (231); The fourth cantilever (252) is parallel to the short side of the edge mass block (23) where it is located, and is connected to the inner side of the frame (21).

5. The micro out-of-plane acceleration sensor for detecting micro-vibrations according to claim 1, characterized in that: The first short side (232) of each edge mass block (23) is aligned with the first long side (231) of another edge mass block (23) on the side where the first short side (232) is located; wherein the first short side (232) is the short side of the edge mass block (23) close to the second cantilever beam (25) to which it is connected.

6. The micro out-of-plane acceleration sensor for detecting micro-vibrations according to claim 1, characterized in that: The bulk material is beryllium copper alloy.

7. The micro out-of-plane acceleration sensor for detecting micro-vibrations according to claim 1, characterized in that: Also included is a groove base (3); A through hole (31) is provided at the bottom of the groove base (3), and the frame (21) of the elastic component (2) is mounted on the top of the groove base (3); The optical fiber (1) passes through the through hole (31) to be aligned with the center of the elastic component (2).

8. A method for detecting acceleration, characterized in that: The method of measuring the acceleration in a direction perpendicular to the elastic component (2) using the micro out-of-plane acceleration sensor for detecting micro vibrations according to any one of claims 1 to 7 comprises: Collect the interference light signal of the optical fiber (1) in the micro out-of-plane acceleration sensor, the spectral function of the interference light signal ; The spectral function of the interference light signal Perform Fourier transform and extract the peak of its spatial spectrum ,in is the spatial frequency point of the peak; According to the peak , calculate the phase angle ;in, , ; According to the phase angle Corresponding relationship with acceleration , calculate the acceleration; in, is the free spectral range of the interference light signal, is the resonant frequency of the sensor, a is the acceleration, λ is the central wavelength of the spectrum, represents the extraction of the real part, represents the extraction of the imaginary part, represents the complex modulus value, n is the refractive index of the medium in the FP cavity, and is the preset coefficient.

9. A miniature out-of-plane acceleration sensor for detecting micro-vibrations, characterized in that: The device comprises a first sensor, a second sensor and a third sensor; the first sensor, the second sensor and the third sensor are all miniature out-of-plane acceleration sensors for detecting micro-vibrations according to any one of claims 1 to 7; The first elastic component (51), the second elastic component (52), and the third elastic component (53) are perpendicular to each other, and the cavity lengths of the first sensor, the second sensor, and the third sensor are different; The first elastic component (51) is an elastic component of the first sensor, the second elastic component (52) is an elastic component of the second sensor, and the third elastic component (53) is an elastic component of the third sensor.

10. A method for detecting acceleration, characterized in that: The method for measuring accelerations in three perpendicular directions using the micro-out-of-plane acceleration sensor for detecting micro-vibrations according to claim 9 comprises: Collecting the composite signal formed by superposition of three interference light signals in the micro out-of-plane acceleration sensor ; The composite signal Perform Fourier transform and extract the i-th peak of the spatial spectrum ; According to the i-th peak , calculate the phase angle of the i-th interference light signal in the composite signal ;in, , ; According to the phase angle of the i-th interference light signal The corresponding relationship between the acceleration in the i-th direction , calculate the acceleration in the i-th direction; in, is the free spectral range of the i-th interference light signal, is the resonant frequency of the sensor, is the acceleration in the i-th direction, λ is the central wavelength of the spectrum, represents the extraction of the real part, represents the extraction of the imaginary part, represents the complex modulus value, i is an integer greater than 0 and less than or equal to 3, n is the refractive index of the medium in the FP cavity, 、 、 and is the preset coefficient.

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