Micro out-of-plane acceleration sensor and acceleration detection method for detecting micro-vibrations

Abstract

The present application relates to the technical field of vibration detection, and provides a micro out-of-plane acceleration sensor for detecting micro vibration and an acceleration detection method. The acceleration sensor comprises an optical fiber and an elastic assembly arranged opposite to 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 central mass block in a 90° rotational symmetry. One end of the first long side of each edge mass block is connected to one vertex of the central mass block through the first cantilever beam, and the other end of the first long side of each edge mass block is connected to the inner edge of the frame through the second cantilever beam. The present application sets the edge mass blocks, the first cantilever beams and the second cantilever beams to form a "U" shaped connection structure, thereby improving the sensitivity and the impact resistance.

Description

Technical Field

[0001] This invention relates to the field of vibration detection technology, and in particular to a miniature out-of-plane acceleration sensor and acceleration detection method for detecting micro-vibrations. Background Technology

[0002] Accelerometer measurement plays a crucial role in modern industry and technology. In aerospace, monitoring the vibration acceleration of critical aircraft components allows for real-time assessment of structural health, prevention of mechanical failures, and ensuring flight safety. In smart manufacturing, high-precision accelerometers can capture minute abnormal vibrations in machine tools, robots, and other equipment, enabling predictive maintenance and improving production efficiency. In the new energy vehicle sector, with the diversification and complexity of operating environments, accelerometers are evolving towards miniaturization and higher sensitivity to meet increasingly complex engineering monitoring needs.

[0003] Compared to electrical accelerometers, optical accelerometers are smaller, lighter, more sensitive, resistant to electromagnetic interference, and have lower deployment costs. They can achieve long-distance signal transmission and are easy to network and reuse on a large scale, making them suitable for use in harsh environments. Currently, fiber optic accelerometers employ various transducer structures, including elastic cylinders, elastic disks, and direct fiber connections. However, their size is limited by manufacturing processes and optical path structures, especially for metal-machined sensors, which struggle to meet miniaturization requirements. Cantilever beam mass block structures, on the other hand, are compact, easily forming near-two-dimensional planar distributions and integrated on substrates using silicon micromachining, offering advantages in size and weight. However, some existing cantilever beam mass block structures often employ a four-beam inertial mass beam sensing structure, consisting of four beams and a mass block. The mass block is directly connected to the frame via beams on the side closest to the frame. This structure often has poor impact resistance, is easily damaged, and is not suitable for applications in harsh environments.

[0004] Therefore, overcoming the shortcomings of the existing technology is an urgent problem to be solved in this technical field. Summary of the Invention

[0005] 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 shock resistance of acceleration sensors in the prior art.

[0006] The present invention adopts the following technical solution:

[0007] 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 opposite to one end of the optical fiber 1.

[0008] 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 and four second cantilever beams 25;

[0009] Each edge mass block 23 is distributed around the central mass block 22 and is rotationally symmetrical at 90°.

[0010] One end of the first long side 231 of each edge mass block 23 is connected to a vertex of the center 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 edge 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 that is close to the frame 21.

[0011] Preferably, the frame 21 is further provided with four connecting portions 211 extending from each of the inner top corners of the frame 21; wherein the connecting portions 211 extend 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.

[0012] 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 means that the other end of the first long side 231 is connected to the end of the connecting part 211 through the second cantilever beam 25.

[0013] Preferably, the first cantilever beam 24 includes a first cantilever 241 and a second cantilever 242 that are perpendicular to each other;

[0014] 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 that side;

[0015] The second cantilever 242 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.

[0016] Preferably, the second cantilever beam 25 includes a third cantilever 251 and a fourth cantilever 252 that are perpendicular to each other;

[0017] 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.

[0018] The fourth cantilever 252 is parallel to the short side of the edge mass block 23 and is connected to the inner side of the frame 21.

[0019] 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 that is close to the second cantilever beam 25 to which it is connected.

[0020] Preferably, the bulk material is a beryllium copper alloy.

[0021] Preferably, it also includes a grooved base 3;

[0022] The bottom of the groove base 3 is provided with a through hole 31, and the frame 21 of the elastic component 2 is installed on the top of the groove base 3;

[0023] The optical fiber 1 passes through the through hole 31 to be aligned with the center of the elastic component 2.

[0024] In a second aspect, the present invention also provides an acceleration detection method, which uses a miniature out-of-plane acceleration sensor for detecting micro-vibrations as described in any of the first aspects to measure acceleration in a direction perpendicular to the elastic component 2, the method comprising:

[0025] The interference light signal of optical fiber 1 in the miniature out-of-plane accelerometer is acquired, and the spectral function of the interference light signal is... ;

[0026] Spectral function of the interference light signal Perform Fourier transform and extract the peak values ​​of its spatial spectrum ,in The spatial frequency point of the peak value;

[0027] According to the peak value The phase angle was calculated. ;in, , ;

[0028] According to the phase angle Correspondence between acceleration The acceleration is calculated.

[0029] in, For the free spectral range of the interference optical signal, The resonant frequency of the sensor. a Let λ be the acceleration, and λ be the center wavelength of the spectrum. The representative extracts the real part. This represents extracting the imaginary part. This represents the calculation of the complex modulus, where n is the refractive index of the medium in the FP cavity. and These are preset coefficients.

[0030] Thirdly, the present invention also provides a miniature out-of-plane acceleration sensor for detecting micro-vibrations, including 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 as described in any of the first aspects;

[0031] 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.

[0032] Among them, 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.

[0033] Preferably, the present invention provides an acceleration detection method, which uses the miniature out-of-plane accelerometer for detecting micro-vibrations described in the third aspect to measure acceleration in three perpendicular directions, the method comprising:

[0034] The composite signal formed by the superposition of three interferometric optical signals is acquired from the miniature out-of-plane accelerometer. ;

[0035] For the composite signal Perform a Fourier transform and extract the i-th peak of the spatial spectrum. ;

[0036] According to the i-th peak value The phase angle of the i-th interfering optical signal in the composite signal is calculated. ;in, , ;

[0037] Based on the phase angle of the i-th interference light signal Correspondence between acceleration in the i-th direction The acceleration in the i-th direction is calculated.

[0038] in, Let i be the free spectral range of the i-th interferometric light signal. The resonant frequency of the sensor. Let λ be the acceleration in the i-th direction, and λ be the center wavelength of the spectrum. The representative extracts the real part. This represents extracting the imaginary part. This represents the calculation of the complex modulus, where i is an integer greater than 0 and less than or equal to 3, and n is the refractive index of the medium in the FP cavity. , , and These are preset coefficients.

[0039] This invention, by setting up an edge mass block 23, a first cantilever beam 24, and a second cantilever beam 25, connects the central mass block 22 to the frame 21 sequentially via the first long side 231 of the first cantilever beam 24, the edge mass block 23, and the second cantilever beam 25, thus forming a "U"-shaped connection structure. Compared to the single beam in the prior art, the "U"-shaped connection structure, due to its longer connection path, provides greater displacement space under force, thereby improving its sensitivity. Simultaneously, the central mass block 22 is connected to the frame 21 through four "U"-shaped connection structures, forming an equivalent spring structure capable of torsional deformation. Its sensitivity is not sensitive to the thickness of the cantilever beams, thus improving its impact resistance. The edge mass block 23 serves as a connection between the first cantilever beam 24 and the second cantilever beam 25, improving the stability of the "U"-shaped connection structure while also increasing the overall mass of the mass block within a limited space, thereby enhancing detection sensitivity. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments of the present invention will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0041] Figure 1 This is a schematic diagram of the structure of a miniature out-of-plane acceleration sensor for detecting micro-vibrations provided in an embodiment of the present invention;

[0042] Figure 2 This is a schematic diagram of the structure of an elastic component in a miniature out-of-plane acceleration sensor for detecting micro-vibrations, provided in an embodiment of the present invention.

[0043] Figure 3 This is a schematic diagram of the structure of an elastic component in a miniature out-of-plane acceleration sensor for detecting micro-vibrations, provided in an embodiment of the present invention.

[0044] Figure 4 This is a schematic diagram of the structure of a miniature out-of-plane acceleration sensor for detecting micro-vibrations provided in an embodiment of the present invention;

[0045] Figure 5 This is a schematic diagram of the groove base in a miniature out-of-plane accelerometer for detecting micro-vibrations provided in an embodiment of the present invention;

[0046] Figure 6 This is a schematic diagram of the structure of an elastic component in a miniature out-of-plane acceleration sensor for detecting micro-vibrations, provided in an embodiment of the present invention.

[0047] Figure 7 This is a schematic diagram of the structure of an elastic component in a miniature out-of-plane acceleration sensor for detecting micro-vibrations, provided in an embodiment of the present invention.

[0048] Figure 8 This is a schematic diagram of the structure of an elastic component in a miniature out-of-plane acceleration sensor for detecting micro-vibrations, provided in an embodiment of the present invention.

[0049] Figure 9 This is a cross-sectional structural schematic diagram of a miniature out-of-plane acceleration sensor for detecting micro-vibrations provided in an embodiment of the present invention;

[0050] Figure 10 This is a schematic diagram of the groove base in a miniature out-of-plane accelerometer for detecting micro-vibrations provided in an embodiment of the present invention;

[0051] Figure 11 This is a schematic diagram of the architecture of an acceleration detection system provided in an embodiment of the present invention;

[0052] Figure 12 This is a schematic flowchart of an acceleration detection method provided in an embodiment of the present invention;

[0053] Figure 13 This is a schematic diagram of the structure of a miniature out-of-plane acceleration sensor for detecting micro-vibrations provided in an embodiment of the present invention;

[0054] Figure 14 This is a schematic diagram of the mounting base in a miniature out-of-plane accelerometer for detecting micro-vibrations provided in an embodiment of the present invention;

[0055] Figure 15 This is a schematic diagram of the mounting base in a miniature out-of-plane accelerometer for detecting micro-vibrations provided in an embodiment of the present invention;

[0056] Figure 16 This is a schematic diagram of the structure of a miniature out-of-plane acceleration sensor for detecting micro-vibrations provided in an embodiment of the present invention;

[0057] Figure 17 This is a schematic diagram of the pre-assembly structure of a miniature out-of-plane acceleration sensor for detecting micro-vibrations provided in an embodiment of the present invention;

[0058] Figure 18 This is a schematic diagram of the pre-assembly structure of a miniature out-of-plane acceleration sensor for detecting micro-vibrations provided in an embodiment of the present invention;

[0059] Figure 19 This is a schematic diagram of the architecture of an acceleration detection system provided in an embodiment of the present invention;

[0060] Figure 20This is a schematic diagram of the composite signal acquired by a miniature out-of-plane acceleration sensor for detecting micro-vibrations provided in an embodiment of the present invention.

[0061] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0062] 1. Optical fiber; 2. Flexible component; 21. Frame; 211. Connector; 22. Central 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. Groove base; 31. Through hole; 32. Platform; 33. Channel; 4. Ceramic ferrule; 51. First 52. Elastic component; 53. Second elastic component; 64. Third elastic component; 7. Mounting base; 75. First groove; 76. First through hole; 77. Second groove; 78. Second through hole; 79. Third groove; 70. Third through hole; 71. First opening; 72. Second opening; 73. Third opening; 74. Third opening; 75. Second opening; 76. Third opening; 80. Encapsulation shell; 81. First shell; 82. Second shell. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of this invention clearer, the 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 merely illustrative and not intended to limit the invention.

[0064] Unless the context otherwise requires, throughout the specification and claims, the term "comprising" is interpreted as openly inclusive, meaning "including, but not limited to." In the description of the specification, terms such as "one embodiment," "some embodiments," "exemplary embodiment," "example," "specific example," or "some examples" are intended to indicate that a particular feature, structure, material, or characteristic associated with that embodiment or example is included in at least one embodiment or example of this disclosure. The illustrative representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics mentioned may be included in any suitable manner in any one or more embodiments or examples; that is, although they may be incorporated into embodiments or examples using the above terms for reasons such as order and position, it does not limit them to be incorporated in combination by a single embodiment or example.

[0065] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this disclosure.

[0066] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of this disclosure, unless otherwise stated, "a plurality of" means two or more. Furthermore, for example, the description may use the prefix "A" or "B" to describe the same type of nouns as two independent entities. In this case, the corresponding features defined with "A" and "B" are used only to distinguish between similar entities and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features.

[0067] In describing some embodiments, the terms "coupled," "coupled," and "connected," and their derivative expressions, may be used. For example, the term "connected" may be used in describing some embodiments to indicate that two or more components have direct physical or electrical contact with each other. Similarly, the term "coupled" may be used in describing some embodiments to indicate that two or more components have direct physical or electrical contact. However, the terms "connected" or "coupled" may also refer to two or more components that do not have 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 scope of this invention.

[0068] In the description of this invention, the expression “A and / or B” (where A and B are used to formally represent specific features) will be used. The corresponding expression includes the following three combinations: only A, only B, and a combination of A and B.

[0069] As used in this invention, “about,” “approximately,” or “approximately” includes the stated value and the average value within an acceptable range of deviation from a particular value, wherein the acceptable range of deviation is determined by a person skilled in the art taking into account the measurement under discussion and the error associated with the measurement of the particular quantity (i.e., the limitations of the measurement system).

[0070] Furthermore, 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.

[0071] Example 1:

[0072] Because existing cantilever beam mass block structures often employ a four-beam inertial mass beam sensing structure, comprising four beams and a mass block, with the mass block directly connected to the frame via a single beam on the side closest to the frame, the sensitivity of the accelerometer is determined by the weight of the mass block and the length and thickness of the beams. Therefore, to ensure sensitivity, the single beam is relatively long and thin, and the mass block is large, resulting in weak impact resistance. To address this issue, Embodiment 1 of this invention provides a miniature out-of-plane accelerometer 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 disposed opposite to one end of the optical fiber 1;

[0073] 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. Each edge mass block 23 is distributed around the central mass block 22 and is 90° rotationally symmetrical (specifically, its position is 90° rotationally symmetrical with respect to 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 edge of the frame 21 through the second cantilever beam 25. The first long side 231 is the long side of the edge mass block 23 closest to the frame 21.

[0074] In this design, the side of the central mass block 22 facing the optical fiber 1 is a light-reflecting surface, which is perpendicular to the optical fiber 1. The optical fiber 1 is aligned with the center of the elastic component 2 and exists at a certain distance from the elastic component 2 to form a Fabry-Pérot 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 under test in a certain way. A probe light signal is input from the other end of the optical fiber 1 and injected into the Fabry-Pérot cavity (FP) through the optical fiber 1. Inside the cavity, a Fabry-Perot interference signal is formed between the end face of the optical fiber 1 and the light reflecting surface. When the object under test generates micro-vibrations, 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 behind due to inertia, which in turn causes 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 Fabry-Perot interference signal. Thus, the acceleration in the direction perpendicular to the light reflecting surface of the elastic component 2 can be measured by the change in the interference signal.

[0075] The bulk material is a 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 a beryllium copper alloy.

[0076] For the central mass block 22, except for the connection position between the central mass block 22 and the first cantilever beam 24, the rest of the central mass block 22 is etched away, forming a gap.

[0077] Similarly, for the edge mass block 23, except for the connection points between the first cantilever beam 24 and the edge mass block 23, and the connection points between the edge mass block 23 and the second cantilever beam 25, the rest of the periphery of the edge mass block 23 is etched away, forming gaps. For the first cantilever beam 24, except for the connection points between the first cantilever beam 24 and the edge mass block 23, and the connection points between the center mass block 22 and the first cantilever beam 24, the rest of the periphery of the first cantilever beam 24 is etched away, forming gaps. For the second cantilever beam 25, except for the connection points between the second cantilever beam 25 and the edge mass block 23, and the connection points 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 gaps.

[0078] It should be noted that, in order to easily distinguish between the solid portion (i.e., the unetched portion) and the etched portion in the elastic component 2, Figure 2 , Figure 3 The accompanying drawings, which detail the specific structure of the elastic component 2, are presented in grayscale. The grayscale areas represent solid parts, while the white areas represent etched-out parts.

[0079] In this embodiment, by setting an edge mass block 23, a first cantilever beam 24, and a second cantilever beam 25, the center 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, so it can provide a larger displacement space when subjected to force, thus improving its sensitivity.

[0080] Meanwhile, the central mass block 22 is connected to the frame 21 through four "U"-shaped connecting structures, forming an equivalent spring structure capable of torsional deformation. Its sensitivity is not sensitive to the thickness of the cantilever beam, further improving its impact resistance. The edge mass block 23 serves as a connection 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.

[0081] In fact, the displacement of the central mass block 22 was derived. Where 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 moment of inertia of the section of the first cantilever beam 24; I2 is the moment of inertia of the section of the edge mass block 23; I3 is the moment of inertia of the section 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.

[0082] 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) is greater than the side length of the center mass block.

[0083] In some alternative implementations, when there is no installation space inside the object to be tested, the elastic component 2 can be directly built into the cavity of the corresponding object to be tested, so that the frame 21 of the elastic component 2 remains fixed to the object to be tested, and the central mass block 22, the edge mass block 23, the first cantilever beam 24 and the second cantilever beam 25 can move within the cavity.

[0084] When the object under test does not have internal installation space, another optional implementation method is as follows: the accelerometer described in this embodiment further includes a grooved base 3; such as Figure 4 and Figure 5As 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 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. The sidewall of the groove base 3 can be adhered and fixed to the object to be measured, thereby realizing the installation of the accelerometer.

[0085] In practical application scenarios, such as Figure 6 As shown, the frame 21 is also provided with four connecting portions 211 extending from each of the 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 (the edge mass block 23 is located in the extension direction of the connecting portion 211), so that the 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 and approaching edge mass block 23);

[0086] 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 means that the other end of the first long side 231 is connected to the end of the connecting part 211 through the second cantilever beam 25.

[0087] by Figure 6 Taking the bottommost connecting part 211 as an example, this connecting part 211 is located at the inner top corner of the bottom right corner of the frame 21 (i.e., Figure 6 The edge mass block 23 (marked as position a) extends towards the bottom left corner of the frame 21, that is, it extends horizontally to the left. The edge mass block 23 perpendicular to this direction is the bottom left edge mass block 23. The end of the connecting part 211 (i.e. Figure 6 The position marked b) is connected to the edge mass block 23 at the lower left corner via the second cantilever beam 25.

[0088] The connecting part 211 is to reduce the structural stability loss caused by the excessive length of the second cantilever 242. That is, by setting the connecting part 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 part 211 are obtained by those skilled in the art based on the requirements.

[0089] In some specific application scenarios, such as Figure 7As shown, 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 that side; the second cantilever 242 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 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 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 and is connected to the inner edge of the frame 21.

[0090] And, as Figure 8 As shown, 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, in order to avoid large areas being etched away and to ensure the impact resistance of the structure.

[0091] In practical use, such as Figure 9 and Figure 10 As shown, the accelerometer also includes a ceramic ferrule 4, which is inserted into the through hole 31. The outer periphery of the ceramic ferrule 4 is bonded and fixed to the inner wall of the through hole 31 with adhesive (such as AB glue). The optical fiber 1 passes through the through hole 31 in such a way that the optical fiber 1 passes through the ceramic ferrule 4 and is aligned with the center of the elastic component 2.

[0092] like Figure 10 As shown, the sidewall of the groove base 3 is designed as a step, and the frame 21 of the elastic component 2 is installed on the top of the groove base 3, which means that the frame 21 of the elastic component 2 is pasted on the platform 32 of the step.

[0093] At the top corner of the tabletop 32 to which the frame 21 is attached, a channel 33 is also designed. The channel 33 connects the top surface of the groove base 3 to the tabletop 32. 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.

[0094] In this embodiment, the displacement of the central mass block is mainly composed of the superposition of bending deformation of each segment and torsional deformation unique to the "U"-shaped connection structure. Compared with a simple straight beam structure, on the one hand, the length of the cantilever beam is extended, improving the displacement sensitivity caused by bending deformation; on the other hand, more torsional deformation is introduced, further improving the displacement of the central mass block.

[0095] In a preferred embodiment, the width of the first cantilever beam in the "U"-shaped connection structure is less than or equal to its own thickness to reduce the torsional constant and improve sensitivity; the width of the edge mass block in the "U"-shaped structure is greater than twice its own thickness to improve the lateral stiffness of the structure and reduce crosstalk, and the length of its edge mass block is greater than the side length of the central mass block. The benefit is that the torsional angle of the first cantilever beam in the "U" shape is converted 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 compensates for the torsional angle of the first cantilever beam in the "U" shape, keeping the central mass block in translation.

[0096] The displacement of the central mass block is largely contributed by the torsional deformation unique to the "U"-shaped connection structure, and it is not sensitive to the thickness of the cantilever beam. Compared with the existing technology that requires the cantilever beam thickness to be much smaller than the mass block thickness, the sensitivity is improved by reducing the cantilever beam thickness and increasing the mass block thickness. The "U"-shaped cantilever beam has the same thickness as the mass block, thus overcoming this processing difficulty.

[0097] In specific application scenarios, the accelerometer described in this embodiment, together with the circulator, broadband light source, real-time spectrum acquisition module, and signal demodulation module, forms an acceleration detection system; such as 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 the elastic component 2, generating an interference light signal. The interference light signal returns along optical fiber 1, and 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 the acceleration.

[0098] Based on the aforementioned accelerometer sensor and accelerometer detection system, this embodiment also provides an accelerometer detection method, which uses the aforementioned miniature out-of-plane accelerometer sensor for detecting micro-vibrations to measure the acceleration in the direction perpendicular to the elastic component 2, such as... Figure 12 As shown, the method includes:

[0099] In step 201, the interference light signal of optical fiber 1 in the accelerometer is acquired, and the spectral function of the interference light signal is... .

[0100] In step 202, the spectral function of the interference light signal is... Perform Fourier transform and extract the peak values ​​of its spatial spectrum ,in The spatial frequency point of the peak value. In practical applications, step 202 can be understood as: performing a Fourier transform on the spectral function of the signal at each moment to obtain the spatial spectrum, and extracting the peak value from the spatial spectrum. .

[0101] In step 203, based on the peak value The phase angle was calculated. ;in, , .

[0102] In step 204, based on the phase angle Correspondence between acceleration The acceleration is calculated.

[0103] in, For the free spectral range of the interference optical signal, Where n is the refractive index of the medium (usually air) in the FP cavity, and L is the cavity length of the FP cavity. The resonant frequency of the sensor. a Let λ be the acceleration, and λ be the center wavelength of the spectrum. The representative extracts the real part. This represents extracting the imaginary part. This represents finding the modulus of a complex number. and These are preset coefficients.

[0104] Example 2:

[0105] like Figure 4 As shown, this embodiment of the invention provides a miniature out-of-plane acceleration sensor for detecting micro-vibrations, including an elastic component 2, a grooved base 3, a ceramic ferrule 4, and an optical fiber 1. As... Figure 2 As shown, the elastic component 2 includes a central mass block 22, four edge mass blocks 23, and eight cantilever beams (including four first cantilever beams 24 and four second cantilever beams 25). The cantilever beams and edge mass blocks 23 are evenly distributed symmetrically around the central mass block 22, forming a "U"-shaped connection structure with the first cantilever beams 24—edge mass blocks 23—second cantilever beams 25, one end connected to the frame 21 and the other end connected to the central mass block 22.

[0106] The eight elastic cantilever beams mainly rely on torsional deformation to act as equivalent springs. The "U"-shaped connection structure is different from the traditional straight beam which is based on bending and tensile deformation. The structure is more compact and can achieve higher acceleration sensitivity within the same size.

[0107] The edge mass block 23 converts the torsional angle of the elastic cantilever beam into out-of-plane displacement 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.

[0108] In this embodiment of the invention, the elastic cantilever beam, the central mass block 22, and the edge mass block 23 are made of beryllium copper. The high toughness of this material gives the sensing structure high impact resistance, making it more suitable for harsh environments. On the other hand, beryllium copper, as the second reflective surface in the FP cavity, has a high reflectivity that allows it to reduce the energy loss of reflected light signals without the need for a reflective coating, thereby improving the interference contrast of the probe light.

[0109] Specifically, the elastic component 2 is processed using a metal wet etching process. After steps such as coating photoresist, UV exposure, and development, the designed sensing structure outline on the film mask is transferred onto the photoresist. Then, a solution is prepared and wet etching is used to completely penetrate the metal substrate, releasing the central mass block 22, the edge mass block 23, and the elastic cantilever beam, ultimately obtaining the sensing structure.

[0110] In this invention, the elastic cantilever beam, the central mass block 22, and the edge mass block 23 are integrally formed in one piece, avoiding the assembly process of adhesive bonding, welding, and screw fastening, simplifying the assembly steps, avoiding problems such as aging and rusting of weld points and fragile adhesive structures, and ensuring stable working performance.

[0111] In this embodiment of the 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 and fixed to the groove base 3 with AB glue. The optical fiber 1 forms an FP interference microcavity with the bottom surface of the central mass block 22 through the ceramic ferrule 4.

[0112] In this embodiment of the invention, the groove base 3 of the accelerometer is fully bonded and fixed to the object to be measured using hot melt adhesive, so that the groove base 3 moves synchronously with the object to be measured. The relative displacement between the groove base 3 and the central mass block 22 in the elastic component 2, which is generated by the inertial lag motion, modulates the probe light signal in the FP interferometer microcavity, thereby realizing acceleration sensing.

[0113] like Figure 11 As shown, this embodiment of the invention provides an optical sensing system for detecting micro-vibrations, including a broadband light source, a circulator, an accelerometer, a real-time spectral acquisition module, and a signal demodulation module. The accelerometer is the miniature out-of-plane accelerometer optical sensor described in Embodiment 1.

[0114] A broadband light source is used to output the raw probe light signal. In this embodiment of the invention, the wavelength range used is the communication band, specifically 1526-1563 nm. In other embodiments, the broadband light source only needs to remain flat within a certain wavelength range. A circulator is used to enable unidirectional transmission of the light signal in the optical path, from the broadband light source through the accelerometer to the real-time spectrum acquisition module.

[0115] An accelerometer is used to detect micro-vibrations of an object that is 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 probe broadband optical signal, forming FP interference light with phase change.

[0116] Specifically, the end face of fiber 1 and the bottom face of the central mass block 22 form a Fabry-Perot cavity. After the original probe light signal is injected into the FP interference microcavity through fiber 1, the reflected light at the two end faces forms FP interference light signals. When the platform rigidly fixed to the accelerometer vibrates slightly, it will drive the groove base 3 of the accelerometer to vibrate, which in turn causes the cantilever beam mass block structure to move. At this time, the central mass block 22 in the elastic component 2 will lag behind 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 reflected at both ends of the cavity length to change.

[0117] The real-time spectral acquisition module is used to acquire the phase change of the reflection interference spectrum corresponding to the change in cavity length in real time; in this embodiment of the invention, the real-time spectral acquisition module is a high-speed spectrometer.

[0118] The signal demodulation module is used to perform FFT operations 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, thus obtaining the micro-vibration information.

[0119] 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. By demodulating this phase information instead of the light intensity signal, the interference of light source noise and environmental noise can be effectively reduced, ensuring the purity and accuracy of the detection signal.

[0120] The optical sensing system of this invention has a completely passive structure, can operate under strong electromagnetic interference, and has excellent performance and small size. At the same time, the system can be integrated into various devices and environments, which greatly improves its application flexibility and adaptability.

[0121] The optical sensing system for detecting micro-vibrations of the present invention includes only a broadband light source module, a circulator, a miniature out-of-plane accelerometer, a real-time spectrum acquisition module, and a signal demodulation module. It involves fewer components and has a simple detection device, enabling accurate measurement of micro-vibrations.

[0122] In this embodiment of the invention, a small-sized micro out-of-plane acceleration sensing structure is fabricated using a metal etching process.

[0123] This invention also provides an acceleration signal detection method, which uses the above-described optical sensing system for acceleration detection.

[0124] Specifically, the acceleration signal detection method includes the following steps:

[0125] Step S1: The original probe light signal generated by the broadband light source first passes through a circulator and enters the accelerometer. Inside the sensor, the light signal is injected into the Fabry-Perot interferometer microcavity of the sensor through optical fiber 1. The reflected light from the end face of optical fiber 1 and the bottom face of the central mass block 22 forms an Fabry-Perot interferometer light signal. When the platform rigidly fixed to the accelerometer vibrates slightly, it will drive the sensor groove base 3 to vibrate, thereby causing the cantilever beam mass block structure to move. At this time, the central mass block 22 in the sensing structure will lag behind due to inertia, which will cause the cavity length of the Fabry-Perot cavity formed by the end face of optical fiber 1 and the bottom face of the central mass block 22 to change, resulting in a phase change in the interference spectrum formed by the reflected light from the two end faces.

[0126] Step S2: Real-time acquisition of spectral information of the interference light signal corresponding to the change in the probe cavity length.

[0127] Step S3: Since low-precision FP interference can be approximated as two-beam interference, the spectrum of its interference light signal is approximately a sine function, and its expression is:

[0128]

[0129] Where FSR is the free spectral range of the spectrum. A Fourier transform of the spectral function yields its spatial spectrum. There will be corresponding characteristic frequency peaks. By extracting the real and imaginary parts at the peaks and performing an arctangent operation, the phase information of the interference spectrum can be obtained.

[0130]

[0131]

[0132]

[0133] The phase change is directly related to the acceleration being measured.

[0134]

[0135] in The resonant frequency of the sensor. aLet λ be the acceleration to be measured, and λ be the center wavelength of the spectrum. This provides information about the acceleration to be measured.

[0136] Example 3:

[0137] Based on Embodiments 1 and 2, this embodiment also provides a sensor capable of measuring three-dimensional acceleration, such as... Figure 13 As shown, this embodiment provides a miniature out-of-plane acceleration sensor for detecting micro-vibrations, including a first sensor, a second sensor, and a third sensor. The first, second, and third sensors are all miniature out-of-plane acceleration sensors for detecting micro-vibrations as described in Embodiment 1. 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, second, and third sensors are different. Specifically, 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 "perpendicular to each other" means that the light-reflecting surfaces of the first elastic component 51, the second elastic component 52, and the third elastic component 53 are perpendicular to each other.

[0138] In a practical application scenario, the cavity length of the first sensor can be 400 μm, the cavity length of the second sensor can be 240 μm, and the cavity length of the third sensor can be 150 μm.

[0139] This embodiment uses three sensors with mutually perpendicular light-reflecting surfaces and different cavity lengths to measure acceleration in three orthogonal directions. The different cavity lengths of each sensor ensure that when the interference light signals from each sensor are combined and transmitted and received, information for calculating acceleration in each direction can be obtained from the combined signal.

[0140] In a preferred embodiment, such as Figure 13 , Figure 14 and Figure 15 As shown, the accelerometer in this embodiment also includes a mounting base 7; the mounting base 7 is a hollow cubic structure, the first surface of the mounting base 7 is designed with a first groove 71 with the 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 the 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 the notch facing outward, and the bottom of the third groove 73 is provided with a third through hole 731.

[0141] like Figure 16As shown, the mounting base 7 has a first opening 74 on the fourth surface opposite to the first surface, a second opening 75 on the fifth surface opposite to the second surface, and a third opening 76 on the sixth surface opposite to the third surface.

[0142] The frame 21 of the first elastic component 51 is mounted 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 mounted 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 mounted 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.

[0143] Wherein, the first optical fiber 61 is the optical fiber of the first sensor, the second optical fiber 62 is the optical fiber of the second sensor, and the third optical fiber 63 is the optical fiber of the third sensor.

[0144] In an optional embodiment, the first opening 74, the second opening 75, and the third opening 76 can be through holes directly drilled on their respective surfaces. However, considering the need to facilitate the installation of the first optical fiber 61, the second optical fiber 62, and the third optical fiber 63, as... 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 that matches the hollowed-out position. The cover can be embedded in the hollowed-out position and fixed by the outer wall of the cover to the inner wall of the hollowed-out position. Furthermore, the cover is provided with a through hole, through which the corresponding optical fiber passes to the inside of the mounting base 7 and passes through the through hole on the opposite side groove (i.e., 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.

[0145] The first groove 71, the second groove 72, and the third groove 73 are implemented based on the same concept as the groove base 3 in Embodiment 1. For example, the sidewall of the first groove 71 is designed as a step, and the frame of the corresponding elastic component is attached to the platform of the step. At the top corner of the platform where the frame is attached, a channel is also designed. The channel connects the top surface of the first groove to the platform. In an optional embodiment, the channel is a cylindrical channel, and the height of the cylindrical channel is perpendicular to the bottom surface of the first groove.

[0146] In practical 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, all by bonding ceramic ferrules 4 to the inner walls of the corresponding through holes, and then the optical fiber 1 passes through the ceramic ferrules. If the first ceramic ferrule is inserted into the first through hole 711, and the outer periphery of the first ceramic ferrule is bonded and fixed to the inner wall of the first through hole 711 using adhesive (such as AB glue), the first optical fiber 61 passes through the first ceramic ferrule and is aligned with the center of the first elastic component 51.

[0147] 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 all offset relative to each other by a preset distance, such as... Figure 17 As shown, this causes the first optical fiber 61, the second optical fiber 62, and the third optical fiber 63 to be staggered within the mounting base 7. The preset distance was obtained by those skilled in the art based on experience.

[0148] In practical applications, this embodiment also has another application scenario: detecting the three-dimensional acceleration of an underwater sound field. In this case, the acceleration sensor described in this embodiment further includes a housing 8, such as... Figure 18 As shown, the encapsulation shell 8 is spherical and is used to withstand hydrostatic pressure and protect the internal structure from damage. The encapsulation 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 together to encapsulate other components of the accelerometer inside the encapsulation shell.

[0149] The encapsulation housing 8 has eight symmetrical cylinders evenly distributed on the first housing 81 and the second housing 82 (of which, four cylinders are located on the outer surface of the first housing 81 and the other four cylinders are located on the outer surface of the second housing 82) for external suspension underwater, and the center of the first housing 81 is provided with a threaded cylinder with an opening at the top (i.e. leading to the interior of the encapsulation housing) for leading out optical fibers.

[0150] The inner wall of the first housing 81 and the inner wall of the second housing 82 are provided with four pillars, which are used for the pillars of the first housing 81 and the pillars of the second housing 82 to mate with each other, thereby enhancing the stability of the internal structure of the encapsulation housing. The edges of the first housing 81 and the edges of the second housing 82 are also provided with screw holes, for corresponding screws to pass through the screw holes of the first housing 81 and the screw holes of the second housing 82, and for nuts to be installed at the other end to achieve the installation and fixation of the first housing 81 and the second housing 82.

[0151] In one optional embodiment, the encapsulation shell 8 is made of aluminum alloy 7075, 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 the compact placement of three miniature out-of-plane accelerometers within a limited space, and the symmetrical structure facilitates stable underwater operation. When assembling the first shell 81 and the second shell 82, an O-ring is used for sealing, with fluororubber as the sealing material; that is, a sealing ring is added at the position where the first shell 81 and the second shell 82 are fixed together. Its overall density is approximately the same as that of water, allowing it to be treated as a point mass for collecting acceleration information in the underwater sound field.

[0152] Based on the aforementioned accelerometer sensor, this embodiment also provides an accelerometer detection system, comprising a circulator, a coupler, a broadband light source, a real-time spectrum acquisition module, and a signal demodulation module, which together form the accelerometer detection system; such as Figure 19 As shown, the broadband light source is used to output a probe light signal; the circulator inputs the probe light signal to the coupler, which divides the probe light signal into a first probe light signal, a second probe light signal, and a third probe light signal, so that each 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 by the coupler to form an interference light signal. The circulator transmits the interference light signal to the real-time spectral acquisition module. The real-time spectral 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.

[0153] In the application scenario of this acceleration detection system, this embodiment also provides an acceleration detection method, which uses the aforementioned miniature out-of-plane acceleration sensor for detecting micro-vibrations to measure acceleration in three perpendicular directions. The method includes:

[0154] The composite signal formed by the superposition of three interferometric optical signals is acquired from the miniature out-of-plane accelerometer. For the composite signal Perform a Fourier transform and extract the i-th peak of the spatial spectrum. That is, perform a Fourier transform on the spectral function of the signal at each moment to obtain the spatial spectrum, and extract each peak from the spatial spectrum; based on the i-th peak... The phase angle of the i-th interfering optical signal in the composite signal is calculated. ;in, , According to the phase angle of the i-th interference light signal Correspondence between acceleration in the i-th direction The acceleration in the i-th direction is calculated; where, Let i be the free spectral range of the i-th interferometric light signal. The resonant frequency of the sensor. Let λ be the acceleration in the i-th direction, and λ be the center wavelength of the spectrum. The representative extracts the real part. This represents extracting the imaginary part. This represents finding the modulus of a complex number, where i is an integer greater than 0 and less than or equal to 3. , , and These are preset coefficients.

[0155] In one specific application scenario, when the cavity length of the first sensor is 400 μm, The first is 3nm; when the cavity length of the second sensor is 240µm, The first is 5 nm; when the cavity length of the second sensor is 150 μm, It is 8 nm.

[0156] Example 4:

[0157] Referring to the foregoing figures, this invention provides a three-dimensional acceleration information detection system for detecting underwater sound fields. It mainly includes 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.

[0158] The housing 8 is designed to withstand hydrostatic pressure, protecting the internal structure from damage. It also features uniformly symmetrically distributed small cylinders for connection with springs or rubber bands, forming an underwater suspension system to maintain stability during underwater applications. The mounting base 7 integrates three accelerometers, allowing them to detect acceleration information in various three-dimensional directions.

[0159] Specifically, the housing 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 a compact arrangement of the three accelerometers within a limited space, and its symmetrical structure contributes to greater stability during underwater applications. The upper and lower hemispherical shells are sealed using O-rings, with fluororubber as the sealing material. Its overall density is similar to that of water, allowing it to be treated as a point mass for collecting acceleration information in the underwater acoustic field.

[0160] Specifically, the three acceleration sensors are respectively placed on the three surfaces of the mounting base 7, forming... Figure 13The structure is designed such that the centers of each elastic component are staggered to prevent the optical fibers from blocking each other. A threaded cylinder with an opening is located on the top of the spherical encapsulation shell 8. The optical fibers of the three accelerometers are led out from this opening and connected to a 1×3 coupler, thereby combining the three interferometric beams together. The beams then enter the circulator and the real-time spectral acquisition module, where the superimposed spectra of the three beams are acquired.

[0161] This invention uses three accelerometers to simultaneously detect acceleration in three directions in three-dimensional space and demodulate the information simultaneously.

[0162] Specifically, the FP cavity lengths of the three sensors were adjusted to be different, causing the intrinsic spatial frequencies corresponding to their interference to separate in the aliased spectrum. The cavity length of the sensor in the X-axis direction was set to 400 μm. The length is 3 nm; the cavity length of the sensor in the Y-axis direction is set at 240 μm. The length is 5 nm; the cavity length of the sensor in the Z-axis direction is set at 150 μm. At 8 nm, three different interference spectra are superimposed to form a composite spectrum, such as Figure 20 As shown in (a) above, its expression is:

[0163]

[0164] in Let be the free spectral range of the i-th interfering optical signal. Performing a Fourier transform on the above spectral function yields its spatial spectrum. There will be corresponding characteristic frequency peaks, such as Figure 20 As shown in (b) above, the positions are respectively in , , Therefore, the phase information collected by the three accelerometers can be separated by using the different cavity lengths. , , .

[0165] Furthermore, by extracting the real and imaginary parts of the three characteristic frequency peaks and performing arctangent operations, the corresponding phase information can be obtained:

[0166]

[0167]

[0168]

[0169] The changes in their respective phase information correspond to the accelerations in their respective detection directions:

[0170]

[0171] in The resonant frequency of the sensor. Let λ be the acceleration to be measured in three directions, λ be the center wavelength of the spectrum, and n be the refractive index of the medium in the FP cavity. Therefore, by setting the FP cavity lengths of the accelerometers in the three directions to be different, information on the acceleration to be measured can be simultaneously detected and demodulated.

[0172] In summary, the technical solutions proposed in this embodiment have the following advantages compared with the prior art:

[0173] (1) The miniature out-of-plane accelerometer 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 symmetrically and evenly distributed around the central mass block 22, forming a "U"-shaped connection structure with the first cantilever beam 24, edge mass blocks 23, and second cantilever beam 25. One end 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 beams. Unlike traditional straight beams based on bending and tensile deformation, it can achieve higher acceleration sensitivity under the same size. Furthermore, adding edge mass blocks 23 between two cantilever beams can effectively utilize limited space to increase the mass of the mass blocks, thereby improving acceleration sensitivity.

[0174] (2) The accelerometer is made of beryllium copper, which has high toughness compared to silicon, silicon nitride and other materials used in other etching processes. This makes the sensor highly shock resistant and more suitable for real-world environments. On the other hand, as the second reflective surface in the FP cavity, the high reflectivity of the metal material reduces the energy loss of reflected light signals without the need for a reflective film, thereby improving the interference contrast of the probe light.

[0175] (3) The aforementioned miniature out-of-plane accelerometer combines small size with high sensitivity. The cantilever beam mass block is integrated into a single process using metal etching, which simplifies the sensor assembly and packaging process, improves the sensor's operational stability, and reduces inter-axis crosstalk. Taking advantage of the mature, short-cycle, and low-cost metal etching technology, the sensor is low-cost, highly consistent, and can be mass-produced. Furthermore, the cost of this process is far lower than that of MEMS silicon micromachining.

[0176] (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 accelerometer, a real-time spectral acquisition module, and a signal demodulation module. The number of devices involved is small and the detection device is simple.

[0177] (5) The method for detecting three-dimensional acceleration information of underwater sound field provided by the present invention utilizes a spherical shell (i.e., encapsulation shell 8) to achieve operation under high pressure underwater, and uses a mounting base 7 to compactly arrange three miniature out-of-plane acceleration sensors in a limited space to form a symmetrical structure. The three miniature out-of-plane acceleration sensors are used to simultaneously detect the sound field acceleration in three directions in three-dimensional space, and simultaneously demodulate to obtain acceleration information in three directions.

[0178] Those skilled in the art will understand that all or part of the steps in the various methods of the embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, which may include: read-only memory (ROM), random access memory (RAM), magnetic disk or optical disk, etc.

[0179] 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 within the protection scope of the present invention.

Claims

1. A miniature out-of-plane acceleration sensor for detecting micro-vibrations, characterized in that, Includes an optical fiber (1) and an elastic component (2) disposed at 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) and four second cantilever beams (25). Each edge mass block (23) is distributed around the central mass block (22) and is 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 edge 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) closest to the frame (21); 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 that side; the second cantilever (242) 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 that first long side (231); 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 edge mass block (23) of the central mass block (2 ...). The first long side (231) of the edge mass block (23) is extended and 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) and connected to the inner edge of the frame (21); the first short side (232) of each edge mass block (23) is aligned with the first long side (231) of the other 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) that is close to the second cantilever beam (25) to which it is connected.

2. The miniature out-of-plane acceleration sensor for detecting micro-vibrations according to claim 1, characterized in that, The frame (21) is also provided with four connecting portions (211) extending from each of the inner top corners of the frame (21); wherein the connecting portions (211) extend 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 edge of the frame (21) through the second cantilever beam (25), which means that the other end of the first long side (231) is connected to the end of the connecting part (211) through the second cantilever beam (25).

3. The miniature out-of-plane acceleration sensor for detecting micro-vibrations according to claim 1, characterized in that, The block material is a beryllium copper alloy.

4. The miniature out-of-plane acceleration sensor for detecting micro-vibrations according to claim 1, characterized in that, It also includes a grooved base (3); The bottom of the groove base (3) is provided with a through hole (31), 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).

5. An acceleration detection method, characterized in that, Measuring acceleration in the direction perpendicular to the elastic component (2) using a micro out-of-plane accelerometer for detecting micro-vibrations as described in any one of claims 1 to 4, the method comprising: The interference light signal of the optical fiber (1) in the miniature out-of-plane accelerometer is acquired, and the spectral function of the interference light signal is... ; Spectral function of the interference light signal Perform Fourier transform and extract the peak values ​​of its spatial spectrum ,in The spatial frequency point of the peak value; According to the peak value The phase angle was calculated. ;in, , ; According to the phase angle Correspondence between acceleration The acceleration is calculated. in, For the free spectral range of the interference optical signal, The resonant frequency of the sensor. a Let λ be the acceleration, and λ be the center wavelength of the spectrum. The representative extracts the real part. This represents extracting the imaginary part. This represents the calculation of the complex modulus, where n is the refractive index of the medium in the FP cavity. and These are preset coefficients.

6. A miniature out-of-plane acceleration sensor for detecting micro-vibrations, characterized in that, It includes 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 as described in any one of claims 1 to 4; 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. Among them, 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.

7. An acceleration detection method, characterized in that, Measuring acceleration in three perpendicular directions using the micro out-of-plane accelerometer for detecting micro-vibrations as described in claim 6, the method includes: The composite signal formed by the superposition of three interferometric optical signals is acquired from the miniature out-of-plane accelerometer. ; For the composite signal Perform a Fourier transform and extract the i-th peak of the spatial spectrum. ; According to the i-th peak value The phase angle of the i-th interfering optical signal in the composite signal is calculated. ;in, , ; Based on the phase angle of the i-th interference light signal Correspondence between acceleration in the i-th direction The acceleration in the i-th direction is calculated. in, Let i be the free spectral range of the i-th interferometric light signal. The resonant frequency of the sensor. Let λ be the acceleration in the i-th direction, and λ be the center wavelength of the spectrum. The representative extracts the real part. This represents extracting the imaginary part. This represents the calculation of the complex modulus, where i is an integer greater than 0 and less than or equal to 3, and n is the refractive index of the medium in the FP cavity. , , and These are preset coefficients.

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