Membrane, FP (Fabry-Perot) sensor and preparation method

Abstract

The invention discloses a diaphragm, an FP (Fabry-Perot) sensor and a preparation method, the diaphragm comprises a diaphragm body, a plurality of vibrating pieces which are distributed in a nested manner are engraved on the diaphragm body in a hollowed-out manner, the vibrating piece on the innermost layer is an area for forming an FP resonant cavity in the diaphragm body, and the vibrating piece on the innermost layer is an area for forming the FP resonant cavity. The adjacent vibrating pieces and the diaphragm body on the outer side of the outermost vibrating piece are not disconnected, and part of the diaphragm body is reserved to serve as a connecting piece; wherein the diaphragm body and the structure on the diaphragm body form a first vibration unit; each non-innermost-layer vibrating piece and a structure surrounded by the non-innermost-layer vibrating piece form a second vibrating unit; and each non-innermost-layer vibration piece, the structure surrounded by the vibration piece and the connecting piece externally connected with the vibration piece form a third vibration unit. The design of the multi-stage vibration unit enables the sensor to cover broadband response from low frequency to high frequency, is convenient to capture multi-band composite signals, and is suitable for a complex frequency spectrum environment.

Description

TECHNICAL FIELD

[0001] The application relates to a diaphragm, an FP sensor and a preparation method, and belongs to the technical field of sensing. BACKGROUND

[0002] The FP (Fabry-Perot) optical fiber sensor (hereinafter referred to as an FP sensor) has become an important tool for sound wave and vibration detection due to its miniaturized design, high sensitivity and low power consumption. The diaphragm of the traditional FP sensor is a solid cylinder with a very small height. This structure makes the FP sensor exhibit extremely high sensitivity near the resonance frequency point, but the response degree sharply decreases in the area far from the resonance peak. This narrowband response characteristic makes it difficult for the FP sensor to completely capture a multi-frequency band composite signal, which seriously restricts the application effect of the FP sensor in a complex frequency spectrum environment. SUMMARY

[0003] The application provides a diaphragm, an FP sensor and a preparation method, and solves the problems disclosed in the background art.

[0004] According to one aspect of the application, a diaphragm is provided, which comprises a diaphragm body, a plurality of vibration pieces are hollow carved and nested distributed on the diaphragm body, the innermost vibration piece is a region forming an FP resonance cavity in the diaphragm body, the adjacent vibration pieces and the diaphragm body outside the outermost vibration piece are not connected, and part of the diaphragm body is reserved as a connecting piece; wherein the diaphragm body and the structure on the diaphragm body form a first vibration unit; each non-innermost vibration piece and the structure surrounded thereby form a second vibration unit; and each non-innermost vibration piece, the structure surrounded thereby and the connecting piece connected outwardly form a third vibration unit.

[0005] Further, in all vibration units, the structure parameters of the vibration pieces and the connecting pieces in the vibration units are adjusted to control the resonance frequency and the sensitivity of the corresponding vibration units; in the diaphragm, the number of resonance peaks is controlled by controlling the number of non-innermost vibration pieces, and the sensitivity of the vibration pieces is controlled by controlling the distribution position of the outer connecting pieces; wherein the outer connecting pieces are the connecting pieces outside the controlled vibration pieces.

[0006] Further, all the vibration pieces are regular structures.

[0007] Further, all the vibration pieces are concentrically distributed.

[0008] Further, all the connecting pieces are distributed on the same straight line.

[0009] According to another aspect of the present application, a FP sensor is provided, comprising a connecting sleeve, a ferrule embedded with an optical fiber, and the above-mentioned diaphragm, the diaphragm is arranged at the first end of the connecting sleeve, the first end of the ferrule is embedded into the ferrule channel of the connecting sleeve from the second end of the connecting sleeve, and the fiber end of the first end of the ferrule is opposite to the innermost vibration piece and forms a FP resonant cavity with the innermost vibration piece.

[0010] Further, the connecting sleeve comprises a first connecting sleeve and a second connecting sleeve, the diaphragm is connected at the first end of the first connecting sleeve, the second end of the first connecting sleeve is detachably connected with the first end of the second connecting sleeve, the inner hole of the first connecting sleeve and the inner hole of the second connecting sleeve are communicated to form the ferrule channel, and the ferrule is embedded into the ferrule channel.

[0011] Further, the surface of the diaphragm facing the optical fiber is coated with a high reflectivity film.

[0012] According to another aspect of the present application, a preparation method of a FP sensor is provided, comprising: Stripping the coating layer of the optical fiber and cleaning the surface of the optical fiber; Injecting a heat-curing glue into the inner hole of the ferrule, embedding the cleaned optical fiber into the inner hole of the ferrule and preliminarily curing, and flattening the first end of the ferrule; Preparing the diaphragm on a substrate; Preliminarily curing the diaphragm and the first end of the connecting sleeve by using the heat-curing glue; Embedding the first end of the ferrule into the ferrule channel of the connecting sleeve from the second end of the connecting sleeve, adjusting the position of the first end of the ferrule until the distance between the first end of the ferrule and the innermost vibration piece reaches a design value, preliminarily curing the ferrule and the connecting sleeve by using the heat-curing glue, and obtaining a preliminarily cured FP sensor; Placing the preliminarily cured FP sensor into a temperature control device for deep curing, and obtaining a prepared FP sensor.

[0013] Further, when connecting the ferrule, detachably connecting the first end of the second connecting sleeve with the second end of the first connecting sleeve, embedding the first end of the ferrule into the ferrule channel, adjusting the position of the first end of the ferrule until the distance between the first end of the ferrule and the innermost vibration piece reaches a design value, and preliminarily curing the ferrule and the second connecting sleeve by using the heat-curing glue.

[0014] The diaphragm body and the structure on the diaphragm body form a first vibration unit, each non-innermost vibration piece and the structure surrounded thereby form a second vibration unit, and each non-innermost vibration piece, the structure surrounded thereby, and the connecting piece connected outwardly form a third vibration unit, the multi-stage vibration unit design enables the sensor to cover a wide frequency band response from low frequency to high frequency, facilitates capturing a multi-frequency band composite signal, and is suitable for a complex frequency spectrum environment. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a structural diagram of a diaphragm; Figure 2 is a distribution diagram of a vibration unit of a diaphragm; Figure 3 is a first structural diagram of an FP sensor; Figure 4 is a second structural diagram of an FP sensor; Figure 5 is a flow chart of a preparation method of an FP sensor. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. The following description of at least one exemplary embodiment is merely illustrative in nature and in no way limits or defines the scope of the present application and its applications or uses. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of the present application.

[0017] Unless otherwise specifically stated, the relative arrangements of parts and steps, numerical expressions, and numerical values set forth in the various examples disclosed herein are not limiting but merely exemplary.

[0018] It should be understood, of course, that the dimensions of the various parts illustrated in the various drawings are shown for simplicity and the actual dimensions can depend on the specific application.

[0019] Techniques, methods, and apparatus known to those of ordinary skill in the relevant art can not be discussed in detail herein. However, where appropriate, such techniques, methods, and apparatus should be considered as being part of the specification.

[0020] In all the examples shown and discussed herein, any specific values should be interpreted as merely illustrative and not as a limitation. Thus, other examples of the exemplary embodiments can have different values.

[0021] It should be noted that like symbols and letters in the drawings represent like parts, such that when a part is discussed in one drawing, it should be understood that such discussion can apply to like parts that are discussed in other drawings.

[0022] In addition, in the description of the embodiments of the present application, the terms "first", "second", and the like are used only to distinguish one part from another, and cannot be understood as indicating or implying relative importance. Thus, the features defined with "first", "second" can explicitly or implicitly include one or more features.

[0023] Referring to Figure 1 ,Figure 1 is a structural diagram of a diaphragm 4 provided by an embodiment of the present application. The diaphragm 4 can at least include a diaphragm body 1, and a plurality of vibrating pieces 2 are nested and distributed in the diaphragm body 1. The innermost vibrating piece 2 is a region of the diaphragm body 1 forming an FP resonant cavity. The vibrating pieces 2 are not connected between adjacent vibrating pieces 2, and the vibrating pieces 2 are not connected between the outermost vibrating piece 2 and the diaphragm body 1 outside the outermost vibrating piece 2. Part of the diaphragm body 1 is reserved as a connecting piece 3. The diaphragm body 1 and the structure on the diaphragm body 1 form a first vibrating unit. Each non-innermost vibrating piece 2 and the structure surrounded by the non-innermost vibrating piece 2 form a second vibrating unit. Each non-innermost vibrating piece 2, the structure surrounded by the non-innermost vibrating piece 2, and the connecting piece 3 connected outwardly of the non-innermost vibrating piece 2 form a third vibrating unit.

[0024] The multi-stage vibrating unit design in the diaphragm 4 described above enables the sensor to cover a wide frequency band response from low frequency to high frequency, facilitates the capture of multi-frequency band composite signals, and is suitable for complex spectrum environments.

[0025] It should be noted that the diaphragm body 1 is a highly thin solid cylinder, Figure 1 The shape in the diaphragm body 1 is a common circle, and the material can be a stainless steel sheet or a carbon fiber composite material. The specific needs are determined according to the actual situation of the application scenario and cost.

[0026] It should be noted that the innermost vibrating piece 2 needs to form an FP resonant cavity, so the vibrating piece 2 is a solid region. The position of the solid region can be at the center of the diaphragm body 1 or eccentrically distributed. Figure 1 In the circular diaphragm body 1, the solid region is arranged at the center position, which not only facilitates engraving, but also facilitates alignment with the optical fiber 8 when implementing the sensor.

[0027] It should be noted that any vibrating piece 2 described above can be a regular structure vibrating piece 2 or an irregular structure vibrating piece 2. However, in order to facilitate processing and control the resonant frequency and sensitivity by adjusting a small number of structure parameters, in some embodiments, all vibrating pieces 2 are arranged as regular structures. For specific structures, please refer to Figure 1 The innermost vibrating piece 2 is a solid square vibrating piece, and the non-innermost vibrating piece 2 is a square frame structure.

[0028] Similarly, in order to further facilitate processing, in some embodiments, all vibrating pieces 2 are concentrically distributed, and all connecting pieces 3 are distributed on the same straight line. For specific structures, please refer to Figure 1 The center of the square vibrating piece and the center of the square frame structure are the center of the diaphragm body 1, and all connecting pieces 3 are distributed on the straight line passing through the center.

[0029] For specific structures, please refer to Figure 2, the vibration characteristics of the diaphragm 4 present a multi-modal response characteristic, specifically: the diaphragm body 1 and all structures on the diaphragm body 1 form a first vibration unit (i.e. Figure 2 structures in the blue range), a first-order vibration mode of the first vibration unit, forming a basic resonant frequency, determines the low-frequency characteristics. Each square frame structure and the structure surrounded by itself form a second vibration unit (i.e. Figure 2 structures in the green range, Figure 2 only the innermost second vibration unit is drawn), that is, the square diaphragm 4 vibration unit formed by the coupling of the square frame and the inner structure, which contributes to the high-frequency vibration characteristics; each square frame structure and the structure surrounded by itself, and the connecting piece 3 connected outwardly, form a third vibration unit (i.e. Figure 2 structures in the red range, Figure 2 only the outermost third vibration unit is drawn), that is, the cantilever beam vibration unit composed of the connecting piece 3 and the inner structure, which also contributes to the high-frequency vibration characteristics.

[0030] Therefore, it can be seen that with each additional layer of square frame and connecting piece 3 connected outwardly, a new vibration mode is introduced, and each of these newly added structural units corresponds to a specific resonant frequency, that is, the number of resonant peaks can be controlled by controlling the number of non-innermost vibration pieces 2 (i.e. square frames), and the more square frames there are, the more resonant peaks there are. Therefore, the number of square frames and connected connecting pieces 3 in the diaphragm 4 can be flexibly configured according to actual needs.

[0031] When the sound pressure acts on the diaphragm 4, the multi-level square frame structure and the connecting piece 3 vibrate cooperatively, so the sensitivity of the vibration piece 2 can be controlled by controlling the distribution position of the outer connecting piece 3 in the diaphragm 4; wherein the outer connecting piece 3 is the connecting piece outside the controlled vibration piece 2; for example, the sensitivity of the innermost vibration piece 2 is controlled by the distribution position of the three connecting pieces 3 outside it, specifically, when the connecting pieces 3 of adjacent two vibration pieces 2 are distributed on both sides and at symmetrical positions (i.e. Figure 1 in the position), the inner sensitivity reaches the maximum, and when the connecting pieces 3 of adjacent two vibration pieces 2 are on the same side, the closer the spatial position, the lower the inner sensitivity.

[0032] Therefore, by increasing the number of nested square frame structures, more low-frequency resonant modes are introduced, and by optimizing the position of the connecting piece 3, the resonant characteristics of the medium and high frequency bands can be enriched, and this modular structural design method provides a customizable adjustment means for the frequency response characteristics of the sensor, which can accurately regulate the number and distribution characteristics of the resonant peaks of the FP sensor, thereby meeting the needs of different application scenarios for frequency band characteristics.

[0033] It should be noted that based on the structure of the above vibration unit, the vibration characteristics of each vibration unit are only related to the structural parameters of the vibration piece 2 and the connecting piece 3, and therefore in some embodiments, by adjusting the structural parameters of the vibration piece 2 and the connecting piece 3 in each vibration unit, the resonant frequency and sensitivity of the corresponding vibration unit can be controlled.

[0034] Still taking the structure in Figure 1 as an example, research shows that the increase of the side length of the frame structure can significantly reduce the corresponding resonant frequency and improve the sensitivity, and the decrease of the thickness of the frame structure can also produce the effect of reducing the frequency and improving the sensitivity, and the increase of the beam width (including the width of the connecting piece 3 and the frame) can increase the resonant frequency but reduce the sensitivity. It is worth noting that the change of the beam degree of the connecting piece 3 is more sensitive to the high-frequency resonant mode, and the adjustment of the beam width of the frame structure mainly regulates the low-frequency characteristics. This size-performance relationship presents complex nonlinear characteristics, which is also affected by multiple factors such as material mechanical properties and boundary constraint conditions.

[0035] Therefore, in actual engineering design, a multi-objective optimization strategy can be established to seek the best balance point between frequency characteristics, sensitivity indicators and structural reliability, and through the combination of finite element simulation and experimental verification, the optimal matching relationship of each structural parameter can be determined. The design method based on multi-parameter collaborative optimization proposed here not only meets the performance requirements of the sensor in different application scenarios, but also ensures the long-term stability and environmental adaptability of the product in actual working conditions, providing a reliable technical path for the customized development of high-performance sensors.

[0036] The above diaphragm 4 adopts a plurality of vibration pieces 2 in a nested distribution, and the connecting pieces 3 are connected between adjacent vibration pieces 2 and between the outermost vibration piece 2 and the diaphragm body 1 outside the outermost vibration piece 2 to realize mechanical coupling. Through this structural innovation, multiple vibration units with different characteristic sizes are integrated on a single diaphragm 4, each unit has a separate resonant peak due to the difference in structural parameters, and the interaction between the resonant peaks can form multiple flat response regions. By accurately controlling the side length of each frame structure, the width and thickness of the connecting piece 3 and other parameters, the independent regulation of each resonant frequency can be realized, and the active design of the resonant frequency can be realized.

[0037] Based on the above diaphragm 4, the application further discloses an FP sensor, which is described with reference to Figure 3The sensor can at least include a connecting sleeve, a ferrule 7 in which an optical fiber 8 is embedded, and the above-mentioned diaphragm 4, the diaphragm 4 is connected to the first end of the connecting sleeve, the first end of the ferrule 7 is embedded into the ferrule channel of the connecting sleeve from the second end of the connecting sleeve, the end of the optical fiber 8 at the first end of the ferrule 7 is opposite to the innermost layer of the vibration piece 2, and an FP resonant cavity is formed between the optical fiber 8 and the innermost layer of the vibration piece 2; through the improvement of the diaphragm 4, the FP sensor can have a wider effective working frequency band.

[0038] It should be noted that the connecting sleeve can generally be a metal connecting sleeve, of course, other hard materials are also available. The optical fiber 8 herein generally uses a single-mode optical fiber. In order to facilitate the connection of the optical fiber 8 to the connecting sleeve, the optical fiber 8 can be fixed in a mounting sleeve, and the mounting sleeve can be adhered to or threaded onto the connecting sleeve. The ferrule 7 can be a ceramic ferrule, which facilitates high-precision coaxial fixation of the optical fiber 8. When the optical fiber 8 is installed, the ceramic ferrule wrapped with the optical fiber 8 is directly embedded into the connecting sleeve.

[0039] In some embodiments, in order to facilitate the rapid realization of the flexible adjustment of the FP cavity length and meet the needs of different measurement scenarios, in some embodiments, the connecting sleeve is divided into two segments, as shown in Figure 4 , the connecting sleeve includes a first connecting sleeve 5 and a second connecting sleeve 6, the diaphragm 4 is connected to the first end of the first connecting sleeve 5, the second end of the first connecting sleeve 5 is detachably connected to the first end of the second connecting sleeve 6, the inner hole of the first connecting sleeve 5 and the inner hole of the second connecting sleeve 6 are in communication to form a ferrule channel, and the ferrule 7 is embedded into the ferrule channel; when it is necessary to adapt to different cavity lengths, the first connecting sleeve 5 and the second connecting sleeve 6 only need to be separated, and different lengths of the first connecting sleeve 5 can be replaced.

[0040] It should be noted that the connecting method of the first connecting sleeve 5 and the second connecting sleeve 6 can adopt a thread, for example, the first connecting sleeve 5 is provided with external threads, the second connecting sleeve 6 is provided with internal threads, and the two are threadedly connected through the internal threads and the external threads. This threaded connection structure not only ensures the precise centering and reliable connection of the assembly, improves the mechanical stability and environmental adaptability of the FP sensor, is particularly suitable for monitoring applications under complex working conditions, but also makes the FP sensor have convenient detachability, and can quickly realize the flexible adjustment of the FP cavity length, and meet the needs of different measurement scenarios.

[0041] When the diaphragm 4 of the above-mentioned FP sensor is excited by external sound waves, the optical interference characteristics of the FP cavity will change accordingly with the frequency, thereby realizing high-sensitivity and wide-band detection of different frequency sound signals. The design of this composite vibration mode breaks through the frequency response limitation of traditional single-resonance-peak sensors.

[0042] Based on the FP sensor of Figure 3 , the present application also relates to a preparation method of an FP sensor, and the steps can at least include: Step 1, stripping the coating layer of the optical fiber 8 and cleaning the surface of the optical fiber 8.

[0043] The coating layer of the optical fiber 8 is stripped using professional tools, and then the surface of the optical fiber 8 is carefully wiped with a cleaning material such as alcohol-dipped dust-free paper to ensure that the residual coating layer and other contaminants are completely removed. The end face of the optical fiber 8 is processed using a precision cutting device to achieve an optical-grade flatness.

[0044] Step 2, injecting hot curing glue into the inner hole of the ferrule 7, embedding the cleaned optical fiber 8 into the inner hole of the ferrule 7 and preliminary curing, and flattening the first end of the ferrule 7.

[0045] The inner hole of the ferrule 7 is injected with an appropriate amount of hot curing glue using a precision dispensing machine. The pre-processed optical fiber 8 is carefully inserted into the glue-injected ferrule 7. After the optical fiber 8 is centered and fixed, the hot curing glue is preliminarily cured by a heating table. After the curing is completed, the excess part of the ferrule 7 protruding outside is cut off using an optical fiber 8 cutting knife. The assembly is installed on an optical fiber 8 grinder for grinding to obtain a highly flat, smooth and perpendicular to the optical fiber 8 axis end face of the optical fiber 8.

[0046] Step 3, preparing the diaphragm 4 on the substrate.

[0047] The diaphragm 4 is prepared on a stainless steel sheet of a specific thickness using femtosecond laser microfabrication technology. The specific preparation process includes: first, selecting a 304 stainless steel sheet as the substrate material, and using a computer-controlled femtosecond laser focusing system to precisely etch the material according to the pre-set three-dimensional processing path.

[0048] The preparation process utilizes the nonlinear interaction between ultrashort pulse laser and material, and directly processes a nested structure with nanometer-level precision on the stainless steel sheet by precisely removing the material layer by layer. The femtosecond laser processing technology has the characteristics of small heat-affected zone and high processing precision, which can ensure that the size tolerance of each structural unit is controlled within ±1 μm, which is crucial for achieving the expected multi-frequency resonance characteristics.

[0049] Step 4, preliminarily curing the diaphragm 4 and the first end of the connecting sleeve with hot curing glue.

[0050] Uniformly apply an appropriate amount of hot curing glue to the connecting surface of the mounting sleeve that fixes the diaphragm 4 and the connecting surface of the connecting sleeve at one end, and then bond them after precise alignment, and preliminarily cure using an ultraviolet curing lamp.

[0051] Step 5, embedding the first end of the ferrule 7 into the ferrule channel of the connecting sleeve from the second end of the connecting sleeve, adjusting the position of the first end of the ferrule 7 until the distance between the first end of the ferrule 7 and the innermost vibration piece 2 reaches the designed value, and preliminarily curing the ferrule 7 and the connecting sleeve with hot curing glue to obtain a preliminarily cured FP sensor.

[0052] Insert the ferrule 7 into the connecting sleeve, and adjust the relative position of the end face of the optical fiber 8 and the innermost vibrating element 2 through the precision adjustment mechanism to make them strictly parallel and coaxial. At the same time, precisely control the FP cavity length to the design value, and evenly apply an appropriate amount of thermosetting adhesive at the connection between the connecting sleeve and the ferrule 7, and use an ultraviolet curing lamp for initial fixation.

[0053] Step 6: Place the pre-cured FP sensor into a temperature-controlled device for deep curing to obtain the completed FP sensor.

[0054] The pre-cured FP sensor was placed in a temperature-controlled chamber, and a specific temperature was set according to the curing characteristics of the thermosetting adhesive. Sufficient time was allowed for the adhesive to fully cure. This staged curing process ensured accurate component positioning and significantly improved the overall stability and environmental adaptability of the FP sensor's mechanical structure.

[0055] The above method uses femtosecond laser micromachining technology to prepare diaphragm 4 and combines it with a staged curing process to realize a high-performance fiber optic FP sensor with multi-resonance frequency characteristics.

[0056] If the above FP sensor is Figure 4 In the structure shown above, in the above preparation method, when connecting the insert 7, the first end of the second connecting sleeve 6 is detachably connected to the second end of the first connecting sleeve 5, the first end of the insert 7 is embedded into the insert channel, the position of the first end of the insert 7 is adjusted until the distance between the first end of the insert 7 and the innermost vibrating element 2 reaches the design value, and the insert 7 and the second connecting sleeve 6 are initially cured with thermosetting adhesive.

[0057] See Figure 5 ,against Figure 4 The specific preparation method of the structure can be as follows: 1) Fiber 8 pretreatment: Use professional tools to remove the coating layer of fiber 8, and then use cleaning materials (such as lint-free paper soaked in alcohol) to carefully wipe the surface of fiber 8 to ensure that the residual coating layer and other contaminants are completely removed. Use precision cutting equipment to process the end face of fiber 8 to achieve optical-grade flatness.

[0058] 2) Assembly of ceramic ferrule 7 and treatment of fiber optic end face: Use a precision dispensing machine to inject an appropriate amount of thermosetting adhesive into the inner hole of ferrule 7. Carefully insert the pre-treated fiber optic 8 into the glued ferrule 7. After the fiber optic 8 is centered and fixed, use a heating table to pre-cure the thermosetting adhesive. After curing, use a fiber optic 8 cleaver to cut off the excess part of the ferrule 7. Install the assembly on a precision fiber optic 8 polishing machine to polish it to obtain a highly flat, smooth fiber optic 8 end face that is perpendicular to the fiber optic 8 axis.

[0059] 3) Diaphragm 4 preparation: Diaphragm 4 is prepared by femtosecond laser microprocessing technology on a stainless steel sheet of a specific thickness. The specific preparation process includes: first, 304 stainless steel sheet is selected as the base material, and the material is precisely etched according to the preset three-dimensional processing path by the computer-controlled femtosecond laser focusing system.

[0060] The preparation process utilizes the nonlinear interaction of ultrashort pulse laser with materials, and directly processes the nested structure with nanometer precision on the stainless steel sheet by layer-by-layer precise material removal. Femtosecond laser processing technology has the characteristics of small heat-affected zone and high processing precision, which can ensure that the size tolerance of each structural unit is controlled within ±1 μm, which is crucial for achieving the expected multi-frequency resonance characteristics.

[0061] 4) Overall assembly and curing process: Uniformly apply an appropriate amount of heat-curing glue to the mounting sleeve connecting surface of the diaphragm 4 and the first connecting sleeve 5 end connecting surface, accurately align and bond the two, and use an ultraviolet curing lamp for preliminary curing. Then, connect the second connecting sleeve 6 with the first connecting sleeve 5 of the fixed diaphragm 4, i.e. threaded connection, insert the ferrule 7 into the second connecting sleeve 6, adjust the relative position of the fiber 8 end face and the innermost layer of the vibrating member 2 through the precise adjustment mechanism, make them strictly parallel and coaxial, and accurately control the FP cavity length to the designed value. After completing the cavity length adjustment, uniformly apply an appropriate amount of heat-curing glue to the connection between the second connecting sleeve 6 and the ferrule 7, and use an ultraviolet curing lamp for preliminary fixation. Place the preliminarily cured FP sensor in a temperature control box, set a specific temperature according to the curing characteristics of the heat-curing glue, and keep it for a sufficient time to allow the glue to cure deeply.

[0062] The above method realizes a high-performance fiber FP sensor with multi-resonant frequency characteristics by using femtosecond laser microprocessing technology to prepare diaphragm 4 and combining with a phased curing process. This phased curing process not only ensures accurate positioning of the assembly, but also significantly improves the overall stability and environmental adaptability of the FP sensor mechanical structure. In particular, the combination of threaded connection and glue fixation makes the FP sensor have excellent anti-vibration performance and long-term reliability. This modular assembly process combined with the threaded adjustment structure not only ensures the performance consistency of the FP sensor, but also facilitates later maintenance and parameter adjustment.

[0063] After the finished product, the FP sensor needs to undergo strict performance tests, including multi-band response characteristic detection and environmental adaptability verification, to ensure that it meets the design requirements of wide frequency band and high sensitivity.

[0064] The above FP sensor can simultaneously excite multiple vibration modes, produce multiple adjustable resonance peaks on a single device, significantly broaden the working frequency range and improve the measurement sensitivity. In addition, this innovative design integrated with wide frequency response, high sensitivity, adjustable cavity length and environmental adaptability is particularly suitable for power equipment monitoring, industrial fault diagnosis and other scenarios that require detection of wideband composite signals, providing a new solution for the application of optical fiber 8 sensing technology in industrial monitoring field, which will effectively promote the practical application and development of high-performance optical fiber 8 sensors in complex environments.

[0065] The above only describes the preferred embodiments of the present application. It should be noted that those skilled in the art can make several improvements and modifications without departing from the technical principles of the present application. These improvements and modifications should also be considered as within the scope of the present application.

Claims

1. A diaphragm, characterized by The diaphragm includes a diaphragm body, a plurality of vibrating pieces are nested and distributed in the diaphragm body, the innermost vibrating piece is a region forming an FP resonant cavity in the diaphragm body, the vibrating pieces are not connected between adjacent vibrating pieces and between the outermost vibrating piece and the diaphragm body outside the outermost vibrating piece, and part of the diaphragm body is reserved as a connecting piece; wherein the diaphragm body and the structure on the diaphragm body form a first vibrating unit; each non-innermost vibrating piece and the structure surrounded thereby form a second vibrating unit; and each non-innermost vibrating piece, the structure surrounded thereby, and the connecting piece connected outwardly form a third vibrating unit.

2. The membrane of claim 1, wherein, In all vibrating units, the resonant frequency and sensitivity of the corresponding vibrating unit are controlled by adjusting the structural parameters of the vibrating piece and the connecting piece in the vibrating unit; in the diaphragm, the number of resonant peaks is controlled by controlling the number of non-innermost vibrating pieces, and the sensitivity of the vibrating piece is controlled by controlling the distribution position of the outer connecting piece; wherein the outer connecting piece is the connecting piece outside the controlled vibrating piece.

3. The diaphragm according to claim 1 or 2, characterized in that All vibrating pieces are regular structures.

4. The diaphragm of claim 3, wherein, All vibrating pieces are concentrically distributed.

5. The diaphragm of claim 1 or 2, wherein, All connecting pieces are distributed on the same straight line.

6. An FP sensor characterized in that, The diaphragm includes a connecting sleeve, a ferrule embedded with an optical fiber, and the diaphragm of any one of claims 1-5, the diaphragm is arranged at the first end of the connecting sleeve, the first end of the ferrule is embedded into the ferrule channel of the connecting sleeve from the second end of the connecting sleeve, and the end of the optical fiber at the first end of the ferrule is opposite to the innermost vibrating piece and forms an FP resonant cavity with the innermost vibrating piece.

7. The FP sensor of claim 6, wherein, The connecting sleeve includes a first connecting sleeve and a second connecting sleeve, the diaphragm is connected to the first end of the first connecting sleeve, the second end of the first connecting sleeve is detachably connected to the first end of the second connecting sleeve, the inner hole of the first connecting sleeve and the inner hole of the second connecting sleeve are communicated to form a ferrule channel, and the ferrule is embedded into the ferrule channel.

8. The FP sensor according to claim 6 or 7, characterized in that, The surface of the diaphragm facing the optical fiber is coated with a high-reflectivity film.

9. A method of manufacturing an FP sensor, characterized by, The FP sensor is the FP sensor of any one of claims 6-8, and the preparation method comprises: The coating layer of the optical fiber is stripped, and the surface of the optical fiber is cleaned; Hot curing glue is injected into the inner hole of the ferrule, the cleaned optical fiber is embedded into the inner hole of the ferrule and preliminarily cured, and the first end of the ferrule is flattened; The diaphragm is prepared on a substrate; The diaphragm and the first end of the connecting sleeve are preliminarily cured by using hot curing glue; The first end of the ferrule is embedded into the ferrule channel of the connecting sleeve from the second end of the connecting sleeve, the position of the first end of the ferrule is adjusted until the distance between the first end of the ferrule and the innermost vibrating piece reaches a design value, the ferrule and the connecting sleeve are preliminarily cured by using hot curing glue, and a preliminarily cured FP sensor is obtained; The preliminarily cured FP sensor is placed in a temperature control device for deep curing, and a prepared FP sensor is obtained.

10. The method of claim 9, wherein, If the FP sensor is the FP sensor of claim 7, the preparation method comprises: When connecting the ferrule, the first end of the second connecting sleeve is detachably connected to the second end of the first connecting sleeve, the first end of the ferrule is embedded into the ferrule channel, and the position of the first end of the ferrule is adjusted until the distance between the first end of the ferrule and the innermost vibrating piece reaches a design value, and the ferrule and the second connecting sleeve are preliminarily cured by using hot curing glue.

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