Optical fiber Fabry-Perot sound sensor and preparation method thereof

Abstract

The invention relates to the technical field of sensors, and provides an optical fiber Fabry-Perot sound sensor and a preparation method thereof. The optical fiber Fabry-Perot sound sensor comprises a mounting assembly, a corrugated sensitive diaphragm and an optical fiber assembly, the mounting assembly is provided with a groove and a flow guide hole communicated with the groove; the corrugated sensitive diaphragm is arranged at the notch end of the groove, and a corrugated structure is formed on the first side surface of the corrugated sensitive diaphragm; the optical fiber assembly is installed on the installation assembly, and the end face of the optical fiber assembly is arranged in the groove and is opposite to the first side face of the corrugated sensitive diaphragm. Wherein the groove defines a Fabry-Perot cavity between the first side surface of the corrugated sensitive diaphragm and the end surface of the optical fiber assembly, and the Fabry-Perot cavity is communicated with the external environment through the diversion hole. The optical fiber Fabry-Perot sound sensor is simple in structure and convenient to assemble, the sensitivity of the optical fiber Fabry-Perot sound sensor is improved, and accurate measurement of sound signals is facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of sensors, and in particular to an optical fiber Fabry-Perot sound sensor and a preparation method thereof. Background Art

[0002] Sound is generated by the vibration of an object and propagates in the form of sound waves. Accurate measurement and interpretation of sound is an important way for people to understand each other and to exchange information with machines and nature. At present, electrical sound sensors are mainly used to collect sound signals. However, during use, the sensing structure and signal processing circuit of the electrical sound sensor need to reasonably match the impedance to achieve long-distance transmission of the signal, which requires additional design in the application of the electrical sound sensor, increasing the complexity of the engineering and system. At the same time, due to the structural and principle limitations of electrical sound sensors, electrical sound sensors cannot be well applied in extreme environments with high temperature, high pressure and strong electromagnetic interference.

[0003] In the related technology, optical fiber sensors are a new type of sensor, which can measure physical quantities such as temperature, pressure, strain, etc. by means of different sensing mechanisms and structural designs, and have the advantages of simple structure, small size, high temperature resistance, anti-electromagnetic interference and low cost, and can detect sound by using the principle of optical interference. However, the current optical fiber sensors used for sound collection have unreasonable structural designs, generally have poor sensitivity, and are difficult to accurately measure sound signals. Summary of the invention

[0004] The present invention provides an optical fiber Fabry-Perot acoustic sensor and a preparation method thereof, which are used to at least solve or improve the problem that the existing optical fiber type sensor has poor sensitivity and is difficult to achieve accurate measurement of acoustic signals.

[0005] In a first aspect, the present invention provides an optical fiber Fabry-Perot acoustic sensor, comprising: a mounting assembly, a corrugation sensitive diaphragm, and an optical fiber assembly; The mounting assembly is provided with a groove and a guide hole communicating with the groove; The corrugated sensitive diaphragm is arranged at the notch end of the groove, and a corrugated structure is formed on the first side of the corrugated sensitive diaphragm; The optical fiber assembly is mounted on the mounting assembly, and the end face of the optical fiber assembly is built into the groove and arranged opposite to the first side face of the corrugated sensitive membrane; The groove defines a Fabry-Perot cavity between the first side surface of the corrugation-sensitive membrane and the end surface of the optical fiber assembly, and the Fabry-Perot cavity is connected to the external environment through the guide hole.

[0006] According to a fiber optic Fabry-Perot sound sensor provided by the present invention, the corrugated structure includes a plurality of step structures; the plurality of step structures are arranged in sequence from the inside to the outside relative to the center of the corrugated sensitive diaphragm, and each of the step structures is extended circumferentially relative to the center of the corrugated sensitive diaphragm.

[0007] According to an optical fiber Fabry-Perot sound sensor provided by the present invention, along the arrangement sequence from inside to outside, the height of the step surface corresponding to each step structure relative to the second side surface of the corrugated sensitive diaphragm decreases successively.

[0008] According to the optical fiber Fabry-Perot sound sensor provided by the present invention, the end face of the optical fiber component is provided with a high-reflection film.

[0009] According to an optical fiber Fabry-Perot sound sensor provided by the present invention, the installation assembly comprises a shell and a base; the shell is provided with a mounting groove and a first channel and a first through hole connected to the mounting groove; the base is provided with the groove and a second channel and a second through hole connected to the groove; The base is arranged in the installation groove, the first channel and the second channel are connected to form the guide hole, the first through hole and the second through hole are connected, a part of the optical fiber assembly is arranged in the first through hole, and another part is arranged in the second through hole.

[0010] According to an optical fiber Fabry-Perot acoustic sensor provided by the present invention, the optical fiber assembly comprises a single-mode optical fiber and an optical fiber collimator; The second through hole includes a first hole segment and a second hole segment, the first through hole is connected to a first end of the first hole segment, and the second end of the first hole segment is connected to a first end of the second hole segment; A portion of the optical fiber collimator is arranged in the first through hole, and another portion is arranged in the first hole section; a portion of the single-mode optical fiber is inserted in the optical fiber collimator, and another portion is inserted in the second hole section and extends out of the housing.

[0011] According to a fiber optic Fabry-Perot sound sensor provided by the present invention, an anti-fool structure is provided between the groove wall of the mounting groove and the side wall of the base, and the anti-fool structure is used to limit the installation posture of the base relative to the mounting groove to ensure that the first channel and the second channel are connected.

[0012] In a second aspect, the present invention provides a method for preparing an optical fiber Fabry-Perot acoustic sensor, comprising: Prepare a shell and a base, wherein the shell is provided with a mounting groove and a first channel and a first through hole communicating with the mounting groove, and the base is provided with the groove and a second channel and a second through hole communicating with the groove; Obtaining a single-mode optical fiber and an optical fiber collimator, stripping a portion of the single-mode optical fiber from its coating, and assembling a portion of the single-mode optical fiber from which its coating is removed and the optical fiber collimator to obtain an optical fiber assembly; The corrugated sensitive diaphragm is prepared by a compression molding process to form a corrugated structure on a first side of the corrugated sensitive diaphragm; Installing the base in the installation groove to ensure that the first channel and the second channel are connected to form a guide hole; Passing the single-mode optical fiber away from the optical fiber collimator through the second through hole and the first through hole in sequence until a portion of the optical fiber collimator is disposed in the first through hole and another portion of the optical fiber collimator is disposed in the second through hole, ensuring that the end face of the optical fiber assembly is built into the groove; The corrugation sensitive membrane is packaged at the notch end of the groove to ensure that the first side surface of the corrugation sensitive membrane is arranged opposite to the end surface of the optical fiber assembly.

[0013] According to a method for preparing an optical fiber Fabry-Perot acoustic sensor provided by the present invention, the steps of preparing the substrate include: CNC machining the metal substrate to prepare a semi-finished substrate; The substrate semi-finished product is processed by femtosecond laser to construct the mounting groove, the first channel and the first through hole on the substrate semi-finished product to obtain the substrate.

[0014] According to a method for preparing an optical fiber Fabry-Perot acoustic sensor provided by the present invention, the step of removing a portion of the coating layer of a single-mode optical fiber and assembling the optical fiber collimator tube to obtain an optical fiber assembly comprises: inserting the portion of the coating layer of the single-mode optical fiber into the optical fiber collimator tube, ensuring that the end of the single-mode optical fiber is flush with the end of the optical fiber collimator tube; The connection between the end of the single-mode optical fiber and the end of the optical fiber collimator is welded by using a carbon dioxide laser to preliminarily complete the assembly of the optical fiber assembly; The welding part on the optical fiber assembly is cut to ensure that the end of the optical fiber assembly forms a smooth end face.

[0015] According to a method for preparing an optical fiber Fabry-Perot acoustic sensor provided by the present invention, after completing the assembly of the optical fiber component, the method further comprises: A high-reflective film is formed on the end face of the optical fiber component by adopting a magnetron sputtering or evaporation process.

[0016] The optical fiber Fabry-Perot sound sensor and the preparation method thereof provided by the present invention can construct a Fabry-Perot cavity between the first side surface of the flared sensitive diaphragm and the end surface of the optical fiber assembly by installing an assembly, a corrugated sensitive diaphragm and an optical fiber assembly. When collecting sound signals, the corrugated sensitive diaphragm generates mechanical vibration under the action of sound, and the vibration of the corrugated sensitive diaphragm causes the cavity length of the Fabry-Perot cavity to change. The change in the cavity length of the Fabry-Perot cavity causes the change in the optical interference signal. The sound information can be measured by detecting the interference spectrum carrying the cavity length information fed back by the optical fiber assembly. In the process of sound detection, since the first side surface of the corrugated sensitive diaphragm is formed with a corrugated structure, it can be ensured that the corrugated sensitive diaphragm maintains linear vibration under the action of sound, and the abnormal vibration of the diaphragm when it is greatly deformed can be avoided to affect the detection accuracy. At the same time, since the Fabry-Perot cavity is connected to the external environment through the guide hole, the air pressure inside and outside the Fabry-Perot cavity can be balanced through the guide hole, so that the optical fiber Fabry-Perot sound sensor can respond to sound signals with lower intensity. Therefore, this design not only improves the sensitivity of the optical fiber Fabry-Perot sound sensor, but also facilitates the accurate measurement of sound signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a schematic diagram of the cross-sectional structure of the optical fiber Fabry-Perot sound sensor provided by the present invention; Figure 2 It is a schematic diagram of the cross-sectional structure of the corrugated sensitive diaphragm provided by the present invention; Figure 3 It is a schematic flow chart of a method for preparing the optical fiber Fabry-Perot sound sensor provided by the present invention; Figure 4 It is a structural schematic diagram of detecting the optical fiber Fabry-Perot sound sensor provided by the present invention; Reference numerals: 1. Fiber Fabry-Perot sound sensor; 11. Mounting assembly; 12. Corrugated sensitive diaphragm; 13. Fiber optic assembly; 14. High-reflection film; 111. Shell; 112. Matrix; 121. Corrugated structure; 1211. Step structure; 131. Single-mode optical fiber; 132. Fiber optic collimator; 101. Fabry-Perot cavity; 102. Guide hole; 2. Demodulator; 3. Monitoring terminal; 4. Bracket; 5. Sound source. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Combine the following Figure 1-Figure 4 , the optical fiber Fabry-Perot sound sensor and the preparation method thereof provided by the embodiment of the invention are described in detail through specific embodiments and their application scenarios.

[0021] In the first aspect, Figure 1 and Figure 2 As shown, an embodiment of the present invention provides an optical fiber Fabry-Perot sound sensor 1, comprising: a mounting assembly 11, a corrugated sensitive diaphragm 12 and an optical fiber assembly 13; The mounting assembly 11 is provided with a groove and a guide hole 102 communicating with the groove; the corrugated sensitive diaphragm 12 is provided at the notch end of the groove, and a corrugated structure 121 is formed on the first side surface of the corrugated sensitive diaphragm 12; The optical fiber assembly 13 is installed on the installation assembly 11, and the end surface of the optical fiber assembly 13 is built into the groove and is arranged opposite to the first side surface of the corrugated sensitive membrane 12; The groove defines a Fabry-Perot cavity 101 between the first side surface of the corrugated sensitive membrane 12 and the end surface of the optical fiber assembly 13 , and the Fabry-Perot cavity 101 is connected to the external environment through the guide hole 102 .

[0022] It is understandable that the corrugated sensitive diaphragm 12 can be an elastic diaphragm, and the corrugated sensitive diaphragm 12 has good elasticity, tensile strength and other mechanical properties; for example, the corrugated sensitive diaphragm 12 can be made of materials such as parylene or silicone rubber. At the same time, the corrugated sensitive diaphragm 12 is usually configured in a circular shape. When facing different test scenarios, the radius and thickness of the corrugated sensitive diaphragm 12 can be reasonably adjusted to achieve different sensitive measurement capabilities.

[0023] The corrugated structure 121 has a corrugated shape similar to that formed on the water surface when a foreign object is thrown into it. The corrugated structure 121 is arranged in the middle area of ​​the corrugated sensitive membrane 12 and is configured to be arranged opposite to the end face of the optical fiber component 13 along the axial direction of the optical fiber component 13. The first side surface of the corrugated sensitive membrane 12 and the end face of the optical fiber component 13 form an interference surface of the optical fiber Fabry-Perot, and play a role in optical signal transmission at the same time, and the end face of the optical fiber component 13 is flattened into a smooth plane to further achieve better reflection and interference effects on the optical signal.

[0024] Thus, by providing the corrugated structure 121 on the first side of the corrugated sensitive diaphragm 12, when the corrugated sensitive diaphragm 12 generates mechanical vibration under the action of sound, the problem that the deformation of the existing flat diaphragm no longer maintains linearity when the deformation is large can be avoided.

[0025] At the same time, the cavity structure of common fiber optic Fabry-Perot sensors is a closed structure. In sound sensing, due to the influence of air pressure, the imbalance between the external air pressure and the air pressure inside the cavity will cause the sensor deformation to deviate from the theoretical value, resulting in an inability to respond to lower intensity sound information; on the contrary, the present application sets a guide hole 102, which can use the guide hole 102 to balance the air pressure inside and outside the Fabry-Perot cavity 101, thereby improving the detection accuracy of the fiber optic Fabry-Perot sound sensor 1.

[0026] In order to further ensure the detection accuracy of the optical fiber Fabry-Perot acoustic sensor 1 , the guide hole 102 may be configured to extend along the axial direction of the optical fiber assembly 13 .

[0027] The optical fiber Fabry-Perot sound sensor 1 shown in this embodiment can construct a Fabry-Perot cavity 101 between the first side surface of the ripple-sensitive diaphragm 12 and the end surface of the optical fiber component 13 by installing the component 11, the corrugation-sensitive diaphragm 12 and the optical fiber component 13. When collecting sound signals, the corrugation-sensitive diaphragm 12 generates mechanical vibrations under the action of sound. The vibration of the corrugation-sensitive diaphragm 12 causes the cavity length of the Fabry-Perot cavity 101 to change. The change in the cavity length of the Fabry-Perot cavity 101 causes the optical interference signal to change. By detecting the interference spectrum carrying the cavity length information fed back by the optical fiber component 13, the sound information can be measured. In the process of sound detection, due to the corrugation-sensitive A corrugated structure 121 is formed on the first side of the diaphragm 12, which can ensure that the corrugated sensitive diaphragm 12 maintains linear vibration under the action of sound, thereby avoiding abnormal vibration of the diaphragm when it is greatly deformed and affecting the detection accuracy; at the same time, since the Fabry-Perot cavity 101 is connected to the external environment through the guide hole 102, the air pressure inside and outside the Fabry-Perot cavity 101 can be balanced through the guide hole 102, ensuring that the optical fiber Fabry-Perot sound sensor 1 can respond to sound signals of lower intensity; therefore, this design not only improves the sensitivity of the optical fiber Fabry-Perot sound sensor 1, but also facilitates the accurate measurement of sound signals, and can be widely used in sound testing of electronic devices such as learning machines and smart large screens.

[0028] In some embodiments, Figure 2 As shown, the corrugated structure 121 includes a plurality of step structures 1211 ; the plurality of step structures 1211 are arranged sequentially from the inside to the outside relative to the center of the corrugated sensitive diaphragm 12 , and each step structure 1211 is circumferentially extended relative to the center of the corrugated sensitive diaphragm 12 .

[0029] Specifically, the first side surface of the corrugated sensitive diaphragm 12 is denoted by P1, and the second side surface of the corrugated sensitive diaphragm 12 is denoted by P2; wherein P1 is disposed toward the groove, and P2 is disposed away from the groove.

[0030] Each step structure 1211 has a step surface perpendicular to the axis of the optical fiber assembly 13, and the step surface of each step structure 1211 extends in a ring shape relative to the center of the corrugated sensitive diaphragm 12; Figure 2 In the placement posture of the corrugation sensitive diaphragm 12 shown, the step surfaces of each step structure 1211 are all arranged horizontally.

[0031] Furthermore, along the arrangement sequence from the inside to the outside, the height of the step surface corresponding to each step structure 1211 relative to the second side surface of the corrugated sensitive diaphragm 12 is successively reduced. This design can ensure that the thickness of the corrugated sensitive diaphragm 12 gradually decreases from the center to the edge of the corrugated sensitive diaphragm 12, which is conducive to reducing the edge thickness of the corrugated sensitive diaphragm 12 and improving the sensitivity of the optical fiber Fabry-Perot sound sensor 1.

[0032] Of course, along the arrangement order from the inside to the outside, the height of the step surface corresponding to each step structure 1211 relative to the second side surface of the corrugated sensitive diaphragm 12 can also be set to first decrease, then increase, and then decrease in the form of a wave distribution. This distribution form can be used for at least one cycle design, and it is only necessary to reduce the edge thickness of the corrugated sensitive diaphragm 12 as much as possible.

[0033] In some embodiments, Figure 1 As shown, the end face of the optical fiber assembly 13 is provided with a high reflection film 14 .

[0034] It is understood that the high-reflectivity coating 14 is an optical film, which is usually used to increase the reflectivity of mirrors or other optical components. The high-reflectivity coating 14 can significantly reduce the transmission and absorption of light, thereby increasing the reflectivity, making it widely used in many optical applications.

[0035] Thus, in this embodiment, a high-reflection film 14 is provided on the end face of the optical fiber component 13, the main purpose of which is to increase the reflectivity of the reflection surface, so as to better form interference and improve the contrast and intensity of the interference spectrum.

[0036] The high reflective film 14 may be a single crystal silicon film or a sapphire film, and the sapphire film is a film made of Al2O3.

[0037] In some embodiments, Figure 1 As shown, the mounting assembly 11 includes a housing 111 and a base 112; the housing 111 is provided with a mounting groove and a first channel and a first through hole communicating with the mounting groove; the base 112 is provided with a groove and a second channel and a second through hole communicating with the groove; The base 112 is disposed in the mounting groove, the first channel and the second channel are connected to form the guide hole 102, the first through hole and the second through hole are connected, a part of the optical fiber assembly 13 is disposed in the first through hole, and the other part is disposed in the second through hole.

[0038] Specifically, the shell 111 and the base 112 can both be made of metal material, or the shell 111 can be made of plastic material and the base 112 can be made of metal material.

[0039] The shell 111 and the base 112 are both columnar structures. The shell 111 includes a first main body section and a second main body section. The mounting groove is provided at the first end of the first main body section, and the second end of the first main body section and the first end of the second main body section are coaxially connected; the first channel and the first through hole are both provided along the axial direction of the optical fiber assembly 13 and penetrate the second main body section; wherein the peripheral wall of the first main body section is provided with a threaded connection structure.

[0040] At the same time, the groove is arranged at the first end of the base 112, the second end of the base 112 is fitted with the bottom surface of the installation groove, the peripheral wall of the base 112 is fitted with the wall surface of the installation groove, and the second channel and the second through hole are both arranged along the axial direction of the optical fiber assembly 13 and penetrate the base 112.

[0041] In some embodiments, Figure 1 As shown, the optical fiber assembly 13 includes a single-mode optical fiber 131 and an optical fiber collimator 132; the second through hole includes a first hole segment and a second hole segment, the first through hole is connected to the first end of the first hole segment, and the second end of the first hole segment is connected to the first end of the second hole segment; A portion of the optical fiber collimator 132 is arranged in the first through hole, and another portion is arranged in the first hole segment; wherein, the diameters of the first through hole and the first hole segment are the same, so that the optical fiber collimator 132 can be installed based on the first through hole and the first hole segment; a portion of the single-mode optical fiber 131 is inserted into the optical fiber collimator 132, and another portion is inserted in the second hole segment and extends out of the shell 111.

[0042] Specifically, the optical fiber alignment tube 132 is a capillary quartz tube, and the inner diameter of the capillary quartz tube is extremely small, and can be of the same size as the single-mode optical fiber 131. The optical fiber alignment tube 132 is used to carry the single-mode optical fiber 131, and the optical fiber alignment tube 132 is used to ensure that the end of the single-mode optical fiber 131 is well aligned with the corrugated sensitive diaphragm 12, so as to achieve better signal reflection and interference effects.

[0043] At the same time, the material of the single-mode optical fiber 131 is ordinary single-mode quartz optical fiber commonly used in the communication industry. The end face of the single-mode optical fiber 131 is used to form an optical fiber Fabry-Perot interference surface with the corrugation sensitive diaphragm 12, and at the same time plays a role in optical signal transmission.

[0044] In some embodiments, a fool-proof structure is provided between the groove wall of the mounting groove and the side wall of the base 112, and the fool-proof structure is used to limit the installation posture of the base 112 relative to the mounting groove to ensure that the first channel and the second channel are connected.

[0045] It is understandable that by designing the fool-proof structure, the installation posture of the base 112 can be ensured based on the fool-proof structure, and the first channel and the second channel can be directly aligned when the base 112 is installed.

[0046] The foolproof structure includes a guide bar and a guide groove, both of which extend along the axial direction of the optical fiber assembly 13 , the guide bar is arranged on the peripheral wall of the base 112 , and the guide groove is arranged on the groove wall of the installation groove.

[0047] In the second aspect, Figure 3 As shown, an embodiment of the present invention provides a method for preparing an optical fiber Fabry-Perot sound sensor, comprising the following steps: Step 310, preparing a shell and a base, wherein the shell is provided with a mounting groove and a first channel and a first through hole connected to the mounting groove, and the base is provided with a groove and a second channel and a second through hole connected to the groove.

[0048] Specifically, the shell can be processed by a casting process or a CNC process.

[0049] At the same time, the step of preparing the substrate includes: CNC processing the metal substrate to prepare a substrate semi-finished product; femtosecond laser processing the substrate semi-finished product to construct a mounting groove, a first channel and a first through hole on the substrate semi-finished product to obtain the substrate.

[0050] Step 320, obtain a single-mode optical fiber and an optical fiber collimator, strip a portion of the single-mode optical fiber from its coating, and assemble the single-mode optical fiber and the optical fiber collimator with a portion of its coating removed to obtain an optical fiber assembly.

[0051] It is understandable that when selecting a single-mode optical fiber and an optical fiber collimator, a fiber cleaver is used to cut both ends of the single-mode optical fiber and the optical fiber collimator respectively, and it is necessary to ensure that the cut surface is smooth.

[0052] At the same time, when stripping the coating, it is necessary to ensure that the stripping length of the single-mode optical fiber is shorter than the length of the optical fiber collimator.

[0053] Furthermore, when removing a portion of the coating layer of the single-mode optical fiber and assembling the optical fiber collimator, the following assembly steps may be referred to: Remove a portion of the coating from the single-mode optical fiber and insert it into the optical fiber collimator, making sure that the end of the single-mode optical fiber is flush with the end of the optical fiber collimator; The connection between the end of the single-mode optical fiber and the end of the optical fiber collimator is welded by a carbon dioxide laser to preliminarily complete the assembly of the optical fiber component; Use a fiber optic cleaver to cut the welding parts on the optical fiber component to ensure that the end of the optical fiber component forms a smooth end face.

[0054] After the welding part is cut, the optical fiber end face detector can be used to detect whether the end face is smooth. If it is not smooth, the end of the optical fiber component needs to be cut again. Furthermore, after the optical fiber assembly is assembled, the preparation method further comprises: forming a high-reflection film on the end face of the optical fiber assembly by magnetron sputtering or evaporation process, wherein the high-reflection film is preferably a single-crystal silicon film.

[0055] Step 330, preparing the corrugated sensitive diaphragm by using a compression molding process to form a corrugated structure on the first side of the corrugated sensitive diaphragm; wherein the structure of the corrugated structure refers to the description of the above embodiment and will not be described in detail here.

[0056] Step 340, installing the substrate in the installation groove, ensuring that the first channel and the second channel are connected to form a guide hole; wherein the substrate can be fixed in the installation groove by using UV glue.

[0057] Step 350, pass the single-mode optical fiber away from the optical fiber collimator tube through the second through hole and the first through hole in sequence, until a part of the optical fiber collimator tube is arranged in the first through hole, and another part of the optical fiber collimator tube is arranged in the second through hole, ensuring that the end face of the optical fiber assembly is built into the groove; wherein the optical fiber collimator tube can be fixed in the first through hole and the second through hole by using UV glue.

[0058] Step 360: encapsulate the corrugation sensitive membrane at the notch end of the groove, ensuring that the first side surface of the corrugation sensitive membrane is arranged opposite to the end surface of the optical fiber assembly.

[0059] It is understandable that after the corrugation sensitive membrane is packaged, a Fabry-Perot cavity is formed between the first side surface of the corrugation sensitive membrane and the end surface of the optical fiber assembly, and the Fabry-Perot cavity is connected to the external environment through the guide hole.

[0060] like Figure 4 As shown, in actual application, after the preparation of the optical fiber Fabry-Perot sound sensor 1 is completed, the single-mode optical fiber can be connected to the demodulator 2 through an optical fiber jumper, and the demodulator 2 can be connected to a monitoring terminal 3 such as a laptop computer or a desktop computer through a network cable.

[0061] At the same time, the optical fiber Fabry-Perot sound sensor 1 can be arranged on the bracket 4 , and the end of the optical fiber Fabry-Perot sound sensor 1 provided with the corrugated sensitive diaphragm is arranged toward the sound source 5 .

[0062] After the test system is turned on, the sound signal emitted by the sound source 5 acts on the corrugated sensitive diaphragm, and the broadband light source provided by the demodulator 2 is transmitted to the Fabry-Perot cavity of the optical fiber Fabry-Perot sound sensor 1 through the single-mode optical fiber, and interference is generated. The corrugated sensitive diaphragm responds to the sound signal and generates mechanical vibration, thereby causing the cavity length of the Fabry-Perot cavity to change. The demodulator 2 reads the spectral information reflected back from the single-mode optical fiber, and transmits the read spectral information to the monitoring terminal 3. The monitoring terminal 3 demodulates the spectral signal in real time to achieve the measurement of the sound.

[0063] Among them, if the detected sound signal does not meet the design requirements, you can consider replacing the corrugation sensitive diaphragm of different specifications, or adjusting the installation position of the substrate to adjust the structure of the Fabry-Perot cavity to ensure the sound signal collection effect of the optical fiber Fabry-Perot sound sensor 1.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An optical fiber Fabry-Perot sound sensor, characterized in that: include: mounting assembly, corrugation sensitive diaphragm and fiber optic assembly; The mounting assembly is provided with a groove and a guide hole communicating with the groove; The corrugated sensitive diaphragm is arranged at the notch end of the groove, and a corrugated structure is formed on the first side of the corrugated sensitive diaphragm; The optical fiber assembly is mounted on the mounting assembly, and the end face of the optical fiber assembly is built into the groove and arranged opposite to the first side face of the corrugated sensitive membrane; The groove defines a Fabry-Perot cavity between the first side surface of the corrugation-sensitive membrane and the end surface of the optical fiber assembly, and the Fabry-Perot cavity is connected to the external environment through the guide hole.

2. The optical fiber Fabry-Perot acoustic sensor according to claim 1, characterized in that: The corrugated structure includes a plurality of step structures; The plurality of step structures are arranged in sequence from the inside to the outside relative to the center of the corrugated sensitive diaphragm, and each of the step structures is extended along the circumferential direction relative to the center of the corrugated sensitive diaphragm.

3. The optical fiber Fabry-Perot acoustic sensor according to claim 2, characterized in that: Along the arrangement sequence from inside to outside, the height of the step surface corresponding to each step structure relative to the second side surface of the corrugated sensitive diaphragm decreases successively.

4. The optical fiber Fabry-Perot acoustic sensor according to claim 1, characterized in that: The end face of the optical fiber assembly is provided with a high reflection film.

5. The optical fiber Fabry-Perot acoustic sensor according to any one of claims 1 to 4, characterized in that: The mounting assembly comprises a housing and a base; The shell is provided with a mounting groove and a first channel and a first through hole communicating with the mounting groove; the base is provided with the groove and a second channel and a second through hole communicating with the groove; The base is arranged in the installation groove, the first channel and the second channel are connected to form the guide hole, the first through hole and the second through hole are connected, a part of the optical fiber assembly is arranged in the first through hole, and another part is arranged in the second through hole.

6. The optical fiber Fabry-Perot acoustic sensor according to claim 5, characterized in that: The optical fiber assembly includes a single-mode optical fiber and an optical fiber collimator; The second through hole includes a first hole segment and a second hole segment, the first through hole is connected to a first end of the first hole segment, and the second end of the first hole segment is connected to a first end of the second hole segment; A portion of the optical fiber collimator is arranged in the first through hole, and another portion is arranged in the first hole section; a portion of the single-mode optical fiber is inserted in the optical fiber collimator, and another portion is inserted in the second hole section and extends out of the housing.

7. The optical fiber Fabry-Perot acoustic sensor according to claim 5, characterized in that: An anti-fool structure is provided between the groove wall surface of the installation groove and the side wall of the base, and the anti-fool structure is used to limit the installation posture of the base relative to the installation groove to ensure that the first channel and the second channel are connected.

8. A method for preparing an optical fiber Fabry-Perot sound sensor, characterized in that: include: Prepare a shell and a base, wherein the shell is provided with a mounting groove and a first channel and a first through hole communicating with the mounting groove, and the base is provided with a groove and a second channel and a second through hole communicating with the groove; Obtaining a single-mode optical fiber and an optical fiber collimator, stripping a portion of the single-mode optical fiber from its coating, and assembling a portion of the single-mode optical fiber from which its coating is removed and the optical fiber collimator to obtain an optical fiber assembly; The corrugated sensitive diaphragm is prepared by a compression molding process to form a corrugated structure on a first side of the corrugated sensitive diaphragm; Installing the base in the installation groove to ensure that the first channel and the second channel are connected to form a guide hole; Passing the single-mode optical fiber away from the optical fiber collimator through the second through hole and the first through hole in sequence until a portion of the optical fiber collimator is disposed in the first through hole and another portion of the optical fiber collimator is disposed in the second through hole, ensuring that the end face of the optical fiber assembly is built into the groove; The corrugation sensitive membrane is packaged at the notch end of the groove to ensure that the first side surface of the corrugation sensitive membrane is arranged opposite to the end surface of the optical fiber assembly.

9. The method for preparing the optical fiber Fabry-Perot acoustic sensor according to claim 8, characterized in that: The steps of preparing the substrate include: CNC machining the metal substrate to prepare a semi-finished substrate; The substrate semi-finished product is processed by femtosecond laser to construct the mounting groove, the first channel and the first through hole on the substrate semi-finished product to obtain the substrate.

10. The method for preparing the optical fiber Fabry-Perot acoustic sensor according to claim 8, characterized in that: The step of removing a portion of the coating layer of the single-mode optical fiber and assembling the optical fiber collimator tube to obtain an optical fiber assembly comprises: Remove a portion of the coating layer of the single-mode optical fiber and insert it into the optical fiber collimator to ensure that the end of the single-mode optical fiber is flush with the end of the optical fiber collimator; The connection between the end of the single-mode optical fiber and the end of the optical fiber collimator is welded by using a carbon dioxide laser to preliminarily complete the assembly of the optical fiber assembly; The welding part on the optical fiber assembly is cut to ensure that the end of the optical fiber assembly forms a smooth end face.

11. The method for preparing the optical fiber Fabry-Perot acoustic sensor according to claim 8, characterized in that: After completing the assembly of the optical fiber assembly, the preparation method further comprises: A high-reflective film is formed on the end face of the optical fiber component by adopting a magnetron sputtering or evaporation process.

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