A fiber-optic fabry-perot acoustic sensor

Abstract

The application discloses an optical fiber Fabry-Perot acoustic wave sensor and relates to the technical field of sensors.The optical fiber Fabry-Perot acoustic wave sensor comprises coaxially arranged upper components, lower components, a center component and a pin component, the pin component is used for placing an optical fiber, the pin component is arranged on the inner side of the center component, the upper components and the lower components are arranged on the outer side of the center component, a sensing diaphragm is arranged between one end of the center component and the upper component, and the upper components and the lower components are detachably connected with the center component.The optical fiber Fabry-Perot acoustic wave sensor adopts a mechanical structure cooperation instead of glue bonding, and is very suitable for underwater environments such as deep sea.The structure of the optical fiber Fabry-Perot acoustic wave sensor adopts modular processing, when the size of the sensing diaphragm needs to be changed, only the upper components need to be replaced, which is very convenient and fast.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sensors, in particular to a fiber Fabry-Perot acoustic sensor. BACKGROUND

[0002] Fabry-Perot interferometer (FPI): an optical interference structure composed of two parallel glass plates, which can be used for filtering, sensing, etc.

[0003] Compared with the traditional electret condenser microphone, the fiber Fabry-Perot acoustic sensor has many advantages, so it is considered as a potential substitute for the electroacoustic sensor. The electret condenser microphone has low sensitivity, poor phase consistency, and weak anti-electromagnetic interference ability. Due to the above-mentioned shortcomings, its use environment is relatively limited, but at the same time, the fiber acoustic sensor has the characteristics of simple structure, easy manufacturing, high sensitivity, good phase consistency, strong anti-electromagnetic interference ability, etc. In harsh environments such as high temperature, high pressure, strong acid and strong alkali, the fiber acoustic sensor has irreplaceability.

[0004] In the prior art, there are many shortcomings in the production of fiber Fabry-Perot acoustic sensors.

[0005] For example, most FP sensor probes need to use glue to fix the sensor diaphragm. In many cases, the flowability of the glue needs to be controlled when the sensor is produced, because the inner diameter of the thin film supporting cylinder is very small, and it is easy to cause the glue to overflow, and even block the thin film supporting cylinder, so it will cause production difficulties, and because of the irregularity of the glue adhesion, the effective radius of the sensor diaphragm will be changed. In addition, in the case of using glue, the sensor is not suitable for deep sea environment operation; it is not modular, the sensor cannot be disassembled after forming, and cannot be replaced, so that most sensors can only work in one scene. If the environment changes or the measured physical quantity changes, a new sensor needs to be replaced. SUMMARY

[0006] The purpose of the present application is to provide a fiber Fabry-Perot acoustic sensor to solve the problems existing in the prior art. By using a mechanical structure instead of glue, the problem of not being able to be used in marine environment is solved, and by modularization, the problem of not being able to disassemble is solved.

[0007] To achieve the above purpose, the present application provides the following scheme:

[0008] The application provides an optical fiber Fabry-Perot acoustic wave sensor, which comprises coaxially arranged upper and lower components, a center component and a pin component for placing an optical fiber, the pin component is arranged on the inner side of the center component, the upper and lower components are arranged on the outer side of the center component, a sensing diaphragm is arranged between one end of the center component and the upper component, and the upper and lower components are detachably connected with the center component.

[0009] Preferably, a gap exists between the upper and lower components.

[0010] Preferably, first and second through holes are arranged in the upper component in communication and coaxially, the diameter of the first through hole is smaller than that of the second through hole, a first step is formed between the first and second through holes, the second through hole is used for placing the sensing diaphragm, one end of the sensing diaphragm is in contact with the first step, the other end of the sensing diaphragm is in contact with one end of the center component, and the inner wall of the upper component at the second through hole is provided with an internal thread for connecting with the center component.

[0011] Preferably, the outer wall of the center component is provided with an external thread for connecting with the upper and lower components, the third, fourth and fifth through holes are arranged in the center component in communication and coaxially, the diameter of the fourth through hole is smaller than that of the third and fifth through holes, a second step is formed between the third and fourth through holes, and a third step is formed between the fourth and fifth through holes, the pin component is located in the fifth through hole, and one end of the pin component is in contact with the third step.

[0012] Preferably, a cutout is arranged on the side wall of the center component, the inner side of the cutout is in communication with the inside of the center component, the outer side of the cutout is in communication with the outside of the center component, one end of the cutout extends to the third through hole, and the other end of the cutout extends to the fifth through hole away from one end of the fourth through hole.

[0013] Preferably, the sum of the length of the upper component and the length of the lower component is A, the length of the upper, center and lower components after being connected is B, and A < B.

[0014] Preferably, a sixth through hole and a seventh through hole are sequentially communicated and coaxial in the lower assembly, an inner wall of the lower assembly at the sixth through hole is provided with an internal thread for connecting with the center assembly, a diameter of the seventh through hole is smaller than that of the sixth through hole, a fourth step is formed between the sixth through hole and the seventh through hole, the pin assembly is located in the sixth through hole, and the other end of the pin assembly is in contact with the fourth step.

[0015] Preferably, an eighth through hole is arranged in the pin assembly, and the eighth through hole is used for placing an optical fiber.

[0016] Preferably, the upper assembly, the lower assembly, the center assembly and the pin assembly are all made of ceramic.

[0017] The present application has the following technical effects relative to the prior art:

[0018] The optical fiber Fabry-Perot acoustic sensor of the present application is very suitable for underwater environments such as deep sea, and the structure of the optical fiber Fabry-Perot acoustic sensor is modularized, so that when the size of the sensing diaphragm needs to be changed, only the upper assembly needs to be replaced, which is very convenient and fast. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0020] Figure 1 is a perspective view of the optical fiber Fabry-Perot acoustic sensor of the present application Figure 1 ;

[0021] Figure 2 is a perspective view of the optical fiber Fabry-Perot acoustic sensor of the present application Figure 2 ;

[0022] Figure 3 is a top view of the optical fiber Fabry-Perot acoustic sensor of the present application

[0023] Figure 4 is a bottom view of the optical fiber Fabry-Perot acoustic sensor of the present application

[0024] Figure 5 is a side view of the optical fiber Fabry-Perot acoustic sensor of the present application Figure 1 ;

[0025] Figure 6 for Figure 5 AA section view;

[0026] Figure 7 Side view of the fiber optic Fabry-Perot acoustic sensor of the present invention. Figure 2 ;

[0027] Figure 8 for Figure 7 BB cross-sectional view;

[0028] Figure 9 This is a cross-sectional view of the fiber optic Fabry-Perot acoustic sensor of the present invention after the sensing diaphragm and optical fiber are placed inside.

[0029] Figure 10 The upper component of the present invention is three-dimensional. Figure 1 ;

[0030] Figure 11 The upper component of the present invention is three-dimensional. Figure 2 ;

[0031] Figure 12 This is a side view of the upper component of the present invention;

[0032] Figure 13 for Figure 12 CC section view;

[0033] Figure 14 The lower component of the present invention is three-dimensional. Figure 1 ;

[0034] Figure 15 The lower component of the present invention is three-dimensional. Figure 2 ;

[0035] Figure 16 This is a side view of the lower component of the present invention;

[0036] Figure 17 for Figure 16 DD sectional view;

[0037] Figure 18 This is a perspective view of the central component of the present invention;

[0038] Figure 19 This is a side view of the central component of the present invention;

[0039] Figure 20 for Figure 19 EE sectional view;

[0040] Figure 21 This is a side view of the pin assembly of the present invention;

[0041] Figure 22 forFigure 21 F-F sectional view of the optical fiber Fabry-Perot acoustic sensor;

[0042] Figure 23 Use schematic diagram of the optical fiber Fabry-Perot acoustic sensor;

[0043] Figure 24 Time domain transient response curve of the optical fiber Fabry-Perot acoustic sensor in air to 6000Hz acoustic wave;

[0044] Figure 25 Frequency domain transient response curve of the optical fiber Fabry-Perot acoustic sensor in air to 6000Hz acoustic wave;

[0045] Wherein: 1 - upper assembly, 2 - lower assembly, 3 - center assembly, 4 - pin assembly, 5 - first through hole, 6 - second through hole, 7 - first step, 8 - third through hole, 9 - fourth through hole, 10 - fifth through hole, 11 - second step, 12 - third step, 13 - cutout, 14 - sixth through hole, 15 - seventh through hole, 16 - fourth step, 17 - eighth through hole, 18 - optical fiber, 19 - sensing diaphragm. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present application will be apparently and completely described 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. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the protection scope of the present application.

[0047] The present application aims to provide an optical fiber Fabry-Perot acoustic sensor to solve the problems in the prior art, replace the use of glue with mechanical structure cooperation, solve the problem of not being able to be used in marine environment, and solve the problem of not being able to be disassembled through modularization.

[0048] In order to make the above-mentioned purposes, features and advantages of the present application more apparent and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0049] As Figures 1-22As shown: the embodiment provides a kind of optical fiber Fabry-Perot acoustic wave sensor, overall length 17.79 millimeters, including coaxially arranged upper component 1, lower component 2, center component 3 and pin component 4, upper component 1, lower component 2, center component 3 and pin component 4 are made of ceramic, optical fiber 18 is placed in pin component 4, pin component 4 is arranged in the inside of center component 3, upper component 1 and lower component 2 are all arranged on the outside of center component 3, the end of center component 3 and upper component 1 are used to place micron level sensing diaphragm 19, one end of optical fiber 18 is inserted into close to sensing diaphragm 19 from below, upper component 1 and center component 3, lower component 2 and center component 3, pin component 4 and center component 3 can be detachably connected.The optical fiber Fabry-Perot acoustic wave sensor of the embodiment is composed of different modules, each part can be independently disassembled or assembled, which can improve the multiplexing of the sensor for different detection environments.Sensing diaphragm 19 is fixed by force, avoiding using glue, so that the embodiment can be operated in underwater environment, and the difference between the thermal coefficients of glue and sensing diaphragm 19 is also avoided, so as to affect the sensing accuracy.

[0050] In the embodiment, the outer shape of upper component 1 is cylindrical, and the outer diameter of upper component 1 is much larger than that of sensing diaphragm 19. This design is to make sensing diaphragm 19 more fixed. If the extrusion area is too small, sensing diaphragm 19 may fall off when it is disturbed by mechanical waves in air or seawater. The outer diameter is preferably 7 mm. The height of upper component 1 should be long enough to provide sufficient thread depth, but not too long to affect the size of the sensor. The height is preferably 8 mm. First through hole 5 and second through hole 6 are provided in upper component 1 and are in communication and coaxial. The thickness of upper component 1 at first through hole 5 should be as small as possible to provide sufficient extrusion force while avoiding interference with the response of sensing diaphragm 19 to sound waves. The length of first through hole 5 is preferably 0.5 mm. The diameter of first through hole 5 can be changed according to the sensing diaphragm 19 used. The diameter of first through hole 5 is preferably 2.5 mm. The diameter of first through hole 5 is smaller than that of second through hole 6. First step 7 is formed between first through hole 5 and second through hole 6. Second through hole 6 is used to place sensing diaphragm 19, and one end of sensing diaphragm 19 is in contact with first step 7. The other end of sensing diaphragm 19 is in contact with one end of center component 3. The inner wall of upper component 1 at second through hole 6 is provided with internal threads for connecting with center component 3. The internal threads are M5 standard threads.

[0051] In this embodiment, the length of the center component 3 is 13 mm, the outer wall of the center component 3 is provided with external threads for connecting with the upper component 1 and the lower component 2, the center component 3 is provided with third through hole 8, fourth through hole 9 and fifth through hole 10 which are coaxial and communicated in sequence, the length of the third through hole 8 is 2 mm and the inner diameter is 2.5 mm, the third through hole 8 is used for reserving space for vibration of the sensing diaphragm 19 and for the end of the optical fiber 18 to extend to a suitable position, the diameter of the fourth through hole 9 is smaller than that of the third through hole 8 and the fifth through hole 10, the second step 11 is formed between the third through hole 8 and the fourth through hole 9, the third step 12 is formed between the fourth through hole 9 and the fifth through hole 10, the length of the fifth through hole 10 is 10 mm and the diameter is 2.5 mm, the pin component 4 is located in the fifth through hole 10, the length of the fourth through hole 9 is 1 mm and the diameter is 1.5 mm, and one end of the pin component 4 contacts the third step 12 to prevent the pin component 4 from extending further forward and to hold the pin component 4, and after the pin component 4 is held, the upper component 1 and the lower component 2 can be used to press the pin component 4 to avoid using glue and to stabilize it.

[0052] In this embodiment, the side wall of the center component 3 is provided with a cutout 13, the inner side of the cutout 13 communicates with the inside of the center component 3, the outer side of the cutout 13 communicates with the outside of the center component 3, the length of the cutout 13 is 12 mm, one end of the cutout 13 extends to the third through hole 8, and the other end of the cutout 13 extends to the end of the fifth through hole 10 away from the fourth through hole 9.

[0053] In this embodiment, there is a gap of 0.5 mm between the upper component 1 and the lower component 2. The sum of the length of the upper component 1 and the length of the lower component 2 is A, and the length of the combination of the upper component 1, the center component 3 and the lower component 2 is B, A < B, so that the cutout 13 communicates with the gap between the upper component 1 and the lower component 2 to ensure that the internal and external pressures of the sensor are equal. Another function of the cutout 13 is to ensure that the pin component 4 can be inserted. If the center component 3 is closed and the outer diameter of the pin component 4 is not standard, assuming that the outer diameter of the pin component 4 is slightly larger than 2.5 mm, it will not be possible to insert the pin component 4 into the center component 3, and if the outer diameter of the pin component 4 is slightly smaller than 2.5 mm, the pin component 4 will not be stable. The existence of the cutout 13 can ensure that these two situations do not occur. If the outer diameter of the pin component 4 is slightly larger, it can still be inserted due to the existence of the cutout 13, and if the outer diameter is slightly smaller, it can be inserted and can be fastened by the raw material belt wrapped around the outside of the center component 3 due to the existence of the upper component 1 and the lower component 2.

[0054] In this embodiment, the lower component 2 includes a cylindrical segment and a conical segment, the height of the cylindrical segment is 5 mm, the height of the conical segment is 4.29 mm, the conical segment is close to the upper component 1, the sixth through hole 14 and the seventh through hole 15 are sequentially communicated and coaxial in the lower component 2, the sixth through hole 14 is arranged in the cylindrical segment, the seventh through hole 15 is arranged in the conical segment, the inner wall of the lower component 2 at the sixth through hole 14 is provided with an internal thread for connecting with the central component 3, the internal thread is an M5 standard thread, the diameter of the seventh through hole 15 is smaller than that of the sixth through hole 14, the diameter of the seventh through hole 15 is 1 mm, the optical fiber 18 is conveniently inserted, the fourth step 16 is formed between the sixth through hole 14 and the seventh through hole 15, the pin component 4 is located in the sixth through hole 14, and the other end of the pin component 4 is in contact with the fourth step 16, so as to give the pin component 4 an upward extrusion force, and the pin component 4 is conveniently fixed.

[0055] In this embodiment, the eighth through hole 17 is arranged in the pin component 4, the eighth through hole 17 is used for placing the optical fiber 18, the diameter of the eighth through hole 17 is between 125 microns and 140 microns, a single-mode optical fiber can be inserted, and the height of the pin component 4 is 10.5 mm.

[0056] In this embodiment, the threaded connection part of the central component 3 and the upper component 1 and the threaded connection part of the central component 3 and the lower component 2 are all provided with an ultra-thin raw material belt, and the use of a precise thread cooperates with the ultra-thin raw material belt to replace smooth contact, so as to ensure that the sensor structure is compact and firm, and prevent sliding.

[0057] The working principle of the optical fiber Fabry-Perot acoustic wave sensor in this embodiment is as shown in Figure 23 The optical fiber Fabry-Perot acoustic wave sensor is applied to an air detection acoustic wave experimental system, and the experimental system is composed of a narrow-bandwidth tunable laser, an optical circulator, an optical fiber Fabry-Perot acoustic wave sensor, a photodetector and an oscilloscope. The tunable laser is connected with the 1 port of the circulator, narrow-band laser is incident on the optical fiber 18 sensor through the 2 port of the circulator, the reflected light of the optical fiber Fabry-Perot acoustic wave sensor is output through the 3 port of the circulator 3, and then converted into an electrical signal by the photodetector, and then displayed on the oscilloscope.

[0058] The sensing diaphragm 19 of the optical fiber Fabry-Perot acoustic wave sensor can reflect the incident light back and be received by the optical fiber 18. If the acoustic wave acts on the sensing diaphragm 19, the sensing diaphragm 19 will vibrate, the distance between the sensing diaphragm 19 and the end face of the optical fiber 18 will change, that is, the cavity length of the sensor will fluctuate, because the change of the cavity length will cause the change of the amplitude of the light signal received by the end face of the optical fiber 18, so the light intensity fed back to the photodetector will also change, the voltage amplitude will also change, and thus the waveform on the oscilloscope will change, so the specific amplitude and frequency parameters of the acoustic wave can be known.

[0059] The light intensity inputted to the photodetector by the fiber Fabry-Perot acoustic sensor can be expressed as the following formula:

[0060]

[0061] Wherein, R Fiber (λ) is the reflectivity of the end face of the optical fiber 18, R Material (λ) is the reflectivity of the sensing diaphragm 19, I(λ) is the incident light intensity of the light source, and L is the initial cavity length. If the acoustic wave has a fixed frequency, the light intensity fed back to the photodetector by the sensor will also fluctuate, and the following formula is obtained by differentiating the above formula:

[0062]

[0063] It can be seen that the change of light intensity ΔI FP can reflect the change of cavity length ΔL.

[0064] The fiber Fabry-Perot acoustic sensor of the embodiment does not need to use glue to fix the sensing diaphragm 19, but uses the extrusion force between the separated mechanical structures to fix the sensing diaphragm 19, and uses mechanical structure cooperation instead of glue bonding, which is very suitable for underwater environments such as deep sea; the fiber Fabry-Perot acoustic sensor of the embodiment uses ceramic as the whole material, which is very corrosion-resistant and has very low cost; the structure of the fiber Fabry-Perot acoustic sensor of the embodiment adopts modular processing, if the size of the sensing diaphragm 19 is to be changed, only the upper assembly 1 needs to be replaced, which is very convenient and fast; the fiber Fabry-Perot acoustic sensor of the embodiment is suitable for large-scale production, can finely control the production of the sensor, has good parameter consistency, the size of each part of the sensor is accurate to 0.01 millimeter, the parameter consistency is very good, and avoids manual production or the use of chemical methods to affect the performance of the sensor array due to the inability to finely control the cavity length and the radius and thickness of the sensing diaphragm 19; the fiber Fabry-Perot acoustic sensor of the embodiment is simple to manufacture and has low cost, since the physical parameters of the sensor are already specified, only the parameters need to be input into the machine tool, and the sensor can be quickly manufactured, compared with other sensors which need to use laser or precision machines to punch and cut in order to make the inner and outer cavity pressures equal, the structure of the fiber Fabry-Perot acoustic sensor of the embodiment will naturally leave a notch 13 and a small hole formed by the gap after assembly to ensure that the sensing cavity of the sensor is equal to the external pressure, and the assembly is very simple.

[0065] The principles and implementation manners of the present application are described in the specification by using specific examples, and the above examples are only used to help understand the method of the present application and its core idea; meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation manners and application ranges will be changed. In conclusion, the content of the specification should not be understood as a limitation of the present application.

Claims

1. An optical fiber Fabry-Perot acoustic wave sensor, characterized by: The application relates to a coaxial optical fiber connector, which comprises an upper assembly, a lower assembly, a center assembly and a pin assembly, the pin assembly is arranged coaxially in the center assembly, the upper assembly and the lower assembly are arranged coaxially outside the center assembly, a sensing diaphragm is arranged between one end of the center assembly and the upper assembly, and the upper assembly and the lower assembly are detachably connected with the center assembly. A first through hole and a second through hole are arranged coaxially and in communication in the upper assembly, the diameter of the first through hole is smaller than that of the second through hole, a first step is formed between the first through hole and the second through hole, the second through hole is used for arranging the sensing diaphragm, one end of the sensing diaphragm is in contact with the first step, and the other end of the sensing diaphragm is in contact with one end of the center assembly; an inner thread is arranged on the inner wall of the upper assembly at the second through hole and is used for connecting with the center assembly. An outer thread is arranged on the outer wall of the center assembly and is used for connecting with the upper assembly and the lower assembly, a third through hole, a fourth through hole and a fifth through hole are arranged coaxially and in communication in the center assembly, the diameter of the fourth through hole is smaller than that of the third through hole and that of the fifth through hole, a second step is formed between the third through hole and the fourth through hole, a third step is formed between the fourth through hole and the fifth through hole, the pin assembly is arranged in the fifth through hole, and one end of the pin assembly is in contact with the third step. A sixth through hole and a seventh through hole are arranged coaxially and in communication in the lower assembly, an inner thread is arranged on the inner wall of the lower assembly at the sixth through hole and is used for connecting with the center assembly, the diameter of the seventh through hole is smaller than that of the sixth through hole, a fourth step is formed between the sixth through hole and the seventh through hole, the pin assembly is arranged in the sixth through hole, and the other end of the pin assembly is in contact with the fourth step.

2. The optical fiber Fabry-Perot acoustic wave sensor of claim 1, wherein: A gap exists between the upper assembly and the lower assembly.

3. The optical fiber Fabry-Perot acoustic wave sensor of claim 1, wherein: A cutout is arranged on the side wall of the center assembly, the inner side of the cutout is in communication with the inside of the center assembly, the outer side of the cutout is in communication with the outside of the center assembly, one end of the cutout extends to the third through hole, and the other end of the cutout extends to the fifth through hole away from one end of the fourth through hole.

4. The optical fiber Fabry-Perot acoustic wave sensor according to claim 3, characterized in that: The sum of the length of the upper assembly and the length of the lower assembly is A, and the length of the upper assembly, the center assembly and the lower assembly after being connected is B, A < B.

5. The fiber-optic Fabry-Perot acoustic sensor of claim 1, wherein: An eighth through hole is arranged in the pin assembly and is used for arranging an optical fiber.

6. The fiber-optic Fabry-Perot acoustic sensor of claim 1, wherein: The upper assembly, the lower assembly, the center assembly and the pin assembly are all made of ceramic.

Images