Double-optical-fiber diaphragm type optical fiber pressure sensor

Abstract

The utility model provides a double-optical-fiber diaphragm type optical fiber pressure sensor. The pressure sensor structure comprises a base, an input optical fiber, an output optical fiber, a double-optical-fiber assembly and a cover plate. A pressure sensing diaphragm is arranged in the cavity of the base; the double-optical-fiber assembly comprises a sensing arm optical fiber, a reference arm optical fiber and a photoelectric element, the sensing arm optical fiber and the reference arm optical fiber are respectively sleeved with a protective sleeve, the sensing arm optical fiber and the reference arm optical fiber are respectively fixed in the positive strain area and the negative strain area of the pressure sensing diaphragm, and the two ends of each optical fiber extend out of the protective sleeve. The light source is connected with a photoelectric element to form a Michelson interference structure or a Mach-Zehnder interference structure; the input end and the output end of the double-optical-fiber assembly are connected with the input optical fiber and the output optical fiber through photoelectric elements respectively. The device is simple and reliable in structure and free of electromagnetic interference, high-precision dynamic pressure measurement can be achieved based on an interference phase demodulation method, and the requirement for monitoring extremely-small pressure fluctuation in a large-pressure environment can be effectively met.

Description

Technical Field

[0001] The utility model belongs to the field of optical fiber pressure measurement, and in particular relates to a double-optical fiber diaphragm type optical fiber pressure sensor. Background Art

[0002] With the rapid development of my country's economy and technology, people have put forward higher and higher requirements for the safe operation of pipelines for transporting fluids such as water, oil, and natural gas, as well as complex pipelines on industrial equipment and large-scale mechanical equipment, especially in the field of high-precision monitoring of the pressure inside flammable and explosive gas and liquid pipelines or containers as low as several kiloPascals or liquid level.

[0003] Traditional pressure sensors are mostly mechanical and electromagnetic pressure sensors. Mechanical pressure sensors are mostly used to measure and display single-point pressure, and the measured data cannot be transmitted to the computer for analysis and processing; electrical pressure sensors usually have poor resistance to electromagnetic interference and cannot work safely and reliably for a long time in harsh environments such as high temperature and strong electromagnetic interference. It is difficult to transmit the measurement signal over long distances. Since sensors cannot be connected in series, a large number of data transmission signal lines are required in large-scale multi-point pressure monitoring systems.

[0004] Based on the above-mentioned demand for high-precision, distributed pressure or liquid level measurement, among the types of pressure sensors that have been developed, piezoresistive / piezoelectric, microwave resonance and other pressure sensors still have the problem of low accuracy in electrical signal transmission and extraction at low pressures, while optical fiber sensors have been widely studied due to their many advantages such as being immune to electromagnetic interference, high measurement accuracy, and corrosion resistance. The basic sensing principle of optical fiber pressure sensors is that the phase of the light wave propagating in the optical fiber changes under the action of pressure, and the phase change is converted into light intensity change through measurement technology, thereby detecting the pressure value to be measured. Phase modulation pressure sensors have high detection sensitivity, a large dynamic measurement range, and flexible and diverse probe forms. According to their structure, phase modulation interferometric pressure sensors include Michelson, Msch-Zehnder and Fabry-Perot sensors.

[0005] The dual optical fiber diaphragm pressure sensor has advantages such as small size and temperature self-compensation, and is particularly suitable for working in harsh environments such as high temperature and radiation. However, there are relatively few packaging methods for optical fiber diaphragm pressure sensors, and they all have some obvious defects. For example, the interface between the sensor and the test device is difficult to disassemble, easy to damage the sensor, and has a complex structure. Therefore, improving the sensor packaging process and reducing the manufacturing process are issues that need to be solved at present. Summary of the invention

[0006] In order to overcome the defects and shortcomings in the above technical solutions, the utility model provides a dual-fiber diaphragm optical fiber pressure sensor, which has the advantages of simple and reliable packaging structure, small size, high sensitivity and simple manufacturing process.

[0007] In order to achieve the above technical effect, the utility model provides a dual-fiber diaphragm optical fiber pressure sensor, including a base, an open cavity is provided in the base, a medium introduction joint is provided on one side of the base located at the bottom surface of the cavity, and a pressure-introducing hole connected to the cavity is provided in the medium introduction joint, the pressure sensor structure also includes an input optical fiber, an output optical fiber and a dual-fiber assembly, a pressure-sensitive diaphragm is provided in the cavity, and the pressure-sensitive diaphragm is divided into a positive strain area and a negative strain area; the dual-fiber assembly includes a sensing arm optical fiber, a reference arm optical fiber, an optoelectronic element and a cover plate, and a plurality of optical fibers are respectively sleeved outside the sensing arm optical fiber and the reference arm optical fiber. A protective sleeve is provided, and epoxy glue is filled in the protective sleeve of each optical fiber. The sensing arm optical fiber and the reference arm optical fiber are respectively fixed in the corresponding protective sleeves by the epoxy glue. The sensing arm optical fiber is fixed in the positive strain area of ​​the pressure-sensitive diaphragm, and the reference arm optical fiber is fixed in the negative strain area of ​​the pressure-sensitive diaphragm. Both ends of the sensing arm optical fiber and the reference arm optical fiber extend out of the protective sleeve and are connected with the photoelectric element to form a Michelson interference structure or a Mach-Zehnder interference structure. The input end and the output end of the dual optical fiber assembly are respectively connected with the input optical fiber and the output optical fiber through the photoelectric element, and the cover plate is sealed and covered on the open surface of the cavity.

[0008] A further technical solution of the utility model is as follows: the electronic components constituting the Michelson interference structure include a first fiber coupler, a first fiber reflector and a second fiber reflector, the first fiber coupler is arranged at one end of the cavity, and the first fiber reflector and the second fiber reflector are both arranged at the other end of the cavity; the first output end of the first fiber coupler is connected to the input end of the sensing arm optical fiber, the second output end of the first fiber coupler is connected to the input end of the reference arm optical fiber, and the input end of the first fiber coupler extends from one side of the cavity to a base to be connected to the input optical fiber; the input end of the first fiber reflector is connected to the output end of the sensing arm optical fiber, the input end of the second fiber reflector is connected to the output end of the reference arm optical fiber, and the output ends of the two fiber reflectors extend from the other side of the cavity to a base to be connected to the output optical fiber.

[0009] A further technical solution of the utility model is as follows: the optoelectronic elements constituting the Mach-Zehnder interference structure include a first fiber coupler and a second fiber coupler respectively arranged at two ends of the cavity, the input end of the first fiber coupler extends from one side of the cavity to a base and is connected to the input fiber, the first output end of the first fiber coupler is connected to the input end of the sensing arm fiber, and the second output end of the first fiber coupler is connected to the input end of the reference arm fiber; the output end of the sensing arm fiber is connected to the first input end of the second fiber coupler, the reference arm fiber is connected to the second input end of the second fiber coupler, and the output end of the second fiber coupler extends from the other side of the cavity to a base and is connected to the output fiber.

[0010] The better technical solution of the utility model is as follows: the base is a conical structure, the cavity is a cylindrical cavity arranged in the middle of the base, the cavity opening is opened on the bottom surface of the base, a sealing groove is arranged at the cavity opening, a sealing ring is placed in the sealing groove, the pressure-sensitive diaphragm is horizontally placed at the cavity opening of the cavity, and is sealed and crimped by a cover plate, and the pressure-sensitive diaphragm and the base form a hollow cavity; the medium introduction joint is arranged at the center position of the top of the base, and a threaded connection port is provided at the medium introduction joint port.

[0011] The preferred technical solution of the utility model is as follows: the middle part of the pressure-sensitive diaphragm is a positive strain area, the periphery of the pressure-sensitive diaphragm is a negative strain area, the sensing arm optical fiber is coiled and fixed in the positive strain area of ​​the pressure-sensitive diaphragm; and the sensing arm optical fiber and the reference arm optical fiber are both fixed on the pressure-sensitive diaphragm by epoxy glue.

[0012] The better technical solution of the utility model is as follows: the cover plate is a stainless steel metal sealing cover, a plurality of hexagonal countersunk holes are provided on the cover plate, the countersunk holes are all symmetrically distributed in a circular shape, a first optical fiber coupler mounting box and a second optical fiber coupler mounting box or a reflector mounting port are provided on the cover plate, and optical fiber outlets are respectively provided on both sides of the cover plate; the base is a stainless steel metal base, and a plurality of threaded holes are correspondingly provided on the bottom of the metal base.

[0013] The preferred technical solution of the utility model is as follows: the protective sleeve is a Teflon tube, the pressure-sensitive diaphragm is a stainless steel metal diaphragm; the optical fiber extending out of the base is protected by a metal armor tube.

[0014] The better technical solution of the utility model is as follows: the sensing arm optical fiber and the reference arm optical fiber are both made of carbon-coated optical fiber with a cladding diameter of 80um; the optical fiber coupler adopts a single-mode optical fiber coupler with a splitting ratio of 1:1; and the two optical fiber reflectors both adopt optical fiber Faraday magnetic gyroscopes.

[0015] A better technical solution of the utility model: the first optical fiber coupler and the second optical fiber coupler both use single-mode optical fiber couplers with a splitting ratio of 1:1; the two optical fiber couplers use the same coupler, both are provided with two output ends and one input end, and the two input ends of the second optical fiber coupler are used as output ends.

[0016] The better technical solution of this utility model:

[0017] The dual-fiber diaphragm pressure sensor of the utility model can be divided into a light-transmitting module, a pressure-sensitive diaphragm, and a sealing structure; the light-transmitting module is composed of a sensing arm optical fiber, a reference arm optical fiber, a jumper head, two reflectors, and an optical fiber coupler; the sensing arm optical fiber and the reference arm optical fiber are inserted into a Teflon protective tube side by side, and then coiled into a spiral shape through a mold and fixed on the pressure-sensitive module, and epoxy glue is injected into the protective tube, one end of the sensing arm optical fiber is connected to the first output end of the optical fiber coupler, and the other end is connected to the first optical fiber reflector; one end of the reference arm optical fiber is connected to the second output end of the optical fiber coupler, and the other end is connected to the second reflector, forming a Michelson interference optical path; the Michelson interference optical path is simple and convenient to build, which can effectively save time and cost. The pressure-sensitive diaphragm of the utility model is made of 304 stainless steel, which can effectively prevent corrosion and is suitable for some more complex environments; the light-transmitting module is pasted on the pressure-sensitive diaphragm with epoxy glue, and the Michelson interference fringes change through the deformation of the pressure-sensitive diaphragm, and the change of the waveform is interpreted, thereby calculating the change of pressure.

[0018] The sealing structure of the utility model consists of a sealing base, a sealing gasket and a sealing cover; the sealing base is made of stainless steel, an M4 threaded hole is arranged on the upper part of the sealing base, the bottom is a pressure inlet, the pressure inlet is a threaded structure, the threaded base is installed on the surface of the object to be measured, the structural installation process is simple and convenient, and it can be well replaced; the sealing gasket is a silicone sealing ring; the sealing cover is made of stainless steel, and an M4 countersunk through hole is opened on the cover plate, which corresponds one to one with the threaded hole of the sealing base.

[0019] The utility model has the following effects:

[0020] (1) The assembly of the utility model is to install the silicone sealing pad at the slotted position of the sealing base, then install the pressure-sensitive diaphragm in the sealing bottom, and then press the sealing cover against the pressure-sensitive diaphragm, and use M4 screws to fix the sealing cover and the sealing base. This structure can be well applied to various pressure environments.

[0021] (2) The utility model includes a dual optical fiber consisting of a sensing arm optical fiber and a reference arm optical fiber. The dual optical fiber is connected with two reflectors and an optical fiber coupler to form a Michelson interference optical path. The construction is simple and convenient, which can effectively save installation time. The dual optical fiber is packaged by mold packaging to ensure the internal optical fiber light transmission performance. The dual optical fiber is packaged in a protective tube by epoxy glue, and the epoxy glue can protect the optical fiber.

[0022] (3) The reference arm of the utility model is fixed inside the Teflon tube, which can effectively prevent the free jitter of the optical fiber of the wall reference arm and the crosstalk caused by it; the pressure-sensitive diaphragm is made of 304 stainless steel, which can effectively resist corrosion and is suitable for some more complex environments.

[0023] The utility model has a simple and reliable structure and is not affected by electromagnetic interference. It can realize high-precision measurement of dynamic pressure based on the interference phase demodulation method, and can effectively solve the monitoring needs of extremely small pressure fluctuations in a high-pressure environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the overall structure of the utility model;

[0025] Figure 2 It is a schematic diagram of optical fiber connection of the Michelson interference structure in the utility model;

[0026] Figure 3 This is a schematic diagram of optical fiber connection of the Mach-Zehnder interference structure in the utility model;

[0027] Figure 4 It is a structural schematic diagram of the base in the utility model;

[0028] Figure 5 It is a schematic diagram of the cover plate in the utility model;

[0029] Figure 6 It is a schematic diagram of the diaphragm in the utility model.

[0030] In the figure: 101—input optical fiber; 102—base; 103—cover plate; 104—sealing groove; 105—output optical fiber; 106—pressure-sensitive diaphragm; 107—cavity; 108—pressure-inducing hole; 200—dual optical fiber assembly; 201—sensing arm optical fiber; 202—reference arm optical fiber; 203—protective sleeve; 204—first optical fiber coupler; 205—second optical fiber coupler; 206—first reflector; 207—second reflector; 301—inner hexagonal countersunk hole; 302—first optical fiber coupler mounting box; 303—sealing cover; 304—optical fiber outlet; 305—second optical fiber coupler mounting box or reflector mounting port; 400—positive strain area, 401—negative strain area DETAILED DESCRIPTION

[0031] The utility model is further described below in conjunction with the accompanying drawings and embodiments. Figures 1 to 5The drawings are all of embodiments, which are drawn in a simplified manner and are only used for the purpose of clearly and concisely illustrating the embodiments of the utility model. The following technical solutions shown in the drawings are specific solutions of the embodiments of the utility model and are not intended to limit the scope of the utility model to be protected. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0032] In the description of the present utility model, it should be understood that the terms "upper", "lower", "inner", "outer", "left", "right", etc. indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the utility model product is usually placed when in use, or the orientation or position relationship commonly understood by those skilled in the art, which is only for the convenience of describing the present utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0033] The embodiment provides a dual-fiber diaphragm optical fiber pressure sensor, such as Figures 1 to 5As shown, the sensor structure includes a base 102, an open cavity 107 is provided in the base 102, a medium introduction joint is provided on one side of the base 102 located at the bottom of the cavity 107, and a pressure-inducing hole 108 connected to the cavity 107 is provided in the medium introduction joint. The base 102 is a conical structure, and the cavity 107 is a cylindrical cavity arranged in the middle of the base 102, and its cavity opening is opened on the bottom of the base 102. A sealing groove 104 is provided at the cavity opening, and a sealing ring is placed in the sealing groove 104. A pressure-sensitive diaphragm 106 is installed in the cavity 107. The pressure-sensitive diaphragm 106 is horizontally placed at the cavity opening of the cavity 107 and is sealed and crimped by the cover plate 103. The pressure-sensitive diaphragm 106 and the base 102 form a hollow cavity. The middle part of the pressure-sensitive diaphragm 106 is a positive strain zone 400, and the periphery of the pressure-sensitive diaphragm 106 is a negative strain zone 401. The dual-fiber optical fiber assembly is fixed on the pressure-sensitive diaphragm 106, and the medium introduction joint is arranged at the top center position of the base 102, and a threaded connection port is provided at the medium introduction joint port. The cover plate 103 is a stainless steel metal sealing cover, and a plurality of hexagonal countersunk holes 301 are opened on the cover plate 103, and the countersunk holes 301 are all distributed symmetrically in a circular shape. A first fiber coupler installation box 302 and a second fiber coupler installation box or a reflector installation port 305 are provided on the cover plate 103. The first fiber coupler installation box 302 is used to install the first fiber coupler 204; the second fiber coupler installation box 305 is used to install the second fiber coupler 205; the reflector installation port is used to install two fiber reflectors, and fiber outlets 304 are opened on both sides of the cover plate to facilitate the introduction and extraction of optical fibers; the base 102 is a stainless steel metal base, and a plurality of threaded holes are correspondingly provided at the bottom of the metal base 102.

[0034] The embodiment provides a dual-fiber diaphragm optical fiber pressure sensor, such as Figures 1 to 5As shown, the pressure sensor structure also includes an input optical fiber 101, an output optical fiber 105 and a dual optical fiber assembly 200, the dual optical fiber assembly 200 includes a sensing arm optical fiber 201, a reference arm optical fiber 202 and a photoelectric element, and protective sleeves 203 are respectively provided outside the sensing arm optical fiber 201 and the reference arm optical fiber 202, and the protective sleeve 203 of each optical fiber is filled with epoxy glue, and the sensing arm optical fiber 201 and the reference arm optical fiber 202 are respectively fixed in the corresponding protective sleeves 203 by epoxy glue, and the sensing arm optical fiber 201 and the reference arm optical fiber 202 are both fixed on the pressure-sensitive diaphragm by epoxy glue, the sensing arm optical fiber 201 is coiled and fixed in the positive strain area 400 of the pressure-sensitive diaphragm 106, and the reference arm optical fiber 202 is fixed in the negative strain area 401 of the pressure-sensitive diaphragm 106. Both ends of the sensing arm optical fiber 201 and the reference arm optical fiber 202 extend out of the protective sleeve 203 and are connected to the photoelectric element to form a Michelson interference structure or a Mach-Zehnder interference structure; the input end and the output end of the dual optical fiber assembly 200 are respectively connected to the input optical fiber 101 and the output optical fiber 105 through the photoelectric element, and the cover plate 103 is sealed and covered on the open surface of the cavity 107. The optical fiber extending out of the base 102 is protected by a metal armor tube. The protective sleeve 203 is a Teflon tube, the pressure-sensitive diaphragm 106 is a stainless steel metal diaphragm, and the optical fiber assembly is fixed on the pressure-sensitive diaphragm 106 by epoxy glue. The sensing arm optical fiber 201 and the reference arm optical fiber 202 are both made of carbon-coated optical fiber with a cladding diameter of 80um.

[0035] like Figure 2 As shown, the electronic components constituting the Michelson interference structure in the embodiment include a first fiber coupler 204, a first fiber reflector 206, and a second fiber reflector 207. The first fiber coupler 204 is arranged at one end of the cavity, and the first fiber reflector 206 and the second fiber reflector 207 are both arranged at the other end of the cavity 107; the first output end of the first fiber coupler 204 is connected to the input end of the sensing arm optical fiber 201, the second output end of the first fiber coupler 204 is connected to the input end of the reference arm optical fiber 202, and the input end of the first fiber coupler 204 extends from one side of the cavity 107 to the base 102 and is connected to the input optical fiber 101; the input end of the first fiber reflector 206 is connected to the output end of the sensing arm optical fiber 201, the input end of the second fiber reflector 207 is connected to the output end of the reference arm optical fiber 202, and the output ends of the two fiber reflectors extend from the other side of the cavity 107 to the base 102 and are connected to the output optical fiber 105.

[0036] like Figure 3As shown, the optoelectronic elements constituting the Mach-Zehnder interference structure in the embodiment include a first fiber coupler 204 and a second fiber coupler 205 respectively arranged at two ends of the cavity 107, the input end of the first fiber coupler 204 extends from one side of the cavity 107 to the base 102 to be connected to the input fiber 101, the first output end of the first fiber coupler 204 is connected to the input end of the sensing arm fiber 201, and the second output end of the first fiber coupler 204 is connected to the input end of the reference arm fiber 202; the output end of the sensing arm fiber 201 is connected to the first input end of the second fiber coupler 205, the reference arm fiber 202 is connected to the second input end of the second fiber coupler 205, and the output end of the second fiber coupler 205 extends from the other side of the cavity 107 to the base 102 to be connected to the output fiber 105.

[0037] In the embodiment of the present invention, the first fiber coupler 204 and the second fiber coupler 205 are both single-mode fiber couplers with a splitting ratio of 1:1; and the two fiber reflectors are both fiber Faraday magnetic gyroscopes.

[0038] The installation process of the utility model is: first, the sensing arm optical fiber 201 and the reference arm optical fiber 202 are inserted into the Teflon tube 204 at the same time; then the inside of the Teflon tube is filled with epoxy glue 207, and the Teflon tube 204 is fixed by sealing, and the fixed sensing arm optical fiber and reference arm optical fiber are coiled into a spiral shape through a mold, and fixed on the metal diaphragm 106 as a whole by epoxy glue; a gasket is installed in the sealing groove 104, and the metal diaphragm 106 fixed with the dual optical fiber assembly is installed in the cavity of the base 102; finally, the cover plate 103 and the base 102 are fixed by threads. The metal cover plate 103 is provided with six identical hexagonal countersunk holes 301, and the countersunk holes 301 are distributed symmetrically in a circular ring center, and the bottom of the metal base 102 is correspondingly provided with threaded holes.

[0039] The metal cover plate 103, metal diaphragm 106 and metal base 102 in this embodiment are all made of 316L stainless steel, which has good corrosion resistance. The sensing arm optical fiber 201 and the reference arm optical fiber 202 are made of carbon-coated optical fiber with a cladding diameter of 80um, which has the advantages of small bending loss, fatigue resistance and long life. The optical fiber coupler 201 adopts a single-mode optical fiber coupler with a splitting ratio of 1:1. The first optical fiber reflector 205 and the second optical fiber reflector 206 both adopt optical fiber Faraday magnetic gyroscopes. The size of the metal diaphragm 106 is 100mm in diameter and 2mm in thickness, and the size of the Teflon tube 204 is 2mm in diameter and 1000mm in length. The hexagonal countersunk threaded hole of the metal cover plate 103 matches the threaded hole of the base 102, and is fixed with an M4 countersunk screw.

[0040] The above is only one embodiment of the present invention, but the present invention is not limited to the above embodiment. As long as the technical effect of the present invention is achieved by any same or similar means, it should fall within the scope of protection of the present invention.

Claims

1. A dual-fiber diaphragm optical fiber pressure sensor, comprising a base (102), an open cavity (107) being provided in the base (102), a medium introduction joint being provided on one side of the base (102) located at the bottom surface of the cavity (107), and a pressure introduction hole (108) being provided in the medium introduction joint and communicating with the cavity (107), characterized in that: The pressure sensor structure also includes an input optical fiber (101), an output optical fiber (105), a dual optical fiber assembly (200) and a cover plate (103); a pressure-sensitive diaphragm (106) is arranged in the cavity; the pressure-sensitive diaphragm (106) is divided into a positive strain area (400) and a negative strain area (401); the dual optical fiber assembly (200) includes a sensing arm optical fiber (201), a reference arm optical fiber (202) and a photoelectric element; protective sleeves (203) are respectively sleeved outside the sensing arm optical fiber (201) and the reference arm optical fiber (202); epoxy glue is filled in the protective sleeve (203) of each optical fiber; the sensing arm optical fiber (201) and the reference arm optical fiber (202) are sealed by the epoxy glue. 2) are respectively fixed in corresponding protective sleeves (203), the sensing arm optical fiber (201) is fixed in the positive strain area (400) of the pressure-sensitive diaphragm (106), and the reference arm optical fiber (202) is fixed in the negative strain area (401) of the pressure-sensitive diaphragm, and both ends of the sensing arm optical fiber (201) and the reference arm optical fiber (202) extend out of the protective sleeve (203) and are connected to the photoelectric element to form a Michelson interference structure or a Mach-Zehnder interference structure; the input end and the output end of the dual optical fiber assembly (200) are respectively connected to the input optical fiber (101) and the output optical fiber (105) through the photoelectric element, and the cover plate (103) is sealed and covered on the open surface of the cavity (107).

2. A dual-fiber diaphragm optical fiber pressure sensor according to claim 1, characterized in that: The electronic components constituting the Michelson interference structure include a first optical fiber coupler (204), a first optical fiber reflector (206) and a second optical fiber reflector (207). The first optical fiber coupler (204) is arranged at one end of the cavity, and the first optical fiber reflector (206) and the second optical fiber reflector (207) are both arranged at the other end of the cavity (107). The first output end of the first optical fiber coupler (204) is connected to the input end of the sensing arm optical fiber (201), and the second output end of the first optical fiber coupler (204) is connected to the reference arm optical fiber (201). The input end of the first fiber coupler (204) extends from one side of the cavity (107) to the base (102) and is connected to the input fiber (101); the input end of the first fiber reflector (206) is connected to the output end of the sensing arm fiber (201), the input end of the second fiber reflector (207) is connected to the output end of the reference arm fiber (202), and the output ends of the two fiber reflectors extend from the other side of the cavity (107) to the base (102) and are connected to the output fiber (105).

3. The dual-fiber diaphragm optical fiber pressure sensor according to claim 1, characterized in that: The photoelectric elements constituting the Mach-Zehnder interference structure include a first fiber coupler (204) and a second fiber coupler (205) respectively arranged at two ends of a cavity (107); an input end of the first fiber coupler (204) extends out of a base (102) from one side of the cavity (107) to be connected to an input fiber (101); a first output end of the first fiber coupler (204) is connected to an input end of a sensing arm fiber (201); and a second output end of the first fiber coupler (204) is connected to an input end of a reference arm fiber (202); the output end of the sensing arm fiber (201) is connected to a first input end of the second fiber coupler (205); the reference arm fiber (202) is connected to a second input end of the second fiber coupler (205); and an output end of the second fiber coupler (205) extends out of a base (102) from the other side of the cavity (107) to be connected to an output fiber (105).

4. A dual-fiber diaphragm optical fiber pressure sensor according to claim 1, 2 or 3, characterized in that: The base (102) is a conical structure, the cavity (107) is a cylindrical cavity arranged in the middle of the base (102), the cavity opening of which is opened on the bottom surface of the base (102), a sealing groove (104) is arranged at the cavity opening, and a sealing ring is placed in the sealing groove (104), the pressure-sensitive diaphragm (106) is horizontally placed at the cavity opening of the cavity (107), and is sealed and crimped through the cover plate (103), and the pressure-sensitive diaphragm (106) and the base (102) form a hollow cavity; the medium introduction joint is arranged at the top center of the base (102), and a threaded connection port is provided at the medium introduction joint port.

5. A dual-fiber diaphragm optical fiber pressure sensor according to claim 1, 2 or 3, characterized in that: The middle part of the pressure-sensitive diaphragm (106) is a positive strain zone (400), the periphery of the pressure-sensitive diaphragm (106) is a negative strain zone (401), the sensing arm optical fiber (201) is coiled and fixed on the positive strain zone (400) of the pressure-sensitive diaphragm (106); and the sensing arm optical fiber (201) and the reference arm optical fiber (202) are both fixed on the pressure-sensitive diaphragm (106) by epoxy glue.

6. A dual-fiber diaphragm optical fiber pressure sensor according to claim 1, 2 or 3, characterized in that: The cover plate (103) is a stainless steel metal sealing cover, and a plurality of hexagonal countersunk holes (301) are provided on the cover plate (103), and the countersunk holes (301) are all distributed in a circular ring shape and in a symmetrical manner. A first optical fiber coupler installation box (302) and a second optical fiber coupler installation box or a reflector installation opening (305) are provided on the cover plate (103), and optical fiber outlets (304) are respectively provided on both sides of the cover plate; the base (102) is a stainless steel metal base, and a plurality of threaded holes are correspondingly provided on the bottom of the metal base (102).

7. A dual-fiber diaphragm optical fiber pressure sensor according to claim 1, 2 or 3, characterized in that: The protective sleeve (203) is a Teflon tube, and the pressure-sensitive diaphragm (106) is a stainless steel metal diaphragm; the optical fiber extending out of the base (102) is protected by a metal armor tube.

8. A dual-fiber diaphragm optical fiber pressure sensor according to claim 1, 2 or 3, characterized in that: The sensing arm optical fiber (201) and the reference arm optical fiber (202) are both made of carbon-coated optical fiber with a cladding diameter of 80 um.

9. The dual-fiber diaphragm optical fiber pressure sensor according to claim 2, characterized in that: The first optical fiber coupler (204) is a single-mode optical fiber coupler with a splitting ratio of 1:1; and the two optical fiber reflectors are both optical fiber Faraday magnetic rotator mirrors.

10. The dual-fiber diaphragm optical fiber pressure sensor according to claim 3, characterized in that: The first optical fiber coupler (204) and the second optical fiber coupler (205) are both single-mode optical fiber couplers with a splitting ratio of 1:1.

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