Double-optical-fiber pressure sensor

Abstract

The invention discloses a double-optical-fiber pressure sensor which comprises a piston, an h-type 304 stainless steel tube, a cantilever beam, a dowel bar, an optical fiber grating and a diaphragm. The fiber bragg grating is divided into a pressure sensing part and a temperature compensation part. The temperature compensation fiber bragg grating is placed in the h-shaped 304 stainless steel pipe, and the displacement change of the piston is transmitted to the free end of the cantilever beam, is not influenced by pressure, only changes along with the influence of the internal temperature, and plays a temperature compensation role. The first pressure sensing fiber bragg grating generates bending deformation by sensing bending deformation of the lower surface of the sensing cantilever beam, the second pressure sensing fiber bragg grating generates axial deformation by sensing pressure applied by the dowel bar, and both the first pressure sensing fiber bragg grating and the second pressure sensing fiber bragg grating are packaged by polycarbonate to realize pressure sensitization; error supplement can be realized by demodulating and calculating wavelength changes of the two, and detection of a pressure part is realized. The PTFE diaphragm is placed at the lower end of the piston, so that the influence of seawater infiltration on detection when the piston moves is prevented. The pressure sensor improves the precision and accuracy of detection data.

Description

Technical Field

[0001] The present invention relates to the technical field of fiber optic sensing, and more specifically to a dual-fiber pressure sensor. Background Art

[0002] The behavior of the ocean can be predicted through various parameter analyses. Among them, the pressure parameter of the ocean is the basis for obtaining parameters such as ocean sound speed, flow velocity, density, and heat content. The on-site real-time monitoring of its parameters is indispensable for fields such as ocean resource development, offshore operations, prevention of global warming, and military defense. Therefore, ocean pressure sensors, as basic equipment for ocean exploration, play an important role in fields such as ocean economy, ocean ecology, and ocean military.

[0003] Compared with traditional electrical sensors such as resistance strain gauges, fiber Bragg gratings in related technologies have the characteristics of small size, high temperature resistance, corrosion resistance, anti-electromagnetic interference, low loss, corrosion resistance, electrical insulation, and anti-electromagnetic interference. As good strain measurement elements, they have been extensively studied by a large number of researchers in different fields in recent years. In ocean sensing, although fiber Bragg gratings are not the mainstream technology as their sensing elements at present, due to the advantages of fiber Bragg gratings in pressure sensing, they can greatly improve and optimize problems such as poor stability caused by traditional XBT (i.e., XBT that uses electrical components for temperature measurement and has no pressure measurement component and has always relied on empirical formulas to calculate depth). Due to the low sensitivity of bare fiber Bragg gratings, most studies have used different methods to sensitize fiber Bragg gratings, but existing studies still have problems such as low sensitivity, large size, and long response time.

[0004] In addition, existing fiber Bragg grating pressure sensors mostly adopt a single strain mode (such as axial or bending strain), and have problems such as low sensitivity, slow response speed, and temperature cross-sensitivity. For example, Patent CN106441659.A realizes pressure detection through a cantilever beam single fiber Bragg grating, but the sensitization effect is limited and temperature interference cannot be eliminated. In addition, traditional sensors have complex structures and insufficient waterproof performance, making it difficult to meet the requirements of ocean exploration.

[0005] Therefore, finding a sensor structure that can simultaneously improve pressure sensitivity, reduce pressure response time, has good stability, and can achieve temperature compensation for the pressure sensing part is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention provides a dual-fiber pressure sensor, aiming at the problems that traditional sensors have complex structures and insufficient waterproof performance, making it difficult to meet the requirements of ocean exploration. The present invention effectively solves the above problems through dual-fiber collaborative measurement, temperature compensation, and modular design.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] An embodiment of the present invention provides a dual-fiber optic pressure sensor, comprising:

[0009] A housing with an open upper end, a hollow cavity inside, and an optical fiber outlet hole at the bottom end;

[0010] A piston covering the opening of the housing for sensing external pressure and generating displacement;

[0011] An H-shaped 304 stainless steel tube disposed in the hollow cavity, in an inverted H shape, welded to the piston at the upper end and welded to the free end of the cantilever beam at the lower end for transmitting the piston displacement;

[0012] A temperature compensation fiber optic grating disposed in the internal space formed by the H-shaped 304 stainless steel tube and the piston for measuring the internal temperature of the sensor;

[0013] A cantilever beam located in the space below the H-shaped 304 stainless steel tube, with one end fixed to the side wall of the housing and the other end being the free end for converting displacement into bending strain;

[0014] A first pressure sensing fiber optic grating pasted on the lower surface of the cantilever beam for detecting bending strain;

[0015] A force transmission rod, welded to the free end of the cantilever beam at the upper end and connected to the second pressure sensing fiber optic grating at the lower end;

[0016] A second pressure sensing fiber optic grating disposed at the lower end of the force transmission rod for detecting axial strain;

[0017] A PTFE diaphragm located below the piston, welded to the side wall of the housing at one end and welded to the inverted H-shaped 304 stainless steel tube at the other end for preventing seawater from seeping in;

[0018] A force transmission base serving as a fixed base for the lower end of the force transmission rod and connected to the bottom of the housing.

[0019] Further, the housing is made of 304 stainless steel.

[0020] Further, the piston is made of 7075 aluminum alloy.

[0021] Further, the dimensions of the piston are: length 15 - 20 mm, width 8 - 12 mm, and thickness 6 - 10 mm.

[0022] Further, the central wavelength of the temperature compensation fiber optic grating is 1310 nm.

[0023] Further, the dimensions of the cantilever beam are: length 8 - 13 mm, width 5 - 7 mm, and thickness 3 - 5 mm.

[0024] Further, the central wavelength of the first pressure-sensing fiber grating is 1570 nm.

[0025] Further, the dimensions of the force transfer rod are: length 6 - 10 mm, width 3 - 5 mm, and thickness 3 - 5 mm.

[0026] Further, the central wavelength of the second pressure-sensing fiber grating is 1550 nm.

[0027] Further, both the first pressure-sensing fiber grating and the second pressure-sensing fiber grating are encapsulated with polycarbonate; the Young's modulus of the polycarbonate is lower than that of the fiber grating material, which is used to enhance the pressure response sensitivity.

[0028] Further, the long end of the h-shaped 304 stainless steel tube is 15 - 20 mm, and the short end is 10 - 13 mm.

[0029] Through the above technical solutions, compared with the prior art, the present invention has the following technical effects:

[0030] The pressure sensor of the present invention separately sets a temperature compensation fiber grating, and uses a piston, a cantilever beam, a force transfer rod, and a polymer material polycarbonate to enhance the sensitivity of the first pressure-sensing fiber grating and the second pressure-sensing fiber grating, improving the pressure sensitivity while reducing the pressure response time; further, the change of pressure sensitivity and pressure response speed can be achieved by adjusting the thickness of the piston, the material and thickness of the cantilever beam, and the material of the polymer, and a waterproof diaphragm is set to improve the accuracy and precision of the detected data. When all components with dimensions less than 20 mm are used for building and assembling, it is convenient to carry and can realize the detection of shallow sea pressure data. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0032] Figure 1 It is a schematic structural diagram of the dual-fiber pressure sensor provided by the present invention.

[0033] Figure 2 It is a top view schematic diagram of the dual-fiber pressure sensor provided by the present invention.

[0034] In the figure: 1 is a piston, 2 is a welding point, 3 is a PTFE diaphragm, 4 is a force transmission rod, 5 is an optical fiber, 6 is a polymer polycarbonate of the second pressure-sensing fiber grating, 7 is the second pressure-sensing fiber grating, 8 is a force transmission base, 9 is a housing, 10 is an h-shaped 304 stainless steel tube, 11 is a temperature compensation fiber grating, 12 is a cantilever beam, 13 is the first pressure-sensing fiber grating, 14 is a polymer polycarbonate of the first pressure-sensing fiber, 15 is the first lead-out optical fiber, and 16 is the second lead-out optical fiber. Detailed implementation manners

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0036] To meet the requirements of high-precision depth detection in the shallow sea area of the ocean, the embodiments of the present invention disclose a dual-fiber pressure sensor, referring to Figure 1-2 as shown, including: a housing 9, a piston 1, an h-shaped 304 stainless steel tube 10, a cantilever beam 12, a force transmission rod 4, a fiber Bragg grating FBG, and a diaphragm, etc.

[0037] The fiber Bragg grating FBG is divided into two parts: pressure sensing and temperature compensation. The temperature compensation fiber grating 11 is placed inside the h-shaped 304 stainless steel tube 10. The upper end of the h-shaped 304 stainless steel tube 10 is welded to the piston 2 to transmit the displacement change of the piston 2 to the free end of the cantilever beam 12. The temperature compensation fiber grating 11 is not affected by pressure and only changes with the internal temperature, playing a temperature compensation role.

[0038] The first pressure-sensing fiber grating 13 generates a bending deformation by sensing the bending deformation of the lower surface of the cantilever beam 12, and is encapsulated with a polymer polycarbonate 14. Polycarbonate has a low Young's modulus and jointly acts with the piston 2 and the lower surface of the cantilever beam 12 to achieve pressure sensitization of the first pressure-sensing fiber grating 13;

[0039] The second pressure-sensing fiber grating 7 generates an axial deformation by sensing the pressure applied by the force transmission rod 4, and is encapsulated with a polymer polycarbonate 6. Polycarbonate jointly acts with the piston 1 and the force transmission rod 4 to achieve pressure sensitization of the second pressure-sensing fiber grating 7.

[0040] The first pressure-sensing fiber Bragg grating 13 is pasted on the lower surface of the cantilever beam 12, and the second pressure-sensing fiber Bragg grating 7 is placed at the lower end of the force transfer rod 4. The first pressure-sensing fiber Bragg grating 13 generates a bending deformation by sensing the deformation of the lower surface of the cantilever beam 12, and the second pressure-sensing fiber Bragg grating 7 generates an axial deformation by sensing the pressure applied by the force transfer rod 4. Acting simultaneously, since the formulas for demodulating the axial strain and bending strain of the fiber Bragg grating are different, error compensation is achieved by demodulating and calculating the wavelength changes of the first pressure-sensing fiber Bragg grating 13 and the second pressure-sensing fiber Bragg grating 7, realizing the detection of the pressure part.

[0041] A PTFE diaphragm 3 is placed at 7 mm below the lower end of the piston 1 to prevent the influence on detection caused by seawater infiltration when the piston 2 moves, ensuring the stability during the detection process of the sensor.

[0042] In the pressure detection part, the present invention realizes pressure detection by sensing the deformation of the cantilever beam caused by pressure. The displacement change of the piston is transmitted to the free end of the cantilever beam through an H-shaped 304 stainless steel tube. The first pressure-sensing fiber Bragg grating generates a bending deformation by sensing the deformation of the lower surface of the cantilever beam, and the second pressure-sensing fiber Bragg grating generates an axial deformation by sensing the pressure applied by the force transfer rod. Acting simultaneously, they jointly realize the detection of the pressure part. Compared with the prior art, the two pressure-sensing fiber Bragg gratings of the present invention are subjected to different strain modes, and the calculation methods of the fiber Bragg grating deformations generated by these two strain modes are different. Error compensation is achieved by demodulating and calculating the wavelength changes of the first pressure-sensing fiber Bragg grating and the second pressure-sensing fiber Bragg grating. It has an automatic temperature compensation function and can better avoid the chirping phenomenon easily generated when the fiber Bragg grating is compressed.

[0043] This structure is provided with a temperature compensation fiber Bragg grating, which reduces the influence caused by the different wavelength displacements of the double pressure-sensing fiber Bragg gratings on the basis of automatic temperature compensation, and can improve the accuracy of pressure detection data; a temperature compensation fiber Bragg grating is placed in the H-shaped 304 stainless steel tube to prevent it from being affected by the seawater temperature; at the same time, a waterproof diaphragm is provided to prevent seawater infiltration, improving the stability of the detection data of the sensor. On the one hand, the present invention adopts the structural design of double pressure-sensing fiber Bragg gratings to improve the detection sensitivity. On the other hand, the pressure-sensing fiber Bragg grating is encapsulated with a polymer material polycarbonate. Polycarbonate has a low Young's modulus and acts together with the piston, cantilever beam, and force transfer rod to sensitize the fiber Bragg grating, improving the pressure detection sensitivity while reducing the pressure detection time.

[0044] Among them, the principle of axial strain: When an external uniform axial pressure is applied to the FBG, the axial strain ε generated by the FBG will change its grating period, and ε can be expressed as:

[0045]

[0046] Among them, Λ is the period of the fiber grating, and ΔΛ is the period change rate of the fiber grating; Δx is the deformation of the pressure-sensing fiber grating FBG, x is the effective length of the FBG. When the FBG is strained, its effective refractive index will also change, which can be expressed as:

[0047]

[0048] In the formula, n eff is the effective refractive index of the optical fiber, and Δn eff is the change in the effective refractive index; p 11 , p 12 are the photoelastic coefficients of the optical fiber that describe the influence of longitudinal strain and transverse strain on the refractive index respectively, and μ is the Poisson's ratio of the optical fiber material. Then the effective photoelastic coefficient is:

[0049]

[0050] Combining the above formulas, the wavelength change caused by axial strain can be expressed as:

[0051] Δλ b =(1 - P e )λ·ε (4)

[0052] For an FBG with a determined central wavelength and material, its wavelength drift is only related to the strain of the FBG. Therefore, the FBG can be used for pressure sensing.

[0053] Bending strain principle:

[0054] Assume that the bending radius of curvature of the optical fiber is R and the diameter of the optical fiber is d. Then the bending strain ε b , and its distribution along the radial direction of the optical fiber is:

[0055]

[0056] Among them, y is the distance from the neutral axis (-d / 2 ≤ y ≤ d / 2)

[0057] The relationship between the Bragg wavelength shift Δλ B of the FBG and the strain is:

[0058]

[0059] Among them, Pe is the effective photoelastic coefficient. Combining the above formulas, the wavelength change caused by axial strain can be expressed as:

[0060]

[0061] Tensile side (y = +d / 2): The wavelength shifts towards the long-wave direction;

[0062] Compression side (y = -d / 2): The wavelength shifts towards the short-wave direction.

[0063] As can be seen from the formula, when the fiber Bragg grating is bent, the change in its curvature will directly affect the wavelength drift. Generally speaking, the greater the curvature, the greater the wavelength drift. This is because when the optical fiber is bent, the propagation path of light in the optical fiber changes, resulting in a change in the refractive index modulation period of the grating, thereby causing a drift in the central wavelength.

[0064] In this embodiment, according to the wavelength changes of the first pressure-sensing fiber Bragg grating and the second pressure-sensing fiber Bragg grating, error compensation is achieved by solving the axial strain and bending strain formulas, and combined with the temperature compensation data of the temperature compensation fiber Bragg grating, an accurate pressure value is output.

[0065] The dual-fiber pressure sensor provided by the embodiment of the present invention separately sets a temperature compensation fiber Bragg grating, and uses a piston, a cantilever beam, a force transmission rod, and a polymer material polycarbonate to sensitize the first pressure-sensing fiber Bragg grating and the second pressure-sensing fiber Bragg grating. Due to the different strain types and calculation formulas of the first pressure-sensing fiber Bragg grating and the second pressure-sensing fiber Bragg grating, error compensation is achieved, while improving the pressure sensitivity and reducing the pressure response time at the same time; the change of pressure sensitivity and pressure response speed can be realized by adjusting the thickness of the piston, the material and thickness of the cantilever beam, and the material of the polymer, and a waterproof diaphragm is set to improve the accuracy and accuracy of the detected data. When implementing the product of the present invention, components with a size less than 20 mm can be used for construction and assembly, which is convenient to carry and can realize the detection of pressure data in the shallow sea of 0-1000 m. Compared with the existing marine pressure sensors, on the basis of stable performance, the present invention not only has higher pressure sensitivity, but also the response speed is improved.

[0066] During specific implementation, refer to Figure 1-2 As described above, each component of the present invention is described in detail. The dual-fiber pressure sensor includes from the outside to the inside:

[0067] The outer shell 9 is rectangular in shape and can be made of 304 stainless steel. The upper end of the outer shell 9 is open, with a hollow cavity inside. A small hole is opened at the bottom to lead out the first lead fiber 15 that sequentially connects the first pressure-sensing fiber Bragg grating 13 and the second pressure-sensing fiber Bragg grating 7, and to lead out the second lead fiber 16 that connects the temperature compensation fiber Bragg grating 11;

[0068] The piston 1 is made of 7075 aluminum alloy, has good strength and lightweight characteristics, strong corrosion resistance and good wear resistance, and is suitable for the marine detection environment. For example, it is 15-20 mm long, 8-12 mm wide, and 6-10 mm thick, and covers the opening of the outer shell 9 to sense the displacement caused by the impact of seawater.

[0069] The H-shaped 304 stainless steel tube 10 is in an inverted H shape, with its upper end welded to the piston 1, as shown by the solder joint 2 in Figure 1 ; the lower end is welded to the cantilever beam 12, with the long end being 15 - 20 mm long and the short end being 10 - 13 mm long, preventing the internal temperature-compensated fiber Bragg grating 11 from being affected by the seawater temperature and transmitting the piston 1 displacement change to the free end of the cantilever beam 12.

[0070] The temperature-compensated fiber Bragg grating 11 uses a fiber Bragg grating with a central wavelength of 1310 nm and is placed inside the H-shaped 304 stainless steel tube 10 to measure the temperature inside the sensor, not affected by the pressure caused by the piston displacement, and plays a temperature compensation role.

[0071] The diaphragm is located 7 mm below the piston 1 and uses a PTFE film 3, which has a certain elasticity. The left end is welded to the 304 stainless steel rectangular housing 9, and the right end is welded to the inverted H-shaped 304 stainless steel tube 10. It only allows air to pass through and does not allow water to pass through, preventing seawater from seeping in when the piston 1 displaces and affecting the first pressure-sensing fiber Bragg grating 13 and the first pressure-sensing fiber Bragg grating 7.

[0072] The cantilever beam 12 is made of 304 stainless steel, for example, 8 - 13 mm long, 5 - 7 mm wide, and 3 - 5 mm thick. One end is fixed to the housing, and the other end is the free end, feeling the displacement generated by the deformation transmitted when the H-shaped 304 stainless steel tube 10 displaces, making the upper surface of the cantilever beam 12 in a tensile state and the lower surface in a compressive state.

[0073] The force transmission rod 4 is made of 304 stainless steel, with its upper end welded to the free end of the cantilever beam 12, for example, 6 - 10 mm long, 3 - 5 mm wide, and 3 - 5 mm thick.

[0074] The first pressure-sensing fiber Bragg grating 13 uses a fiber Bragg grating with a central wavelength of 1570 nm and is pasted on the lower surface of the cantilever beam 12 to sense the bending deformation generated by the bending of the lower surface. It is coated with the polymer polycarbonate 14. Polycarbonate has a low Young's modulus and, together with the piston 1 and the upper surface of the cantilever beam 12, realizes pressure sensitization of the first pressure-sensing fiber Bragg grating 13.

[0075] The second pressure-sensing fiber Bragg grating 7 uses a fiber Bragg grating with a central wavelength of 1550 nm and is located at the lower end of the force transmission rod 4. It generates axial deformation by sensing the pressure applied by the force transmission rod 4. It is coated with the polymer polycarbonate 6. Polycarbonate has a low Young's modulus and, together with the piston 1 and the force transmission rod 4, realizes pressure sensitization of the second pressure-sensing fiber Bragg grating 7. The detection of the pressure part is realized by demodulating and calculating the wavelength changes of the pressure-sensing FBG2 and the pressure-sensing FBG3.

[0076] The core function of the force transmission base 8 is to fix the force transmission rod 4 and ensure the effective transmission of the axial force. Figure 1 As shown, the force transmission base 8 is connected to the bottom of the 304 stainless steel rectangular column housing 9, serving as a fixed base for the lower end of the force transmission rod 4, ensuring that the force transmission rod 4 maintains stability in the vertical direction when subjected to force, preventing lateral deviation or vibration interference, thereby ensuring accurate transmission of axial strain. In addition, uniform stress distribution can be achieved. When the external pressure is transmitted to the force transmission rod 4 through the piston 1 and the cantilever beam 12, the force transmission base 8 disperses the concentrated force borne by the lower end of the force transmission rod to the housing 9, avoiding material fatigue or deformation errors caused by local stress concentration, and improving the long-term reliability of the sensor.

[0077] However, since the first pressure sensing fiber Bragg grating 13 and the first pressure sensing fiber Bragg grating 7 are affected by both pressure and temperature, a temperature compensation fiber Bragg grating 11 is added to the H-shaped 304 stainless steel tube 10. It is only affected by temperature and not strain, and is used to measure the internal temperature of the sensor structure to eliminate the temperature effect on the two pressure sensing fiber Bragg gratings. The effective refractive index of the first pressure sensing fiber Bragg grating 13 and the first pressure sensing fiber Bragg grating 7 changes after being affected by external pressure and temperature, causing the central wavelength to shift. When the laser is transmitted through the optical fiber, the wavelength band that meets the fiber Bragg grating conditions will be reflected back, and the external pressure information can be calculated by the reflected light using a mediation device.

[0078] The dual-fiber pressure sensor provided by the present invention achieves a pressure sensitivity of more than 1 nm / Mpa and a pressure response speed of less than 35 ms. At the same time, a PTFE diaphragm is used to prevent the infiltration of water molecules, thereby enhancing the stability of the pressure sensing fiber grating.

[0079] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0080] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A dual optical fiber pressure sensor, characterized in that: include: The outer shell (9) is open at the top, has a hollow cavity inside, and has an optical fiber lead-out hole at the bottom; A piston (1) covers the opening of the housing and is used to sense external pressure and generate displacement; An H-shaped 304 stainless steel tube (10) is arranged in the hollow cavity and is in an inverted H-shape, with the upper end welded to the piston and the lower end welded to the free end of the cantilever beam (12) for transmitting the displacement of the piston; A temperature compensation fiber grating (11) is arranged in the internal space formed by the H-shaped 304 stainless steel tube and the piston, and is used to measure the internal temperature of the sensor; A cantilever beam (12), located in the space below the H-shaped 304 stainless steel tube (10), with one end fixed to the side wall of the housing (9) and the other end being a free end, for converting displacement into bending strain; A first pressure sensing fiber grating (13) is adhered to the lower surface of the cantilever beam and is used to detect bending strain; A force transmission rod (4), the upper end of which is welded to the free end of the cantilever beam, and the lower end of which is connected to the second pressure sensing optical fiber grating (7); A second pressure sensing optical fiber Bragg grating (7) is arranged at the lower end of the force transmission rod (4) and is used to detect axial strain; A PTFE diaphragm (3) is located at the lower end of the piston (1), one end of which is welded to the side wall of the housing (9) and the other end of which is welded to an inverted H-shaped 304 stainless steel tube (10) to prevent seawater from penetrating; The force transmission base (8) serves as a fixed base for the lower end (4) of the force transmission rod and is connected to the bottom of the housing (9).

2. The dual optical fiber pressure sensor according to claim 1, characterized in that: The housing (9) is made of 304 stainless steel.

3. The dual optical fiber pressure sensor according to claim 1, characterized in that: The piston (1) is made of 7075 aluminum alloy.

4. The dual optical fiber pressure sensor according to claim 1, characterized in that: The dimensions of the piston (1) are: 15-20 mm in length, 8-12 mm in width, and 6-10 mm in thickness.

5. The dual optical fiber pressure sensor according to claim 1, characterized in that: The central wavelength of the temperature-compensated optical fiber grating (11) is 1310 nm.

6. The dual optical fiber pressure sensor according to claim 1, characterized in that: The dimensions of the cantilever beam (12) are: 8-13 mm in length, 5-7 mm in width, and 3-5 mm in thickness.

7. The dual optical fiber pressure sensor according to claim 1, characterized in that: The central wavelength of the first pressure sensing fiber grating (13) is 1570 nm.

8. The dual optical fiber pressure sensor according to claim 1, characterized in that: The dimensions of the force transmission rod (4) are: 6-10 mm in length, 3-5 mm in width, and 3-5 mm in thickness.

9. The dual optical fiber pressure sensor according to claim 1, characterized in that: The central wavelength of the second pressure sensing optical fiber Bragg grating (7) is 1550 nm.

10. The dual optical fiber pressure sensor according to claim 1, characterized in that: The first pressure sensing optical fiber Bragg grating (13) and the second pressure sensing optical fiber Bragg grating (7) are both packaged with polycarbonate; the Young's modulus of the polycarbonate is lower than that of the optical fiber Bragg grating material, and is used to enhance the sensitivity of the pressure response.

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