Surface-mounted optical fiber Fabry-Perot high-temperature pressure sensor

Abstract

The invention belongs to the field of pressure sensors, and particularly relates to a surface-mounted optical fiber Fabry-Perot high-temperature pressure sensor. According to the surface-mounted optical fiber Fabry-Perot high-temperature pressure sensor provided by the embodiment of the invention, when the pressure sensing diaphragm is scoured by the liquid metal coolant, the pressure is converted into the change of the length of the Fabry-Perot cavity, incident light forms a multi-beam interference signal, the direction of the multi-beam interference signal is changed through the gold-plated reflector, and the multi-beam interference signal is converged and collected by the spherical lens and transmitted to the optical fiber lead; the optical signals enter an optical fiber demodulator to demodulate and restore the optical signals into pressure; multi-beam interference sensing is adopted, and an internal packaging structure is utilized to realize the change of a light path, so that small-size accurate measurement of a narrow pipeline space is realized; optical fiber transmission is resistant to high temperature of a liquid metal fluid environment and strong electromagnetic interference, and high-accuracy, high-sensitivity and high-response-speed real-time pressure monitoring and long-term pressure measurement work can be kept in the high-temperature and strong-electromagnetic-interference liquid metal reactor environment.

Description

Technical Field

[0001] This application belongs to the field of pressure sensors, specifically relating to a surface-mount fiber optic Fabry-Perot high-temperature pressure sensor. Background Technology

[0002] Pressure is one of the important physical quantities describing the flow-induced vibration state of an object. In various testing and inspection work in engineering projects such as nuclear reactors, pressure is a crucial measurement. Pulsating pressure is a key indicator for measuring the scouring intensity of coolant fluid on critical nuclear reactor equipment, and it is of great significance for assessing fatigue damage to critical nuclear reactor equipment. With the continuous development of nuclear reactor technology, lead-based materials, due to their excellent neutronic properties, superior thermal performance, and reliable safety, have been widely used in the research of fourth-generation advanced nuclear energy systems. As a new type of nuclear reactor, the coolant fluid in a liquid metal nuclear reactor is a novel liquid-liquid metal eutectic alloy. Pulsating pressure sensors used in liquid metal reactors must withstand extreme tests such as high temperature, high pressure, and strong electromagnetic interference.

[0003] Traditional electrical and mechanical pressure sensors suffer from drawbacks such as slow response speed or large size, limiting their use in liquid metal environments. Traditional mechanical pressure sensors directly utilize elastic elements to detect pressure, resulting in slow response speed, limited frequency and dynamic range, and large size. Electrical sensors convert the deformation of elastic elements into electrical signals to measure pressure, offering higher sensitivity and faster response, but are unsuitable for the highly interference-prone environment of liquid metal reactors. Summary of the Invention

[0004] The purpose of this application is to provide a surface-mount fiber optic Fabry-Perot high-temperature pressure sensor to solve the problem of limited use of traditional pressure sensors in confined spaces between fuel plates and in liquid metal environments.

[0005] The technical solution to achieve the purpose of this application is as follows:

[0006] This application provides a surface-mount fiber optic Fabry-Perot high-temperature pressure sensor, comprising: fiber optic cable, spherical lens, gold-plated reflector, and pressure chip;

[0007] The pressure chip includes a Fabry-Perot cavity, a pressure-sensitive diaphragm, and a substrate, wherein the pressure-sensitive diaphragm and the substrate are bonded together, and the gap between them forms the Fabry-Perot cavity;

[0008] After the incident beam is collimated, it is transmitted to the surface of the gold-plated mirror, which changes the direction of the beam and enters the Fabry-Perot cavity.

[0009] When the pressure-sensitive diaphragm is flushed by the liquid metal coolant, it converts the pressure magnitude into a change in the length of the Fabry-Perot cavity, forming a multi-beam interference signal. The signal is redirected by a gold-plated reflector, converged and collected by a spherical lens, and transmitted to the optical fiber conductor. The optical fiber demodulator then demodulates the optical signal to restore the pressure magnitude.

[0010] Optionally, the substrate of the pressure-sensitive diaphragm is a silicon wafer, wherein the silicon wafer has a diameter of 50 mm and a thickness of 0.4 mm. <100> Crystal orientation;

[0011] The substrate uses the same silicon wafer as the pressure-sensitive diaphragm.

[0012] Optionally, wet etching is performed on the upper and lower surfaces of the silicon wafer to form cavities, and wet etching is performed again to form a boss structure on the inner surface of the bottom of the cavity; the boss structures on the upper and lower surfaces are chemically and mechanically polished.

[0013] Optionally, the processed silicon wafer is bonded to another silicon wafer to form a pressure-sensitive diaphragm, and the wafer is diced to form multiple pressure sensing units.

[0014] Optionally, the fiber optic cable consists of a fiber optic ferrule and an encapsulation shell, which are fixed together using a nano-silver sintering process.

[0015] Both the fiber optic ferrule and the encapsulation shell are made of 316 stainless steel.

[0016] The surface-mount fiber optic Fabry-Perot high-temperature pressure sensor also includes: a packaging structure;

[0017] The encapsulation structure is made of 316 stainless steel and encapsulates and fixes the optical fiber wire, ball lens, gold-plated reflector and pressure chip.

[0018] Optionally, the spherical lens is made of quartz glass with a light transmittance of 1.51.

[0019] Optionally, the gold-plated reflector is made of 316 stainless steel with a gold-plated surface, which causes the beam path to be deflected 90°.

[0020] Optionally, the fiber optic cable is led out through a sealed head and connected to the fiber optic demodulator.

[0021] Optionally, the sensor can withstand environments up to 550℃ and has a sensitivity greater than 0.4 nm·kPa. -1 .

[0022] The beneficial technical effects of this application are as follows:

[0023] This application provides a surface-mount fiber optic Fabry-Perot high-temperature pressure sensor, comprising an optical fiber conductor, a spherical lens, a gold-plated reflector, and a pressure chip. When the pressure-sensing diaphragm is subjected to slickness from a liquid metal coolant, the pressure magnitude is converted into a change in the length of the Fabry-Perot cavity. The incident light forms a multi-beam interference signal, which is redirected by the gold-plated reflector, converged and collected by the spherical lens, and transmitted to the optical fiber conductor. The signal is then demodulated by an optical fiber demodulator to restore the pressure magnitude. Employing multi-beam interference sensing and utilizing an internal encapsulation structure to alter the optical path, this sensor enables precise measurement within a confined space. The fiber optic transmission is resistant to the high temperatures and strong electromagnetic interference of the liquid metal environment, maintaining high accuracy, high sensitivity, high response speed, and small size even in the high-temperature, high-electromagnetic-interference environment of a liquid metal reactor. This allows for real-time monitoring and long-term pressure measurement of structures such as steam generators and fuel assemblies subjected to slickness from liquid metal. Attached Figure Description

[0024] Figure 1 A schematic diagram of a surface-mount fiber optic Fabry-Perot high-temperature pressure sensor provided in this application embodiment;

[0025] In the diagram: 1-Fiber optic cable; 2-Packaging structure; 3-Spherical lens; 4-Gold-plated reflector; 5-Pressure chip; 6-Fabry-Perot cavity; 7-Pressure-sensing diaphragm; 8-Substrate. Detailed Implementation

[0026] To enable those skilled in the art to better understand this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only a part of the embodiments of this application, and not all of them. Based on the embodiments described in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] To address the problems in the prior art, the inventors of this application provide a surface-mount fiber optic Fabry-Perot high-temperature pressure sensor. Utilizing the influence of the sensor's mechanical properties on its optical properties, a composite Fabry-Perot cavity structure is employed. When the pressure-sensing diaphragm is subjected to force, both the inner and outer surfaces undergo significant deformation, resulting in a reduction in the length of the Fabry-Perot cavity in the air medium. This converts the pressure value on the diaphragm into the cavity length value. Sensing is achieved through multi-beam interference, and pressure measurement can be realized by transmitting the interference signal via optical fiber.

[0028] Based on the above, in order to clearly and in detail illustrate the advantages of this application, the specific embodiments of this application will be described below in conjunction with the accompanying drawings.

[0029] See Figure 1 The figure is a schematic diagram of a surface-mount fiber optic Fabry-Perot high-temperature pressure sensor provided in an embodiment of this application.

[0030] This application provides a surface-mount fiber optic Fabry-Perot high-temperature pressure sensor, comprising: fiber optic cable 1, spherical lens 3, gold-plated reflector 4, and pressure chip 5.

[0031] The pressure chip 5 includes a Fabry-Perot cavity 6, a pressure-sensitive diaphragm 7, and a substrate 8. The pressure-sensitive diaphragm 7 and the substrate 8 are bonded together, and the gap between them forms the Fabry-Perot cavity 6.

[0032] After the incident beam is collimated, it is transmitted to the surface of the gold-plated reflector 4, changing the direction of the beam and entering the Fabry cavity 6.

[0033] When the pressure-sensitive diaphragm 7 is flushed by the liquid metal coolant, the pressure magnitude is converted into a change in the cavity length of the Fabry-Perot cavity 6, forming a multi-beam interference signal. The signal is redirected by the gold-plated reflector 4, converged and collected by the spherical lens 3, and transmitted to the optical fiber cable 1. The optical signal is then demodulated and restored to the pressure magnitude by the optical fiber demodulator.

[0034] It is understandable that when the pressure-sensitive diaphragm 7 is subjected to force, its inner surface (reflecting surface at the far end of the Fabry cavity) and its outer surface (force-bearing surface) undergo significant deformation, resulting in a reduction in the length of the Fabry cavity in the air medium. The pressure value on the diaphragm is inversely correlated with the length of the Fabry cavity, and there is a corresponding relationship. The multi-beam interference signal formed by the change in cavity length can reflect the magnitude of the pressure after analysis.

[0035] In some possible implementations of this application, the substrate of the pressure-sensitive diaphragm 7 is a silicon wafer, the silicon wafer having a diameter of 50 mm and a thickness of 0.4 mm. <100> Crystal orientation;

[0036] The substrate 8 uses the same silicon wafer as the pressure-sensitive diaphragm 7 as a substrate.

[0037] In one example, the upper and lower surfaces of the silicon wafer are wet-etched to form cavities, and wet-etched again to form a boss structure on the inner surface of the bottom of the cavity; the boss structures on the upper and lower surfaces are chemically and mechanically polished.

[0038] The processed silicon wafer is bonded to another silicon wafer to form a pressure-sensitive diaphragm 7, and then dicing is performed to form several independent sealed pressure sensing units that meet the required specifications and dimensions.

[0039] In some possible implementations of the embodiments of this application, the optical fiber conductor 1 is composed of an optical fiber ferrule and a package shell, the two are fixed by a nano-silver sintering process, and the cross-section is polished by an optical fiber polishing machine.

[0040] Both the fiber optic ferrule and the encapsulation shell are made of 316 stainless steel, which is conducive to welding and resistant to corrosion and high temperatures, making it suitable for environments with liquid metal fluids.

[0041] In some possible implementations of the embodiments of this application, the sensor further includes an encapsulation structure 2;

[0042] The encapsulation structure 2 is made of 316 stainless steel and encapsulates and fixes the optical fiber wire 1, the ball lens 3, the gold-plated reflector 4, and the pressure chip 5.

[0043] It should be noted that traditional direct encapsulation designs cannot meet the needs of measuring lateral pressure in narrow spaces between fuel plates, for example. The pressure-sensing diaphragm is parallel to the surface of the fuel plate and cannot measure pressure perpendicular to the surface of the fuel plate. The narrow space between the fuel plates also cannot achieve a 90° bend in the optical fiber. The internal encapsulation structure of this application uses a gold-plated reflector to adjust the internal beam path by 90°.

[0044] In some possible implementations of the embodiments of this application, the material of the spherical lens 3 is quartz glass with a light transmittance of 1.51.

[0045] It should be noted that the spherical lens 3 has a collimating effect on the light and also focuses the light reflected from the Fabry-Perot cavity 6, which is beneficial for the fiber optic cable 1 to collect the light.

[0046] In some possible implementations of this application, the gold-plated reflector 4 is made of 316 stainless steel and has a gold-plated surface, which causes the beam path to be deflected by 90°.

[0047] It should be noted that the surface of the reflector is plated with gold to increase the reflectivity of red light, thereby changing the direction of the light path and achieving the goal of balancing miniaturization and measurement accuracy.

[0048] In some possible implementations of the embodiments of this application, the optical fiber conductor 1 is led out through a sealing head and connected to the optical fiber demodulator.

[0049] In some possible implementations of this application, the sensor can withstand an environment of up to 550°C and has a sensitivity greater than 0.4 nm·kPa. -1 .

[0050] The following detailed explanation of the working process of a surface-mount fiber optic Fabry-Perot high-temperature pressure sensor provided in this application embodiment, using a specific example.

[0051] S1. Installation

[0052] After cleaning the spherical lens 3 and the gold-plated reflector 4 with alcohol, they are placed into their respective positions in the encapsulation structure 2.

[0053] Insert the fiber optic ferrule of fiber optic cable 1 into the entrance hole on the package shell, connect the light source and fine-tune the positions of the fiber optic ferrule, ball lens 3 and gold-plated reflector 4 until a full-shaped, stray light spot with strong light appears.

[0054] Lead the fiber optic cable 1 out through the sealing head and connect it to the fiber optic demodulator; place the pressure chip 5 at the corresponding position of the packaging structure 2 and fine-tune it until a high-quality interference spectrum signal appears;

[0055] The above components are fixed with special adhesive to prevent slippage. The ball lens 3 and pressure chip 5 are welded to the packaging structure 2 using glass solder. The gold-plated reflector 4 is laser-welded, and the packaging of the packaging structure 2 is laser-welded.

[0056] S2. Inspection and Testing

[0057] Check for defects on the surface of the surface-mounted fiber optic Fabry-Perot high-temperature pressure sensor and for bending or damage to fiber optic cable 1.

[0058] According to the test procedure, the sensor is welded to the surface of the measuring point, wherein the pressure-sensitive diaphragm 7 is installed on the side of the liquid metal fluid;

[0059] Check if the signal of the fiber optic demodulator is normal, and set parameters such as sensitivity.

[0060] Heat and pressurize to the test conditions, then begin testing and recording.

[0061] The cavity length was calculated, and the pressure changes during the test were demodulated.

[0062] The embodiments of this application, following the above-described process, were applied to test results in a liquid metal environment at 550°C, 0MPa, 1MPa, and 2MPa, demonstrating high-sensitivity and reliable measurement.

[0063] The embodiments of this application have the following beneficial effects:

[0064] (1) By utilizing the influence of the mechanical properties of the sensor on its optical properties, a composite Fabry-Perot cavity structure is adopted. When the pressure-sensitive diaphragm is subjected to force, the inner and outer surfaces undergo significant deformation, resulting in a reduction in the cavity length of the air medium Fabry-Perot cavity. The pressure value of the diaphragm is converted into the cavity length value of the Fabry-Perot cavity. Sensing is achieved through multi-beam interference. The optical path is changed by utilizing the internal encapsulation structure, enabling precise measurement of small dimensions in narrow tube spaces.

[0065] (2) Both the fiber optic ferrule and the encapsulation shell are made of 316 stainless steel, which is easy to weld and can withstand corrosion and high temperature, making it suitable for environments with liquid metal fluids.

[0066] (3) The ball lens has a collimating effect on light, which focuses the light reflected from the Fabry cavity to facilitate collection by the optical fiber wire; the gold-plated reflector is gold-plated on the surface to increase the reflectivity of red light, which is used to change the direction of the light path, thus achieving the goal of miniaturization and measurement accuracy.

[0067] (4) The optical fiber transmission is resistant to high temperatures and strong electromagnetic interference in the liquid metal fluid environment, achieving high-sensitivity measurement at 550℃ with a sensitivity greater than 0.4 nm·kPa. -1 .

[0068] The present application has been described in detail above with reference to the accompanying drawings and embodiments. However, the present application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present application. All content not described in detail in this application can be derived from existing technology.

Claims

1. A surface mountable fiber optic Fabry-Perot high temperature pressure sensor, characterized by, It comprises: a fiber guide wire (1), a ball lens (3), a gold-plated mirror (4) and a pressure chip (5); the pressure chip (5) comprises a Fabry-Perot cavity (6), a pressure-sensitive diaphragm (7) and a substrate (8), the pressure-sensitive diaphragm (7) and the substrate (8) are bonded, and the gap therebetween forms the Fabry-Perot cavity (6); after collimation, the incident light beam is transmitted to the surface of the gold-plated mirror (4), changes the direction of the light beam, and enters the Fabry-Perot cavity (6); when the pressure-sensitive diaphragm (7) is flushed by a liquid metal coolant, the pressure is converted into a change in the cavity length of the Fabry-Perot cavity (6), forming a multi-beam interference signal, which is changed in direction by the gold-plated mirror (4), collected by the ball lens (3), and transmitted to the fiber guide wire (1), and then enters the fiber demodulator to demodulate the optical signal into a pressure value.

2. A surface-mount optical fiber Fabry-Perot high temperature pressure sensor according to claim 1, wherein, The substrate of the pressure-sensitive diaphragm (7) is a silicon wafer with a diameter of 50 mm and a thickness of 0.4 mm and a <100> crystal orientation. The substrate (8) uses the same silicon wafer as the substrate of the pressure-sensitive diaphragm (7).

3. A surface-mount optical fiber Fabry-Perot high temperature pressure sensor according to claim 2, wherein, The upper and lower surfaces of the silicon wafer are wet etched to form a concave cavity, and then wet etching is performed again to form a convex structure on the inner surface of the bottom of the concave cavity; the convex structures on the upper and lower surfaces are chemically and mechanically polished; the processed silicon wafer is bonded with another silicon wafer to form the pressure-sensitive diaphragm (7).

4. The surface-mount fiber-optic Fabry-Perot high-temperature pressure sensor of claim 1, wherein, The fiber guide wire (1) is composed of a fiber ferrule and a packaging shell, and the two are fixed by using a nano-silver sintering process. The fiber ferrule and the packaging shell are made of 316 stainless steel.

5. A surface-mount optical fiber Fabry-Perot high temperature pressure sensor according to claim 1, wherein, It also comprises: a packaging structure (2); The packaging structure (2) is made of 316 stainless steel, and the fiber guide wire (1), the ball lens (3), the gold-plated mirror (4) and the pressure chip (5) are packaged and fixed.

6. A surface-mount optical fiber Fabry-Perot high temperature pressure sensor according to claim 1, wherein, The material of the ball lens (3) is quartz glass, and the light transmittance is 1.

51.

7. A surface-mount optical fiber Fabry-Perot high temperature pressure sensor according to claim 1, wherein, The gold-plated mirror (4) is made of 316 stainless steel, and the surface is gold-plated to make the light beam path turn 90°.

8. A surface-mountable fiber-optic Fabry-Perot high-temperature pressure sensor according to claim 1 or 4, characterized in that, The fiber guide wire (1) is led out through a sealing head and connected to a fiber demodulator.

9. A surface-mountable fiber-optic Fabry-Perot high-temperature pressure sensor according to claim 1, wherein, The sensor can resist environment up to 550℃, and the sensitivity is greater than 0.4nm·kPa -1 .

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