High temperature and pressure integrated measurement sensor

Abstract

The invention relates to the technical field of pressure sensing, and discloses a high temperature and pressure integrated measurement sensor, which comprises an optical fiber assembly and a diaphragm assembly which are fixedly connected with each other, the optical fiber assembly comprises an optical fiber base, and an optical fiber probe assembly is arranged in the optical fiber base; the diaphragm assembly comprises a diaphragm base welded to the optical fiber base, the bottom of the optical fiber probe assembly is located in the diaphragm base, a pressure sensing hole is formed in the bottom of the diaphragm base, sapphire glass and a pressure sensitive diaphragm are arranged above the pressure sensing hole, and the pressure sensitive diaphragm is connected with the bottom of the diaphragm base in a sealed mode. A vacuum cavity is arranged between the sapphire glass and the pressure sensitive diaphragm; compared with an existing pressure sensor based on the electrical principle, the sensor has the advantages of being high in high-temperature resistance, good in vibration resistance, small in assembling and debugging difficulty and capable of achieving temperature and pressure integrated measurement, and the problem that an existing sensor cannot be used in the extreme environments of high temperature, strong vibration and the like is solved.

Description

Technical Field

[0001] This invention relates to the field of pressure sensing technology, specifically to a high-temperature and temperature-pressure integrated measurement sensor. Background Technology

[0002] Combustion chamber temperatures in power equipment such as aircraft engines and rocket engines exceed 1000℃, downhole temperatures in oil exploration and production wells can reach 220℃, and pressure vessels and pipelines in metallurgical and chemical production operate at temperatures as high as 480℃. In these high-temperature scenarios, temperature and pressure are key parameters affecting equipment performance and safety, requiring real-time and accurate monitoring to improve combustion performance and propulsion efficiency, and to assess component health.

[0003] Currently used silicon-based MEMS sensors exhibit internal PN junction leakage at 120°C, leading to performance degradation or even failure. Furthermore, silicon undergoes plastic deformation at temperatures above 500°C, making it unsuitable for high-temperature measurements. Conventional high-temperature pressure measurements often involve leading out and cooling the pressure medium through a long pressure tube, followed by measurement using a cryogenic pressure sensor. This method frequently results in signal distortion, poor real-time performance, and the limitation to short-duration measurements.

[0004] Fiber optic sensing technology has broad application prospects in aerospace, geological exploration, petrochemical and other fields due to its high precision, resistance to electromagnetic interference, and high temperature resistance. Currently, commonly used optical FP pressure sensors based on MEMS principles use high-temperature resistant materials such as quartz, silicon, and sapphire to fabricate MEMS chips. While the chips themselves possess high temperature resistance, MEMS-based sensors still have high requirements for subsequent assembly, optical path alignment, and fiber optic packaging. Currently, they still suffer from drawbacks such as assembly and debugging difficulties, poor product consistency, and poor vibration resistance, making them unsuitable for use in extreme environments such as high temperatures and strong vibrations. Summary of the Invention

[0005] In view of the above-mentioned shortcomings in the prior art, the present invention aims to provide a high-temperature and temperature-pressure integrated measurement sensor to solve the problem that existing sensors cannot meet the requirements of use in extreme environments such as high temperature and strong vibration.

[0006] To achieve the aforementioned objectives, the present invention provides a high-temperature and temperature-pressure integrated measurement sensor, comprising an optical fiber assembly and a diaphragm assembly fixedly connected to each other. The optical fiber assembly includes an optical fiber base, with a vertically penetrating mounting hole at the center of the optical fiber base, and an optical fiber probe assembly disposed within the mounting hole. The diaphragm assembly includes a diaphragm base, with the top of the diaphragm base fixedly connected to the bottom of the optical fiber base. The bottom of the optical fiber probe assembly passes through the mounting hole and is located within the diaphragm base. A pressure-sensing hole is provided at the bottom of the diaphragm base. Above the pressure-sensing hole, a sapphire glass and a pressure-sensitive diaphragm are disposed below the optical fiber probe assembly. The sapphire glass is sealed and fixedly connected to the inner wall of the diaphragm base on all four sides. The pressure-sensitive diaphragm is sealed and connected to the bottom of the diaphragm base. A vacuum cavity is provided between the sapphire glass and the pressure-sensitive diaphragm.

[0007] The basic principle of the high-temperature and pressure integrated measurement sensor in this invention is as follows: the fiber optic assembly and the diaphragm assembly can be fixed together by laser welding. After welding, the structural components maintain their original positional relationship under high temperature and strong vibration environments, thereby maintaining the intensity of the returned optical signal. When the sensor is working, the laser emitted from the laser source is input from the fiber optic probe assembly. After transmission through the fiber optic probe assembly, the light is reflected on the lower surface of the sapphire glass and the upper surface of the pressure-sensitive diaphragm, and coupled back into the fiber to form a FP interference signal. By demodulating the FP interference signal, the external pressure value can be obtained. Simultaneously, since the fiber optic probe assembly integrates a fiber Bragg grating, temperature information can be obtained by demodulating the center wavelength of the fiber Bragg grating, realizing integrated measurement of temperature and pressure.

[0008] Furthermore, as a specific configuration of the fiber optic probe assembly, the fiber optic probe assembly includes a fiber Bragg grating located within the mounting hole. The top of the fiber Bragg grating is located outside the mounting hole. The fiber Bragg grating is fixedly connected to the fiber optic base via high-temperature resistant inorganic adhesive. The bottom of the fiber Bragg grating passes through the mounting hole and is located above the sapphire glass. A hollow fiber is disposed at the bottom of the fiber Bragg grating, and a graded-index fiber is disposed at the bottom of the hollow fiber. This fiber (composed of the fiber Bragg grating, hollow fiber, and graded-index fiber) has a self-focusing effect, enabling the emitted light of the fiber optic probe assembly to have a collimation range of 1mm to 2mm. The fiber Bragg grating is a fiber Bragg grating written using femtosecond writing technology, which can operate for extended periods in environments not exceeding 500℃ without optical performance degradation.

[0009] Furthermore, the fiber optic base is made of a low-expansion alloy, and the coefficient of linear expansion of the fiber optic base is the same as that of the fiber optic cable. After the entire sensor is encapsulated, only a small encapsulation stress exists between the fiber optic assembly and the fiber optic base, and this stress remains small during subsequent temperature changes.

[0010] Furthermore, the sapphire glass is sealed and fixedly connected to the inner wall of the diaphragm base via solder. Specifically, the solder is a low-temperature glass solder or a brazing solder, used to connect and fix the sapphire glass and the diaphragm base. When the solder is a low-temperature glass solder, the softening temperature of the glass solder is >500℃, the sintering temperature is ≤800℃, and the coefficient of linear expansion is between that of the sapphire glass and the low-expansion alloy. When the solder is a brazing solder, the solidus temperature of the brazing solder should be >500℃, the liquidus temperature should be ≤800℃, and the brazing solder should be able to fully wet the sapphire and the low-expansion alloy, resulting in good sealing and firmness after welding.

[0011] Furthermore, the sapphire glass is planar and circular in shape, with a thickness of 0.3-1 mm and a diameter of 6-10 mm. The upper and lower surfaces of the sapphire glass are coated with an anti-reflection film and an anti-reflection film, respectively. The anti-reflection film has a reflectivity of less than 1% and a transmittance of ≥99% in the C-band wavelength range; the anti-reflection film has a reflectivity of ≥20% in the C-band wavelength range. The anti-reflection film can increase the transmittance of light emitted from the light source on this plane and reduce the reflected light from the upper surface of the sapphire. The anti-reflection film can increase the reflectivity of light emitted from the light source.

[0012] Furthermore, the sapphire glass is wedge-shaped, with a thickness of 0.3~1mm, a diameter of 6mm~10mm, and a slope angle of 2°~8°. In this case, the interference signal reflected by the wedge-shaped plane cannot couple into the fiber optic probe assembly. Therefore, the upper surface of the sapphire glass does not need to be coated. At the same time, in order to enhance the interference signal intensity of the vacuum cavity, an optical anti-reflection film is coated on the lower surface of the sapphire glass to improve its reflectivity to light emitted by the light source.

[0013] Furthermore, the diaphragm base is made of a low-expansion alloy, and the coefficient of linear expansion of the diaphragm base is the same as that of the sapphire glass. After the entire sensor is encapsulated, only a small encapsulation stress exists between the sapphire glass and the diaphragm base, and this stress remains small during subsequent temperature changes.

[0014] Furthermore, a welding ring is provided on the sensing side of the pressure-sensitive diaphragm, and the diaphragm base, pressure-sensitive diaphragm, and welding ring are welded together using vacuum electron beam welding. This creates a vacuum cavity between the sapphire glass and the pressure-sensitive diaphragm, which can be used to realize absolute pressure measurement of the sensor.

[0015] Furthermore, the pressure-sensitive diaphragm is made of the same material as the welded pressure ring. Using the same material results in better welding quality and a better welding effect, ensuring the airtightness of the welded area. During subsequent sensor operation, the consistent linear expansion coefficient of the same material leads to lower stress at the weld, thus improving sensor performance.

[0016] Furthermore, the pressure-sensitive diaphragm is made of a high-temperature resistant alloy, and is a circular flat diaphragm or a corrugated diaphragm. The thickness of the pressure-sensitive diaphragm is 0.05mm~0.5mm, and the diameter is 8mm~12mm; the maximum deflection of the pressure-sensitive diaphragm... for:

[0017]

[0018] in, The external load is pressure P. The radius of the pressure-sensitive diaphragm, For the bending stiffness of the sensitive diaphragm, The elastic modulus of metallic materials. The thickness of the metal sheet. Let P be the Poisson's ratio for the metallic material. From the above formula, it can be seen that once the diameter and thickness of the pressure-sensitive diaphragm are determined, its maximum deflection is only related to the external pressure P. By adjusting the diaphragm diameter and thickness, a pressure-sensitive diaphragm meeting the design requirements can be obtained. Practical measurements show that when the pressure-sensitive diaphragm is corrugated, the linearity between its deflection and external pressure is better, and the planar curvature deformation at the center of the pressure-sensitive diaphragm is smaller, which can improve the reduction in reflected signal intensity caused by local curvature deformation.

[0019] The beneficial effects of this invention are as follows: 1. High Temperature Resistance: Traditional sensors based on electrical principles cannot operate directly in high-temperature environments due to limitations in their electronic components. The sensor in this invention is made of high-temperature resistant materials and encapsulated using welding and high-temperature resistant inorganic adhesive bonding methods. Therefore, it has a higher temperature resistance than traditional sensors and can operate continuously in environments not exceeding 500°C without additional protection measures.

[0020] 2. Excellent Vibration Resistance: Currently, most high-temperature pressure sensors developed by universities and research institutions adopt MEMS solutions, with MEMS cores typically made of materials such as quartz, silicon, sapphire, and silicon carbide. While these cores possess high-temperature resistance, MEMS solutions require precise alignment between the optical fiber and the MEMS core during sensor assembly. Even minor deviations can lead to signal quality degradation or sensor failure, resulting in difficult assembly during production and poor vibration resistance during use. In contrast, the sensor in this invention utilizes a metal sensitive diaphragm, sapphire glass, and low-expansion alloys, assembled and fixed using a welding process, resulting in superior vibration resistance.

[0021] 3. Reduced Assembly and Debugging Difficulty: Existing optical MEMS-based sensors often require precise signal calibration on an optical platform using a multi-dimensional displacement calibration stage, which is quite difficult. Furthermore, the tolerance for optical path errors during assembly and debugging is low, and even minor positional deviations during dispensing curing and assembly can lead to signal quality degradation or even failure. The sensor in this invention utilizes a metal diaphragm and sapphire glass to construct a low-reflectivity FP interferometer cavity, with a large cavity area, reducing the requirements for fiber alignment. Moreover, because the sensor employs a fiber Bragg grating with a self-focusing lens, the emitted light signal is more collimated and energy-concentrated, ensuring the return light signal strength is maintained even with a low-reflectivity FP interferometer cavity.

[0022] 4. Integrated Temperature and Pressure Measurement: Pressure sensors require temperature compensation during use. Common methods for acquiring temperature signals include using electrical sensors such as thermocouples and platinum resistance thermometers, and optical sensors such as fiber Bragg gratings and fiber optic interferometers. The sensor in this invention uses a fiber Bragg grating with a self-focusing lens as the detection channel for temperature and pressure signals, achieving integrated temperature and pressure measurement using a single optical fiber.

[0023] In summary, the high-temperature and temperature-pressure integrated measurement sensor proposed in this invention has advantages such as high temperature resistance, vibration resistance, and simple assembly and debugging. It can be used in extreme environments such as engine pressure monitoring and oil exploration, solving the problem that existing sensors cannot meet the requirements of use in extreme environments such as high temperature and strong vibration. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a high-temperature and temperature-pressure integrated measurement sensor.

[0025] Figure 2 This is a schematic diagram of the structure of a planar circular sapphire glass.

[0026] Figure 3 This is a schematic diagram of the structure of a wedge-shaped sapphire glass.

[0027] Figure 4 This is a schematic diagram of the optical path of a sensor made of sapphire glass in a planar circular shape.

[0028] Figure 5 This is a schematic diagram of the optical path of a sensor made of wedge-shaped sapphire glass.

[0029] Figure 6 This is a schematic diagram of the fiber optic probe assembly.

[0030] Among them, 1. Fiber optic probe assembly; 101. Fiber Bragg grating; 102. Hollow fiber; 103. Graded-index fiber; 2. High-temperature resistant inorganic adhesive; 3. Fiber optic base; 4. Laser welding; 5. Diaphragm base; 6. Sapphire glass; 601. Optical antireflective film; 602. Optical antireflective film; 7. Pressure-sensitive diaphragm; 8. Welding ring; 9. Solder; 10. Vacuum electron beam welding; 11. Vacuum cavity. Detailed Implementation

[0031] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0032] First embodiment, reference Figure 1 As shown, this invention provides a high-temperature and temperature-pressure integrated measurement sensor, which includes an optical fiber assembly and a diaphragm assembly fixedly connected to each other. The optical fiber assembly includes an optical fiber base 3, with a vertically penetrating mounting hole at the center of the optical fiber base 3, and an optical fiber probe assembly 1 disposed within the mounting hole. The diaphragm assembly includes a diaphragm base 5, with the top of the diaphragm base 5 fixedly connected to the bottom of the optical fiber base 3. The bottom of the optical fiber probe assembly 1 passes through the mounting hole and is located within the diaphragm base 5. A pressure-sensing hole (not shown in the figure) is provided at the bottom of the diaphragm base 5. Above the pressure-sensing hole, a sapphire glass 6 and a pressure-sensitive diaphragm 7 are disposed below the optical fiber probe assembly 1. The sapphire glass 6 is sealed and fixedly connected to the inner wall of the diaphragm base 5 on all four sides. The pressure-sensitive diaphragm 7 is sealed and connected to the bottom of the diaphragm base 5. A vacuum cavity 11 is disposed between the sapphire glass 6 and the pressure-sensitive diaphragm 7.

[0033] Specifically, the optical fiber base 3 and the diaphragm base 5 are fixed by laser welding 4, which can ensure the strength of the overall sensor structure and maintain the relative positional relationship between the optical fiber and the sapphire glass 6 under high temperature and strong vibration environments.

[0034] Specifically, such as Figure 6 As shown, in one specific configuration of the fiber optic probe assembly 1, the fiber optic probe assembly 1 includes a fiber Bragg grating 101 located within the mounting hole. The top of the fiber Bragg grating 101 is located outside the mounting hole. The fiber Bragg grating 101 is fixedly connected to the fiber optic base 3 via a high-temperature resistant inorganic adhesive 2. In this embodiment, the high-temperature resistant inorganic adhesive 2 is a high-temperature resistant adhesive material with alumina powder as the main component. This high-temperature resistant inorganic adhesive 2 is a single-component material that is easy to operate and has good bonding strength and can withstand high temperatures after bonding and curing.

[0035] The bottom of the fiber Bragg grating 101 passes through a mounting hole and is located above the sapphire glass 6. A hollow fiber 102 is disposed at the bottom of the fiber Bragg grating, and a graded-index fiber 103 is disposed at the bottom of the hollow fiber 102. The fiber optic probe assembly 1, composed of the fiber Bragg grating 101, the hollow fiber 102, and the graded-index fiber 103, has a self-focusing effect. The emitted light from the fiber optic probe assembly 1 has a collimation range of 1mm to 2mm. The fiber Bragg grating 101 is written using femtosecond writing technology and can operate for extended periods in environments not exceeding 500℃ without optical performance degradation.

[0036] Specifically, after being precisely cut, hollow fiber 102 and graded-index fiber 103 are welded to single-mode fiber with fiber Bragg grating 101. During the welding process, the discharge time and discharge power are controlled to achieve the design parameters, so that the emitted light from the fiber end face is approximately collimated in the range of 1mm to 2mm, and the energy of the emitted light spot is relatively concentrated. Moreover, since the numerical aperture of graded-index fiber 103 is larger than that of single-mode fiber, the energy of reflected signal coupled into the fiber can be increased.

[0037] In this embodiment, the method for fabricating the fiber optic probe assembly 1 includes: 1. Clean the fiber optic base 3 in an ultrasonic cleaner for 30 minutes to remove iron filings, impurities and surface oil from the mounting holes, and then heat and dry it. 2. Under a distance-measuring microscope, the fiber Bragg grating 101, hollow fiber 102, and graded-index fiber 103 are precisely cut using a fiber optic cleaver and then fused together. By adjusting the discharge parameters of the fiber optic fusion splicer, such as pre-fusion time, pre-fusion strength, fusion time, and fusion strength, the irregularly shaped fibers are fused to obtain the fiber optic probe assembly 1. After fusion, the fusion strength and collimation effect of the output light of the fiber optic probe assembly 1 are tested. 3. Insert the end of the fiber Bragg grating 101 with lens in the fiber probe assembly 1 that has passed the test into the mounting hole of the fiber base 3 and out through the other end of the fiber base 3. Adjust the length of the fiber end face extension according to the design parameters. When the set position is reached, inject an appropriate amount of high temperature resistant inorganic adhesive 2 at the junction of the fiber and the fiber base 3 at the insertion position. 4. After the inorganic adhesive has cured at room temperature for 24 hours, it is then cured in an oven at 90℃ and 120℃ for 1 hour respectively to complete the assembly of the fiber optic probe assembly 1.

[0038] The preparation method of the diaphragm module is as follows: 1. Clean the diaphragm base 5 in an ultrasonic cleaner for 30 minutes to remove iron filings, impurities and surface oil, and then heat and dry it. 2. Following the order of diaphragm base 5, solder 9, and sapphire glass 6 pieces, and as follows... Figure 1 The assembly positions shown indicate the initial assembly of the three materials. During assembly, it is necessary to ensure that the optical antireflective film 601 is facing upwards and the optical antireflective film 602 is facing downwards. 3. Add appropriate weights to the sapphire glass 6 to prevent it from slipping during heating. The heating equipment is set with a temperature profile according to the process requirements to heat and melt the glass solder, so that the sapphire glass 6 and the diaphragm base 5 are sintered and fixed together by the glass solder. 4. After the glass sintering is completed, check whether the airtightness of the welding position meets the requirements; 5. Using tooling fixtures, fix the diaphragm base 5, pressure-sensitive diaphragm 7, and welding ring 8 along the outer circle after glass sintering. After laser spot welding for positioning, perform vacuum electron beam welding 10 to complete the assembly of the diaphragm assembly.

[0039] The fiber optic probe assembly and diaphragm assembly are arranged according to... Figure 1 Install according to the assembly relationship shown. Solder the fiber optic probe assembly 1 to the fiber optic jumper. While rotating and adjusting, observe the returned FP interference signal intensity curve in the demodulation system. When the signal meets the requirements, mark the position. Solder and fix the fiber optic probe assembly 1 and the diaphragm assembly to complete the assembly of the entire sensor.

[0040] The basic principle of the high-temperature and pressure integrated measurement sensor of this invention is as follows: the optical fiber assembly and the diaphragm assembly can be fixed by laser welding 4. After welding, the structural components can maintain their original positional relationship under high temperature and strong vibration environments, thereby maintaining the intensity of the returned light signal. When the sensor is working, the laser emitted by the laser source is input from the optical fiber probe assembly 1. After being transmitted through the optical fiber probe assembly 1, the light is reflected on the lower surface of the sapphire glass 6 and the upper surface of the pressure-sensitive diaphragm 7, and coupled back into the optical fiber to form FP interference signals. By demodulating the FP interference signals, the external pressure value can be obtained. At the same time, since the optical fiber probe assembly 1 integrates a fiber Bragg grating 101, the temperature information can be obtained by demodulating the center wavelength of the fiber Bragg grating 101, realizing the integrated measurement of temperature and pressure. The high temperature in this invention refers to the high-temperature working environment, which is an environment with a temperature ≤500℃. The operating temperature range of the high-temperature and pressure integrated measurement sensor of this invention is -40℃ to 500℃.

[0041] Preferably, but not limited to, the optical fiber base 3 is made of a low-expansion alloy, and the linear expansion coefficient of the optical fiber base 3 is the same as that of the optical fiber. After the entire sensor is encapsulated, only a small encapsulation stress exists between the optical fiber assembly and the optical fiber base 3, and this stress remains small during subsequent temperature changes.

[0042] Specifically, the sapphire glass 6 is sealed and fixedly connected to the inner wall of the diaphragm base 5 by solder 9. Specifically, the solder 9 is a low-temperature glass solder or a brazing solder, used to connect and fix the sapphire glass 6 and the diaphragm base 5. When the solder 9 is a low-temperature glass solder, the softening temperature of the glass solder is >500℃, the sintering temperature is ≤800℃, and the coefficient of linear expansion is between that of the sapphire glass 6 and the low-expansion alloy. When the solder 9 is a brazing solder, the solidus temperature of the brazing solder should be >500℃, the liquidus temperature should be ≤800℃, and the brazing solder should be able to fully wet the sapphire and the low-expansion alloy, resulting in good sealing and firmness after welding.

[0043] A welding ring 8 is provided on the sensing side of the pressure-sensitive diaphragm 7. The diaphragm base 5, the pressure-sensitive diaphragm 7, and the welding ring 8 are welded together using vacuum electron beam welding 10. This forms a vacuum cavity 11 between the sapphire glass 6 and the pressure-sensitive diaphragm 7, which can be used to realize the absolute pressure measurement of the sensor.

[0044] The pressure-sensitive diaphragm 7 is made of a high-temperature resistant alloy, such as GH4169 or Inconel 718, allowing it to operate at temperatures from -50℃ to 500℃. The diaphragm 7 is either a circular flat diaphragm or a corrugated diaphragm, with a thickness of 0.05mm to 0.5mm and a diameter of 8mm to 12mm. The maximum deflection of the pressure-sensitive diaphragm 7... for:

[0045]

[0046] in, The external load is pressure P. The radius of the pressure-sensitive diaphragm 7 is... For the bending stiffness of the sensitive diaphragm, The elastic modulus of metallic materials. The thickness of the metal sheet. Let P be the Poisson's ratio for the metallic material. From the above formula, it can be seen that once the diameter and thickness of the pressure-sensitive diaphragm 7 are determined, its maximum deflection is only related to the external pressure P. By adjusting the diaphragm diameter and thickness, a pressure-sensitive diaphragm 7 that meets the design requirements can be obtained. Actual measurements show that when the pressure-sensitive diaphragm 7 is a corrugated diaphragm, the linearity between its deflection and the external pressure is better, and the planar curvature deformation at the center of the pressure-sensitive diaphragm 7 is smaller, which can improve the decrease in reflected signal intensity caused by local curvature deformation.

[0047] Preferably, but not limited to, the pressure-sensitive diaphragm 7 is made of the same material as the welded pressure ring 8. Using the same material results in better welding quality and a better welding effect, ensuring the airtightness of the welded area. During subsequent sensor operation, the consistent linear expansion coefficient of the same material leads to lower stress at the weld, thus improving sensor performance.

[0048] The second embodiment further defines the first embodiment by specifying the shape of the sapphire glass 6. For other details not mentioned, please refer to the prior art or the first embodiment. Figure 2 and Figure 4As shown, in this embodiment, the sapphire glass 6 is a planar circular shape with a thickness of 0.3~1mm and a diameter of 6mm~10mm. The upper and lower surfaces of the sapphire glass 6 are respectively coated with an anti-reflection film 601 and an anti-reflection film 602. The anti-reflection film 601 has a reflectivity of less than 1% and a transmittance of ≥99% in the C-band wavelength range; the anti-reflection film 602 has a reflectivity of ≥20% in the C-band wavelength range. The anti-reflection film 601 can increase the transmittance of light emitted from the light source on this plane and reduce the reflected light from the upper surface of the sapphire. The anti-reflection film 602 can increase the reflectivity of light emitted from the light source.

[0049] The third embodiment further limits the first embodiment, specifically limiting the shape of the sapphire glass 6. For other details not mentioned, please refer to the prior art or the first embodiment. In this embodiment, such as... Figure 3 and Figure 5 As shown, the sapphire glass 6 is wedge-shaped, with a thickness of 0.3~1mm, a diameter of 6mm~10mm, and a slope angle of 2°~8°. In this case, the interference signal reflected by the wedge-shaped plane cannot couple into the fiber optic probe assembly 1, so the upper surface of the sapphire glass 6 does not need to be coated. At the same time, in order to enhance the interference signal intensity of the vacuum cavity 11, an optical anti-reflection film 602 is coated on the lower surface of the sapphire glass 6 to improve its reflectivity to the light emitted by the light source. Figure 1 , Figure 4 and Figure 5 In this context, P refers to the external pressure applied to the pressure-sensitive diaphragm 7.

[0050] In summary, the high-temperature and temperature-pressure integrated measurement sensor proposed in this invention has advantages such as high temperature resistance, vibration resistance, and simple assembly and debugging. It can be used in extreme environments such as engine pressure monitoring and oil exploration, solving the problem that existing sensors cannot meet the requirements of use in extreme environments such as high temperature and strong vibration.

Claims

1. A high-temperature and temperature-pressure integrated measurement sensor, characterized in that, The device includes an optical fiber assembly and a diaphragm assembly that are fixedly connected to each other. The optical fiber assembly includes an optical fiber base with a vertically penetrating mounting hole at its center, and an optical fiber probe assembly is disposed within the mounting hole. The diaphragm assembly includes a diaphragm base with its top fixedly connected to the bottom of the optical fiber base. The bottom of the optical fiber probe assembly passes through the mounting hole and is located within the diaphragm base. A pressure-sensitive hole is provided at the bottom of the diaphragm base. Above the pressure-sensitive hole, a sapphire glass and a pressure-sensitive diaphragm are disposed below the optical fiber probe assembly. The sapphire glass is sealed and fixedly connected to the inner wall of the diaphragm base on all four sides. The pressure-sensitive diaphragm is sealed and connected to the bottom of the diaphragm base. A vacuum cavity is provided between the sapphire glass and the pressure-sensitive diaphragm.

2. The high-temperature and temperature-pressure integrated measurement sensor according to claim 1, characterized in that, The fiber optic probe assembly includes a fiber Bragg grating located within the mounting hole. The top of the fiber Bragg grating is located outside the mounting hole. The fiber Bragg grating is fixedly connected to the fiber optic base by a high-temperature resistant inorganic adhesive. The bottom of the fiber Bragg grating passes through the mounting hole and is located above the sapphire glass. A hollow fiber is disposed at the bottom of the fiber Bragg grating, and a graded-index fiber is disposed at the bottom of the hollow fiber.

3. The high-temperature and temperature-pressure integrated measurement sensor according to claim 2, characterized in that, The optical fiber base is made of a low-expansion alloy, and the linear expansion coefficient of the optical fiber base is the same as that of the optical fiber.

4. The high-temperature and temperature-pressure integrated measurement sensor according to claim 1, characterized in that, The sapphire glass is sealed and fixed to the inner wall of the diaphragm base by solder around its perimeter.

5. The high-temperature and temperature-pressure integrated measurement sensor according to claim 4, characterized in that, The sapphire glass is in the shape of a planar circle, with a thickness of 0.3~1mm and a diameter of 6mm~10mm. The upper and lower surfaces of the sapphire glass are coated with an optical anti-reflection film and an optical anti-reflection film, respectively. The optical anti-reflection film has a reflectivity of less than 1% and a transmittance of ≥99% in the C-band wavelength range. The optical anti-reflection film has a reflectivity of ≥20% in the C-band wavelength range.

6. The high-temperature and temperature-pressure integrated measurement sensor according to claim 4, characterized in that, The sapphire glass is wedge-shaped, with a thickness of 0.3-1mm, a diameter of 6mm-10mm, a bevel angle of 2°-8°, and an optical anti-reflective film coated on the lower surface of the sapphire glass.

7. The high-temperature and temperature-pressure integrated measuring sensor according to any one of claims 4 to 6, characterized in that, The diaphragm base is made of a low-expansion alloy, and the linear expansion coefficient of the diaphragm base is the same as that of the sapphire glass.

8. The high-temperature and temperature-pressure integrated measurement sensor according to claim 1, characterized in that, A welding ring is provided on the sensing side of the pressure-sensitive diaphragm, and the diaphragm base, the pressure-sensitive diaphragm, and the welding ring are welded together using vacuum electron beam welding.

9. The high-temperature and temperature-pressure integrated measurement sensor according to claim 8, characterized in that, The pressure-sensitive diaphragm is made of the same material as the welded pressure ring.

10. The high-temperature and temperature-pressure integrated measurement sensor according to claim 8, characterized in that, The pressure-sensitive diaphragm is made of a high-temperature resistant alloy. It is either a circular flat diaphragm or a corrugated diaphragm, with a thickness of 0.05mm to 0.5mm and a diameter of 8mm to 12mm. The maximum deflection of the pressure-sensitive diaphragm... for: in, The external load is pressure P. The radius of the pressure-sensitive diaphragm, For the bending stiffness of the sensitive diaphragm, The elastic modulus of metallic materials. The thickness of the metal sheet. is Poisson's ratio for metallic materials.

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