Research On Optical Fiber Fabry-Perot Liquid Pressure Sensor With Open Cavity

The liquid level and pressure is an important monitoring parameter in many industries such as petrochemical,biomedicine,water storage and water supply,environmental meteorology,etc.The accuracy of liquid level and pressure measurement is related to the production and quality of these industries and the safety and stability of production,transportation and storage processes.Compared with traditional electromagnetic sensors,optical fiber sensors have good insulation,corrosion resistance,light weight,small size,easy assembly and long-distance detection,good adaptability to harsh environments such as inflammables and explosives.These sensors play an important role in liquid level and pressure measurement applications in special environments.Since the level measurement can be achieved by measuring the hydraulic pressure and converting it.For high accuracy and high stability liquid pressure measurement,research on the open-cavity structure,temperature stability and pressure stability of the optical fiber Fabry-Perot liquid pressure sensor is carried out in this paper.The specific research contents of this paper include:1?The basic model of the optical fiber Fabry-Perot liquid pressure sensor is built.The mechanical and optical measurement principles of the sensor are analyzed.The influencing factors of the measurement accuracy of the sensor are researched.These factors includ the deformation theory of the diaphragm under different pressure and diaphragm size ranges and the influence of ambient air pressure,Fabry-Perot cavity pressure and ambient temperature on the length of the Faber cavity.2?Aiming at the influencing factors of sensor measurement accuracy,the method of improving the structure of the fiber optic liquid pressure sensor and the structure of the package is analyzed.The optical fiber Fabry-Perot liquid pressure sensor with open cavity structure is designed and fabricated.Then according to the specific parameters of the fabricated sensor,the measurement accuracy of the two sensors,open cavity structure and closed structure,is simulated and analyzed.The simulation analysis proves that the open cavity structure can effectively reduce the temperature sensitivity and pressure sensitivity of the sensor.3?An experimental system for the open-cavity optical fiber Fabry-Perot liquid pressure sensor was built.The optical fiber Fabry-Perot liquid pressure sensor with open-cavity structure and closed structure was tested.When the temperature range is 10~40 °C and the hydraulic range is 0.5~1.3 MPa,the temperature drift of the opencavity sensor is within 0.02%~0.09% F.S./K,and the optical signal output by the sensor does not change with the change of ambient pressure.The experimental results show that the open cavity structure is beneficial to improve the temperature stability of the optical fiber Fabry-Perot liquid pressure sensor.It can eliminate the influence of external air pressure changing on the liquid pressure measurement of the sensor.