Study on The Technology of Optical Fiber High-Temperature Pressure Sensor with Weak Temperature Sensitivity

Abstract

In aerospace, petrochemical, gas turbines and other high-temperature environments, pressure measurement of equipment has always been a challenge to be solved. The electrical high temperature pressure sensor has the problem of component failure in the high temperature environment, and it is difficult to use in the high temperature environment for a long time. The detection device of the optical fiber sensor does not include electrical components, so it has the advantages of high working temperature, high measurement accuracy, anti-electromagnetic interference and so on. In order to measure pressure in high temperature environment with sensor, a temperature-weakly sensitive optical fiber Micro-Electro-Mechanical System (MEMS) pressure sensing technology is proposed. The technique uses Extrisic Fabry-Perot Interference (EFPI) model. It uses the MEMS pressure chip to passively modulate the optical signal of the interference, and then realizes the pressure signal measurement. Among them, MEMS pressure sensitive chip is the core component of the sensor. The MEMS pressure sensitive chip adopts the design method of all solid state vacuum absolute pressure. Changes in environmental pressure will deform the membrane. This phenomenon can cause changes in the cavity of the EFPI cavity. Therefore, stress information can be obtained by measuring changes in EFPI cavity. The thermal stress and temperature parasitical response introduced by thermal expansion of the material are calculated by simulation. The influence of temperature signal on chip displacement is analyzed by the above results. On this basis, combined with the sub-micron white light interference response technology and low thermal stress packaging technology, the high temperature pressure sensor prototype is developed. In order to test the actual measurement ability of the sensor, this paper does the pressure test and high temperature test respectively. When the pressure changes from 0kpa to 100kpa, the spectral intensity of the sensor output has a linear relationship with the pressure. During the temperature change from 20℃ to 400℃, the spectral intensity of the sensor output did not change significantly. The experimental test results show that the pressure measurement of 0~100kPa can be satisfied in the range of 20~400℃, and the measurement error introduced by temperature change is less than 4%. Therefore, the fiber pressure sensor can be used to measure pressure in high temperature environment.