Study on the vibration performances for a high temperature fiber F-P accelerometer

Abstract In order to meet the vibration detection needs in high temperature environments such as aerospace, nuclear power, high temperature casting, etc., a fiber F-P accelerometer is investigated. This paper studies the vibration characteristics of a fiber-optic F-P high temperature sensor based on MEMS technology. It introduces the sensor mechanism, simulation, design and manufacturing process, and on this basis, deeply studies the vibration characteristics of the sensor in different directions. The sensitive part of the detection probe, essentially composed of a single-mode fiber and an SiC element sensitive to vibrations, constitutes the F-P resonant cavity. The thermal properties of all elements of the probe made it possible to detect vibrations in the probe main and lateral axis in the temperature range of 27 °C to 800 °C. In the main measurement axis of the probe, experimental results show that the sensor can detect vibration signals with high accuracy. It has a sensitivity of about 370 mV/g in the flat range of 100 to 1000 Hz and its natural frequency is about 3750 Hz. The sensor has frequency repeatability errors of less than 0.5%, and excellent linearity of about 1 between input and output frequencies. Arranged on its lateral axis, the probe shows a working frequency range of 100 to 700 Hz and its resonance frequency is approximately 1450 Hz. In the lateral axis, it reproduces all input frequencies with a linearity of 1 and at an amplitude of 11% of that of the main axis. The field application shows that the relative error on the frequency measurements is less than 4% in both axes, and the absolute error less than 5 Hz according to the technical index of the test site. To obtain this stability and good precision in the two measurement axes, the method of automatic and rapid tracking of the Q-point was used as demodulation algorithm.