Dynamic test of an acoustic/pressure sensor with precise cavity length control

Abstract

A novel Fabry-Perot interferometer pressure/acoustic sensor has been designed, fabricated, and tested. The sensor consists of an angle-polished fiber, a V-shaped groove on a silicon substrate, and a silicon nitride diaphragm on the side wall of the groove. The design uses MEMS technology to ensure precise cavity length control and diaphragm design flexibility. Two shock wave tests were performed on the sensors: one where a balloon was popped near the sensors, and another that used a shock tube to simulate a blast event. Multi-sensor assemblies, where all the sensors were calibrated to have similar center wavelengths, were also put together. The assemblies were tested simultaneously using a single laser source. The results of all these tests showed that the performance of the Fabry-Perot sensors closely matched that of the reference sensors used.