Phase detection using doppler effect based optical heterodyne interferometry

Abstract

This study introduces the heterodyne interferometry using Doppler effect by moving reflectors, rather than the conventional Zeeman laser or acousto-optic modulator (AOM). Two schemes using reflectors are introduced to obtain beat signal resulting from frequency modulation. One is to the reflector attached to a commercial piezoelectric sensor, and the other is the corner cube retro (CCR) reflector fabricated using MEMS technique. The MEMS CCR reflector is made of four mirrors aligned in horizontal and vertical axes, and each mirror is designed to work at different frequencies. The proposed scheme eliminates the need for additional equipment for the heterodyne system, and one MEMS CCR reflector is expected to work identically to that of AOMs due to its compact size. Furthermore, this scheme can be applied in combination with other sensing technologies, leading to the improvements in the precision of measurements