High-speed scanning fiber-optic heterodyne interferometer using a micro-electro-mechanical system mirror and an f-theta lens

摘要

This paper describes a novel fiber-coupled heterodyne interferometer using a micro-electro-mechanical system (MEMS) mirror and an f-theta lens. In this interferometer system, the cross-polarized laser beams operating at 2 μm with the frequency difference of 100 kHz are introduced by means of the two acousto-optic modulators (AOM). The sample with diameter of 300 mm is uniformly scanned by the 1 mm laser beam with the help of the combined optical scanning configuration, a MEMS mirror and an f-theta lens. The output intermediate signal from the two channels, reference channel and the measurement channel, are processed in the 12 bit analog-to-digital (A/D) process system. Details of our interferometer scheme are discussed.