Disturbance-free phase-shifting laser diode interferometer using adaptive feedback control

Appl Opt. 2009 Oct 10;48(29):5561-6. doi: 10.1364/AO.48.005561.

Abstract

A feedback-control-equipped phase-shifting laser diode interferometer that eliminates external disturbance is proposed. The feedback loop is stabilized by adaptive control of the polarity of the interference signal. Conventional phase-shifting interferometry can be used with the feedback control, resulting in simplified signal processing and accurate measurement. Several experiments confirm the stability of the feedback control with a measurement repeatability of 1.8 nm.