Low-coherence interference microscopy with an improved switchable achromatic phase-shifter

Abstract

We present results obtained with a computer-controlled low-coherence interference microscope featuring a modified optical layout that uses a pair of fast switchable achromatic phase-shifters. This layout makes it possible to use ferro-electric liquid-crystal devices made with readily available FLC materials having a switching angle of 45°, and obtain phase shifts of 0° and ±90°. The use of phase shifts of 0° and ±90° simplifies calculations of the fringe visibility and the fractional fringe-order and yields maximum accuracy.