Application of a digital phase comparator technique to interferometer data

Abstract

Substantial improvements have been made to increase the frequency bandwidth of the UCLA multichannel interferometer system on TEXT-Upgrade. Recently, a digital phase comparator technique was implemented that has several advantages over the conventional analog phase comparator. The probe and reference wave forms are directly digitized and the phase computed in software using a numerical demodulation algorithm. For the purpose of reducing the data load, aliasing of the laser difference frequency is employed to vary the time response according to experimental demands.