Temporal coherence of laser fields analyzed by heterodyne interferometry

Abstract

For partially coherent fields, where the coherence time may be quite large, a new method is described to obtain the coherence function and other statistical properties. Coherence lengths of over 100 m were measured, and it was deduced that microphonic noise is the dominant source of incoherence in laser fields. It is also found experimentally that seemingly uncorrelated fields may have a strong phase relationship.