Abstract

The introduction of lasers into spectroscopic instrumentation has produced outstanding gains in detection compared to conventional light sources. These improvements arise not only from the higher optical power output of the laser, but also from the unique coherence properties of laser radiation. A new class of sensitive, spectroscopic techniques has been developed in which the heat produced by nonradiative decay of excited species acts to perturb the optical path within the sample [1,2]. The spatial coherence of a laser beam probing the sample allows extremely small perturbations in optical path to be observed allowing the detection of very weakly absorbing samples.

© 1987 Optical Society of America