FOURIER-TRANSFORM HETERODYNE SPECTROSCOPY OF LIQUID AND SOLID-SURFACES

Fourier-transform heterodyne spectroscopy is a simple but powerful tec hnique to study narrow line shapes and small frequency shifts. We revi ew the technique and its application to the study of hydrodynamic fluc tuations. We introduce a simple scheme for obtaining the full spectrum of light scattered from liquid and solid surfaces. Using this scheme we obtained a spectral resolution of 200 mu Hz. Two applications of th e technique, one involving the detection of counter-propagating capill ary waves, the other measurement of the epitaxial crystal-growth speed of a crystalline silicon interface, are presented.