The Use of a Correlator in Brillouin Scattering

Abstract

In Brillouin scattering one usually employs a scanned Fabry-Perot interferometer to obtain spectral information on the scattered light. Since signals are rather weak it is necessary to use some averaging procedure to obtain a satisfactory signal to noise ratio. Usually this is done by adding the signal in a multichannel scaler which is triggered at the beginning of each scan. One of the difficulties of this technique is that the interferometer cavity spacing is usually not quite stable which means that the phase of the signal within each scan is not the same. The characteristic time of this phase drift puts a limit on the possible data accumulation time. There are several ways to circumvent this problem and we wish to report here on one such possibility.