HIGHER MOMENTS OF SCATTERED-LIGHT FIELDS BY HETERODYNE ANALYSIS

In heterodyne detection (such as in coherent lidar) the optical local oscillator defines a single mode of the incoming-signal light field; this single-mode selectivity has been previously predicted to preserve the full fluctuation character of scattered light. This is in contrast with direct-detection schemes, as in photon-correlation spectroscopy, where aperture averaging usually reduces the range of fluctuations. Examples of Gaussian and non-Gaussian statistics in laser light scattered from a moving ground-glass screen have been studied. This simple laboratory experiment has several advantages over equivalent direct-detection schemes and has been shown to yield experimentally the theoretically predicted factorial intensity moments (up to the seventh order) that result from zero-mean, circulo-complex Gaussian statistics.