Enhanced fluctuations in radiation scattered by a moving random phase screen

We discuss the properties of enhanced non-Gaussian fluctuations that occur in radiation scattered by a moving deep random phase screen (e.g., a perfectly conducting, very rough surface) when the scattering configuration is such that the electric field at the point of observation is composed of relatively few independent randomly phased contributions. Fraunhofer and Fresnel region effects are considered both from the information-content point of view and in the context of unwanted noise in measuring and detection systems.