Fluctuations in radiation scattered into the Fresnel region by a random-phase screen in uniform motion

Abstract

The scattering of radiation by a rigid deep random-phase screen in uniform linear motion is studied and formulae are derived for the spatial and temporal correlation functions of the scattered field and intensity in the Fraunhofer and Fresnel regions. A joint Gaussian distribution is used to represent the phase screen and the illuminating beam is assumed to have a curved wavefront and Gaussian intensity profile. It is shown that the coherence properties of the scattered radiation depend on an apparent area of illumination which is a function both of the actual width of the illuminating beam and of the slope distribution of the scattered wavefront. The dependence of the second intensity moment on distance from the screen is discussed and compared with that predicted by previous authors.