Abstract
There exists a vast literature relating to the statistical properties of light obtained by scattering laser light by a moving diffuser. Some publications are restricted to an analysis of the effects produced by a uniformly moving diffuser with a slit aperture along its direction of motion.1,2 We show that this case is rather exceptional, because it generates a field that is spatially completely coherent at each frequency.3 The physical reasons for this result are discussed. We also derive an expression for the spectrum of the far field produced by scattering of a polychromatic plane wave incident normally on the diffuser. We find that it differs from the spectrum of the incident field in two respects: It suffers a Doppler shift due to the motion of the diffuser, and it is modified in a manner that depends on the correlation properties of the diffuser. Numerical examples are given which show that, although these effects are relatively small, they are within the range of experiment.