We give a sufficient condition for the field scattered from a surface (S) illuminated by a laser beam to be a stationary gaussian field. This condition is fulfilled for the optical shot noise. As an example we calculate the spectrum of the field scattered from a granular surface. We show that it does not depend on the statistical properties of (S) when the number of grains tends to infinity.
MARTINE ROUSSEAU, "Statistical Properties of Optical Fields Scattered by Random Media. Application to Rotating Ground Glass," J. Opt. Soc. Am. 61, 1307-1316 (1971)