Characteristics of focusing of light beams with random phase modulation

A study was made of the spatial distribution of the intensity of radiation scattered by a random phase screen and focused by a lens. Two maxima were observed experimentally in the distribution of the intensity along the direction of propagation of a beam: these maxima were located near the focal plane. The experimental results were interpreted with the aid of a model of a beam subject to random phase modulation. It was found that one of the maxima in the intensity distribution corresponded to the "noise" component of the scattered radiation, and the other to the coherent component.