Enhanced backscattering through a deep random phase screen

Abstract

The distribution of intensity scattered by a plane mirror placed in the Fresnel region behind a smoothly varying deep random phase screen is calculated for arbitrary angles of incidence of the illuminating beam. It is found that enhancement occurs in the backward direction because of the coherent addition of doubly scattered waves, as in particle-scattering systems, and also as a result of statistical geometrical-optics effects. These effects are largest when reflection takes place near the focusing plane of the phase screen and lead to an enhancement factor proportional to the logarithm of the phase variance introduced by the screen. The coherence and higher-order statistical properties of the scattered wave are briefly examined.