COHERENCE IN THE SINGLE AND MULTIPLE-SCATTERING OF LIGHT FROM RANDOMLY ROUGH SURFACES

One of the most interesting phenomena associated with the scattering o f light from a randomly rough surface is that of enhanced backscatteri ng. This is the presence of a well-defined peak in the retroreflection direction in the angular distribution of an incoherent component of m ean scattered intensity of the light scattered from such a surface tha t is primarily due to the coherent interference of each multiply refle cted optical path with its time-reversed partner. It is an example of a broader class of multiple-scattering phenomena that goes under the n ame of weak localization. Not all manifestations of weak localization in the interaction of light with a randomly rough surface are in backs cattering. It was recently shown that the average diffuse intensity fr om randomly rough surfaces with even symmetry can be enhanced or reduc ed in the specular direction because of the constructive interference between correlated pairs of scatters. We present a recent theoretical analysis and experimental results that cover four kinds of enhancement : enhanced backscattering, enhanced transmission, enhanced specular, a nd enhanced refraction for one-dimensional and two-dimensional surface s. These are manifestations of coherent effects that remain after ense mble averaging.