Enhanced backscattering phenomenon in a random continuum

Abstract

The enhancement effect of the backscattered intensity in a random continuum under the forward scatter approximation is studied. This effect is attributed to the gain of coherence recovered from random decorrelation when the backward scattered ray passes through the same random structure as the incident ray. This effect can be completely described by the enhancement factor defined as the ratio of the average backscattered power over that in the absence of multiple scattering. In this paper, this enhancement phenomenon is investigated for two kinds of sources: a point source and a beam wave, and two kinds of power spectral functions: a Gaussian spectrum and a power law spectrum. For the case of a point source two ranges of scattering strength are considered: weak scattering and strong scattering. In the limit of weak scattering, the supereikonal approximation is applied. On the other hand, in the limit of strong scattering, the statistical saturation is assumed to be reached. For the case of a beam wave, only strong scattering is considered. Computations have been made as the beam size is varied. It is found that the enhancement effect subsides as the beam size is increased.