Enhanced backscattering of light from a non-Gaussian random metal surface

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Abstract
We study theoretically the scattering of a finite beam of p- or s-polarized light from a randomly rough metal surface defined by the equation x3 = ζ(x1), where the surface profile function ζ(x1) is not a Gaussian random process. The surface that we study is a parallel array of identical ridges and grooves, of Gaussian form, whose separations along the x1 axis are random, i.e., a random grating. First we show that the surface defined in this way is a non-Gaussian surface. A numerical algorithm based on the fast Fourier transform is then developed for constructing such surface profiles, and the probability-density functions for the height and slope of the surface at an arbitrary point are calculated. The angular distribution of the intensity of the incoherent component of the light scattered from an ensemble of such surfaces is then calculated by purely numerical methods for surfaces with large root-mean-square slope (=1). A well-defined peak in this angular distribution in the retroreflection direction—enhanced backscattering—is observed for both polarizations. It is shown that this enhanced backscattering is a multiple-scattering effect.