Angular correlation functions of light scattered from weakly rough metal surfaces

The angular correlation functions of light diffusely scattered from weakly rough metal surfaces are studied. In experimental work, surfaces are well characterized, have highly one-dimensional roughness, and are studied in the case of p polarization. If there is significant plasmon polariton excitation, one type of intensity correlation function indicates that the diffuse intensity decorrelates rapidly as the angle of incidence is varied. It exhibits peaks that arise from an autocorrelation of identical intensities, or from the correlation of intensities related by the reciprocity principle. A second intensity correlation function expresses the symmetry of the diffuse intensity about the specular direction and is significant without plasmon polariton excitation. It is shown that the intensity correlation functions are directly related to two fundamental amplitude correlation functions. The latter are studied with perturbation theory, including all terms to fourth order in the surface profile function. The relation of the observed effects to backscattering enhancement is thus established, and favorable comparisons are made with the experimental results. [S0163-1829(99)05103-6].