Scattering of light from the random interface between two dielectric mediawith low contrast

We calculate the coherent and incoherent scattering of p- and s-polarized l ight incident from a dielectric medium characterized by a real, positive, d ielectric constant epsilon(0) onto its one-dimensional, randomly rough inte rface with a dielectric medium characterized by a real, positive, dielectri c constant epsilon. We use a perturbation theory with a new small parameter , namely, the dielectric contrast eta = epsilon(0) - epsilon between the me dium of incidence and the scattering medium. The proper self-energy enterin g the expression for the reflectivity is obtained as an expansion in powers of eta through the second order in eta, and the reducible vertex function in terms of which the scattered intensity is expressed is obtained as an ex pansion in powers of eta through the fourth. The roughness;induced shifts o f the Brewster angle (in p polarization) and of the critical angle for tota l internal reflection (epsilon(0) > epsilon) are obtained. The angular depe ndence of the intensity of the incoherent component of the scattered light displays an enhanced backscattering peak, which is due to the coherent inte rference of multiply scattered lateral waves supported by the interface and their reciprocal partners. Analogs of the Yoneda peaks observed in the sca ttering of x rays from solid surfaces are also present. The results obtaine d by our small-contrast perturbation theory are in good agreement with thos e obtained in computer simulation studies. (C) 2000 Optical Society of Amer ica [S0740-3232(00)01207-2] OCIS codes: 240.5770, 290.5880, 290.1350, 290.4 210, 260.6970.