On the origin of increased backward radiation from a liquid-solid interface at the Rayleigh angle

This letter describes a simple experimental technique to identify the physical source of increased backward radiation from a liquid-solid interface at the Rayleigh angle. Extensive spatial averaging is used to distinguish between the two principal mechanisms, namely back reflection as a finite beam effect and backscattering due to inherent material inhomogeneities. In all cases considered, the increased backward radiation was found to be caused exclusively by backscattering, and no appreciable back reflection was detected