OPTICAL BACKSCATTERING MEASUREMENTS FROM FRACTAL SURFACES AND THEIR POSSIBLE RELEVANCE TO RADAR SCATTERING FROM THE SEA-SURFACE

In spite of recent progress, existing theories of electromagnetic wave scattering by rough surfaces cannot yet explain several important features of microwave sea echo, particularly in grazing incidence geometries. To explain them it is necessary to develop scatttering models that can reproduce the features in a robust way. The aim of this paper is to report laboratory optical frequency experiments designed to aid achievement of this objective. In particular, polarization sensitive measurements of the backscattered intensity are reported for a range of characterized fractal surfaces using visible laser radiation. The appearance of enhanced backscattering peaks are observed even quite close to grazing incidence for some type of surfaces and indicate the importance of multiple scatttering. It is also shown that the dependence of the backscattering cross-section on incidence angle bears some gross similarities to that obtained from microwave scattering from the sea surface for high index fractal surface that exhibit intermittency.