Effect of enhanced backscattering on systems operating in double passage geometries

摘要

Abstract: One of the simplest manifestations of multiple scattering is the phenomenon of enhanced backscattering, which arises from the constructive interference of radiation which has traversed reversible paths from the source through the scattering medium and back in the source direction. Closely related effects occur when radiation is back-reflected through weakly scattering random media: a `double passage' geometry commonly encountered in monostatic lidar, radar and sonar systems. In addition to an enhanced signal level, double passage through a random medium can also lead to increased signal fluctuation or fading by comparison with a bistatic configuration, in which scattering on the outward and return paths is uncorrelated. The relative merits of these two modes of operation depends on system geometry and background noise as well as the nature of signal fluctuations. In this paper the effects of enhanced backscattering on system performance are discussed with reference to a range of noise and signal fluctuation models. Quantitative calculations of the performance of a simple detection scheme are used to illustrate the different regimes of operation and make comparisons between monostatic and bistatic configurations and between direct and homodyne detection.!19