Backscatter Linear and Circular Polarization Analysis of Roughened Aluminum

A study of cross-polarized and copolarized intensities backscattered from roughened aluminum surfaces is presented for both linear and circular incident polarization states. The angular variation of measured Mueller matrices is shown to contain only diagonal elements, as predicted by the reciprocity theorem. The ratio of cross-depolarized to copolarized scattered intensities is significantly larger for circular than for linear input polarization states. In the linear case the ratio saturates beyond 50 degrees , whereas in the circular case the ratio continues to increase monotonically with angle. A phenomenological model for copolarization and cross-polarization intensities is shown to predict the observed behavior of both linear and circular input polarization states up to incident angles of 70 degrees .