Calculations of Mueller matrices for optical waves scattered from a random medium with random rough surfaces and discrete particles

摘要

Mueller matrices are important in radar polarimetry as they characterize a target or a random medium at the incident frequency. Many random media which exist in nature have random rough surfaces and randomly distributed spherical particles. Two models for a slab of such random media are presented. Both models contain randomly distributed spherical particles. Planar surfaces are considered for the first model and Gaussian statistical rough surfaces are considered for the second one. Kirchhoff rough surface scattering theory is used to calculate the scattering of optical waves from the rough surface. Vector radiative transfer theory is used to calculate the volume scattering due to the particles. The scattered wave is computed for an arbitrarily polarized incident wave for optical thickness $tau $EQ 0.1 to 5, size parameters ka $EQ 0.4 to 1 and various surface roughnesses. The scattered wave is expressed in terms of the modified Stokes vectors and then used to construct the Mueller matrices. Polarization signatures are constructed from the Mueller matrices of the reflection side at the backscattering direction. The Mueller matrices are found to have some symmetrical properties and there are eight nonvanishing elements.