Measurements of structure-induced polarization features in forward scattering from collections of cylindrical fibers

Many applications in remote sensing, material sciences and biomedical field are characterized by a transition domain between single scattering and multiple-scattering regimes. This regime is described by typical polarization features which can be used to retrieve structural information. An electronically agile technique was used for measuring in real time the Stokes vectors of light incident on and emerging from an inhomogeneous medium. Subsequently, the Mueller matrix associated with the scattering medium is determined. We focus our attention on forward scattering from systems consisting of random as well as partially oriented long cylindrical fibers. We discuss the effects of: (1) shape of individual scattering centers, (2) structure parameter, and (3) optical density of the scattering medium. The anisotropic behavior of the structure function at different packing fractions determines nontrivial characteristics of the polarization transfer. The complex effective index of refraction can be polarization dependent as a result of the optical anisotropy due to both the shape of the individual scatterers and the structure characteristics of the scattering system. Some of the Mueller matrix elements are shown to be related to the optical anisotropy of the system for the case of long cylindrical fibers. The polarization efficiency, the structure parameter, and the packing fraction are used to quantify this relationship. We also found that some of the matrix elements are more sensitive to the degree of structural anisotropy and the packing fraction, while other elements are sensitive to structural non-uniformities across the investigated area.