Imaging through turbid media using polarization modulation: dependence on scattering anisotropy

We report our investigations of the dependence of the process of imaging through turbid media using polarization modulation on the scattering anisotropy. Two-dimensional images were extracted from scattering media using a technique that involved filtering in two domains, viz., spatial filtering and temporal fourier filtering, both of which depend on the scattering anisotropy. The latter was implemented by rotating the plane of polarization of the input light and selecting that scattered component which preserved the modulation over a certain period of time. This enhanced the contrast and resolution of images extracted from mere spatial filtering, and significantly extended the depth of imaging. We found that polarization modulation yielded higher contrast and higher resolution images in isotropically scattering media as compared to anisotropic media. The range of optical thicknesses over which polarization modulation performed efficiently was found to be larger in isotropic scatterers. (C) 2004 Elsevier B.V. All rights reserved.