Enhancement of the point-spread function for imaging in scattering media by use of polarization-difference imaging

Polarization-difference (PD) imaging techniques have been demonstrated to i mprove the detectability of target features that are embedded in scattering media. The improved detectability occurs for both passive imaging in moder ately scattering media (<5 optical depths) and active imaging in more highl y scattering media. These improvements are relative to what is possible wit h equivalent polarization-blind, polarization-sum (PS) imaging under the sa me conditions. In this investigation, the point-spread functions (PSF's) fo r passive PS and PD imaging in single-scattering media are studied analytic ally, and Monte Carlo simulations are used to study the PSF's in single- an d moderately multiple-scattering media. The results indicate that the PD PS F can be significantly narrower than the corresponding PS PSF, implying tha t better images of target features with high-spatial-frequency information can be obtained by using differential polarimetry in scattering media. Alth ough the analysis was performed for passive imaging at moderate optical dep ths, the results lend insight into experiments that have been performed in more highly scattering media with active imaging methods to help mitigate t he effects of multiple scattering. (C) 2000 Optical Society of America [S07 40-3232(00)00501-9].