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 improve the detectability of target features that are embedded in scattering media. The improved detectability occurs for both passive imaging in moderately scattering media (<5 optical depths) and active imaging in more highly scattering media. These improvements are relative to what is possible with equivalent polarization-blind, polarization-sum (PS) imaging under the same conditions. In this investigation, the point-spread functions (PSF's) for passive PS and PD imaging in single-scattering media are studied analytically, and Monte Carlo simulations are used to study the PSF's in single- and moderately multiple-scattering media. The results indicate that the PD PSF can be significantly narrower than the corresponding PS PSF, implying that better images of target features with high-spatial-frequency information can be obtained by using differential polarimetry in scattering media. Although the analysis was performed for passive imaging at moderate optical depths, the results lend insight into experiments that have been performed in more highly scattering media with active imaging methods to help mitigate the effects of multiple scattering.