Contrasts of the polarization difference projection images with'linearly and circularly polarized lights

Polarization gating has been an attractive technique for optical imaging in turbid media. In this study, we investigate the polarization difference projection image (PDPI) in turbid media with linearly and circularly polarized lights. An iris is placed at the focal spot of the imaging optics to examine the influence of spatial filtering on imaging contrast. Polystyrene microsphere suspensions in Rayleigh and Mie domains are used as the phantoms. Scattering coefficient μ s and anisotropy factor g are varied independently to obtain the quantitative relation between the PDPI contrasts and the optical properties of the phantom. We also compare the PDPI contrast with the contrast of degree of polarization (DOP). Primary results show that the PDPI contrast is better than DOP image contrast either in Rayleigh or Mie scattering domain. In the Mie scattering domain, linear and circular PDPI contrasts are compared for different scattering coefficients. We also discussed how Fourier spatial gating improves the image contrast. The results are compared with Monte Carlo simulation.