Optimal configurations for active polarimetric imaging systems in the presence of different sources of Poisson shot noise

We address polarimetric imager optimization in the presence of Poisson-distributed noise arising from active illumination, passive contribution, and sensor noise. This issue is of great importance for designing imagers that reach the fundamental noise limit set by shot noise. We show that to maximize the contrast between two regions with different polarimetric properties, the illumination has to be either unpolarized, or totally polarized, and the analysis either unpolarized, which amounts to intensity imaging, or purely polarized. We precisely define the domains of optimality of each of these configurations and present examples showing the influence of passive contribution on the contrast in scalar polarimetric imaging.