Enhanced characterization of depolarizing samples using indices of polarization purity and polarizance–reflection–transformation spaces

Depolarizing behavior is commonly observed in most natural samples. For this reason, optical tools measuring the differences in depolarization response among spatially separated structures are highly useful in a wide range of imaging applications for enhanced visualization of structures, target identification, etc. One commonly used tool for depolarizing discrimination is the so-called depolarizing spaces. In this article, we exploit the combined use of two depolarizing spaces, the indices of polarization purity (IPP) and polarizance–reflection–transformation (PRT) spaces, to improve the capability of optical systems to identify polarization–anisotropy depolarizers. The potential of these spaces to discriminate among different depolarizers is first studied from a series of simulations by incoherently adding diattenuations or retarders, with some control parameters emulating samples in nature. The simulated results demonstrate that the proposed methods are capable of increasing differences among depolarizers beyond other well-known techniques. Experimentally, validation is provided by conducting diverse phantom experiments of easy interpretation and mimicking the stated simulations. As a useful application of our approach, we developed a model able to retrieve intrinsic microscopic information of samples from macroscopic polarimetric measurements. The proposed methods enable non-invasive, straightforward, macroscopic characterization of depolarizing samples, and may be of interest for enhanced visualization of samples in multiple imaging scenarios.