Extracting Superficial Scattering by Q-Sensing Technique

Optical properties determine how light interacts with biological tissues. The current methods for measuring these optical properties are influenced by both deep and superficial skin layers. Polarization-based methods have been proposed in order to determine the influence of deep layer scattering. Polarized light allows for the separation of ballistic photons from diffuse ones, enhancing image contrast and resolution while providing additional tissue information. The Q-sensing technique captures co-polarized $\left(I_{\parallel }\right)$ and cross-polarized $\left(I_{\perp }\right)$ signals, making it possible to isolate the superficial scattering. However, the random structure of tissues leads to rapid depolarization of the polarized light. Detecting where the light becomes depolarized aids in sensing abnormalities within the tissues. Hence, this research focuses on identifying where depolarization occurs within the tissue. Tissue-mimicking phantoms, simulating the optical properties of biological tissues, are created to measure depolarization at various thicknesses. Experimental findings are validated with a Monte Carlo simulation, modeling polarized light behavior through the polydisperse tissue (as the tissue scatterers are heterogeneous in size). Additionally, the research demonstrates how polarized light can extract the optical properties of the medium.