Simulating light propagation: Towards realistic tissue models

We present a tool for Monte Carlo simulations of polarized light transport in biological tissue samples. This tool can be adapted to various scenarios thanks to a user interface that allows both complex geometrical structures and different illuminating beam profiles to be generated. By combining spheres, cylinders and half-spaces, the user is able to create highly intricate physical models, with each geometrical element able to be assigned its own optical properties: absorption and scattering coefficients, refractive index and scattering law. The scattering law models currently utilized by the tool are the Mie scattering law and the polarized version of the generalized Henyey-Greenstein scattering law: these models can be customized by modifying the appropriate parameters. A tracing method is used to track the propagating photons and handle the reflection/transmission processes (using the Fresnel relations) at interfaces between two different media. Virtual CCDs coupled with polarizers are used to carry out the imaging of the backscattered and transmitted light. The Mueller matrix of the sample can be obtained by measuring the changes that occur in the polarization states (represented by complex Jones vectors) of the propagating photons. The propagating light's temporal and spatial profiles can also be visualized.