A Heuristic Time-Domain Raman Forward Solver for Photon Migration in a Two-Layer Diffusive Medium

An analytical heuristic model has been developed to describe the time-domain reflectance Raman signal in a two-layer diffusive medium. The model is based on the solution of two coupled diffusion equations at the excitation and emission wavelengths, respectively. The accuracy of the model is verified by comparison with the results of Monte Carlo simulations. This solver correctly accounts for the Raman emitters within the layers and the full wavelength dependence of the optical properties of the layers. The computational efficiency of the solver is compatible with the requirements of rapid reconstructions of Raman spectra from time-domain Raman measurements acquired for a large number of different wavelengths.