Fourier transform light scattering of tissues

We review the basic principles of light-tissue interaction and common methods of investigation. The mathematical framework for describing weakly scattering regime (the Born approximation) as well as the strong scattering regime (the diffusion equation) are described. Traditional techniques based on polarization, time-resolved, single and multiple scattering are reviewed. We then introduce Fourier transform light scattering (FTLS), which is a recent development from our own laboratory. FTLS is the spatial analogue of Fourier transform spectroscopy, in the sense that it provides angular scattering (spatial frequency) data from phase and amplitude measurements in the spatial (image) domain. We show that FTLS can be used as a diagnostic tool by translating the quantitative phase information into data of clinical relevance. Further, FTLS allows us to extract scattering parameters of the tissue from imaging unlabeled, thin tissue slices, using a relationship which we call the scattering-phase theorem. Using these measurements, FTLS can predict the outcome of many other experiments, including time resolved and enhanced backscattering experiments.