A perturbation approach to characterize absorptive inclusions in diffusing media by time-resolved contrast measurements

Time-resolved measurements of ultrashort light pulses transmitted through turbid scattering media have been performed to determine the possibilities and the limitations of a first-order perturbation approach to recover the absorption coefficient of different tissue-like cylindrical absorptive phantoms. The model accounts for the effect of a spatially varying absorption coefficient of an inclusion on the time-resolved transmittance. We have determined the absorption coefficient of the inhomogeneities located at the midplane of a scattering cell by fitting the diffusion approximation-based perturbation model to the experimental time-resolved contrast measurements. The accuracy of the model predictions is discussed. An error analysis of the fitting procedure is also presented.