We have developed a new experimental setup based on optical Kerr gating in order to isolate either the transmitted or the scattered light going through an optically thick medium. This selectivity can be obtained by finely tuning the focusing of the different laser beams in the Kerr medium. We have developed an experimental setup. A Monte Carlo simulation scheme generates an accurate model of scattering processes taking into account the time of flight, the geometry of the Kerr gating and the polarization. We show that our experimental setup is capable of analyzing the transmitted light with optical densities up to OD = 9.7, and scattered light beyond OD = 347 in poly-disperse silica spheres in water (distribution centered on ~0.9 µm radius) at λ = 550 nm. Strongly positive correlations are obtained with simulations.
Abstract:The aim of this work is to evaluate the influence of absorption processes on the Time Of Flight (TOF) of the light scattered out of a thick medium in the forward direction. We use a Monte-Carlo simulation with temporal phase function and Debye modes. The main result of our study is that absorption inside the particle induces a decrease of the TOF on a picosecond time scale, measurable with a femtosecond laser apparatus. This decrease, which exhibits a neat sensitivity to the absorption coefficient of particles, could provide an efficient way to measure this absorption.
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