| Dynamic Light Scattering technique can be applied to study the transport properties of light in highly scattering medium. In experiment, we can use low-coherence interferometer obtain the path-length-resolved power spectra of backscattered light by measuring the scattered light. However, the corresponding analytical theory both single scattering theory and Diffusing Wave Spectroscopy (DWS) only can used in single scattering regime and the diffusion regime, respectively. As the complexity of multiple scattering for the regime between these two extremes, when scattered only a few times, it is not well understand that so far no effective method of theoretical analysis for this region.The discrete equivalent spherical scatterers aggregate model is developed for investigating the photon's transport properties in highly scattering media. Based on Monte Carlo method, we propose a new ellipse algorithm to determine the scattering point distributions. Use Mie theory and the radiative-transfer equation, combination with the obtained scattering point distributions, the path-length dependent scattering order distribution, the scattering intensity in different scattering order with different particle size are numerically calculated for different regimes. For the scattered light in short path-length region, the contribution of single scattered light is dominant and the influence of multiple scattered is quite small. As the path-length increases, influence of multiple scattering becomes outstanding. which agrees with DWS theoretical prediction when the path-length longer enough, the region between these two extremes are consistent with the experimental results. The simulation results show that the photon's transport process in highly media essentially is a multiple scattering process. The numerical algorithm can be used effectively to analyze the dynamic scattering properties of scattered light from the single-scattering to the multiple-scattering regime. |
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