Durian D J
Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, California 90095-1547, USA.
Opt Lett. 1998 Oct 1;23(19):1502-4. doi: 10.1364/ol.23.001502.
The diffusion approximation is widely invoked to model the propagation of light in turbid media. When absorption is not weak in comparison with scattering, there is currently a controversy as to if, and how, the diffusion coefficient depends on absorption. Here it is shown that better agreement with random walk simulation is obtained if the photon-diffusion coefficient is taken as D=c/(3micro(s)(')+micro(a)) . One can reconcile this result with recent work advocating D=c/3micro(s)(') by noting that the diffusion equation must be correspondingly changed to a telegrapher's equation.
扩散近似法被广泛用于模拟光在浑浊介质中的传播。当吸收与散射相比并非很小时，目前对于扩散系数是否以及如何依赖于吸收存在争议。本文表明，如果将光子扩散系数取为D = c/(3μs'+μa)，则能与随机游走模拟取得更好的一致性。通过注意到扩散方程必须相应地改为电报方程，就可以使这个结果与最近主张D = c/3μs'的工作相协调。
