Biomedical applications of near infrared radiation (NIR) techniques (i.e., based on light wavelengths roughly between 400 and 1100 nm) require that a preliminary estimate of the tissue volume being investigated be found. One possible estimate is the depth to which a photon penetrates a tissue before it eventually emerges at a separating plane at a given time. A simple model for this problem can be based on a lattice random walk and was initially analyzed when the associated optical coefficients are isotropic with respect to the geometry. Here we include the effects of anisotropy in the optical coefficients, finding that at long times the statistical properties of the depth of penetration can be accounted for by very simple scaling factors while at short times the anisotropy factors can be quite significant.

中文翻译：

---

混浊介质各向异性对光子穿透深度的影响

近红外辐射 (NIR) 技术（即基于大致在 400 到 1100 nm 之间的光波长）的生物医学应用需要找到对正在研究的组织体积的初步估计。一种可能的估计是光子在给定时间最终出现在分离平面之前穿透组织的深度。该问题的简单模型可以基于晶格随机游走，并且最初在相关光学系数相对于几何形状各向同性时进行分析。在这里，我们将各向异性的影响包括在光学系数中，发现在很长一段时间内，穿透深度的统计特性可以通过非常简单的比例因子来解释，而在短时间内，各向异性因子可能非常重要。