Wang L V, Liang G
Optical Imaging Laboratory, Biomedical Engineering Program, Texas A&M University, College Station, Texas 77843-3120, USA.
Appl Opt. 1999 Aug 1;38(22):4951-8. doi: 10.1364/ao.38.004951.
The focusing of light into a turbid medium was studied with Monte Carlo simulations. Focusing was found to have a significant effect on the absorption distribution in turbid media when the depth of the focal point (the distance between the focal point and the surface of the turbid media) was less than or comparable with the transport mean free path. Focusing could significantly increase the peak absorption and narrow the absorption distribution. As the depth of the focal point increased, the peak absorption decreased, and the depth of peak absorption increased initially but quickly reached a plateau that was less than the transport mean free path. A refractive-index-mismatched boundary between the ambient medium and the turbid medium deteriorated the focusing effect, increased the absorption near the boundary, lowered the peak absorption, and broadened the absorption distribution.
利用蒙特卡罗模拟研究了光聚焦到浑浊介质中的情况。当焦点深度（焦点与浑浊介质表面之间的距离）小于或与输运平均自由程相当时，发现聚焦对浑浊介质中的吸收分布有显著影响。聚焦可显著增加峰值吸收并使吸收分布变窄。随着焦点深度增加，峰值吸收降低，峰值吸收深度最初增加，但很快达到一个低于输运平均自由程的平稳状态。环境介质与浑浊介质之间的折射率失配边界会使聚焦效果变差，增加边界附近的吸收，降低峰值吸收，并拓宽吸收分布。
