Tsang L, Ding K H, Shih S E, Kong J A
Department of Electrical Engineering, University of Washington, Seattle 98195, USA.
J Opt Soc Am A Opt Image Sci Vis. 1998 Oct;15(10):2660-9. doi: 10.1364/josaa.15.002660.
In a dense discrete random medium, the propagation and scattering of waves are affected not only by the individual properties of the particles such as size, shape, and permittivity, but also by group properties such as the statistics of relative particle positions and relative orientations. We use Monte Carlo simulations to investigate the interactions of electromagnetic waves with a dense medium consisting of spheroidal particles for cases of random orientation and for cases of aligned orientation. A shuffling process is used to generate the positions of densely packed spheroids. Multiple-scattering equations are formulated by means of the volume integral equation and are solved numerically. The scattering results are averaged over realizations. Numerical results are presented for the extinction rates and the phase matrices. Salient features of the numerical results indicate that (1) the extinction rates of densely packed small spheroids are smaller than those of independent scattering; (2) for aligned spheroids, the extinction rates are polarization dependent; and (3) the co-polarized part of the phase matrix for densely packed spheroids is smaller than that of independent scatering, while the cross-polarized part is larger than that for independent scattering. This means that the ratio of cross-polarization to co-polarization is significantly higher than that of independent scattering.
在密集离散随机介质中，波的传播和散射不仅受粒子的个体属性（如尺寸、形状和介电常数）影响，还受群体属性（如相对粒子位置和相对取向的统计特性）影响。我们使用蒙特卡罗模拟来研究电磁波与由椭球体粒子组成的密集介质在随机取向和排列取向情况下的相互作用。通过洗牌过程生成紧密堆积椭球体的位置。借助体积积分方程建立多重散射方程并进行数值求解。对散射结果进行多次实现的平均。给出了消光率和相位矩阵的数值结果。数值结果的显著特征表明：（1）紧密堆积的小椭球体的消光率小于独立散射的消光率；（2）对于排列的椭球体，消光率与偏振有关；（3）紧密堆积椭球体的相位矩阵的共偏振部分小于独立散射的，而交叉偏振部分大于独立散射的。这意味着交叉偏振与共偏振的比率显著高于独立散射的比率。
