粒子的形状和凝聚对光散射特性有着很大的影响。基于分形生长的受限扩散(DLA)模型，模拟了凝聚粒子的三维空间分形结构，并采用回转半径法计算了凝聚粒子的分形维数。利用离散偶极子近似(DDA)方法研究了纳米石墨凝聚粒子的光散射特性，对于原始粒子数不同的凝聚粒子及分形结构不同的凝聚粒子，数值计算了散射强度和偏振度随散射角的分布规律。结果表明凝聚粒子的散射特性与包含的粒子数目、入射波长和分形维数有关，与等体积球的散射特性也存在很大的差异。

The shape and aggregation of particle have a strong influence on the light scattering property. The diffusion-limited aggregation model (DLA) of fractal growth is used to simulate the possible structures of aggregates, and the fractal dimension of aggregates is calculated with the method of gyration radius. The light scattering property of nano-graphite aggregates is studied on the basis of discrete dipole approximation (DDA) method. For aggregates with different numbers of primary particles and with different fractal structures, numerical results of the scattering intensity and the degree of linear polarization to different incident wavelengths are illustrated. The results show that the light scattering properties of nano-graphite aggregates are related to incident wavelength, particle numbers and fractal dimension, and are different from those of the equal volume sphere.