Asano S
Appl Opt. 1979 Mar 1;18(5):712-23. doi: 10.1364/AO.18.000712.
Light scattering characteristics of spheroidal particles are studied for a wide range of particle parameters and orientations. The method of computation is based on the scattering theory for a homogeneous spheroid developed by us, and the calculation is extended to fairly large spheroidal particles of a size parameter up to 30. Effects of the particle size, shape, index of refraction, and orientation on the scattering efficiency factors and the scattering intensity functions are investigated and interpreted physically. The scattering properties of prolate and oblate spheroids with incidence parallel to the rotation axis constitute the extremes. The prolate spheroids at parallel incidence have steep and high resonance maxima in the scattering efficiency factors and broad and low forwardscattering peaks in the intensity functions; on the other hand, the oblate spheroids at parallel incidence have broad and low resonance maxima and sharp and high forwardscattering peaks. With an increase of the incidence angle, he scattering behavior of prolate spheroids approaches that of oblate spheroids at parallel incidence and vice versa. It is shown that, for oblique incidence, the scattering properties of a long slender prolate spheroid resemble those of an infinitely long circular cylinder. Effects of absorption on the extinction efficiency factors and scattering intensity functions are examined. Some problems in numerical calculation of the spheroidal wave functions and the infinite series solutions are discussed.
针对广泛的粒子参数和取向，研究了球形粒子的光散射特性。计算方法基于我们开发的均匀球体散射理论，计算范围扩展到尺寸参数高达30的相当大的球形粒子。研究了粒径、形状、折射率和取向对散射效率因子和散射强度函数的影响，并进行了物理解释。入射平行于旋转轴时，长球体和扁球体的散射特性构成了两种极端情况。平行入射时，长球体在散射效率因子中有陡峭且高的共振最大值，在强度函数中有宽且低的前向散射峰；另一方面，平行入射时，扁球体有宽且低的共振最大值和尖锐且高的前向散射峰。随着入射角的增加，长球体的散射行为趋近于平行入射时扁球体的散射行为，反之亦然。结果表明，对于斜入射，细长的长球体的散射特性类似于无限长圆柱体的散射特性。研究了吸收对消光效率因子和散射强度函数的影响。讨论了球形波函数和无穷级数解数值计算中的一些问题。
