离轴球形粒子对高斯波束的散射

Scattering of Gaussian Beam by Spherical Off-axis Particle

本文根据广义米氏理论，将入射高斯波束用矢量球谐函数展开，研究离轴球形粒子的电磁（光）散射。获得波束因子／ｇ表达式和它的局域近似结果，以及散射系数ａｎ和ｂｎ的计算公式。讨论了波束宽度和粒子离轴位置对散射系数、消光系数、散射强度角分布。

Electromagnetic scattering of a Gaussian beam from a spherical dielectric object off-axis is described.The incident polarized Gaussian beam is first expanded in terms of angular spectrum of plane waves. These waves are then represented as the vector spherical harmonics. The generalized Lorenz-Mie Theory(GLUT) has been used to investigate the interaction between nonplane wave with a spherical particle.The formulations of the scattering coefficients a. and b. are similar to those of the Lorenz-Mie Theory, the only difference is the introduction of an infinite set of beam shape coefficients andTE that describe the nonplane wave characters of the incident beam. The scattering coefficients TM and TE where at and re the usual scattering coefficients for an incindent plane wave. Using the results of Localized Approximation for the beam shape coefficients, the numerical results of scattering character, cross sections, the external and internal fields are calculated and discussed for a sphere illuminated with a Gaussian beam.