基于等效原理和互易性定理研究了两个靠近目标对平面波、高斯波束的光散射问题,给出了这一复合光散射模型的二阶散射结果。通常一阶散射结果容易求解,但由于耦合效应的复杂性,很难给出二阶散射结果的解析形式。为了解决这一问题,应用互易性定理给出了求解任意相邻介质目标二阶散射场的公式,同时借助等效原理将求解散射场公式中的体积分简化为面积分的形式,从而降低了求解难度。求解了两相邻球形粒子的复合散射场,并将求解结果与应用时域积分方程法求得的结果进行了比较。同时,还讨论了束腰半径、目标位置对散射截面及偏振度的影响。

Based on the equivalence principle and the reciprocity theorem, the problem of light scattering of plane wave/Gaussian beam from arbitrary two adjacent objects is considered and a solution that accounts for multiple scattering up to second-order is evaluated. In general, the first-order solution can easily be obtained. However, due to the difficulty in formulating the coupled scattering field, it is impossible to find an exact analytical solution for the second-order scattered field. In order to overcome this difficulty, the second-order solution of light scattering of plane wave/Gaussian beam from two adjacent conducting/dielectric objects is derived by employing the reciprocity theorem and this solution is simplified from volume integral to surface integral form by using the equivalence principle. In specific, the composite scattering field from two adjacent spheres is calculated. The bi-static scattering is discussed, and the results are compared with numerical computations based on time-domain integral equation method (TDIEM). Meanwhile, the dependence of the scattering section and the degree of polarization on the beam-waist radius and the locations of the objects are also discussed.