微小颗粒的光散射数值模拟

简单介绍了以经典Mie理论为基础的光散射测量技术在颗粒直径和颗粒浓度测量中广泛的应用。分别以Mie理论和离散偶极子近似理论(DDA)为基础, 用数值计算方法分析了球型颗粒的光散射特性，给出了微小颗粒对平行入射光散射的强度函数和散射偏振度的数值计算方法。得到了强度函数和偏振度随相关物理参量变化的三维图，为微小颗粒散射研究提供了一种三维视图。计算结果表明：当尺度参量x＜4时，2种方法所得结果差异不大；随尺度参量增大，2种方法所得结果出现较大差异。与经典Mie理论相比，由于离散偶极子近似理论可以解决各种形状的颗粒散射问题，其应用前景更广泛。

Numerical simulation of light scattering from small particles

Light scattering measurement technology based on the classical Mie theory is widely used in the measurement of particle diameter and particle density measurement.The characteristics of light scattering from spherical particles in aerosol are analyzed with a numerical calculation method based on the classical Mie theory and discrete-dipole approximation(DDA) theory respectively.A numerical calculation method for intensity function and polarization ratio of the collimated incident beam scattered by small particles is given.The 3D graph for variation of the intensity function and polarization ratio with the relative physical parameters was obtained for the research of small particle scattering.The calculation results show that the results obtained by two methods based on DDA theory or classical Mie theory differ slightly when dimension parameter x<4,and the results differ greatly along with the increase of dimension parameters.In comparison with the classical Mie theory,the DDA theory has greater potential in application since it may solve particle scattering problem for different shapes of particles.