Numerical Calculation of Anisotropic Mie Scattering Using Discrete Dipole Approximation Method

Micro- and nano-particles are widely involved in the fields of chemical, biological, and environmental science. It is crucial to characterize the morphology of the particles which may be strongly linked with their physical and chemical properties. The intensity patterns of the scattered light from the particles are expected to carry their substantial information such as refractive index, diameter, and shape. Standard Mie theory is commonly employed to analyze the scattering features assuming that the considered particle owns a spherical shape. In reality, however, a majority of particles exhibit anisotropic features either in shape or in refractive index distribution. In this case, Mie theory turns to be very complicated and numerical methods are necessary for an accurate calculation of the scattering patterns. In this study, we present a feasible method to numerically analyze the scattering of anisotropic particles using the discrete dipole approximation method. The approach can calculate the near-field electric field distribution of dielectric particles in any shapes, and is capable to further obtain the far-field scattering particles in any detection angles. Based on this approach, morphological characteristics of anisotropic particles may be rapidly retrieved through the analysis of scattering images, paving the way towards more accurate particle metrologies.