Measurement and Evaluation of Elastic Light Scattering from a Single Levitated Irregular Particle

Abstract

This study introduced a convenient experimental method to measure and to evaluate the elastic light scattering from a single irregular particle. The particle levitation system was used to trap a particle and to maintain the particle at null position by utilizing electrodynamic balance. Moreover, the Raman spectroscopy was applied to observe the light scattering of a single particle. The influences of relative humidity on optical properties of particle were also discussed. For comparison with experimental results, the classical Lorenz-Mie theory was employed to compute the phase function of a single particle. The experimental results demonstrated that the measurements of light scattering were in approximate trend with the model. In particular, numerical simulation results showed that the scattering intensity was underestimated in backward scattering directions. Consequently, the effect of surface roughness and irregular morphology of particle might be resulted in deviations of backward scattering. Besides, the experiments suggested that while using the weighted average method to estimate the refractive index might cause some significant deviations of light scattering between measuring and modeling.