Multi-Gaussian phase function model for off-axis laser beam scattering.

Within the small-angle approximation, a multi-Gaussian phase function model provides a new description of the multiple-scattering process and leads to improved agreement with experimental data. A general formula for the off-axis laser beam irradiance is given explicitly for a two-component Gaussian phase function. The predictions of the theory are compared with both the calculations based on the Mie scattering phase function and the results of measurements. It appears that the best fit of the model to experimental results requires an adjustment of the weight factors of the component phase functions. The solution, written in the form of a multiple-scattering series, allows one to interpret individual terms of the scattering series as scattering events of different orders.