Approximate method for fast retrieval of particle size distribution in spectral extinction technique

Generalized eikonal approximation (GEA) method, used as an alternative to the rigorous Mie theory in this paper, is introduced for retrieval of the particle size distribution (PSD) in the independent model. To compute the extinction efficiency accurately, the combination of GEA method and Mie theory is adopted, which can not only extend the applicable range of the approximation method but also improve the speed of the whole retrieval. Both simulations and experimental results show the method can be successfully applied to the retrieval of PSD when the refractive index is within the validity range. By using this method, we find the complexity and computation time of the retrieval are significantly reduced, and the memory resources can also be saved effectively. Thus all of these factors make the method more suitable for realization of on-line particle sizing.