Intercomparison of inversion algorithms for particle-sizing using Mie scattering

The applicability of different inversion algorithms to retrieve a size distribution of particles in air from light scattering is examined. The investigation is focused on an optical measurement setup with an elliptical mirror as the main optical element. In order to evaluate the capabilities of the individual inversion methods, light scattering by spherical particles is simulated in the size ranges of 0.1 - 10 mu m and 0.05 - 1 mu m. The distribution of the particle diameters is modeled with three different parametric functions, i.e., RRSB, logarithmic-normal and a more specific distribution from an ultrasonic nebulizer. Different kinds of noise, e.a., additive and/or multiplicative, are applied in different levels to the simulated scattering measurement to include real physical measurement conditions. The convergence properties of the scattering simulation are investigated with respect to the number of size classes, and thus, information concerning the size resolution required to simulate a measurement for a given particle size distribution is obtained. Further parameters of interest are the minimum angular resolution of the measurements, the number of size classes of the retrieved particle size distribution and the measured polarization of the scattered light.