Determination of size distribution of spherical polydispersions using scattered radiation data

Results of a numerical experiment are presented to show that measurements of the monochromatic light scattered by typical atmospheric aerosols (assumed spherical) can be used to obtain meaningful information about the variations of the particle number density with particle radius. Simulated measurements of about three significant figure reliability taken at 1 degrees intervals in the range 80-180 degrees are analyzed using the well-known least-square method to retrieve particle number density information in as many as twenty subintervals. For this purpose, it is necessary to have some a priori information about the largest and smallest particles present in the polydispersion and also about the refractive index of the material. The results of this numerical experiment also showed that measurements of the components of the scattered radiation parallel and perpendicular to the plane of scattering, i.e., the polarization measurements, rarely contained extra information about the size distribution. The results of inverting Setzer's radiation measurements [Appl. Opt. 8, 905 (1969)] are compared with the size distribution measured by him using direct technique.