A small particle size analyzer based on Fraunhofer pattern recognition

A small particle analyzer has been constructed and used to determine the populations of 2 micron diameter and 4-7 micron diameter spheres in mixtures of these two types of spheres in glycerine. A library of reference patterns is formed by making irradiance measurements along 50 adjacent chord lines within a 30[degrees] sector centered on the optic axis in the Fraunhofer diffraction region. Each reference pattern becomes one column of a scattering matrix G(p)f so that G(p) represents an overdetermined system with 50 rows and 2 columns. [...]