Feasibility of using glory and speckle patterns for sizing spherical and irregular particles

A backscattered laser light technique for sizing spherical and irregular particles is investigated in this paper. Two different interference patterns (glory and speckle), appearing in the backscatter region when a single droplet is illuminated with a laser light source, were recorded by a CCD camera. A theoretical model, based on a geometrical optics approximation, has been first developed to retrieve particle size from the analysis of these patterns and then applied to liquid and frozen water droplets with sizes ranging from 1 to 2 mm. The satisfactory agreement obtained between the theoretical model and the experimental data encourage further development of this technique.