Measurement of size and concentration of scattering particles by speckle photography

Publisher Website
Google Scholar
Abstract
An experimental investigation of speckle patterns formed when a collimated beam of laser light is scattered by small spherical particles dispersed uniformly throughout a volume is reported. Double-exposure speckle photography is used to measure the decrease of correlation that occurs when the angle of incidence of the collimated beam is changed by an amount α. The results are presented graphically and in the form of empirical equations involving dimensionless groups of the following parameters: particle diameter, number of particles per unit volume, and depth of the test volume. The data form two distinct regimes—one for low numbers per unit volume and one for high numbers per unit volume. The effect of other experimental variables such as particle refractive index, film exposure characteristics, and the geometry of the recording system are studied.