Abstract

Measurement of forward light scattering is important for several reasons. Due to the sheer magnitude of the volume scattering function in the forward direction, it must be resolved at and near zero degrees to do high resolution imagery calculations and to predict laser beam propagation. Another fundamental reason is the direct relationship of the forwardscattering amplitude to the extinction cross section via the optical theorem. The major difficulty in measuring the forwardscattering is the presence of the intense unscattered incident field. A novelty filter based on beam fanning in a photorefractive barium titanate crystal is used to separate the scattered and unscattered beams. Because of the constant Brownian motion of the aerosol particles the scattered field has a time dependence; this is a necessary condition to take advantage of the novelty filter. In this work we present measurements of intensity of the scattered field as a function of angle at and near zero degrees for polystyrene spheres of radii ranging from 5 to 45 μm.

© 1991 Optical Society of America