ROLE OF MULTIPLE-SCATTERING IN CROSS-CORRELATED LIGHT-SCATTERING WITHA SINGLE LASER-BEAM

Previous systems for measuring cross-correlated light scattering by sm all particles suspended in a liquid with multiple-scattering suppressi on have illuminated the particles with two laser beams. It is shown th at multiple-scattering suppression should also occur in cross correlat ion for a system that employs a single laser beam and two closely spac ed detectors with wide fields of view. The single-scattering, double-s cattering, and single-double-scattering cross-term contributions to th e intensity cross-correlation function are calculated. It is found tha t the two cross terms, when added together, are unimportant for both a utocorrelation and cross correlation. The amplitude of the double-scat tering term can be greatly diminished by judicious detector spacing be cause the spatial coherence area in the detector plane for double scat tering is much smaller than that for single scattering. (C) 1997 Optic al Society of America.