Multiple Scattering Suppression in Laser Light Scattering

A laser-light-scattering method that includes cross-correlation processing of photodetector output signals has been devised for use in measuring the Brownian motions, and thereby indirectly the sizes, of particles suspended in liquids. Older laser-light-scattering methods for determining particle sizes from cross- or autocorrelation of photodetector outputs entail various deficiencies and difficulties, which include the need for precise alignment of two lasers of different wavelengths in a cross-correlation method, inability to obtain useful data at concentrations greater than 0.5 percent in one autocorrelation method, restriction to measurements at shallow depths in another autocorrelation method, and restricted angular range. The present method requires only one laser, can be used at various depths (for example in general liquid vessels or eye lenses), and yields useful data at concentrations >0.5 percent. This method can be used to determine typical particle sizes from 30 Å to 3 µm.