COMPACT FIBER OPTIC DYNAMIC LIGHT-SCATTERING SYSTEM

Fiber optic dynamic light scattering (FODLS) is fast developing as a t echnique for sizing particles in concentrated dispersions. Fiber optic systems have the potential to be made into online particle size measu ring equipment in process industries. Two different laser light source s were used to study monodisperse polystyrene latex dispersion with di fferent particle sizes and volume fractions. The apparent diffusion co efficients were a function of particle size, volume fraction, and sign al to noise ratios. The apparent diffusion coefficient data showed tha t FODLS probes collective diffusion for smaller particles and self dif fusion for larger particles. It was observed that for a polydisperse c oncentrated dispersion, both self and collective diffusion were probed by FODLS. This means that the apparent diffusion coefficient can be u sed only as a relative quantity. (C) 1997 Academic Press.