COMMERCIAL SPECTROPHOTOMETER FOR PARTICLE SIZING

Particle-size distribution and the concentration of polystyrene partic les suspended in water were accurately recovered from the inversion of spectral extinction data measured with a commercial spectrophotometer . The instrument was modified by placing a spatial filter in the colle ction optics to prevent low-angle scattered light from affecting the m easurement of transmitted power. The data were inverted by use of a no nlinear iterative algorithm. When the extinction coefficient is measur ed in the lambda range of 0.3-1.1 mu m, the particle distributions can be retrieved over a diameter range of 0.6-2.8 mu m for a wide interva l of sample concentrations. The average diameters are recovered with a precision of better than +/-1% and with accuracies consistent with th e uncertainties by which the nominal diameters are known. The relative standard deviations of distributions corresponding to monodisperse sa mples are +/-5-10%, whereas the accuracy on the measured concentration s is similar to 5%. (C) 1997 Optical Society of America