Commercial spectrophotometer for particle sizing

Particle-size distribution and the concentration of polystyrene particles 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 collection optics to prevent low-angle scattered light from affecting the measurement of transmitted power. The data were inverted by use of a nonlinear iterative algorithm. When the extinction coefficient is measured in the l range of 0.3-1.1 μm, the particle distributions can be retrieved over a diameter range of 0.6-2.8 μm for a wide interval of sample concentrations. The average diameters are recovered with a precision of better than ±1% and with accuracies consistent with the uncertainties by which the nominal diameters are known. The relative standard deviations of distributions corresponding to monodisperse samples are ±5-10%, whereas the accuracy on the measured concentrations is ∼5%. © 1997 Optical Society of America.