Optical particle-sizing method that provides optical isolation of the sampling volume

We have constructed and tested a novel particle sizer that employs particle counting (the time-domain approach) rather than the ensemble-diffraction a pproach that currently dominates the market in atmospheric-dust particle si zers. The method does not depend on mechanical devices to restrict particle s within the sampling volume but instead allows for optical isolation of th e sampling volume. This technique is useful for atmospheric-dust measuremen ts for which nonobtrusive measurement is often desirable. (C) 1999 Optical Society of America.