A study on the measurement of particle size distribution with laser diffraction systems

Abstract

The measurement of particle size distribution using a superimposed Fraunhofer diffraction pattern of moving particles on the focal plane was investigated. The following results were obtained. (1) Analysing the obscuration of diffracted light intensity of slits by obstacles behind the slits, the influence of particle numbers in a unit volume (cm³) on the diffracted light intensity was estimated. (2) At the mean particle size 60μm, it is found that this system can measure the correct particle size distribution for the particle numbers<6 × 10⁴ in a unit volume (cm³).