Extending laser diffraction for particle shape characterization: technical aspects and application

Extending the laser diffraction technique to measurement of both particle size and shape is quite an interesting topic, especially for on-line process control and monitoring. It is possible as the scattering pattern of particles contains both types of information. This article describes the application of a novel sensor with two-dimensional pixel arrays for obtaining particle shape information. The fluctuating scattered light intensities in the azimuthal directions are transformed via cross-correlation into Particle Angle Spectra, which reflect the shape information. Possibilities for improvement of this information by using single-sweep analysis, small numbers of particles in the measurement zone, principal component analysis and Fourier analysis are discussed. Its potential for application is demonstrated by monitoring the shape change of cubic crystals during attrition.