Wolfgang Witt

Angular spectrum of light transmitted through turbid media: theory and experiment.

Measurements of the angular spectrum of light transmitted through turbid slabs with monodispersions of polystyrene spheres have been performed. The results obtained are compared with theoretical calculations, based on the small-angle approximation of the radiative transfer theory. The experimental data and the theoretical results coincide with a high accuracy, which allows us to develop the laser diffraction spectroscopy of optically thick light-scattering layers.

In-line particle sizing for process control in new dimensions

Abstract The combination of laser diffraction with upstream sampling realized a break-through for the in- and on-line particles size analysis in industrial applications. Today, the combination of representative sampling, dry dispersion, particle size analysis by laser diffraction and integrated feedback of the sample is well accepted in many industrial applications. No more interactions of the user are required, and for standard applications the on-line monitoring of particle sizes became nearly as simple as the monitoring of any other process parameter. The increase of inspection interval from 24-hour operation to months has increased user confidence in this technology, and industries with more demanding measurement requirements are seeking to benefit from this performance. This challenge could not be solved with simple scale-ups or scale-downs. New solutions had to be found for the sampling system, the measuring sensor, the adaptation to the environmental conditions and the processing of fast growing volume of data.