Measuring device and method for the determination of particle size distributions by scattered light measurements

摘要

For the determination of fine particle size distributions by scattered light measurements, an assembly of suspended particles is illuminated with coherent light, the scattered light pattern is focused on a light sensitive multi-element detector of a registration device and is transformed there to electrical signals. From the digitized electrical signals, the particle size distribution is computed with a computer. For the simplification of the setup and for the improvement of the accuracy of the computable particle size distribution, it is provided that the registration device is a video camera and that the particle size distribution is computed via the solution of a Fredholm integral equation from the signals produced by the light intensities at the pixels of the video camera. The video camera is a CCD camera. For the variation of the brightness, a rotating disc with gray filters of different transmittivities is provided in the measuring light beam, or the camera is equipped with an electronic shutter for different exposure times. Different fractions of particle sizes is measured also by variation of the angle between the optical axes of illumination and imaging devices.