The intensity of light scattered by a particle at two small angles is measured. The ratio of these measurements depends on particle size, but has minimal dependence on refractive index. By using a pulse height analyzer as the display device, particle size distribution changes can be detected rapidly. The instrument allows more than one particle in the focal volume at any instant and selects the scattered light pulses randomly for processing, enabling dense particulate matter to be sized accurately. The instrument's detailed design features are presented. Calibration has been performed using monodisperse aerosols of accurately known diameters. The effect of refractive index is investigated, and the performance and limitations of the instrument are discussed. It is shown that, by incorporating the concept of random selection of input pulses, the concentration handling capacity is improved by an order of magnitude.
- Pub Date:
- January 1977
- Particle Size Distribution;
- Size Determination;
- Air Pollution;
- Particle Density (Concentration);
- Instrumentation and Photography