Refract-reflect laser particle size measurement method

Laser particle size analyzer has been widely used in the measurement of particle size distribution in various fields due to its advantages of fast speed and non-contact. However, the relationship between the angular distribution of scattered light and particle size is complex. In order to obtain the consistent relative accuracy under different particle sizes, the measurement range of particle size distribution will be small and cannot meet the requirements of wide distribution particle size measurement. According to the Fresnel principle of Mie scattering approximation, it was proposed to use the catadioptric optical path. The particle scattering signal was divided into two beams by the splitter, and the transmitted as well as reflected scattering signals were collected by two sets of compound lenses and two photodetectors, respectively. The combined signal was inversed to obtain the particle size distribution, thereby improving the range of particle size measurement. Two kinds of standard particles and their mixtures were used in the experiment. The results show that the relative error of the volume median diameter D50 measured by a single standard particle is not greater than 7.9%, and the correct peak distribution can also be obtained for mixed particles.