Influence of the Laser Beam Shape and Particle Through-position in the Beam Cross-section on Light-blockage Size Measurement

摘要

The result of the light-blockage particle size measurement varies with the laser beam shape and the particle through-position in the beam cross-section for the energy inhomogeneity. To generate the rule of this phenomenon two parameters are defined as k_a and P_((g)inc)/P_0, presenting the influence factor of the illumination nonuniformity on a particle and the percent incident energy on a particle respectively. A moving three-dimensional coordinate system is employed to simulate the moving process of particle through the detecting area. And a mathematical model applicable for the light-blockage size measurement is built and analyzed through solving integral equations. Values of the two parameters are computed and plotted against the beam shape factor, the particle radius and the particle though-position. The results indicate that the optimum ratio of the major axis to minor axis of the beam cross-section is in the interval of 1～2 and the optimal particle through-position is on the semi-axis.