The Experimental Study On Particle Size Measurement By Laser Interferometric Imaging

Particle field is widely present in various industrial and research fields. The research of the size distribution in particle field is of great significance to the production optimization. This thesis studies the particle size measurement based on the interferometric particle imaging technique (IPI), whose advantages are non-contactable, high accuracy and speedy. The IPI technique irradiates the particle field with a laser sheet, scattering happens when the laser encounters particles, using a CCD camera to receive the particle image on the side direction. The size and location of the particle are calculated by extracting the interference fringe information from the particle image. The main work as follows has been done in this paper.1. The measurement principle of the IPI has been studied by phase difference method and Young's interference method, which obtained the formulas of particle size when the relative refractive index m>1 and m<1, and discussed the impacts of some parameters on the results, including the scattering angle, the wavelength of incident light, the collection angle and the refractive index.2. Based on low-power semiconductor lasers and CCD cameras, the measurement system of IPI was designed, the standard particles of 51.1?m and 119.4?m in diameter were measured respectively. Achieving particle location by convolution, extracting the interference fringe information from the Fourier transform frequency spectrum chart of the particle image, the size of particle was calculated by the formula using the data mentioned above. The measurement results are that the particle diameters are 47.94?m and 111.24?m, and the relative errors are 6.2% and 6.8%.3. The water spray field was measured in different regions by using IPI system, the particle size distribution of different measuring points and SMD variation curve along X axis and Y axis are obtained.