Design And Implementation Of Laser Particle Size Analyzer Based On Optical Diffraction With Method Of Image Processing

With more and more attention people paid to air pollution,the emission standard of pollutant gases has been made stricter,extremely for stationary pollution sources.Many research institutions at home and abroad begin to make relative technique and device to measure the pollution.Based on such topic,this paper studies how to build the measurement system to measure the size distribution of air pollution.Firstly,this paper makes simulation of diffraction result of particle swarm on MATLAB based on theory of Fraunhofer model as well as common particle distribution,contributing to choose right optical components and build the optical measurement platform.Meanwhile,this paper tests the Fraunhofer model which is the basic foundation model of famous laser particle size analyzer called HELOS.After building up such platform,under the relationship between CCD physical distance and pixel distance on the image,this paper makes experiment on particle samples whose size distribution is known to let the experimental light power get closer to the theoretical light power,in which situation we need to adjust relative experimental parameter.Then,this paper make use of some particle size inversion algorithm to inverse the original size distribution according to experimental light power.Finally,we compare the inversion result between our measurement system and HELOS system to validate the correctness.The conclusion is that the measurement range of particle size of this system is between 0.1um and 10 um,the average error between experimental light power and theoretical light power is 28%.Algorithm of known pattern behavior badly under condition of log-normal distribution model,algorithm of unknown pattern conclude CHAHINE and TSVD and TIKHONOV,500 times iteration of CHAHINE algorithm is better than the other two algorithms,the average distribution error is 36%.