Study On Laser Particle Size Measurement Technology Based On Linear CCD Detector

Particle size measurement is widely used in industrial production and scientific study.The commonly used method for micron-scale particle size measurement is laser particle size measurement.The traditional laser particle size measurement is based on the annular photodiode array detector.However,it can not meet the needs of some special production because of its large area,high cost and low spatial resolution.Therefore,the laser particle size measurement system based on linear array CCD detector is built in this paper.The simulation data and experimental data show that this method can effectively avoid the shortcomings of traditional measurement methods.The main researches are as following:1.The characteristics of scattering intensity distribution of particles with different diameters were studied;We discuss the complexity of calculating the scattering light intensity distribution of particles by Mie's light scattering theory;The limitation of the Fraunhofer diffraction theory to describe the scattering intensity distribution of particles is analyzed;The basic strategy of the inversion calculation of different parameters corresponding to different light scattering theory is given.2.Metal structure switch type flow sample pool was designed.The experimental setup of the optical structure of the front Fourier lens based on the linear array CCD detector is completed.The system parameters of the experimental device are studied,and the optimum range of the axial distance between the Fourier lens focal length and the sample pool distance Fourier lens is given.3.According to the design principle of the traditional annular photodiode array detector.The influence of the scattering angle linear partitioning method and the scattering angle logarithmic partitioning method on the particle size measurement are analyzed.The method of dynamic scattering angle division is proposed based on the linear array CCD detector,and the partition of particle size corresponding to different scattering angles was given.4.The scattering intensity of small diameter particles is calculated by Mie's light scattering theory.The particle size distribution(PSD)is obtained by the successive overl relaxation(SOR)method and using the H4 regularization operator and the ? regularization parameter is chosen according to the V curve criterion.Finally,the scattering intensity ofthe nominal particles is calculated and the validity of the improved regularization algorithm is proved.5.The integral transformation algorithm is used to calculate the scattered light intensity of large particle size particles by Fraunhofer diffraction theory.The principle of the Chin-Shifrin integral transform inversion algorithm is studied.According to the influence of the measurement noise on the inversion algorithm,the improved Chin-Shifrin algorithm is proposed.Different algorithms are used to calculate the experimental data,and the results show that the improved Chin-Shifrin algorithm can effectively restrain the influence of the measurement noise on the PSD.In this paper,the experimental setup of laser particle size measurement system based on linear array CCD detector and the acquisition of light scattering data are completed,and different algorithms are used to calculate the collected data.The experimental results show that the feasibility of using the linear array CCD to replace the traditional annular diode array detector for laser particle size measurement,which is helpful to promote the development of on-line laser particle size measurement technology.