Technique For Particle Measurement Based On Light Scattering With The Radiation Of A Divergent Light

Particle measurement technique based on forward light scattering with Mie theoryhas been the most widely used light scattering particle measurement technology. Withthe development of science and technology, more and more fine particles are on theapplication. In order to meet the requirement for the measurement of fine particles,researchers unceasingly consummate and innovate the traditional forward lightscattering method. In these techniques, the collimated beam and/or convergent beam areoften used as the incident beam. The former is known as conventional Fourier system(CFS)，which has the advantage of large measurement range. However, the lower size ofparticle is limited as the focal length of lens cannot be too short. The latter is calledreverse Fourier system (RFS), whose measurement limit can be reduced effectivelybecause the equivalent focal length can be very small. The negative effects are causedby the disturbance from the light reflection between the surfaces of the sampling celland the detector. The Generalized Fourier system (GFS), which employs a divergentGaussian beam scattering model, is a new particle measurement technique and thesupplement for the above mentioned two methods.In this paper, the theoretical model of GFS is presented. Analytical expressions,based on the ray propagation, are deduced to describe the scattered light distribution onthe detector. Particle size distributions are extracted from the measurements by using theinverse algorithm under different optical arrangements and these results are comparedwith those obtained from the conventional Fourier system (CFS) technique. Thepoly-disperse system is also studied to test the consistency with the mono-dispersesystem for a fixed particle size. The method of GFS has several advantages such assimple optical setup and structure, accurate result and so on, so it has potentialapplication values which provide a new method for light scattering technique.In this paper, the details are presented in both theory and experiment. In chapter1,the development and present status of particle measurement technique based on forwardlight scattering and the backgrounds of the GFS are introduced along with thesignificance of the particle and the on-line measurement. Chapters2and3are thetheoretical parts, which briefly introduce the concept of the particle measurementtechnology based on light scattering, present the theoretical model of the GFS, calculateand analyze the scattered light distributions under different setups. Chapters4and5arethe experimental parts, in which the experimental setup is constructed and experimental study is performed. The operating principle and the characteristic parameter of thesingle-mode fiber laser and the receiving lens, the experimental results and the relativediscussion are also described in this part. In chapter6, the work in this thesis issummarized and the perspectives are also presented.Simulation and experimental results show that the theoretical model of the GFScan be used for particle measurement effectively.