Research About Sub-micro Particles Sizing Based On Dynamic Light Scattering

With the development of technology, particles play a more important role in nationaleconomy. People pay more attention to research about particles properties, especially theirsizing. Many algorithms and instruments have been supposed to measure that particles,especially the method of light scattering is applied in this field.The normal measuring methods are briefly introduced and their application range isalso analyzed in this paper. Based on this, the research object, research about dynamiclight scattering (DLS) for measuring sub-micro particles, is brought out, then, themeasuring theory and the inversion arithmetic of DLS are described in detail. Thetechnology about dynamic light scattering is the method based on Doppler effect, it isadapt to measure sub-micro particles. The merit of DLS is high-accurate and thetechnology does not interfere measured objects. But owing of highly instruments'pricesand highly experimental demands, the research about the technology is rare in the presentin our country.The paper research about the technology deeply by using BI-9000AT autocorrelatorfrom Brookhaven Co.. Firstly, the experimental scheme is designed according the theoryof dynamic light scattering. The experiment device is set up, and its reliability andstability are proved by measuring standard particles. Then, a lot of sub-micro particles aremeasured by the experiment device, and the solutions, to improve the measurementprecision in lab environment, are given.At the last, a new method, genetic algorithmic (GA), is presented to inverse DLSfunction. GA obtains the results by optimizing the DLS function. The paper compared theGA with other inversion methods by simulated data and actual measured data. Theexperimental results show that GA can accurately deduce particles' size and distribution,and it is not sensitive to noise in the data.