Research Of Laser Particle Size Analyzer Based On CCD Technology

Particle testing is widely involved in scientific research and industry. Among the frequently used examination method for particle size and distribution is the laser scattering, but now silicon photocell and photodiode whose outputs are unstable analog signals and are normally used for detectors of laser particle analyzer at the market.It's a common trend to use CCD as detector of laser particle analyzer because CCD sensor has high resolution and it outputs the stable digital signal.In this paper, using image processing technique to design detector is presented based on the study of CCD Sensor technology,and realizes a laser particle size analytical system based on scattering theory. The main works completed are as follows:Firstly, by study of Mie theory and the working principle of laser particle size analyzer, the research has analysed a single particle and the particle group scattering intensity distribution. The calculation process of optical energy coefficient matrix is derived.Secondly, the system of laser particle sizer based on CCD sensor technology is researched, which includes optical system as well as image acquisition. The detector of the particle sizer are designed and implemented. The main of idea is to capture light scattering energy of the image adopting CCD, then use image processing techniques to design, and achieve experimental systems of Laser Particle Size Distribution Test.Thirdly,particle size inversion algorithms which are non-independent-mode and independent-mode are researched,and the respective characteristics of them are summarized. It is necessary for the inversion algorithm of non-independent mode to suppose that the particle size distribution model,but in such circumstances, actual particle distribution are not accorded with ideal value, which will lead to considerable error and greatly limit its applications. Inversion algorithm of independent model can calculate any particle size distribution without needing to suppose that the size distribution model, but it easily leads to measurement errors of particle size because that which has bad ability to overcome the noise. In this paper,an amelionated non-mode inversion algorithm is presented based on the study of non-mode data processing algorithm. Then theoretical analysis and experiment demonstration about the performance of the algorithm were carried out.Finally,the experimental tests of standard samples of (1～100)μm are completed after building experimental system and then experimental results are analyzed.By the researches of this thesis, system theoretical analysis and experiment researches on the laser particle size measurement based on Mie theory are completed. Experiment researches show that it is feasible to use CCD as the detector of laser particle analyzer and then use image processing techniques for working with scattering image. It satisfies the requirements of particle size measurement in modern powder industry.