Research On Light Scattering Techniques Of Ultrafine Particle Size Measurement

The particle problem involves every trade of the national economy, and theparticles' size and distribution widely affect the industry production, environmentalprotection and the human body health. So the techniques of particle size analysis havegotten researchers' attention greatly and increasingly. Stemming from its ability tomake quick, automatic, facile, and precise measurements as well as its adaptability tothe on-line measurement and measuring extremely wide dynamic size range ofparticles presented in various forms, the light scattering technique is thought much ofamong the various methods of particle size analysis. The measurement method bylight scattering is widely used and prospective.Along with the progress of science and industry production, the particle has thetrend of getting smaller and smaller. The measurement of ultrafine particle, whichdiameter is under 1 micron, is greatly wanted.In this thesis we investigate the light scattering techniques of ultrafine particle sizemeasurement. The main contents include:1. The Mie theory and its calculation methods. We introduce the expressions ofclassical Mie theory, and analyze the calculation algorithm for the intensityscattered by particle. The different approximate expressions for particles withdifferent sizes are provided.2. The development of a particle counter based on principle of light scattering.The portable particle counter is based on the light scattering technique, whichmeasurement range is 0.3~5.0μm. It can detect the clean room (area) withcleanliness class from 100000 to 10. The counter includes a right-angle opticalsystem, electric circuit control system and gas flow channel. It adopts anadvanced microbridge mass airflow sensor as flowmeter which can accuratelycontrol the sampling of air.3. The set up of micro particle measurement system. The Mie theory is socomplicated that there are different approximate methods to measure differentparticles. Thus the instruments only base on light scattering theory always havecertain measurement range and application conditions. In order to research thetechnique of wide range measurement, for ultrafine particles and microparticles, we set up a micro particle analysis and measurement system. Themeasuring method of several sensing techniques' is discussed, which is basedon light scattering theory. The other sensing techniques include micro precisionimaging, flow field and optical flow analysis. An experimentation system isdesigned, in which we put forward a kind of light gathering structure of fiberarray.