| Stemming from its ability to make quick, automatic, facile, precise and reproduciblemeasurements as well as its adaptability to the on-line measurement and measuringextremely wide dynamic size range of particles presented in various forms, the lightscattering technique is thought much of among the various methods of particle sizinganalysis. It is developed quickly and has become one of the most widely employedmethods in the area of particle sizing, owing to the matured relative technique such asopto-electronic element and computer data-processing. Along with the increasinglyadvancement of technology and persistent development of industrial manufacture, it isdemanded that the lower limit of particle size measured should be extended and theinstrument should be able to measure particles dispersed in extremely broad distribution.Aimed to measure the ultrafine particles, some of the laser particle sizermanufacturers in the world conceive, early or late, to widen the detecting angular range ofthe small-angle forward scattering particle size analyzer and add detecting components atlarge scattering angles. Extreme large angle detectors are employed to detect large-angleforward scattering, side scattering as well as backward scattering (FSBS for short). So it isnamed as entire angular range light scattering technique in this study. Some countries, e.g.England, Japan, America and etc., generated their products in the international market in90's. Nevertheless, as a result of keeping secret, technique on this aspect is rarely reportedin detail and up to now it is beyond our ability to produce this kind of particle sizinganalyzer. Therefore, it is terribly necessary and urgent to start our research work in thisarea to fill up the blankness of our country. The society significance as well as its economyimportance sticks out a mile.In this study, research work is carried through both in theory and in experimentation.In chapter 3, the measuring principle of the small-angle forward scattering particle sizinganalyzer is introduced. The lower limit of particle size measured is discussed, combiningwith its resolving power, difference of patterns of light scattered by particles of differentsizes as well as the apparatus error. And instrumentalities to extend the lower limit areintroduced. In chapter 6, two important factors (i.e. the influence on the final results causedby the misalignment of the forward detector and the input refractive index) of the small-angle forward scattering particle sizing analyzer are discussed in detail by means ofsimulation. In chapter 4, theoretical frames of the entire angular range light scatteringtechnique (FSBS), including two kinds of detecting modes (i.e. to detect the intensity oflight scattered and/or to detect the energy of light scattered), are put forward. Ihe lowerlimit is discussed in the last section of the chapter. Chapter 5 deals with simulations ofFSBS, considering the range of particle size distribution, the partition of particle size, theobjective function of optimizing method as well as the amount of the detectors at largeangles and its location. In chapter 7, the main factors influencing results measured in FSBStechnique is analyzed by means of numerical calculation.Experimental investigation is performed around the topic of extending the lower limitof particle size. In chapter 8, technique based on the anti-Fourier transform has beenexperimented. In chapter 9, experiments worked on FSBS technique are carefully unfolded.Both in chapter 8 and in chapter 9, the influences of sample-pool and decentralizingmedium on the final results are discussed in detail and the necessary modifications areadministered.It is proved in theory as well as in experiment that the lower limit of particle sizemeasured can be extended effectively by widening the detecting angular range and byadding detecting-components at extreme large angles. The measuring principle and thecorresponding experimental investigations are shown to be feasible and coincide with thefinal results. |
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