Simulation And Experiment On Sizing Of Micrometer-Scale Particles Based On Mie's Light Scattering Theory

Particle size measurement is of great significance in both research and industry.To that end, light scattering has been well established to be the most advanced andpromising approach in this category, due to its many advantages over other methods.In 1908, German scientist Gustav Mie formed the well-celebrated ansantz forlight scattering by small spherical particles, which lays the mathematical foundationfor numerous modern laser scattering instruments. It has since been exploited bymany sizers commercially available nowadays.The main work of the present dissertation is classified as theoretical studies,numerical simulation and experimental investigation, which are numerated as follows:I. History, status quo and vendors of sizers based upon light scattering bothdomestic and abroad were surveyed.II. For Mie formalism, derivation process and procedures for performingnumerical computation pertaining to light scattering based on full Mietheory were edified. Extensive computer experiments were exercised ofangular distributions of light scattering curves for monodisperse andparticle potpourri scattering systems.III. An optimization algorithm, the simplex method, was tested onmulti-disperse particles. Through detailed analysis, this approach wasshown to be slow in time and inaccurate, and was henceforth discarded.IV. Inspired by the so-called Phillips-Twomey algorithm known in particlesize retrieval, we used a similar matrix alternative to re-gain informationof particle diameters for RR distribution. It is straightforward togeneralize this method to any parameter-dependent particle sizing models.V. Intrinsically novel with the present setup, a linear CCD array and asolid-state green laser are employed to replace the conventional concentricsemi-ring detector and the large-chassis He-Ne laser, respectively. Thishelps achieve the compactness for the whole instrument.VI. The feasibility of our sizer was confirmed by measuring the refractiveindex of polystyrene beads provided by the State Center for StandardSubstances of PR China. A value of n=1.6 bestows upon important opticalparameters for the plastic beads. The successful size retrieval for beads ofnominal diameters of 4.91 and 9.88 micrometers corroborated itsrobustness.