Low-coherence Dynamic Light Scattering Measurement Of Particle Size And Size Distribution In Suspension,

With the development of technology, the application of particle in industrial production becomes more and more widely. The research about particles properties, especially particle size and particle size distribution is significant. Many particle measurement methods and instruments have been developed, light scattering measurement is widely developed and applied due to its unique advantages.Light scattering can be divided into static light scattering and dynamic light scattering according to the different principles. Dynamic light scattering can characterize the dynamical properties and particle size by measuring fluctuations of the scattered light intensity. In this paper, we use low-coherence interferometer combining with traditional dynamic light scattering techniques and propose a low-coherence dynamic light scattering method to measure the particle's dynamic properties, further-broadening the application of dynamic light scattering. This method can effectively suppress the effects of multiple scattering in dense suspension. Using single scattering as the basis theory, we can obtain the particle size and size distribution from the detected scattered light signals.In this paper, the basic principle of dynamic light scattering and the low-coherence dynamic light scattering system were introduced; Theoretically discuss the wall drag effect near to the solid-liquid interface. Use the established phase modulated low-coherence dynamic light scattering system to measure particle size in suspension and discuss the influence of solid-liquid interface wall-drag effect on the measurement of particle size by dynamic light scattering. Use the suspensions of 10vol.% polystyrene latex with different particle radii as the samples, the results are corrected by considering the wall drag effect. It was found that using phase modulated low-coherence dynamic light scattering measure particle can obtain the accurate information of particle size. At last, using phase modulated low-coherence dynamic light scattering method to measure the particle size and particle size distribution in colloidal suspensions with different volume fraction, we also explored the applications with different volume in this way.