Development of Dynamic Light Scattering Method using Radiation Pressure-Induced Motion of Particles in Suspension

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The dynamics of particles in suspension under the laser radiation pressure and the spatiotemporal properties of the light scattered from these particles have been analyzed theoretically and experimentally for investigating an applicability of the laser radiation pressure as a tool to accurately extract information of the static and dynamic structures of particles in suspension. The statistical properties of coherent light multiply scattered backward by the highly concentrated system of particles have also been investigated theoretically and experimentally. The main results are summarized in the following :1. Suppression of the Brownian motion of particles : Suppression of the Brownian motion of particles in suspension due to a gradient force component of the radiation pressure is found to have the particle-size dependence. This dependence on the particles size is also found as an increase of the correlation time of corresponding temporal fluctuations of the scattered light. A new conce … More pt of the dynamic light scattering method using the radiation pressure of laser light has been proposed for sizing the particles accurately.2. Translational motion of particles : Size-dependence of the velocity of the translational motion of particles in the beam-propagation direction due to the scattering force component of the radiation pressure has been revealed. It is also found that the spatial distribution of the velocity is strongly dependent on the particle size, especially for particles in the Mie scattering regime. A new technique for the particle sizing was proposed which utilizes the radiation-pressure induced motion of particles in suspension.3. Spatiotemporal properties of enhanced backscattering of light : It has been found theoretically and experimentally that the size of particles in suspension and the polarization derection of scattered light strongly influence the shape and peak value of the enhanced backscattering peak and the temporal behavior of the backscattered light. It has been revealed that these effects can be described by the optical-path distribution of the scattered light in the medium. Less