Measurement of particle size and refractive index based on interferometric particle imaging

Abstract

The interferometric particle imaging (IPI) technique makes use of the angular oscillations of scattered light for droplet or bubble sizing. The out-of-focus image of the scattered light consists of fringes, the spacing of which reflects the interference between the surface-reflected light and the first-order refracted light. In this work, a method is presented for measuring both the refractive index and the size of a particle simultaneously with the IPI technique which employs two CCD cameras located at different scattering angles in the forward direction. The refractive index is evaluated by comparing the fringe spacings of the interferogram images and the particle diameter is extracted from either of the interferogram images with a combination of the measured refractive index. The method is validated by the measurements of water droplet and glycerol droplet suspended in air.A method is presented for measuring both the refractive index and the size of a particle simultaneously with the IPI technique which employs two CCD cameras located at different scattering angles in the forward direction. The refractive index is evaluated by comparing the fringe spacings of the interferogram images and the particle diameter is extracted from either of the interferogram images with a combination of the measured refractive index. The method is validated by the measurements of water droplet and glycerol droplet suspended in air.