3D particle positioning from CCD images using the generalized Lorenz–Mie and Huygens–Fresnel theories

Abstract

3D spherical particle positioning is found by using a defocusing method that consists in measuring the central spot size of an experimental image from a particle and comparing its nearest value with a numerically calculated central spot size matrix array. The numerical calculations were carried out using the generalized Lorenz–Mie and the Huygens–Fresnel diffraction theories. On comparison, the experimental results are in good agreement with the predictions made with the numerical calculations and an error analysis is presented.