Optics and Photonics Society of Iran

Finding dynamical characteristics of a single particle has an especial importance in the area of soft and biological physics. This work introduces a new experimental method to track a spherical colloidal particle in three dimension by applying optical microscopy. The work is based on applying image processing methods and using the obtained relative phase from transport of intensity equation (TIE). We applied our method to study a single micron-sized spherical particles floating in the fluid. At first step, we found the coordinates of the particle in three dimension, then we obtained the sedimentation velocity and diffusion coefficients using the experimental data. Comparing the experimental results with theoretical one showed a good coincidence between them.