A brief review of the existing particle sizing methods is presented. An optical method under development is introduced from the analys is of the polarization ratio of the light scattered by the particles base don Lorenz–Mie theory. The theoretical back ground is summarized with the numerical calculation presented. A photogrammteric system has been set up to perform the measurements. Calibration of the experimental set up has been carried out on polystyrene microspheres of different size. The experimental values of the polarization ratio have been obtained by analyzing the particle images taken by the CCD to render the particle size under investigation. Several experiments and their results are demonstrated to illustrate the application fields of the optical method presented in the current study.