Evaluation of the beam wondering in free space optics by image analysis

This paper proposes a simple method to determine the laser beam wandering and scattering in free space optics. The main application of this method is to determine the dimensions of a device required to compensate for beam wandering and scattering due to the air turbulences in FSO communications. The method uses color image analysis for automatic determination of the shape of the laser spot, which provides information about the spot area and the maximum amplitude of beam wandering. Results show that when the spot is photographed on a non-colored paper screen, the method is able to determine the laser spot shape accurately. Moreover, the method is robust to the variation of the screen background illumination.