A 2D droplet sizing technique is applied to measure the diameter of droplets present in an engine chamber before the combustion process. This technique is based on the evaluation of the number of fringes due to the interference between the laser light reflected by the droplets and the light refracted. Usually, the collection optics are placed between 30 degrees and 80 degrees of the laser beam. The main interest of this paper is that this technique is applied with a forward-scattering angle range around 90 degrees. So, the evaluation of the droplets diameter from the fringe numbers is more difficult due to the low level of the scattered light and to the quasi non-validity of the geometrical approximations. This technique is applied for a droplet diameter range of 5 micrometers to 50 micrometers . In order to improve this particular application of this droplet sizing technique, the comparison with a calibrated spray is done. Finally, this technique will be used in an optical access internal combustion engine, where the pictures will be taken only via the transparent piston head.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.