The output fluence of a high peak power laser like the French laser project 'Laser Megajoule' is strongly related to the damage threshold of mirrors and polarizers consisting of multilayer dielectric coatings. It has been recognized for a long time that growth defects as nodules are playing a significant role in 1.06 micrometers laser damage of these components. In order to determine the critical parameters of the nodule and the associated mechanisms during the laser damage process, we have performed laser irradiation of samples inside the vacuum chamber of a scanning electron microscope (SEM). The SEM allows us to choose a particular area of the sample and to observe it before and after irradiation at a micro size scale. The damage evolution ca be analyzed shot by shot. In this paper, the experimental method is described. SEM pictures of irradiated laser shots are showed. Data about damage mechanisms are derived from these very high resolution morphological observations.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.