fragment (input image) temperature changes at 60 s from treatment conclusion. Apex values represent temperatures higher than those before treatment, while valleys show lower temperatures, respectively. In order to avoid pulse stacking, it is important to know the structure of the beam of a typical CO2 laser. Since the distribution of fluences within the laser beam is Gaussian, or bell-shaped, there is a significant difference in ablative depths between the center and the edges of the beam. This may result apparent differences in the distribution of heat on the surface of the skin.