The invention relates to a method for annealing the surface of a substrate having a coating, said method comprising: moving the substrate (1) supporting the coating to be annealed (2) under a flash lamp (4), the surface of the substrate (1) supporting said coating (2) being turned towards the flash lamp (4); and irradiating the coating to be annealed by the intense pulsed light emitted by the flash lamp (4) through a mask (3) located between the flash lamp and the coating to be annealed and including a slot with a longitudinal axis which is perpendicular to the direction of travel of the substrate, the frequency of the flash lamp and the speed of travel of the substrate being adjusted such that each point of the coating to be annealed receives at least one light pulse, characterised in that the distance between the lower surface of the mask and the surface of the coating to be annealed is no less than 1 mm, and in that the shape and the size of the slot are such that the mask conceals the coating to be anneal
