Annealing method using flash lamps

A process for annealing a surface of a substrate bearing a coating, said process comprising:

• running the substrate bearing the coating to be annealed under a flash lamp emitting intense pulsed light, the surface of the substrate that bears said coating being turned toward the flash lamp;
• and
• irradiating the coating to be annealed with the intense pulsed light emitted by the flash lamp through a mask located, in a fixed position relative to the flash lamp, between the flash lamp and the coating to be annealed and comprising a slit, a longitudinal axis of the slit being perpendicular to a run direction of the substrate, a frequency of the flash lamp and a run speed of the substrate being adjusted so that each point of the coating to be annealed receives at least one light pulse,
• wherein
• a distance between a lower face of the mask and the surface of the coating to be annealed is at most equal to 1 mm, and
• a shape and extent of the slit are such that the mask occults the coating to be annealed in all zones where the light intensity that, in an absence of the mask, would arrive at the coating to be annealed is lower than a threshold light intensity called a nominal light intensity.

An apparatus for annealing a surface of a substrate bearing a coating, comprising:

• a flash lamp configured to emit intense pulsed light;
• conveying means for running a flat substrate bearing the coating to be annealed in front of the flash lamp;
• a mask located, in a fixed position relative to the flash lamp, between the flash lamp and the conveying means, said mask comprising a slit, a longitudinal axis of the slit being perpendicular to a run direction of the substrate, and the slit being positioned so that the light emitted by the flash lamp is projected through the slit in a direction of the flat substrate bearing the coating to be annealed;
• and
• means for adjusting a distance between the mask and the conveying means such that a distance between a lower face of the mask and the surface of the coating to be annealed is adjustable to a value lower than 1 mm.