I. MECHANISM It is relatively easy to focus the beam from an industrial laser to a submillimeter diameter on a metal surface. With laser outputs in the kilowatt range, the resulting irradiance melts the workpiece in a few microseconds. When the beam is shut off or travels away from the heated area, the molten material solidifies, forming a weld. Lasers and beam delivery systems for welding are very similar to those used for cutting or drilling because the power density requirements are similar. In fact, some systems can do all of these processes with only a change in assist gas, focal point, or pulse cycle.