Deep penetration welding at∼ 1μm is only possible with brilliant lasers providing high
power and small focus diameters. The absorptivity increases with shorter wavelengths and
higher temperature of the surface of the specimen. To exploit these facts, a 1μm and a
frequency doubled thindisk laser were combined. The precursory green laser beam is used
to heat up the surface. Under these conditions the IR-beam interacts with the preheated …