Continuous Wave Laser Welding of Copper with Combined Beams at Wavelengths of 1030nm and of 515nm

AbstractThe low absorptivity of ∼1μm laser *beam sources in copper materials is a major challenge. 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 material which leads to an enhanced absorptivity and a lower threshold for deep-penetration welding