We report on industrial high-power lasers in the green wavelength regime. By means of a thin disk oscillator and a resonator-internal nonlinear crystal for second harmonic generation we provide 2000 W continuous-wave laser radiation at a wavelength of 515 nm, transported by a fiber with a 150 µm core diameter and NA 0.1. Application tests show that this laser is perfectly suited for copper welding due to the superior absorption of the green wavelength compared to IR, which allows the production of spatter-free weld spots and seams with an unprecedented reproducibility in diameter and welding depth. Now with 2 kW available power in the green, the welding performance for high quality welds can be increased compared to the already available 1 kW green laser system. The higher power leads to a larger melt volume and higher process efficiency. It is also possible to weld other materials with high quality results, for example stainless steel or aluminum. A particular advantage compared to the common IR lasers is the ability of the green laser for heat conduction mode because of the higher absorption. But due to the high beam quality also high-quality deep penetration welding is applicable, with the comfort to use scanner optics with a big field of work. This offers a whole range of new applications, e.g. remotedeburring of copper parts or producing a shiny copper surface by using shielding gas in addition. A further significant benefit of the green wavelength is that the surface condition does not influence the welding process, which allows to skip many expensive preprocessing steps such as tin-coating. Especially for e-mobility tasks the green 2 kW laser source is a suitable option for increasing productivity and quality: One example are copper foil stacks for battery production, which can be welded with higher speed and reduced spatter formation without ultrasonic pre-welding.
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