2 kW cw laser in the green wavelength regime for copper welding

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. Careful shaping and stabilization of the polarization and spectral properties leads to an excellent optical-to-optical efficiency (pump to green) above 55%. The beam parameter product is designed and measured to be below 7 mm.mrad which allows the transport with a fiber of 150 mu m core diameter and standard numerical aperture of 0.1. Fiber and beam guidance optics are adapted to the green wavelength, enabling low transmission losses and stable operation. The laser, beam guidance as well as a chiller and the common customer interfaces are packaged within a compact footprint of less than 1 m(2). The green laser is equipped with a wide range of sensors and interfaces, enabling the user to integrate the laser in a production network and to benefit from features such as condition monitoring and predictive maintenance. 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. With the new green 2 kW laser, the welding performance for high quality welds can be increased compared to the already available 1 kW system.