Actively shifting the beam focus on the workpiece is another method to increase the usable feed rate during laser beam cutting of thick sheet metal. During laser beam welding, it can also enable better weld seam quality and process stability. PI developed a piezo-based, high-dynamics Z axis focus shifter module in cooperation with the Fraunhofer IOF, the Fraunhofer IWS, and the industrial partners Kjellberg Finsterwalde, Heliatek and Optics Balzers. The module can be combined with conventional methods and also 2-D beam manipulation in the XY machining plane, adding highly dynamic Z-axis focus manipulation capabilities in the direction of the beam axis, increasing the machining speed while improving the quality as well.
The design features an elliptical aspheric mirror membrane to avoid imaging errors and maximize the beam aperture. The dielectric coating provides high reflectivity.