Lehrstuhl für Fertigungstechnologie, Universität Erlangen-Nürnberg

Quality Control Loop to the focus position of CO2 High Power Lasers for Laser Beam Welding using Adaptive Optics

Datum: 09.12.1997



  • Prof. Dr.-Ing. Dr. h.c. M. Geiger
  • Prof. Dr. rer. nat. J. Christiansen, Erlangen

The objective of this project was the development of a control system for the process optimized adaption of the focus position at laser beam welding as well as the proof of its practicability within a commercial laser system. By means of the applied opto-mechanical component, the adaptive optics, highly dynamic alterations of the focus position axial to the work piece surface have been realized, a correlation with the plasma signal found, and an innovative control strategy developed for the first time. The focus position as the controlled variable is calculated from the plasma signal and put at disposal to the manipulator. The strong plasma fluctuation and the complex influence of the process parameters at laser beam welding necessitate the novel control principle, which allows a reliable extraction of the focus position. This control principle bases on an on-line focus position sensor which guarantees a robust control by means of a high dynamic of the manipulator and the processing of the modulation of the plasma signal.