Design, alignment and applications of optical systems for parallel processing with ultra-short laser pulses

During the last years, the average power of commercial ultra-short pulsed laser sources increased significantly. The efficient utilization of the high average laser power in the field of material processing requires an effective distribution of the laser power onto the work piece. One approach to increase the efficiency is the application of beam splitting devices to enable parallel processing. But the shaping and steering of multiple beams requires particular optical systems which are not state of the art today. Limitations for large spot arrays are evaluated and considered for the design concept of appropriate optical systems. For the purpose of micro structuring with high demands on the spatial accuracy, an optical system based on a diffractive 14×14 beam splitter (DOE) is designed and set up. All partial beams are coupled into a scanner device by using a relay lens system. Furthermore, this relay lens system offers a practicable solution to remove higher diffraction orders of the DOE. Due to the scanner a highly dynamic, simultaneous deflection of all partial laser beams can be achieved. For the alignment and the experimental evaluation of the complex optical system appropriate measurement devices are necessary. The simultaneous determination of several spot positions is realized by a camera system and adapted evaluation software. First experiments of large-area processing metal foils show promising results.