High precision ultrashort pulsed laser drilling of thin metal foils by means of multibeam processing
In the field of micro- and nanostructuring multibeam ultra short pulsed (USP) laser processing attracts increasing attention due to its ability to generate periodic pattern with high throughput. For the generated structures, there is a wide range of applications including e.g. functional or design structures for the automotive industry, consumer electronics or filtration technology. Compared to state-of-the-art single-beam laser drilling by means of pulsed femto- and picosecond laser radiation, the multibeam approach allows for the application of high pulse energies maintaining the surface quality of a typical USP laser process. On the one hand the homogenous distribution of the applied pulse energy across the surface of the processed workpiece by a multitude of beamlets results in a reduced process time and a more economic laser process. On the other hand fundamental aspects of process strategies and thermal management have to be reconsidered. Due to the number (>100) of beamlets focused onto a relatively small scan field area of less than 4x4 mm, the relevance of contamination, microscopic and macroscopic heat accumulation become increasingly relevant. Therefore, specially designed scanning strategies, suction units and additional surface treatments have to be applied to generate hole pattern with packing density of more than 30 percent and reduced surface contamination.