Beam engineering for high throughput material processing with high power, femtosecond lasers

Ultra-short pulse laser (UPL) industry is counting on high power P sources (100W class) to increase the throughput of a wide variety of industrial fabrication process. Nevertheless, this poses the challenge to overcome heat accumulation phenomena observed when P exceeds few tens of Watts compromising the machining quality. Novel beam engineering strategies are required to tackle this issue and guarantee high throughput with the high, distinctive, UPL machining quality. Here a study is reported on a variety of laser processes carried out with 100W class femtosecond lasers following two possible beam engineering strategies i.e. beam scanning with high speed (both a 100 m/s polygon scanner head and a 2D, 20 m/s fast, galvo-head) and parallel processing with multiple beams (obtained with both a DOE and an SLM head). Results show that by increasing P from few to 100 W also the throughput increases by nearly a factor 10 for micro-cutting (with galvo head and DOE) and even higher for surface texturing (with polygon scanner) while the machining quality is kept unchanged. Furthermore, we optimised the use of an SLM head for precise micro drilling of matrix holes showing the benefit of this technological approach in term of throughput. A full characterisation of the results carried out via optic and electronic microscopy will be also reported. We believe that all these results further increase the USP laser technology effectiveness level which is primed for industrial applications.