New, Fast, Galvo Scanner Head for High Throughput Micromachining

Femtosecond lasers have been proved to be an effective fabrication tool to process with high machining quality and negligible thermal effects a wide variety of materials. However, the system technology enabling fast and precise scanning on the workpiece, currently limits the average power of these laser sources to less than 10 Watts of average power in most industrial application. To overcome this limitation, a proportional up-scaling of both, the laser repetition rate and scan speed is needed, demanding for faster scanning technologies. Recently, rugged, femtosecond lasers delivering pulses with repetition rates of several MHz and pulse energy up to some hundreds of mu J have been introduced to the market. In parallel, the development and commercialization of novel galvanometric scanner heads, enabling scan speeds well above 10 m/s is ongoing. Here we explored the capabilities of a novel set-up consisting of an industrial femtosecond laser delivering 100 W with a repetition rate up to 13 MHz coupled with an innovative galvanometric scanner head enabling scan speeds up to 30 m.s(-1). On stainless steel, we carried out engraving tests with both single line grooving and multiple surface raster scanning. By systematic variation of repetition rate and pules overlap we investigate how the machining quality and the ablation rate depend on the average laser power at different fluence levels. Heat accumulation effects are evaluated via Scanning Electron Microscope. Finally, we show how to scale-up the cutting of a 500 mu m thick stainless-steel part varying the scan speed from 1 m.s(-1) to 20 m.s(-1).