High-speed synchrotron X-ray imaging of micro-hole formation during the ablation of grooves by ultrashort laser pulses

The formation of slits with very high aspect ratios is critical for the production of additively manufactured parts for advanced electric drives. In this work, high-speed synchrotron X-ray imaging is utilized to observe slit/groove formation in stainless steel using ultrashort laser pulses. The results reveal that, under the pulse conditions employed here, a narrow, deep slit or groove can be created by the eventual consolidation of micro-holes which are generated in the early stages of the laser-material interaction. The success or otherwise of this micro-hole consolidation has a complex relationship to the process parameters.