Fabrication of Rectangular Micro-Channels by Ultrashort Pulse Ablation Using a Bessel Beam

This paper reports on combining non-diffracting Bessel beams and ultra-short pulsed laser abla-tion for the generation of micro-channels. The small focal spot and the long focus depth make Bes-sel beams suitable as an ideal tool for fabricating sharp-edged channels. In this context, we present a study on the generation of rectangular micro-channels that are highly interesting for future investi-gations on material properties of additive manufactured and cast aluminum samples, e.g., using them as initial notches or defects, respectively, for fatigue and damage tolerance assessment. In or-der to achieve the highest quality of rectangular microchannels, optimal processing conditions were achieved by analyzing the influence of the laser power, the number of exposure cycles, and the axial position of the sample on the ablation process. Similar experiments using a Gaussian Beam were performed to compare the different beam shapes regarding the resulting channel geometry and abla-tion efficiency. Nevertheless, the walls of the Bessel beam processed channels are almost perpen-dicular to the surface and the bottom of the channel is almost flat. Thus, the Bessel beam generated micro-channels are more rectangular than the ones processed with the Gaussian beam.

Automated summary

This study reports on the combination of non-diffracting Bessel beams and ultra-short pulsed laser ablation for generating micro-channels, analyzing optimal processing conditions by investigating laser power, exposure cycles, and sample axial position. Compared to Gaussian Beam processing, channels processed with Bessel beams exhibit more rectangular geometry.