Two-beam interference patterning of biodegradable magnesium alloy: Influence of number of passes and spots overlap

Laser based texturing methods provide enhanced surface properties exploitable, especially in biomedical applications. Direct writing methods allow for processing features in tens of micrometers in size due to the use of diffraction limited beams. Feature size can be further reduced exploiting the light interference combined with the pulsed laser ablation. In this work, an industrial grade single mode nanosecond-pulsed green fiber laser was used to realize two-beam direct laser interference patterning system. The system was employed on a biodegradable Mg alloy to test the feasibility of the approach for submicrometric patterning. The combination of low melting point and high thermal conductivity of Mg alloy with the use nanosecond pulses generates difficulties in terms of the machining quality. The influence of number of pulses and number of passes was evaluated on the patterned area diameter as well as the pattern periodicity. Finally, patterned regions were overlapped on a scanned line to assess the feasibility of the process on larger areas.