Periodic Surface Structuring of Copper with Spherical and Cylindrical Lenses

Abstract

The use of a cylindrical lens in femtosecond laser surface structuring is receiving attention to improve the processing efficiency. Here, we investigate the structures produced on a copper target, in air, by exploiting both spherical and cylindrical lenses for beam focusing, aiming at elucidating similarities and differences of the two approaches. The morphological features of the surface structures generated by ≈180 fs laser pulses at 1030 nm over areas of 8 × 8 mm2 were analyzed. For the spherical lens, micron-sized parallel channels are formed on the target surface, which is covered by subwavelength ripples and nanoparticles. Instead, the cylindrical lens leads to a surface decorated with ripples and nanoparticles with a negligible presence of micro-channels. Moreover, the morphological features achieved by focusing ≈180 fs laser pulses at 515 nm with the cylindrical lens and varying the scanning parameters were also studied. The experimental results evidence a direct effect of the hatch distance used in the scanning process on the target surface that contains dark and bright bands corresponding to regions where the rippled surface contains a richer decoration or a negligible redeposition of nanoparticles. Our findings can be of interest in large area surface structuring for the selection of the more appropriate focusing configuration according to the final application of the structured surface.

Femtosecond laser-induced nano- and microstructuring of Cu electrodes for CO2 electroreduction in acetonitrile medium

“…Recently, the fabrication of LIPSS has been tested for secondary electron emission reduction on copper samples using linearly and circularly polarized femtosecond laser pulses, reporting on the influence of the formed surface textures on the secondary electron yield (SEY), thus addressing the possible role on the secondary electron yield of LIPSS on a copper surface with subwavelength-sized features 48 . The use of a cylindrical lens in femtosecond laser surface structuring also received attention, with aim of improving the processing efficiency, suitable for large area processing with circular and elliptical laser beams 49 .…”