Picosecond laser drilling grids in aluminium foil at 532 and 355 nm wavelengths

Abstract

Abstract Ultra-short laser drilling technique enables production of filters, membranes, microfluidic, photonic, and biomedical devices. Micro-hole grids were drilled in aluminum foil using a 28 picosecond Nd:YAG laser operated at wavelength of 532 and 355 nm with energy up to 18 and 12 mJ, respectively. Varying pulse energy and number, micro-holes obtained at 355 nm and 3.6–9 mJ had the appropriate mean diameter of 36–86 μm. However, the circularity changed in 0.5–0.94. For the 2nd harmonic the mean diameter varied 15–61 μm at 0.36–9 mJ with the circularity of 0.81–0.92. The morphology of the area surrounding micro-holes investigated by scanning electron microscopy exhibited distribution of droplets dominated size 0.9–10 μm, which is feasible for filtration of contaminated liquids. Local elemental composition of the area determined by energy dispersive spectroscopy discovered significant increase in the concentration of C and O, and also emergency of F, depending on laser fluence under vapor-dominated ablation mode, where nuclear reactions are excited in hot plasma.