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

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 μ m. However, the circularity changed in 0.5–0.94. For the 2nd harmonic the mean diameter varied 15–61 μ m 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 μ m, 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.

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