Advanced remote laser cutting of battery foils using an interference approach

This work demonstrates how an interference pattern can improve the performance of remote laser cutting of pure copper foils, making the cutting process effective even for a low power laser source. The proof of concept is carried out by using a nanosecond laser source with a pulse duration of 5 ns, coupled with a two-beam scanning interference setup, producing a spatial period of 12.5 µm. In the experiments, processing parameters as pulse-to-pulse distance, laser power and scanning speed are varied, to optimize the foil breakthrough and their effect on the generated material modifications are investigated. A comparison between the processing results employing the interference pattern and single beam with a Gaussian energy distribution is carried out. While the single beam process is not sufficient for cutting a 10 µm thin metallic foil, the interference treatment shows an improvement over 100%. In addition, only small spatter formations are detected, with average particle sizes of 1.75 ± 0.82 µm on the top side of the foil. The bottom side of a fully separated copper foil only depicts small spatter formations of less than 1 µm.