Fabrication of hierarchical surface textures using multi-pulse direct laser interference patterning with nanosecond pulses

In this study, we report on the one-step fabrication of hierarchical microstructures on stainless steel substrates using multi-pulse Direct Laser Interference Patterning. The complex structures are produced using a two-beam interference setup with nanosecond laser pulses. The effect of laser fluence and number of pulses on the formation of multi-scale microstructures is systematically investigated. The resulting surface structures are characterized by scanning electron microscopy and white light interference microscopy. It was observed that at low laser fluence, the periodic microstructures remain defined and grow in height above the initial surface, independent on the number of pulses. For higher laser fluences as well as larger number of pulses, the structures adopt a crater-like morphology including a periodic line-like structure.