Layered Ripples Covered Pyramidal Structures Formed on 316L Stainless Steel by Femtosecond Laser Processing

The formation of layered ripples covered pyramid structure is reported on 316L stainless steel surface with femtosecond laser pulses in this paper. These unique structures form though a combination of preferential ablation of flat regions around the pyramids and extension of layered ripples created during the ablation process. The cause of the formation about these structure is investigated using multi-means and the results show that these structures are derived from an inhomogeneous distribution of laser fluence, which is caused through a combination of the redeposition of nanoparticles and the local oxidation as well as the geometric factors.