Ultra-fast laser machining of stainless steel

Ultra-fast laser machining is emerging as an effective tool for modifying surface morphology in many technological fields. The process entails laser ablation, which in turn involves complex interplay between phenomena pertaining to laser matter interaction, thermo-physical effects, ionisation and material expansion, amongst others. In addition, the transient formation of surface plasmon polaritons and subsequent interaction with the impinging radiation can lead to quasi-periodic surface structures, in particular when metals or semiconductors are used. In the present paper, stainless steel is machined with the goal of producing smooth surfaces. Nonetheless, as demonstrated by highly sensitive scanning probe surface diagnostics, texturing is achieved at multiple length scales. Mechanisms leading to the observed surface features are proposed and the relationship with process parameters briefly discussed.