Abstract
Controlling laser induced surface morphology is essential for developing specialized functional surfaces. This work presents novel, multi-scale periodic patterns with two-dimensional symmetry generated on stainless steel, polyimide and sapphire. The microstructures were realized by combining Direct Laser Interference Patterning with the generation of Laser Induced Periodic Surface Structures in a one-step process. An industrial, fiber femtosecond laser source emitting at 1030 nm with a pulse duration of 500 fs was utilized for the experiments. In the case of stainless steel, it was possible to create line-like or pillar-like surface patterns by rotating the polarization orientation with respect to the interference pattern. In the case of polyimide and sapphire, the absorption of the laser radiation was promoted by a multiphoton mechanism. In polyimide, grooves and pillars of several microns in depth were produced over an area much larger than the spot size. Finally, for sapphire, the simultaneous generation of interference-like pattern and laser induced periodic surface structures was realized. The results reported here provide valuable data on the feasibility to combine two state-of-the-art techniques with an industrial apparatus, to control the induced surface morphology.
Highlights
In the last decades, several aspects have increased the interest in ultrashort-pulsed laser (USP)material processing [1]
We investigate the super-positioning of direct laser interference patterning (DLIP) and laser induced periodic surface structures (LIPSS) methods to generate repetitive surface structures on stainless steel, polyimide and sapphire
The chosen spatial period for DLIP was selected to be comparable with the employed laser wavelength
Summary
Several aspects have increased the interest in ultrashort-pulsed laser (USP). Feature sizes are becoming smaller, which demands advanced USP laser processes for precise material machining and manipulation [2]. Several applications employing USP lasers have been established in the area of surface functionalization. Precise laser machining methods have been utilized to produce structural colors [3,4], to control the surface wettability [5], to achieve directional water transport [6] as well as to tune the adhesion of cells and bacteria for biomedical applications [7,8], and to control surface friction and wear properties [9,10,11,12,13]. Several examples in nature have shown that even better performances can be obtained combining surface features with different length-scales, e.g., by producing nanostructures on top of micro features (hierarchical surface patterns) [14].
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