Beam Shaping the Direct Laser Interference Patterning Spot

Abstract

Direct Laser Interference Patterning (DLIP) using ultrashort pulsed laser sources is a single-step process to produce micro- and nanostructured surfaces by ablation. Spatial periods of a few micrometers are patterned using a laser scanner system with two interfering beams. In this study, the field of DLIP processing is expanded by handling spatial periods in the range of 1 µm and below. Precise periodic ablation is achieved with an optical setup tailored for a homogenous topography of spatial periods in the micro and sub-micrometer range. The lateral intensity distribution of the interference area used for ablation is shaped using beam shapers in order to achieve a homogenous intensity distribution and hence increase the homogeneity of the periodic texture in the ablated area. The shape of the interference area is formed into a square profile for the purpose of seamless stitching plenty of to be processed areas. This creates large area periodic textures with high homogeneity. Two beams with ultrashort laser pulses of 10 ps duration and a wavelength of 532 nm are used to structure line-like periodic surface textures with spatial periods of 650 nm. The beam shaping elements modify the lateral intensity distribution in the interference area and the affiliated profile. This enables precise patterning of tool steels with spatial periods in sub-micrometer range for applications in the field of life science surfaces.