Fabrication of hierarchical micro patterns on PET substrates using direct laser interference patterningTuesday (27.09.2016) 14:45 - 15:00 Part of:
Hierarchical microstructured surfaces offer benefits compared to single-scale micro-patterns in terms of improved surface functionalities as well as a combination of advanced surface properties. In this study, the fabrication of hierarchical three-level length-scales microstructures on polyethylene terephthalate (PET) substrates is demonstrated using direct laser interference patterning. The first level pattern is produced by two-beam laser interference creating a periodic array with 10 µm spatial period using a ultraviolet (266 nm) nanosecond pulsed Nd:YAG laser. Afterwards, the 2nd and 3rd level patterns are fabricated also using direct laser interference patterning (at 263 nm wavelength) but with a pixel-wise patterning configuration. In this way, the 2nd level pattern results from the periodic variation of the laser intensity within a holographic pixel (with spatial periods between 1 and 2 µm) while the size of the 3rd level pattern is related to the distance between the individual holographic pixels (35 µm). The effect of the laser fluence on the structure quality and depth for all hierarchical levels is investigated. Finally, optical properties of the produced multiscale patterns are determined and compared to numerical calculations.