Direct Laser Interference Structuring (DLIP) is a manufacturing technology capable to functionalize large areas with high-precision periodic patterns. However, for industrial use of this emerging technology, solutions must be developed for specific requirements. With the objective of optimizing Direct Laser Interference Patterning in terms of process speed, an advanced optical module was developed that permits to superimpose two laser beams obtaining the interference pattern within an elongated area (linear spot) to meet the requirements of high-speed processing. After that, the influence of the process parameters on the quality of the surface patterns produced with the developed optical assembly was determined. It could be shown that the pulse overlap, in contrast to the applied average fluence, has a significant influence on the resulting structure heights of the produced patterns. Furthermore, it became apparent that during the course of the process, the underlying physical process dynamics seem to change, which was indicated by the resulting structure heights variations over the process. The gained findings will make a contribution to improving the quality of surface patterns produced with DLIP and to enabling reliable manufacturing qualities in the future.

Smart surfaces are a source of innovation in the 21^st Century. Potential applications can be found in a wide range of fields where improved optical, mechanical or biological properties can enhance the functions of products. In the last years, a method called Direct LaserInterference Patterning (DLIP) has demonstrated to be capable of fabricating a wide range of periodic surface patterns even with resolution at the nanometer and sub-micrometer scales. This article describes recent advances of the DLIP method to process 2D and 3D parts. Firstly, the possibility to fabricate periodic arrays on metallic substrates with sub-micrometer resolution is shown. After that, different concepts to process three dimensional parts are shown, including the use of Cartesian translational stages as well as an industrial robot arm. Finally, some application examples aredescribed.

Periodic surfaces structures with micrometer or submicrometer resolution produced on the surface of components can be used to improve their mechanical, biological or optical properties. In particular, these surfaces can control the tribological performance of parts, for instance in the automotive industry. In the recent years, substantial efforts have been made to develop new technologies capable to produce functionalized surfaces. One of these technologies is Direct Laser Interference Patterning (DLIP), which permits to combine high fabrication speed with high resolution even in the sub-micrometer range. In DLIP, a laser beam is split into two or more coherent beams which are guided to interfere on the work piece surface. This causes modulated laser intensities over the component’s surface, enabling the direct fabrication of a periodic pattern based on selective laser ablation or melting. Depending on the angle between the laser beams and the wavelength of the laser, the pattern’s spatial period can be perfectly controlled. In this study, we introduce new modular DLIP processing heads, developed at the Fraunhofer IWS and the Technische Universität Dresden for high speed surface laser patterning of polymers and metals. For the first time it is shown that effective patterning speeds of up to 0.90 m2/min and 0.36 m²/min are possible on polymer and metals, respectively. Line- and dot-like surface architectures with spatial periods between 7 μm and 22 μm are shown.

Surfaces equipped with periodic patterns with feature sizes in the micrometer, submicrometer and nanometer range present outstanding surface properties. Many of these surfaces can be found on different plants and animals. However, there are few methods capable to produce such patterns in a one-step process on relevant technological materials. Direct laser interference patterning (DLIP) provides both high resolution as well as high throughput. Recently, fabrication rates up to 1 m²·min-1 could be achieved. However, resolution was limited to a few micrometers due to typical thermal effects that arise when nanosecond pulsed laser systems are used. Therefore, this study introduces an alternative to ns-DLIP for the fabrication of multi-scaled micrometer and submicrometer structures on nickel surfaces using picosecond pulses (10 ps at a wavelength of 1064 nm). Due to the nature of the interaction process of the metallic surfaces with the ultrashort laser pulses, it was not only possible to directly transfer the shape of the interference pattern intensity distribution to the material (with spatial periods ranging from 1.5 μm to 5.7 μm), but also to selectively obtain laser induce periodic surface structures with feature sizes in the submicrometer and nanometer range. Finally, the structured nickel sleeves are utilized in a roll-to-roll hot embossing unit for structuring of polymer foils. Processing speeds up to 25 m·min-1 are reported.