Starting from a simple concept, transferring the shape of an interference pattern directly to the surface of a material, the method of Direct Laser Interference Patterning (DLIP) has been continuously developed in the last 20 years. From lamp-pumped to high power diode-pumped lasers, DLIP permits today for the achievement of impressive processing speeds even close to 1 m2/min. The objective: to improve the performance of surfaces by the use of periodically ordered micro- and nanostructures. This study describes 20 years of evolution of the DLIP method in Germany. From the structuring of thin metallic films to bulk materials using nano- and picosecond laser systems, going through different optical setups and industrial systems which have been recently developed. Several technological applications are discussed and summarized in this article including: surface micro-metallurgy, tribology, electrical connectors, biological interfaces, thin film organic solar cells and electrodes as well as decorative elements and safety features. In all cases, DLIP has not only shown to provide outstanding surface properties but also outstanding economic advantages compared to traditional methods.
Smart surfaces are a source of innovation in the 21st 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 Laser Interference 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 are described.
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 last years, substantial efforts have been made to develop new technologies capable to produce functionalized surfaces. One of these technologies is the Direct Laser Interference Patterning (DLIP) technology, 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 optical 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.
Direct Laser Interference Patterning (DLIP) has shown to be a fabrication technology capable of producing large area periodic surface patterns on almost any kind of material. The produced structures have been used in the past to provide surfaces with new enhanced properties. On the other hand, the industrial use of this technology is still at the beginning due to the lack of appropriate and affordable systems, especially for small and medium enterprises. In this paper, the use of DLIP for the fabrication of periodic structures using different structuring strategies and optical concepts is discussed. Different technological challenges are addressed.
Periodic patterned surfaces can be used to provide unique surface properties in applications, such as biomaterials, surface
engineering, photonics and sensor systems. Such periodic patterns can be produced using laser processing tools, showing
significant advantages due to a precise modification of the surfaces without contamination, remote and contactless
operation, flexibility, and precise energy deposition. On the other hand, the resolution of such laser based surface
structuring methods, like direct laser writing, is generally inversely proportional to the fabrication speed. Therefore, the
development of new laser structuring technologies as well as strategies offering both high speed and resolution is
necessary. In this study, the fabrication of spatially ordered structures with micrometer and submicrometer lengthscales
at high surface processing fabrication speed is demonstrated. The procedures shown here are applied to process both
planar surfaces and also three dimensional components. Different application examples of structured surfaces on
different materials are also described. The applications include the development of thin film structured electrodes to
improve the efficiency of organic light emitting diodes (OLEDs) as well as the direct fabrication of decorative elements
on technological steels. Finally, an example of fabrication at high fabrication speed is shown.
Periodic patterned surfaces do not merely provide unique properties, but act as intelligent surfaces capable of selectively
influencing multiple functionalities. One of the most recent technologies allowing fabrication of periodic arrays within
the micro- and submicrometer scales is Direct Laser Interference Patterning (DLIP). The method permits the direct
treatment of the material's surface based on locally induced photothermal or photochemical processes. Furthermore,
DLIP is particularly suited to fabricate periodic patterns on planar and non-planar surfaces offering a route to large-scale
production. In this paper, the fabrication of spatially ordered structures on different materials such as polymers, metals
and diamond like carbon films is discussed. Several application examples as function of the processed material are
introduced, including bio functional surfaces for cell guidance on polymers, wear resistant properties for structured
diamond carbon like coatings and metals, as well as micro-patterned flexible polymers with controlled optical properties.
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