DOI: 10.1002/adem.201600173 High-Speed Surface Structuring of Polycarbonate Using Direct Laser Interference Patterning: Toward 1 m 2 min 1 Fabrication Speed Barrier** By Valentin Lang,* Teja Roch and Andr  es Fabi  an Lasagni Periodic structures with micro- or sub-micrometer resolution can be used to improve the mechanical, biological, or optical properties of surfaces. Direct laser interference patterning combines high resolution (sub-micrometer feature sizes) with high fabrication speed. New processing heads for high- speed laser interference patterning of polycarbonate are introduced, which provide effective patterning speeds up to 0.9 m 2 min –1 . The surface topography of the processed polymer is analyzed by confocal microscopy and scanning electron microscopy. Focused ion beam is used to create cross-sections to determine the structuring mechanism. Finally, high-speed interference patterning is compared to conventional direct laser writing. It has been shown in the past that surfaces with controlled topographic characteristics provide enhanced surface prop- erties compared to surfaces with a “random” roughness. [1] These surfaces have generally deterministic periodic surface patterns with feature sizes in the nano-, submicro-, or micrometer range. [2–4] In the last 20 years, a large number of studies have focused on creating surface patterns, which are inspired by nature, in order to improve the surface properties on relevant techno- logical materials. [5–8] Etsion and Burstein showed, for example, the benefits of laser-patterned surfaces on the tribological performance of machine components. [9–11] An- other advantage of submicro- and micrometer-sized patterns was demonstrated by Kurella by investigating an improved functionality and biocompatibility of implants due to laser surface patterning. [12] Blä si et al. verified the promising applicability of nano-patterns as photonic structures in thin films for optical applications, such as organic light-emitting diodes and solar cells. [13–17] In order to fabricate periodic patterns on technical components, different technologies are available. However, the challenge is not just to be capable to produce periodic patterns in the micrometer and sub-micrometer scale but to fabricate them at both low cost and high throughput. [18,19] In Lasagni et al., [20] different mask-less fabrication methods were compared. This comparison focused on typical fabrications speeds (in terms of treated area per unit of time) that can be achieved as function of the size of the features that can be produced (resolution). Technologies like photolithography, direct laser writing, or micro-milling reach relatively low processing speeds (between 0.01 and 200 cm 2 min 1 ) for feature sizes between 0.1 and 100 mm. [21–23] Furthermore, the fabrication speed is inversely proportional to the achievable structure size, i.e., a lower fabrication speed has to be used for smaller structures. Furthermore, lithographic technologies cannot be used on complex geometries, e.g., 3D parts, which strongly limit their applicability for real technological parts. [23] A fabrication method that provides both high resolutions (even below the micrometer scale) and high fabrication speed is direct laser interference patterning (DLIP). [24] This tech- nique allows the processing of different pattern geometries (e.g., line-, dot-, or cross-like pattern) on a wide variety of materials (polymers, metals, and coatings) [25–35] at fabrication speeds up to approximately 0.1 m 2 min 1 . [20] The interference pattern is obtained by overlapping a certain amount of [*] V. Lang, Prof. A. F. Lasagni, Dr. T. Roch Institute of Manufacturing Technology, Technische Universität Dresden, George-Bähr-Straße 3c, 01069 Dresden, Germany Fraunhofer Institute for Material and Beam Technology, Winterbergstraße 28, 01277 Dresden, Germany E-mail: valentin.lang@tu-dresden.de [**] The work of A. Lasagni was supported by the German Research Foundation (DFG), Excellence Initiative by the German federal and state governments to promote top-level research at German universities (Grant No.: F-003661-553-41A-1132104). V. Lang and T. Roch acknowledge the Bundesministerium für Bildung und Forschung (BMBF) for financial support (Verbundförder- projekt “Laser Interference High Speed Surface Functionaliza- tion,” FKZ 13N13113). DOI: 10.1002/adem.201600173 © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim wileyonlinelibrary.com 1 ADVANCED ENGINEERING MATERIALS 2016, COMMUNICATION