Investigation of the nanoscale material behaviour during the forming of metallic materials using embossing and ruling kinematics to produce optically functional microstructures

• Applicant: Professor Dr.-Ing. Dirk Oberschmidt
• Subject Area: Primary Shaping and Reshaping Technology, Additive Manufacturing
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 440840282

The aim of the entire project is the fundamental investigation of mechanisms for the production of large-area micro-optical structures with high structure density in metals by shaping the near-surface region. The dimensions of micro-optics are only a few orders of magnitude above or even below the application wavelength. Accuracy requirements can extend into the nanometer range. As optical arrays, micro-optics are used in honeycomb capacitors, for beam homogenization in laser systems, as exposure equipment and for light guiding in the display technology. Economical production is achieved by replication in plastics and glasses using injection molding or embossing processes with thermal support if necessary. In the production of master structures, lithographic and machining processes (ultra-precision machining) compete. The production of optical structures in molding tools by means of ultra-precision machining is a single-item process and requires considerable effort in terms of manufacturing time and machine requirements. The effort increases when arrays or large-area diffractive optics are manufactured. The possibility of producing ultra-precise optical structures in metallic surfaces by means of shaping would through simplifying the kinematic effort of machine tools also significantly reduce the manufacturing time. The project focuses on deepening the understanding of the technological limitations of creating blaze gratings and lens master arrays using micro-forming. Profile quality and roughness must be subject to tight limits, even for dense micro-forming, to enable applications for wavelengths in the visible range or lower. Therefore, for fabrication processes of micro-optical arrays and diffraction gratings, a fundamental understanding will be explored as a basis for optimizing processing parameters to produce patterned surfaces with high structure density. The following research questions are addressed: • How can defects of ruled gratings such as over- and under-displacement be reduced? What influence do process parameters have on defects? • How do lens master structures affect each other by reducing their spacing? • What embossing strategy can be used to achieve an increase in structure density? • What are the optical properties of formed diffraction gratings and micro-lens arrays? The project explores the understanding of micro-forming of metallic materials, which helps to increase the quality of formed diffraction gratings and micro-lens arrays.

• DFG Programme: Research Grants