Fast tool machining and hot embossing for the manufacture of diffractive structured surfaces

Nowadays, highly functional optical elements are part of day-to-day use by most of us, whether in form of camera systems in mobile phones or as security features on banknotes and identification documents. The conventional production of diffractive optical elements is mainly covered by lithographic processes. Nevertheless, due to long production times, this process is very expensive when it comes to mass production and the structuring of large areas. For this reason, a novel manufacturing process for structured moulds was developed by the Leibniz Institute for Materials Engineering (IWT). This involves a diamond turning process in combination with a high frequency nano Fast Tool Servo (nFTS) to generate the negative diffractive structure on a metal surface. Afterwards, the structured surface can be replicated in large numbers in a hot embossing process and thus increase market share. In recent work, this process has been investigated in cooperation with Karlsruhe Institute of Technology. The surfaces reproduced in this process meet the highest requirements in terms of precision and shape accuracy of the structure elements. Moreover, the optical functionality of such structures applied as security holograms was successfully demonstrated.