Deep Proton Writing: A tool for rapid prototyping polymer micro-opto-mechanical modules

One of the important challenges to prototype optical and micro-optical systems is the ability to include geometries with high enough optical surface quality. This generally means that the surface flatness and The resolution should be controlled within a sub-micrometer scale and that the resulting surface roughness should be only a fraction of the operating wavelengths. In our labs at the Vrije Universiteit Brussel we are therefore focusing on the continuous development of a rapid prototyping technology for the fabrication of micro-optical modules. In this technology, which we call Deep Proton Writing (DPW), we bombard polymer samples with micro-sized bundles (with diameters from 20 mu m to 300 mu m) of accelerated protons that have controllable energy between 5.5-16.5 MeV With this set-up we can sculpt structures with optical grade surfaces anywhere between 20 mu m and 1000 mu m thick. The strength of the DPW micro-machining technology is the ability to fabricate monolithic building blocks that include micro-optical and mechanical features which can be precisely integrated into more complex photonic systems. The DPW is furthermore compatible with low-cost mass-replication techniques such as micro injection moulding and hot embossing.