Optically functionalization of 3D surfaces via voxel-based hierarchically micro structuralizing, a study case: Patterned optical ID

Optics is one of the most important applications of functional surfaces enabled by micro-/Nano-structuring. Mass production of optical functional surfaces mainly relies on replication technologies. In optical applications, structural consistency is essential for the precise control of functions such as micro-mirror/lens arrays. A big challenge from the design phase when fabricating functional surfaces is the geometrical constraint, e.g. patterning orient-consistent micromirrors on three-dimensional surfaces. This present paper demonstrates a voxel-based method to indirectly pattern consistently oriented microstructures onto 3D surfaces by creating a hierarchical structure, consisting of the substrate level of a “Minecraft”-like voxel structure and the feature level of micro features machined on the voxels. As a study case, RSA905 injection moulding inserts with 3D functional surfaces for optical encoding are fabricated with diamond machining: a spherical and a sinusoidal sample with a data matrix as an optical ID on each. The encoding is based on the optical contrast generated by the surfaces' directional reflection, which is led by the bevel surfaces of the micro ridge arrays. With the quantified evaluation of the resultant surface quality and functionality, the feasibility of the “Minecraft” method is validated, the surface quality is correlated with its complexity and the process optimization routine is determined. Moreover, by over 15,000 injection moulding cycles, the method is also proved suitable for batch production of 3D functional surfaces by micro injection moulding.