Multi-photon polymerization by means of Nanoscribe’s direct laser writing systems allows for the fabrication of complex and replicable 2.5D structures. Polymer micro-optics can be used as moulds for replication or masters for pattern transfer. The key advantage compared to 2.5D gray scale lithography or 2D UV-exposure and subsequent reflow techniques is clear: arbitrary complex shapes can be fabricated in one single step.
These can be refractive optics such as arrays of aspheres, diffractive optics such as Fresnel lenses or even stacked micro-lenses. In addition, negative-tone resists may be used which are less sensitive to the development process compared to positive-tone resists - thus allowing for high reproducibility of the complete process chain. Furthermore, micro-optics of up to several 100 µm height can be fabricated with optimal resolution.