Curing subpixel structures for high-resolution printing of translucent materials using standard DLP-projectors

For polymer 3D printing technologies, there exists a gap between large build volumes, low resolution and small build volumes, high resolution. On the one hand side, classical stereolithographic techniques can be used to build volumes in the range of several cm³ and an accuracy of 10 μm, on the other hand it is possible to cure structures with the size of several nanometers with two-photon polymerization. Combining both advantages – large building volume and high resolution – in one printing technology would offer a huge variety of applications e.g. printing optical components and adding a functionalization of the surface by a 3D printed micro structure in the same process. In this presentation, we demonstrate curing of subpixel structures with a standard DLP-projector with an imaged pixel size of around 40 μm. To use this in a printing process, the behavior of the resins under UV radiation must be known and predictable because different parameters are needed depending on the size and shape of the cured area. Therefore, a parameter study was done to evaluate the dependency of the cured thickness on the shape, the area and the energy of the irradiated pattern. These parameters were used to simulate the cured thickness for a certain irradiance pattern applied by the projector. Based on these simulations a subpixeling technique was applied in order to cure small structures and test simple applications.