Adaptive stitching for meso-scale printing with two-photon lithography

An inevitable trade-off between resolution and total size exists when 3D printing objects. This is also the case for two-photon or multi-photon lithography. While it is capable of reaching a sub-micron feature size, it needs to combine a high precision movement mechanism with a lower precision one when writing centimetric size objects. As a result, the final part consists of a combination of many individual blocks, where the overlapping areas often create bumps and imperfections in the final object. In the current contribution, we demonstrate how an adaptive stitching algorithm can lead to a reduction in the total amount of stitching blocks of up to 40% for slender objects (i.e. with features smaller than the individual block size). As is demonstrated on a winding microfluidic channel, this can lead to substantial manufacturing time gains of up to 25%. As our tiling is irregular, we also explain how to create the writing masks for the blocks and decide on their order. In the special case in which one does not need to print one single large continuous part, but rather many individual ones (such as a microlens array), we demonstrate how zero-overlap stitching can be achieved with a modified version of our adaptive algorithm.