On Iterative Pre-Compensation of 3D Laser-Printed Micro-Optical Components Using Confocal-Optical Microscopy

State-of-the-art 3D two-photon laser printing systems already use pre-compensation algorithms to reduce systematic deviations between the printed and the targeted structures. Nevertheless, the remaining deviations are often still larger than the uncontrollable or "statistical" deviations. In principle, it is straightforward to correct for systematic deviations by measuring the difference between printed structure and target and by subtracting the difference from the first target to obtain the next-iteration target. However, in reality, one faces several issues such as noise and systematic errors of the characterization measurement itself, as well as unwanted translations and rotations between the coordinate systems of the characterization setup and the printer, respectively. Two examples of printed structures requiring sub-micrometer accuracy are considered, a large 1D micro-lens array and a specific diffractive optical element. For both, the device performance before the pre-compensation workflow described herein is insufficient for the targeted application and has become sufficient after this workflow. The workflow involving optimizations using cross-correlations with confocal-optical-microscopy data is documented by an open-access program (available via GitLab). This program includes an easy-to-use graphical user interface so that other researchers can immediately profit from it. In multi-photon 3D-laser-nano printing, several systematic factors like shrinkage or stitching lead to deviations between the printing result and the required designed structure. Fortunately, these errors can be corrected by modifying the design before printing. A method is presented to measure the systematic deviations using confocal-optical microscopy and provide a flexible user-friendly program to calculate a pre-compensated design from them.image