Automated integration of time-control in pseudo-polychromatic monitoring strategy for complex thin-film filters

Precise optical monitoring of the layer thickness is crucial for the fabrication of complex error-sensitive thin-film filters. In this study, we extend a previously developed pseudo-polychromatic monitoring algorithm by integrating automatically placed time-controlled layers. While time-based monitoring is often applied empirically for convenience, we highlight its positive impact on the performance of the pseudo-polychromatic approach. Concerning automated selection of time-control, several configurations were tested on three multi-bandpass filter designs. Results show that hybrid strategies can reduce equivalent random thickness errors by more than 0.1–0.2 nm, compared to purely optical approaches Although results are specific to our monitoring scheme, this work opens the door for broader analytical studies on the influence of time-controlled layers across a range of commonly used optical monitoring techniques.