Automated calculation of optical monitoring strategy based on use of sensitive wavelengths and error self-compensation effects

Defining an appropriate optical monitoring strategy is critical to ensure accurate layer thicknesses in thin-film optical filter fabrication. This work focuses on active monochromatic monitoring combined with level-cut layer termination. We propose a method that limits monitoring wavelength changes while still selecting high-sensitivity wavelengths for each layer. This approach minimizes individual thickness errors and simultaneously preserves inter-layer error self-compensation. The method was validated on multiple examples of non-quarter-wave filters. Compared to existing strategies, it offers a practical balance between accuracy, robustness, and ease of implementation.