Researchers from the Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP) of the Chinese Academy of Sciences have developed a new wear threshold model for diamond ruling tools, improving the precision and stability of manufacturing high-performance echelle gratings.

Published in the Journal of Manufacturing Processes on May 6, the study provides a practical method for predicting tool wear based directly on grating diffraction efficiency. This helps reduce fabrication risks and improve production yield in advanced spectroscopic systems.

Echelle gratings are essential optical components of high-resolution spectrometers used in astronomy, semiconductor inspection, biomedical sensing, and precision measurement. Their groove structures must be manufactured with extreme precision, as even slight geometric errors can greatly reduce diffraction efficiency and spectral performance.

Mechanical ruling with diamond tools remains one of the few viable methods for producing large-area high-quality master echelle gratings, but gradual tool wear during the ruling process often limits consistency, increases costs, and raises the likelihood of production failure.

To address this challenge, the researchers established a new approach linking diamond tool wear directly to grating optical performance. Rather than evaluating wear solely through traditional geometric or mechanical parameters, they used rigorous coupled-wave analysis (RCWA) to model the impact of changes in tool condition on groove shape and, consequently, diffraction efficiency.

By creating a quantitative mapping between wear parameters and optical performance, the researchers proposed a wear threshold model that identifies when tool degradation begins to significantly compromise grating quality.

The results showed that diffraction efficiency remained relatively stable as long as tool wear stayed within a certain range. However, once the wear threshold was exceeded, performance deteriorated rapidly. This threshold-based strategy enables manufacturers to identify when a ruling tool requires re-sharpening to prevent significant performance loss, thereby reducing waste and production time.

The study also found that gratings with smaller groove bottom angles exhibited greater wear tolerance and maintained stable performance over longer ruling distances.

To verify the model, the researchers conducted experiments on CIOMP's ultra-precision grating ruling platform. Multiple gratings were fabricated using different tool geometries and wear conditions, and the measured diffraction efficiencies closely matched the theoretical predictions. These results demonstrate that the model can serve as a reliable guide for real manufacturing.

Beyond immediate production benefits, this study highlights the broader importance of integrating precision metrology with performance-oriented design in ultra-precision manufacturing. By transforming tool wear assessment from a purely mechanical issue into an optical performance criterion, it offers a more practical path toward the stable and scalable fabrication of next-generation diffraction gratings.

This work provides technical support for high-end optical instrumentation and advanced manufacturing fields that depend on large-area, high-efficiency gratings, including space observation, semiconductor lithography, and precision spectroscopy.