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

The study provides a practical method for predicting tool wear based directly on grating diffraction efficiency, helping reduce fabrication risks and improve production yield in advanced spectroscopic systems. The research results were published in the Journal of Manufacturing Processes.

Echelle gratings are essential optical components in high-resolution spectrometers used in astronomy, semiconductor inspection, biomedical sensing, and precision measurement. Their groove structures must be manufactured with extreme precision because 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 research team established a new approach that linked diamond tool wear directly to grating optical performance. Instead of evaluating wear only through traditional geometric or mechanical parameters, the team used rigorous coupled-wave analysis (RCWA) to model how changes in tool condition altered groove shape and ultimately affected 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 study showed that within a permissible wear range, diffraction efficiency remained relatively stable even as gradual wear occurred. Once the wear threshold was exceeded, however, grating performance deteriorated rapidly. This threshold-based strategy allows manufacturers to determine when a ruling tool should be re-sharpened before major performance loss occurs, greatly reducing wasted substrates and production time. The model also revealed that gratings with smaller groove bottom angles exhibited greater wear tolerance and maintained stable performance over longer ruling distances.

Experimental validation was carried out using CIOMP’s ultra-precision grating ruling platform. By fabricating multiple gratings under different tool geometries and wear conditions, the team confirmed that the model accurately predicted diffraction efficiency trends throughout the ruling process. The measured results closely matched theoretical predictions, demonstrating that the proposed framework can serve as a reliable guide for real-world manufacturing.

Beyond immediate production benefits, this work 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, the study offers a more practical path toward stable, scalable fabrication of next-generation diffraction gratings.

This research 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.