Echelle gratings serve as the core dispersive components in high-end spectroscopic instruments, whose performance directly determines the resolution and accuracy of spectral analysis. The wear of diamond tools is a critical factor limiting the groove accuracy and diffraction efficiency of echelle gratings. Accurately characterizing tool wear and predicting tool life are therefore essential for fabricating high-performance gratings. Distinguishing itself from traditional tool-performance-oriented wear characterization methods, this study, based on rigorous coupled-wave analysis, establishes a mapping relationship between tool wear and diffraction efficiency for 80 gr/mm echelle grating. A tool wear threshold model is proposed using diffraction efficiency as the criterion, and its validity is verified experimentally. The results indicate that gratings with a smaller groove bottom angle have a larger permissible wear tolerance. For a grating with a 70° groove bottom angle, the tool wear remains within the threshold throughout the ruling process, and the diffraction efficiency shows low sensitivity to wear, decreasing by an average of only 0.166% ± 0.118% per km of ruling distance. In contrast, for a 100°groove bottom angle, limited wear tolerance leads to rapid efficiency decline after exceeding threshold, averaging 3.661% ± 0.227% per km, necessitating timely tool re-sharpening to restore performance. The proposed model enables effective tool wear status determination from grating performance, significantly reducing ruling failure risk, shortening development cycles, and provides a solid theoretical foundation and key technical support for precise and stable fabrication of high-performance master echelle gratings.
Wang et al. (Tue,) studied this question.