Correcting groove error in gratings ruled on a 500-mm ruling engine using interferometric control.

Groove error is one of the most important factors affecting grating quality and spectral performance. To reduce groove error, we propose a new ruling-tool carriage system based on aerostatic guideways. We design a new blank carriage system with double piezoelectric actuators. We also propose a completely closed-loop servo-control system with a new optical measurement system that can control the position of the diamond relative to the blank. To evaluate our proposed methods, we produced several gratings, including an echelle grating with 79 grooves/mm, a grating with 768 grooves/mm, and a high-density grating with 6000 grooves/mm. The results show that our methods effectively reduce groove error in ruled gratings. (C) 2017 Optical Society of America