1980 年 29 巻 4 号 p. 256-262
An aberration-corrected concave grating especially for reducing coma-type aberration has been developed to improve the resolution of Seya-Namioka monochromators by utilizing the technology of varied groove spacings. The optimum amount of space variation is calculated by using the light path function, and the concave grating is ruled with a numerically controlled ruling engine. A concave grating with 1/600 mm average spacing and 500 mm radius of curvature was designed and ruled for a Seya-Namioka monochromator which covers the spectral wavelength range of 200-800 nm. The quality of spectral images obtained with the new concave grating was examined both theoretically and experimentally and the results show the effectiveness of aberration correction in the resolution and luminosity of the monochromator.