The 1 m Seya-Namioka monochromater for gas spectrometry

The outline of the 1 m Seya-Namioka monochromater is described. The monochromater is that of a 1 m vertical dispersion type with two kinds of diffraction gratings. One of the grating is a gold coated replica with the grating number of 1200/mm, of which blaze wavelength is 536 A. The other is a gold coated replica with the grating number of 2400/mm, of which blaze wavelength is 508 A. The ranges of wavelength measured are between 0 and 3000 A with the former grating and between 0 and 1500 A with the latter. The optical system of the monochromater consists of a plane mirror made of SiC and a concave mirror made of fused quarts coated with platinum. The image at the exit slit is studied considering the concave grating with the grating number of 2400/mm. The focus point of this monochromater depends on the wavelength. The intensity of photons obtained by this system is estimated. (Kato, T.)