CONSTRUCTION, ADJUSTMENT AND PERFORMANCE OF A 6.600-M GRAZING INCIDENCE VACUUM SPECTROGRAPH

The instrument described is adapted to a 6.600 m concave grating with 1200 grooves mm-1 and a ruled area 80 mm*20 mm. The grazing angle is 5 degrees , and the plate holder covers a wavelength range of 0-60 nm. A peculiar deviation of the focal curve from the Rowland circle is discussed. The lower limit of the grating reflectivity corresponds to approximately 3.5 nm, and good resolution is obtained. Improvements in the sliding spark technique are described.