The Reflectivity of Glass and Aluminium Gratings at Grazing Incidence Below 1000 Å

Abstract

Emission spectra of solids in the 40–1000 Å region may show a variety of different band shapes due to non-linear wavelength response of the diffraction grating used as dispersing element. It is concluded that aluminium is unsuitable as a grating material for use at grazing incidence and that glass is to be preferred. Intensities predicted theoretically in various spectral orders do not agree with those observed for one particular glass grating. Where the ultimate in resolution is not required it is shown how to position a grating whose radius does not match the instrumental Rowland circle while still achieving good focus.