Collimating Grating Monochromators for the Vacuum Ultraviolet

A non-focusing, grazing incidence monochromator which utilizes planar gratings and collimating slit systems is described. Such an instrument is capable of moderate spectral resolution in the vacuum ultraviolet and allows for relatively simple scanning mechanisms. Monochromators of this type have been built for laboratory studies and for incorporation in a satellite-borne experiment for monitoring solar intensities in the extreme ultraviolet. Measurements made on rare gas spectra indicate approximate agreement between computed and observed instrumental line widths.