Special report, exit slit mirrors for the Ebert spectrometer

The use of a very long straight entrance slit in an Ebert grating spectrometer with two plane mirrors at the shorter exit slit to increase the energy density is described. This system has been employed in a far ultraviolet rocket spectrometer to provide higher sensitivity than has been achieved previously. The imaging properties and required slit and mirror adjustments are presented. Experimental results are included.