Periodic wavelength dispersion in a scanning UV monochromator

Abstract

An analysis has been made of some wavelength dispersion problems associated with the McPherson model 225 1-m VUV scanning monochromator. The measurements show a periodic error in the dispersion of such a monochromator, refocussed for a fast-ion beam light source. They indicate a wavelength error from this source of up to +/-0.1 A with a period of 25 A, this latter corresponding to one rotation of the grating drive screw.