A constant deviation grazing incidence monochromator

Abstract

A 2 m grazing incidence monochromator is described which has the useful feature of presenting, through the exit slit, a beam of monochromatic radiation whose direction is constant as its wavelength is changed. This is achieved without translating the entrance slit or changing the direction of light input, thus allowing the instrument to be used with fixed light sources such as a synchrotron. It is shown that the slit-width limited resolution has been achieved. Measurements made using a 300 MeV synchrotron light source and gratings blazed at different angles have shown that the blaze effects are very important at short wavelengths. The efficiency of the instrument has been measured at 500 Å, allowing estimates to be made of efficiencies at other wavelengths.