Electron Microscope Method for Measuring Diffraction Grating Groove Geometry

Abstract

This paper reports an electron microscope method developed for measuring grating groove depths. The method was used recently for a set of test gratings with 1280 grooves/mm that were blazed in the vacuum ultraviolet. The efficiency of some of these gratings was later measured as a function of wavelength using spectrographic facilities at the Naval Research Laboratory. The correspondence between the blaze wavelengths measured for these gratings by the electron microscope method and by the wavelength of peak performance efficiency is reported. All of the gratings studied were ruled in gold with a groove step height near 500 Å.