OBSERVATION AND MEASUREMENT OF SURFACE RELIEF OF DIFFRACTION GRATINGS USING ELECTRON MICROSCOPY TECHNIQUES

Two methods for the direct presentation and precise determination of surface relief of diffraction gratings are described, both of which utilize metallic replication techniques. A comparison of the results obtained is made with an interferometric measuring technique and the results are in agreement to within the errors of measurement. Surface irregularities of 2 nm have been measured from the electron micrographs of the surfaces of diffraction gratings, but the methods are applicable to any similar surface study.