The normal-incidence rotating-sample ellipsometer is an instrument that can be used to characterize grating surfaces from the measured ratio ρof complex reflection coefficients ry/rx of light polarized perpendicular and parallel to the grating groove direction. Experimental results at different wavelengths for different gratings with spatial frequencies from 150 to 5880 grooves/mm are presented. The groove depth of the 5880-grooves/mm gold-coated grating can be estimated from the measured ρ and rigorous grating theory.
Y. Cui and R. M. A. Azzam, "Applications of the normal-incidence rotating-sample ellipsometer to high- and low-spatial-frequency gratings," Appl. Opt. 35, 2235-2238 (1996)