Thin-film interference effects were observed in the normal-incidence efficiency of a 2400-groove/mm replica grating. The efficiency was measured in the 100–350-Å wavelength range and had an oscillatory behavior that resulted from the presence of a thin SiO<sub>2</sub> coating. The thicknesses of the SiO<sub>2</sub> and the underlying oxidized aluminum layers were inferred from computer modeling of the zero-order efficiency. The efficiencies in the diffracted orders were calculated with the modified integral approach and accounting for the multilayer coating and the groove profile derived from atomic force microscopy. The calculated and measured efficiencies were in good agreement.
© 1999 Optical Society of America
(050.1950) Diffraction and gratings : Diffraction gratings
(050.1960) Diffraction and gratings : Diffraction theory
(260.3160) Physical optics : Interference
(260.7200) Physical optics : Ultraviolet, extreme
(310.6860) Thin films : Thin films, optical properties
John F. Seely, Leonid I. Goray, William R. Hunter, and Jack C. Rife, "Thin-Film Interference Effects on the Efficiency of a Normal-Incidence Grating in the 100–350-Å Wavelength Region," Appl. Opt. 38, 1251-1258 (1999)