The angular distributions of light scattered by gold-coated and aluminum-coated gratings with amplitudes of ～90 nm and periods of 6.67 μm were measured and calculated for light incident from a He-Ne laser at an angle of 6°. Experimental results are compared with predictions of Beckmann's scalar theory and Rayleigh's vector theory. The measured scattering pattern has a background of scattered light due mainly to residual surface roughness. Also the power in the higher-order peaks is larger by several orders of magnitude than the computed one, which can be attributed mainly to the low-order contributions of the harmonics in the profile.
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