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Proceedings Paper

Scattering from sinusoidal gratings
Author(s): Byong Chon Park; Theodore V. Vorburger; Thomas A. Germer; Egon Marx
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Paper Abstract

Laser light scattering from holographic sinusoidal gratings has been investigated with a view to its use in the calibration of the linearity of BRDF instruments, a task that requires a wide dynamic range in the scattered intensity. An aluminum-coated grating of an amplitude of approximately 90 nm and a spatial wavelength of 6.67 micrometer was used. Measurements and calculations were performed for an angle of incidence of 6 degrees and for light incident from a HeNe laser (lambda equals 0.6328 micrometer). Experimental results are compared with the predictions of two theories: Beckmann's scalar theory and Rayleigh's vector theory applied to sinusoidal gratings. Both theories, which apply to perfectly conducting scatterers, produce nearly identical results. However, these predictions differ significantly from some of the experimental results. The measured scattering pattern has a large background of scattered light and the higher-order peak intensities are larger by several orders of magnitude than the computed ones. The measured peak intensities are polarization dependent. The large background scattering is shown to be due to the residual surface roughness. The profile of the grating was measured using a stylus instrument with a 1-micrometer-radius tip and a 0.1-micrometer-radius tip, and it appears that the profile does not contain significant harmonics that might be responsible for the large higher-order peak intensities. Scattering from a gold-coated specimen with the same specifications was also measured and compared with that from the aluminum-coated one to determine the effect of non-topographic scatter. Possible causes of the discrepancy between the measured and the computed magnitude and polarization dependence of the higher-order peak intensities are discussed.

Paper Details

Date Published: 26 September 1997
PDF: 13 pages
Proc. SPIE 3141, Scattering and Surface Roughness, (26 September 1997); doi: 10.1117/12.287806
Show Author Affiliations
Byong Chon Park, Korea Research Institute of Standards and Science (South Korea)
Theodore V. Vorburger, National Institute of Standards and Technology (United States)
Thomas A. Germer, National Institute of Standards and Technology (United States)
Egon Marx, National Institute of Standards and Technology (United States)

Published in SPIE Proceedings Vol. 3141:
Scattering and Surface Roughness
Zu-Han Gu; Alexei A. Maradudin, Editor(s)

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