1 March 1989 Gaussian-Apodized Apertures And Small-Angle Scatter Measurement
Author Affiliations +
Gaussian-apodized apertures are investigated for the purpose of reducing the diffraction background of a small-angle scatterometer. The farfield irradiance distributions of weakly truncated and untruncated Gaussian beams are compared. The envelope of diffraction ringing is shown to decrease proportionately with the level of truncation in the pupil. Spherical aberration and defocus are shown to have little effect on the higher-order diffraction rings of Gaussian-apodized apertures. A method is presented for determining the scattered irradiance level for a given bidirectional reflectance distribution function in relation to the peak irradiance of the point spread function. An example is provided that demonstrates that the small-angle diffraction background can be reduced by orders of magnitude as compared with a scatterometer with an unapodized pupil. Analysis of the point spread function is provided from 0 to 16 arcmin for an exit pupil diameter of 25.4 mm and A = 0.6328 Am. The numerical methods utilized to obtain these results are discussed.
Steven J. Wein, William L. Wolfe, "Gaussian-Apodized Apertures And Small-Angle Scatter Measurement," Optical Engineering 28(3), 283273 (1 March 1989). https://doi.org/10.1117/12.7976945


A Small-Angle Scatterometer
Proceedings of SPIE (April 05 1989)
Axial behavior of Cantor rings diffractals
Proceedings of SPIE (November 19 2003)
Intrapixel sensitivity in NIR detectors for NGST
Proceedings of SPIE (March 05 2003)
Proceedings of SPIE (June 10 1987)

Back to Top