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Proceedings Paper

Design of a diffractive anti-aliasing filter using information density
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Paper Abstract

Aliasing is introduced in sampled imaging systems when light level requirements dictate using a numerical aperture that passes spatial frequencies higher than the Nyquist frequency set by the detector. One method to reduce the effects of aliasing is to modify the optical transfer function so that frequencies that might otherwise be aliased are removed. This is equivalent to blurring the image prior to detection. However, blurring the image introduces a loss in spatial detail and, in some instances, a decrease in the image signal-to-noise ratio. The tradeoff between aliasing and blurring can be analyzed by treating aliasing as additive noise and using information density to assess the imaging quality. In this work we use information density as a metric in the design of an optical phase-only anti-aliasing filter. We used simulated annealing to determine a pupil phase that modifies the system optical transfer function so that the information density is maximized. Preliminary results indicate that maximization of the information density is possible. The increase in information density appears to be proportional to the logarithm of the electronic signal-to-noise ratio and insensitive to the number of phase levels in the pupil phase. We constrained the pupil phase to 2, 4, 8, and 256 phase quantization levels and found little change in the information density of the optical system. Random and zero initial-phase inputs also generated results with little difference in their final information densities.

Paper Details

Date Published: 30 July 2002
PDF: 9 pages
Proc. SPIE 4736, Visual Information Processing XI, (30 July 2002); doi: 10.1117/12.477571
Show Author Affiliations
Joseph Neil Mait, Army Research Lab. (United States)
Joseph van der Gracht, HoloSpex, Inc. (United States)
Gary W. Euliss, Applied Photonics, Inc. (United States)

Published in SPIE Proceedings Vol. 4736:
Visual Information Processing XI
Zia-ur Rahman; Robert A. Schowengerdt; Stephen E. Reichenbach, Editor(s)

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