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Optical Engineering

Sampled-grating and crossed-grating models of moire patterns from digital imaging
Author(s): John Charles Krumm; Steven A. Shafer
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Paper Abstract

Traditional "crossed-grating" moire as well as the newer "sampled- grating" (scanning) moire have proved to be effective methods of shape measurement. There is speculation that the moire patterns of a sampled grating, which are due to aliasing, can be modeled with crossed gratings. We compare the two by writing notationally consistent models of each and show that while crossed gratings can correctly predict the frequencies of a sampled grating, they cannot correctly predict the amplitudes. Our sampled-grating model is a new formulation that accounts for multiple stages of sampling and transmission. We show how neglecting multiple stages can lead to mistakes in moire analysis. We demonstrate our models with an experiment using a digital imaging system.

Paper Details

Date Published: 1 February 1991
PDF: 12 pages
Opt. Eng. 30(2) doi: 10.1117/12.55777
Published in: Optical Engineering Volume 30, Issue 2
Show Author Affiliations
John Charles Krumm, Carnegie-Mellon Univ. (United States)
Steven A. Shafer, Carnegie Mellon Univ. (United States)


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