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Proceedings Paper

An Optical Processor For Product Inspection
Author(s): David P. Casasent; Jeffrey Richards
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Paper Abstract

Coherent optical proce'ssors are described that optically generate feature spaces in parallel at high speed. A wedge ring detector sampled Fourier feature space is described, since it provides dimensionality reduction and features that are invariant to translation and in-plane rotation of the input object. Thus, the object being inspected can be positioned and oriented anywhere within the input field of view. An optical Hough transform processor is also described. This Hough feature space is attractive for many mensuration functions required in inspection. New techniques for using Hough space features are presented and demonstrated. These new techniques provide in-plane distortion-invariance, and determination of the orientation and location of the object in the field of view. We also discuss how the Fourier coefficients, the wedge ring detector sampled Fourier coefficients, and the Hough transform features can all be produced on a single optical processor. To provide a cost-effective real time system, an inexpensive liquid crystal television is used as the input transducer, with its electrical input obtained from a CCD camera viewing the product to be inspected. Several different inspection problems and quantitative optical laboratory test data are included to demonstrate and quantify the performance and use of this processor for product inspection.

Paper Details

Date Published: 12 March 1988
PDF: 15 pages
Proc. SPIE 0850, Optics, Illumination, and Image Sensing for Machine Vision II, (12 March 1988); doi: 10.1117/12.942861
Show Author Affiliations
David P. Casasent, Carnegie Mellon University (United States)
Jeffrey Richards, Carnegie Mellon University (United States)

Published in SPIE Proceedings Vol. 0850:
Optics, Illumination, and Image Sensing for Machine Vision II
Donald J. Svetkoff, Editor(s)

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