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Optical Engineering

An Optical Open Area Ratiometer
Author(s): Fred M. Dickey; Mark A Petersen
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Paper Abstract

An optical method for measuring the percent of open area of perforated sheet materials is presented. The technique, which is based on Fourier optics, uses a detector to measure a small central portion of the light in the Fraunhofer diffraction pattern of the perforated sheet. This approach offers accuracy and speed while avoiding diffraction problems associated with arrays of small holes. In addition it can be used with translucent materials. A brief theoretical analysis is presented as well as results obtained with a laboratory system. The system is being developed to inspect perforated materials fabricated for use on noise suppression systems for aircraft engines, however, it should be useful in the general noncontact determination of the open area of perforated materials.

Paper Details

Date Published: 1 October 1980
PDF: 4 pages
Opt. Eng. 19(5) 195793 doi: 10.1117/12.7972605
Published in: Optical Engineering Volume 19, Issue 5
Show Author Affiliations
Fred M. Dickey, Boeing Military Airplane Company (United States)
Mark A Petersen, Boeing Military Airplane Company (United States)

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