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Proceedings Paper

The thermal photocopier: a new concept for thermal NDT
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Paper Abstract

The thermal line scanner has proven to be a successful method of rapidly scanning large areas of aircraft fuselage for delaminations and metal pipes for corrosion. The limitation of this technique is with the finite depth by which flaws can be located due to the fixed distance that the thermal camera follows the moving line source. To identify deeper flaws within a material, the thermal imager and line source must have a greater separation distance so that the heat has more time to propagate through the material. Ultimately, one would want to identify flaws at any depth requiring continual scans with greater separation between the line source and imager. The Thermal Photocopier is a hybrid of the thermal line scanner. It utilizes a moving line source and a stationary infrared camera. Any one image captured by the computer shows the sample in gradient cooling due to the moving heat source. An algorithm has been developed that reconstructs full-field images of the material at specific cool down times. These frames represent various depths into the sample as the heat propagates through the thickness of the material. Therefore, an object can be analyzed from the front to the back surface for flaws using this modified thermal detection system. This system has been tested on aluminum and composite materials of varying thickness yielding results consistent with thermographic images obtained with flash and quartz lamps.

Paper Details

Date Published: 12 April 2004
PDF: 8 pages
Proc. SPIE 5405, Thermosense XXVI, (12 April 2004); doi: 10.1117/12.541881
Show Author Affiliations
Deonna F. Woolard, Randolph-Macon College (United States)
K. Elliott Cramer, NASA Langley Research Ctr. (United States)


Published in SPIE Proceedings Vol. 5405:
Thermosense XXVI
Douglas D. Burleigh; K. Elliott Cramer; G. Raymond Peacock, Editor(s)

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