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Proceedings Paper

Dynamic lighting system for specular surface inspection
Author(s): Ralph Seulin; Fred Merienne; Patrick Gorria
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Paper Abstract

Specular surfaces inspection is a problem met frequently within the automatic control of metallic products. A tried technique to reveal the aspect defects is the imaging of the reflection of a structured lighting as Dark Field Illumination through the surface. In order to inspect the whole surface, an element of the lighting structure has to scan every part of the surface. In the case of important surface curvature gradients, entire scanning is not ensured if the object is moving in front of the static lighting. To overcome this limitation, an inverse process is proposed: the lighting structure is dynamic while the object is static. The scanning of the surface by the various lighting configurations enables the aspect control. A modeling of the surface to be inspected and defects to be detected is made. Inverse ray tracing is used to analyze the reflection of the lighting through the surface. This modeling enables to ensure the revealing of defects by respecting the chosen criteria of detection. A relation binding the physical size of defects and its size on the image is established. A metrological approach of the problem is then performed.

Paper Details

Date Published: 4 April 2001
PDF: 8 pages
Proc. SPIE 4301, Machine Vision Applications in Industrial Inspection IX, (4 April 2001); doi: 10.1117/12.420913
Show Author Affiliations
Ralph Seulin, Univ. de Bourgogne (France)
Fred Merienne, Univ. de Bourgogne (France)
Patrick Gorria, Univ. de Bourgogne (France)

Published in SPIE Proceedings Vol. 4301:
Machine Vision Applications in Industrial Inspection IX
Martin A. Hunt, Editor(s)

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