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Proceedings Paper

Three-dimensional measurement of specular free-form surfaces with a structured-lighting reflection technique
Author(s): Denis Perard; Juergen Beyerer
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Paper Abstract

A structured-lighting reflection technique was developed in order to detect and measure small wavinesses and curvature defects on specular free-form surfaces. It can reconstruct the 3D relief of specular free-form surfaces and display the curvature at each point. A calibrated camera observes the reflection of a retro-illuminated LCD panel through the free- form surface. The use of a coded lighting technique and the knowledge of the setup geometry allow to locate each observed point on the LCD panel. Using the principle of inverse ray tracing, a surface modelled with Bezier polynomials is fitted to the observed data. Unlike structured-lighting projection techniques which are directly sensitive to the topography of the surface to be inspected, the structured-lighting reflection techniques are essentially sensitive to the gradient and thus enable the detection and measurement of curvature defects which are imperceptible using the projection techniques.

Paper Details

Date Published: 10 December 1997
PDF: 7 pages
Proc. SPIE 3204, Three-Dimensional Imaging and Laser-based Systems for Metrology and Inspection III, (10 December 1997); doi: 10.1117/12.294443
Show Author Affiliations
Denis Perard, Univ. Karlsruhe (Germany)
Juergen Beyerer, Univ. Karlsruhe (Germany)

Published in SPIE Proceedings Vol. 3204:
Three-Dimensional Imaging and Laser-based Systems for Metrology and Inspection III
Kevin G. Harding; Donald J. Svetkoff, Editor(s)

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