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Proceedings Paper

Extended-field confocal imaging for 3D surface sensing
Author(s): Joseph Cohen-Sabban; Jerome Gaillard-Groleas; Pierre-Jean Crepin
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Paper Abstract

A novel optoelectronic set up based on a confocal extended field proprietary design has been developed for high resolution 3D surface sensing as well as for roughness and surface flaw characterization. The classical optical sectioning property of the basic confocal imaging design assumes that a monochromatic light beam is propagating forth and back from the elementary point source to the spatial filtering pinhole. When using a polychromatic light source, the residual chromatic aberration of the optical system reduces the optical sectioning global performance by enlarging the axial resolution (optical sectioning) by a quantity almost equal to the length of the axial chromatic aberration. When dealing with 3D surface sensing of the axial chromatic aberration can be considered as generating a highly accurate axial color coding, provided that an adequate color decoding of the backreflected light beam is realized. Consequently, it appears that it is possible to design customized confocal extended field point sensors with depths of field ranging from a few tens of microns (with subnanometric axial resolution) up to tens of millimeters (with micrometric axial resolution). Owing to the large Numerical Aperture of the confocal imaging set up perfectly specular optical surfaces can be easily captured with this type of instrument. Examples of Metrological 3D surface sensing of aspheric ophtalmic progressive lenses, small lens arrays and MOEMS will be presented and discussed.

Paper Details

Date Published: 26 February 2004
PDF: 6 pages
Proc. SPIE 5252, Optical Fabrication, Testing, and Metrology, (26 February 2004); doi: 10.1117/12.513583
Show Author Affiliations
Joseph Cohen-Sabban, STIL SA (France)
Jerome Gaillard-Groleas, STIL SA (France)
Pierre-Jean Crepin, STIL SA (France)


Published in SPIE Proceedings Vol. 5252:
Optical Fabrication, Testing, and Metrology
Roland Geyl; David Rimmer; Lingli Wang, Editor(s)

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