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Proceedings Paper

Inspection of rough surfaces by optical triangulation
Author(s): Manuel Filipe M. Costa; Jose B. Almeida
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Paper Abstract

In this communication we describe an optical non contact microtopographer that we developed and are presently expanding and improving. The system is based on a simple triangulation procedure: the topographic information is obtained from the horizontal shift incurred by the bright spot created, by an oblique light beam, on a surface when it is displaced vertically. A laser beam is focused onto a small, diffraction limited, spot on the surface and is made to sweep it. The horizontal position of the bright spot is perpendicularly imaged onto a linear CCD array and the information about the individual detectors that are activated, above a certain controllable intensity threshold level, is used to compute the corresponding horizontal shift on the reference plane. Simple calculations allow us to obtain the distance between the surface and a reference plane at each sampled point and so a map of the surface topography can be built statistic surface characterization parameters may be calculated. We will also show that this kind of triangulation based surface inspection system can be applied not only to large distance range sensing, but also to smaller samples or smother surface with resolutions that can be driven down to the sub micron range.

Paper Details

Date Published: 9 February 1993
PDF: 5 pages
Proc. SPIE 1712, 14th Symposium on Photonic Measurement, (9 February 1993); doi: 10.1117/12.140170
Show Author Affiliations
Manuel Filipe M. Costa, Univ. do Minho (Portugal)
Jose B. Almeida, Univ. do Minho (Portugal)

Published in SPIE Proceedings Vol. 1712:
14th Symposium on Photonic Measurement
Janos Schanda; Tivadar Lippenyi, Editor(s)

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