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Proceedings Paper

Conoscopic holography based profilometers for defect inspection: improviements in speed, resolution, and noise reduction
Author(s): Ignacio Álvarez; José M. Enguita; César Fraga; Jorge Marina; Yolanda Fernández
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Paper Abstract

One of the more challenging applications of optical metrology is real-time dimensional control and surface inspection in industrial applications, where strong requirements of cost, speed of operation, ease of setup and applicability in adverse environments, greatly limit the number of applicable technologies. An optic profilometer, based on Conoscopic holography, has been designed specifically for this purpose and used in several on-line inspection systems. This device is able to obtain a distance profile of a target in a single shot; works at long distance standoff (700-1200mm) and still keeps good resolution (under 0.2mm) with a very easy and reliable setup. However, there are still some drawbacks that should be addressed. The first one is the signal processing, which is a relatively expensive process and limits the acquisition rate at no more than 70 profiles per second. The second one is speckle noise, which is an inherent problem in systems that use coherent-light illumination and triangulation, and therefor could be extrapolated to many other optical inspection systems. This paper shows the current lines of research to solve both problems and presents some initial, yet very interesting, results. These improvements can be applicable to other ranges of devices using this technology in adverse environments, for roughness and vibration measurement or surface defects detection.

Paper Details

Date Published: 22 April 2006
PDF: 16 pages
Proc. SPIE 6189, Optical Sensing II, 61890H (22 April 2006); doi: 10.1117/12.661455
Show Author Affiliations
Ignacio Álvarez, Univ. of Oviedo (Spain)
José M. Enguita, Univ. of Oviedo (Spain)
César Fraga, Univ. of Oviedo (Spain)
Jorge Marina, Univ. of Oviedo (Spain)
Yolanda Fernández, Univ. of Oviedo (Spain)

Published in SPIE Proceedings Vol. 6189:
Optical Sensing II
Brian Culshaw; Anna G. Mignani; Hartmut Bartelt; Leszek R. Jaroszewicz, Editor(s)

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