A long standoff profilometer for surface inspection in adverse environments based on conoscopic holography

Jose M. Enguita; Ignacio Alvarez; Cesar Fraga; Jorge Marina; Yolanda Fernandez; Gabriel Sirat

doi:10.1117/12.612259

13 June 2005 A long standoff profilometer for surface inspection in adverse environments based on conoscopic holography

Jose M. Enguita, Ignacio Alvarez, Cesar Fraga, Jorge Marina, Yolanda Fernandez, Gabriel Sirat

Proceedings Volume 5856, Optical Measurement Systems for Industrial Inspection IV; (2005) https://doi.org/10.1117/12.612259
Event: Optical Metrology, 2005, Munich, Germany

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, setup and applicability in adverse environments, greatly limit the number of applicable technologies. This paper shows an optic profilometer developed specifically for this purpose. This device, based on Conoscopic holography, is able to obtain a distance profile of a target in a single-axis scan; works from long distances and still keeps good resolution with a very easy and reliable setup. The first part of the paper introduces the working principles of Conoscopic holography and shows the sensor set-up. Necessary algorithms for obtaining the distance information are presented and the whole process is illustrated with real captures of test objects. The second part focuses on a real example of this technology applied in an on-line inspection system in steel continuous casting funded by the European Committee for Steel and Carbon, and which is currently working in Aceralia LDA steelmaking factory in Asturias (Spain). The system is placed in the process line and performs on-line detection of surface defects over hot steel slabs from a distance of 1200 mm. 100% of the production can be inspected without interfering with the process and without adding any delay.

Citation Download Citation

Jose M. Enguita, Ignacio Alvarez, Cesar Fraga, Jorge Marina, Yolanda Fernandez, and Gabriel Sirat "A long standoff profilometer for surface inspection in adverse environments based on conoscopic holography", Proc. SPIE 5856, Optical Measurement Systems for Industrial Inspection IV, (13 June 2005); https://doi.org/10.1117/12.612259

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