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Proceedings Paper

Multi-sensor evaluation of a wooden panel painting using terahertz imaging and shearography
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Paper Abstract

Cultural heritage objects are increasingly being investigated using advanced non-destructive optical measurement techniques. Holographic and speckle interferometry based instrumentation allow dimensional measurement of objects at the tens of nanometer scale. For the structural diagnostics of artwork, double-exposure techniques are often used to locate defects, delaminations, voids and other structural features. Shearography is a speckle interferometry configuration that uses a close-to-common-path shearing interferometer configuration to give a direct sensitivity to displacement gradient at the object surface. This configuration is particularly useful for measurements outside the optical laboratory, as the stability requirements are much reduced compared with holography techniques. Terahertz imaging is a new category of sensor, used to investigate materials using electromagnetic radiation in the 0.1 to 10 THz frequency range. At these frequencies many materials become semi-transparent, so bulk structural diagnostics can be performed. Typically terahertz imaging is performed using a scanning pixel, or multi-pixel, sensor. In this manuscript shearography is first used to identify areas of interest of possible structural anomalies in the artwork. These regions of interest are then studied in more detail using the terahertz imaging instrument. Together the two instruments provide an analysis of both the surface and bulk structural features. The approach is demonstrated experimentally using a wooden panel painting.

Paper Details

Date Published: 10 July 2009
PDF: 8 pages
Proc. SPIE 7391, O3A: Optics for Arts, Architecture, and Archaeology II, 73910E (10 July 2009); doi: 10.1117/12.827528
Show Author Affiliations
Roger M. Groves, Technische Univ. Delft (Netherlands)
Univ. Stuttgart (Germany)
Boris Pradarutti, Fraunhofer-Institut für Angewandte Optik und Feinmechanik (Germany)
Eleni Kouloumpi, National Art Gallery and Alexandros Soutzos Museum (Greece)
Wolfgang Osten, Univ. Stuttgart (Germany)
Gunther Notni, Fraunhofer-Institut für Angewandte Optik und Feinmechanik (Germany)

Published in SPIE Proceedings Vol. 7391:
O3A: Optics for Arts, Architecture, and Archaeology II
Luca Pezzati; Renzo Salimbeni, Editor(s)

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