10 July 2009 Terahertz metrology of tree rings for dendrochronology and cultural heritage applications
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Terahertz imaging will be presented as a novel method of nondestructively measuring otherwise inaccessible tree-rings for the purpose of dendrochronologically cross-dating cultural heritage artifacts. Wood specimens were measured using time-domain terahertz pulse reflectometry. Two-dimensional images of tree-rings were generated through analysis of both time- and frequency-domain terahertz signals, which changed proportionally to the variations in wood density. Terahertz pulse separation enabled wood specimens with at least two layers of coatings (primer and/or paint) to be measured and the terahertz images were quantitatively compared to the optical photographs of related, uncoated specimen. Tree-ring series and timelines were obtained for each terahertz image with respect to the source (reference) ring series. Short ring width blocks were aligned to the reference series and combined to create an extended timeline for each terahertz image. It was determined that while spatial resolution may be improved with analysis at high frequencies, the lower signal to noise reduces the precision of the ring measurement. Constructing longer timelines from ring blocks, significantly improves the overall quality of a match.
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J. B. Jackson, J. B. Jackson, J. Labaune, J. Labaune, G. Mourou, G. Mourou, I. Duling, I. Duling, C. Lavier, C. Lavier, M. Menu, M. Menu, } "Terahertz metrology of tree rings for dendrochronology and cultural heritage applications", Proc. SPIE 7391, O3A: Optics for Arts, Architecture, and Archaeology II, 73910C (10 July 2009); doi: 10.1117/12.827508; https://doi.org/10.1117/12.827508

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