A Survey of Terahertz Applications in Cultural Heritage Conservation Science

Jackson, J. Bianca; Bowen, James; Walker, Gillian; Labaune, Julien; Mourou, G.; Menu, Michel; Fukunaga, Kaori

doi:10.1109/tthz.2011.2159538

Cited by 185 publications

(83 citation statements)

References 55 publications

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“…This includes gases [44][45], liquids [46], liquid crystals [47][48], and different types of solids [49][50][51][52][53]. But also artwork [54] and plants [55][56] have been investigated by THz-TDS.…”

Section: Introductionmentioning

confidence: 99%

Distinguishing Gasoline Engine Oils of Different Viscosities Using Terahertz Time-Domain Spectroscopy

Adbul-Munaim

Reuter

Koch

et al. 2015

J Infrared Milli Terahz Waves

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THz-TDS in the range of 0.5-2.0 THz was evaluated for distinguishing among gasoline engine oils of three different grades from the same manufacturer. Absorption coefficient showed limited potential and only distinguished (p < 0.05) the 20W-50 grade from the other two grades in the 1.7-2.0 THz range. Refractive index data demonstrated relatively flat and consistently spaced curves for the three oil grades. ANOVA results confirmed a highly significant difference (p < 0.0001) in refractive index among each of the three oils across the 0.5 -2.0 THz range. Linear regression was applied to refractive index data at 0.25 THz intervals from 0.5 -2.0 THz to predict kinematic viscosity. All seven linear regression models, intercepts, and refractive index coefficients were highly significant (p < 0.0001). All models had a similar fit with R 2 ranging from 0.9773 to 0.9827 and RMSE ranging from 6.33 to 7.75.The refractive indices at 1.25 THz produced the best fit. The refractive indices of these oil samples were promising for identification and distinction of oil grades.

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Section: Introductionmentioning

confidence: 99%

Distinguishing Gasoline Engine Oils of Different Viscosities Using Terahertz Time-Domain Spectroscopy

Adbul-Munaim

Reuter

Koch

et al. 2015

J Infrared Milli Terahz Waves

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“…This radiation mainly interacts with the intermolecular chemical bonds, so provides image contrast depending on the chemical composition of the materials present. This technique is beginning to be applied in heritage science [34,35]. The phantoms were imaged with a TeraPulse4000 system (Teraview Ltd, Cambridge, UK) at the University of Western Australia.…”

Section: Terahertz Imaging and Spectroscopymentioning

confidence: 99%

An assessment of multimodal imaging of subsurface text in mummy cartonnage using surrogate papyrus phantoms

Gibson¹,

Piquette²,

Bergmann

et al. 2018

Herit Sci

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Ancient Egyptian mummies were often covered with an outer casing, panels and masks made from cartonnage: a lightweight material made from linen, plaster, and recycled papyrus held together with adhesive. Egyptologists, papyrologists, and historians aim to recover and read extant text on the papyrus contained within cartonnage layers, but some methods, such as dissolving mummy casings, are destructive. The use of an advanced range of different imaging modalities was investigated to test the feasibility of non-destructive approaches applied to multi-layered papyrus found in ancient Egyptian mummy cartonnage. Eight different techniques were compared by imaging four synthetic phantoms designed to provide robust, well-understood, yet relevant sample standards using modern papyrus and replica inks. The techniques include optical (multispectral imaging with reflection and transillumination, and optical coherence tomography), X-ray (X-ray fluorescence imaging, X-ray fluorescence spectroscopy, X-ray micro computed tomography and phase contrast X-ray) and terahertz-based approaches. Optical imaging techniques were able to detect inks on all four phantoms, but were unable to significantly penetrate papyrus. X-ray-based techniques were sensitive to iron-based inks with excellent penetration but were not able to detect carbon-based inks. However, using terahertz imaging, it was possible to detect carbon-based inks with good penetration but with less sensitivity to ironbased inks. The phantoms allowed reliable and repeatable tests to be made at multiple sites on three continents. The tests demonstrated that each imaging modality needs to be optimised for this particular application: it is, in general, not sufficient to repurpose an existing device without modification. Furthermore, it is likely that no single imaging technique will to be able to robustly detect and enable the reading of text within ancient Egyptian mummy cartonnage. However, by carefully selecting, optimising and combining techniques, text contained within these fragile and rare artefacts may eventually be open to non-destructive imaging, identification, and interpretation.

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“…Plan-type images (C-scans) can be displayed using various parameters of the temporal pulse shape E(t), such as the value of the electrical field at maximum, at minimum, or the difference between maximum and minimum, or calculated intensity over a specific time interval (time window) and centroid-or weighted peak-time. In the frequency domain, the spectral amplitude E(ω) at a specific frequency ω or in a frequency range is a meaningful quantity to plot, offering the possibility of identifying materials with special spectral absorption characteristics (Jackson et al, 2011).…”

Section: Panel Paintings and Gilded Finishes In Europe: An Overviewmentioning

confidence: 99%

Inspection of panel paintings beneath gilded finishes using terahertz time-domain imaging

Dandolo

Cosentino²,

Jepsen

2015

Studies in Conservation

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Scientific analysis of panel paintings could provide key information to art historians and conservators about the composition and condition of the constituent layers. Knowledge of the structure, stratigraphy, and condition of the subsurface layers of these objects is highly relevant to conservation measures, when stability problems such as delamination or internal cracking are considered. Terahertz time-domain imaging (THz-TDI) in reflection geometry is capable of highlighting interfaces between layers in a stratigraphic buildup, and thus makes structural information available in the form of subsurface 3D images and stratigraphic images (B-scans). The technique is contactless and non-invasive, and has been successfully applied to investigation of panel paintings. Regarding gilded panel paintings, the extremely high reflectivity of metals at submillimeter wavelengths generally precludes the transmission of electromagnetic waves through metallic films. Therefore, imaging of subsurface features below gilded finishes may be regarded as Very challenging. A small but non-negligible direct transmission through metal films occurs if the film thickness is of the order of the skin depth of the metal in the terahertz range, due to the skin effect. The thickness of gold leaf, a fraction of a micrometer, matches the skin depth of gold in the terahertz frequency range covered by THz-TDI devices. We therefore investigated and imaged subsurface features of panel paintings through gilded finishes with THz-TDI. Subsurface layers of three gilded panel paintings (two contemporary tempera panel replicas and one fourteenth-century icon) have been successfully imaged behind gold finishes with THz-TDI.

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A Survey of Terahertz Applications in Cultural Heritage Conservation Science

Cited by 185 publications

References 55 publications

Distinguishing Gasoline Engine Oils of Different Viscosities Using Terahertz Time-Domain Spectroscopy

Distinguishing Gasoline Engine Oils of Different Viscosities Using Terahertz Time-Domain Spectroscopy

An assessment of multimodal imaging of subsurface text in mummy cartonnage using surrogate papyrus phantoms

Inspection of panel paintings beneath gilded finishes using terahertz time-domain imaging

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