Abstract-Toward a multimodal fusion of layered cultural object images: complementarity of optical coherence tomography and terahertz time-domain imaging in the heritage field

Corinna L. Koch Dandolo, Maxime Lopez, Kaori Fukunaga, Yoshimi Ueno, Ruven Pillay, David Giovannacci, Yann Le Du, Xueshi Bai, Michel Menu, Vincent Detalle,

https://www.osapublishing.org/ao/abstract.cfm?uri=ao-58-5-1281

Terahertz time-domain imaging (THz-TDI) and spectral-domain optical coherence tomography (SD-OCT) are two techniques capable of providing 3D datasets from which depth profiles and cross-sectional images of an object can be derived. They are novel photonics technologies of particular relevance to the field of heritage science, for which the comprehension of the stratigraphic structure of a cultural heritage object may help in the understanding of its artistic technology and state of preservation. The differences in imaging depth, field of view, and axial/lateral resolutions of the two imaging techniques provide different but complementary information of the same scene. Through the use of multimodal image fusion, the user will benefit from access to a detailed comparison of the information content of the two different datasets and images. To carry this out, we have developed a first data processing chain with the aim of representing THz-TDI and SD-OCT cross-sectional images in a unique image grid and space, in which the different datasets are dimensionally consistent.

© 2019 Optical Society of America

Abstract-Terahertz Spectroscopy and Quantum Mechanical Simulations of Crystalline Copper-Containing Historical Pigments

Elyse M. Kleist, Corinna L. Koch Dandolo, Jean-Paul Guillet, Patrick Mounaix,Timothy M. Korter,

https://pubs.acs.org/doi/10.1021/acs.jpca.8b11676

Terahertz spectroscopy, a non-invasive and non-destructive analytical technique used in art conservation and restoration, can provide compelling data concerning the composition and condition of culturally valuable and historical objects. Terahertz spectral databases of modern and ancient artists’ pigments exist, but lack explanations for the origins of the unique spectral features. Solid-state density functional theory simulations can provide insight into the molecular and intermolecular forces that dominate the observed absorption features, as well as reveal deviations from simple harmonic vibrational behavior that can complicate these spectra. The characteristic terahertz spectra of solid azurite, malachite, and verdigris are presented here, along with simulations of their crystalline structures and sub-3.0 THz lattice vibrations. The powerful combination of theory and experiment enables unambiguous spectral assignment of these complex materials and highlights the challenges that anharmonic peak broadening in organic-containing materials may present in the construction of reference pigment databases.

Abstract-Terahertz Time-Domain Imaging to Guide a Conservation Intervention on a Stratified Easel Painting

Corinna L. Koch Dandolo, Gilda María Pasco,  Saldaña, Mirta Asunción,  Insaurralde Caballero, Monserrat Alma Gómez Sepúlveda, Arturo Ignacio Hernández-Serrano, Alejandro Mesa Orozco, Joselyn Alvarado Calderón, Melba Samara Calderón Zárate, Karen Luna González, Eunice Corazón Peralta de Dios, Gerardo Hernández Rosales, Enrique Castro-Camus

https://link.springer.com/article/10.1007%2Fs10762-018-0505-3

Very few real easel paintings have been scanned by means of terahertz time-domain imaging (THz-TDI) up to now. In this study, four different areas of an eighteenth century easel painting have been scanned by THz-TDI with the aim of proving useful information to the conservators for its imminent restoration treatment, owing to the complexity of its structure. Despite the unevenness of the layers composing the painting (lining canvas, original canvas, patching materials, and paint layers), the recorded THz dataset has been processed so that the THz images of the single layers composing the multilayered object have been clearly obtained. Relevant information about the painting structure, the presence of structural defects, overpainting, and the existence and extension of the original remains could have been determined. Infrared photography and X-ray radiography have been used for integrating the collected THz data and comparing the different outputs.

Abstract-Terahertz frequency modulated continuous wave imaging advanced data processing for art painting analysis

Corinna L. Koch Dandolo, Jean-Paul Guillet, Xue Ma, Frédéric Fauquet, Marie Roux, and Patrick Mounaix

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-26-5-5358

Reflection terahertz frequency modulated continuous waves scanner (300 GHz) has been proficiently optimized for imaging two easel paintings of different age. The information content of the obtained THz images has been fully inspected by selecting the appropriate THz image parameter. At the same time, a new data processing has been developed for improving the level of detail held by the axial parametric THz images by means of Gaussian fit of the reflected signals. By carefully weighting the reflected signals as a function of the optical path, the reflected amplitude has been corrected for the positioning of the object surface with respect to the beam focal point. The artifact affecting the THz images recorded from an uneven painting surface have been resolved and the obtained images fairly represent to the original painting.

© 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Non-invasive Florentine Renaissance Panel Painting Replica Structures Investigation by Using Terahertz Time-Domain Imaging (THz-TDI) Technique

Corinna L. Koch Dandolo, Marcello Picollo, Costanza Cucci, Peter Uhd Jepsen,

http://link.springer.com/article/10.1007/s10762-016-0311-8

The potentials of the Terahertz Time-Domain Imaging (THz-TDI) technique for a non-invasive inspection of panel paintings have been considered in detail. The THz-TD data acquired on a replica of a panel painting made in imitation of Italian Renaissance panel paintings were processed in order to provide insights as to the limits and potentials of the technique in detecting different kinds of underdrawings and paint layers. Constituent layers, construction techniques, and anomalies were identified and localized by interpreting the extracted THz dielectric stratigraphy.