Terahertz meets sculptural and architectural art: Evaluation and conservation of stone objects with T-ray technology

Conservation of cultural heritage is an area where novel scientific techniques are having enormous impact. Given the value and uniqueness of art pieces, non-invasive diagnostic methods are highly appreciated by conservators. Terahertz radiation has shown enormous potential as non-contact probe that can be used for the three-dimensional reconstruction of internal structure of stone-made objects. In this article we report the evaluation of the internal damage state of two art pieces, a medallion from the Castle of Celle and a window sill from the St. Peter of Trier Cathedral. We also used terahertz radiation to follow and assess the restoration process of the window sill. We found that terahertz spectroscopy is an excellent non-destructive evaluation method for stone artwork that shows enormous potential as a tool for conservation.

[1]  Costas Fotakis,et al.  Terahertz time domain spectroscopy for the analysis of cultural heritage related materials , 2008 .

[2]  Joris Dik,et al.  Terahertz imaging of hidden paint layers on canvas , 2009, 2009 34th International Conference on Infrared, Millimeter, and Terahertz Waves.

[3]  E. Castro-Camus,et al.  Beating the wavelength limit: three-dimensional imaging of buried subwavelength fractures in sculpture and construction materials by terahertz time-domain reflection spectroscopy. , 2013, Applied optics.

[4]  Wolf-Dieter Grimm,et al.  Bildatlas wichtiger Denkmalgesteine der Bundesrepublik Deutschland , 1990 .

[5]  Jürgen Ihlemann,et al.  Plasma Jet Coupled with Nd:YAG Laser: New Approach to Surface Cleaning , 2007 .

[6]  Martin Koch,et al.  OSCAT: Novel Technique for Time-Resolved Experiments Without Moveable Optical Delay Lines , 2011 .

[7]  K. Fukunaga,et al.  Real-time terahertz imaging for art conservation science , 2008 .

[8]  Iwao Hosako,et al.  Application of terahertz spectroscopy for character recognition in a medieval manuscript , 2008, IEICE Electron. Express.

[9]  M. Koch,et al.  Terahertz quasi time domain spectroscopy. , 2009, Optics express.

[10]  Wai Lam Chan,et al.  Imaging with terahertz radiation , 2007 .

[11]  D. S. Chambers.  The Art of Restoration , 1970 .

[12]  M. Schell,et al.  Terahertz-time domain spectrometer with 90 dB peak dynamic range , 2014 .

[13]  M. Menu,et al.  Terahertz imaging for non-destructive evaluation of mural paintings , 2008 .

[14]  M. Picollo,et al.  Terahertz spectroscopy applied to the analysis of artists’ materials , 2010 .

[15]  S. Hunsche,et al.  THz-imaging: a new method for density mapping of wood , 1998, Wood Science and Technology.

[16]  Iwao Hosako,et al.  Terahertz spectroscopy for art conservation , 2007, IEICE Electron. Express.

[17]  Iwao Hosako,et al.  Innovative non-invasive analysis techniques for cultural heritage using terahertz technology , 2010 .

[18]  M. Koch,et al.  Terahertz spectroscopy and imaging – Modern techniques and applications , 2011 .

[19]  David Erhardt.  Materials science: The art of restoration , 2004, Nature.

[20]  Wolfgang Viöl,et al.  Cleaning of Wall Paintings and Architectural Surfaces by Plasma , 2007 .

[21]  Masayoshi Tonouchi,et al.  Cutting-edge terahertz technology , 2007 .

[22]  Gerard Mourou,et al.  Investigation of Terra Cotta artefacts with terahertz , 2011 .

[23]  S. Tsuchikawa,et al.  Simultaneous prediction of density and moisture content of wood by terahertz time domain spectroscopy , 2014 .