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Confocal Terahertz Imaging of Ancient Manuscripts

  • Mariano Flammini
  • Claudia Bonsi
  • Chiara Ciano
  • Valeria Giliberti
  • Emanuele Pontecorvo
  • Paola Italia
  • Eugenio DelRe
  • Michele Ortolani
Article

Abstract

Terahertz imaging has the potential to identify and decipher portions of ancient manuscripts, which may be unreadable at infrared and visible wavelengths. We use a scanning confocal terahertz microscope to scan a medieval parchment with music notes and pentagrams written with different inks. The microscope is based on a continuous-wave solid-state source at 0.3 THz, emitting in the free space with a horn antenna, and a high numerical-aperture ellipsoidal reflector. We present terahertz images with diffraction-limited lateral resolution of approximately 0.5 mm, where the different inks all give similar high contrast. Symbols written on the “verso” side of the parchment, barely glimpsed in the near-infrared photograph, leave a clear imprint in the terahertz images. Artifacts due to imperfect flatness of the parchment are also briefly discussed.

Keywords

Confocal microscopy Schottky diode detector Terahertz Paper Ink Diffraction limit 

Notes

Acknowledgments

We acknowledge support from the Grant office of Sapienza University of Rome through project THESMA. We thank S. Nieddu, S. Cristelli, and G. Amico for their valuable help in the experiment.

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Copyright information

© Springer Science+Business Media New York 2016

Authors and Affiliations

  1. 1.Dipartimento di FisicaSapienza University of RomeRomeItaly
  2. 2.Dipartimento di Studi Greco-Latini, Italiani e Scenico-MusicaliSapienza University of RomeRomeItaly
  3. 3.Center for Life and Nano SciencesIstituto Italiano di TecnologiaRomeItaly

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