Terahertz imaging super-resolution for documental heritage

Danae Antunez Vazquez, Laura Pilozzi, Eugenio Del Re, Claudio Conti, Silvia Sotgiu, Federica Delia, Mauro Missori

Abstract

THz time-domain spectroscopy (THz-TDS) and pulsed imaging have been demonstrated to be able to provide a non-invasive examination of cultural heritage materials. However, the spatial resolution of THz pulsed imaging is of the order of 1 mm for THz waves, a value that is often not sufficient for the examination of small details on written heritage. This paper will focus on the development of a far-field super-resolution THz imaging system based on a freestanding knife edge and a reflective confocal configuration for the THz beam line. This system has been designed for the recognition of inks, pigments, and dyes used in graphic signs and for the detection of texts buried beneath graphical layers. To optimize the set-up preliminary experiments were realized by imaging the diffraction pattern of a slit, where the freestanding knife set-up showed an improved resolution. After, a reflective set-up was realized and tested on paper samples with graphite patterns. Results demonstrated the super-resolution of THz imaging by showing written features separated by less than the wavelength used. The future direction will be the application of the set-up to real ancient documents for their diagnostics.

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IMEKO-MetroArchaeo-2023-104.pdf

DOI

10.21014/tc4-ARC-2023.104

IMEKO TC

TC4 - Measurement of Electrical Quantities

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