THz time-domain spectroscopy: investigation of
thin layers of inks.

Year: 2016

Authors: Taschin A., Bartolini P., Tasseva J., Striova J., Fontana R., Riminesi C., Torre R.

Autors Affiliation: European lab. for Non-Linear Spectroscopy (LENS), Univ. di Firenze, Italy;
Dip. di Fisica e Astronomia, Univ. di Firenze, Italy;
Istituto Nazionale Ottica, CNR, Firenze, Italy;
Istituto per la Conservazione e la Valorizzazione dei Beni Culturali, CNR, Sesto Fiorentino, Italy

Abstract: We develop an original experimenal procedure and a comprehensive method of data analysis to measure the optical parameters of drawing media data in the THz spectral range. The method based on the Thz – Time Domain Spectroscopy ia applied to recover material parameters on drawing inks deposited on polyethylene pellicles with thicknesses down to tens of micrometers. In particular, we investigated three commercial inks: a red ink (based on cochineal carmine), a blue ink (indigo) and a black ink (irin-gall). The implemented experimental procedure and numerical method enable us to extract the absorption coefficient and refractive index spectra in an absolute scale, opening the possibility to investigate the material parameters in the THz range with a complete quantitative study.

Conference title: IMEKO International Conference on
Metrology for Archaeology and Cultural Heritage

KeyWords: THz spectroscopy; Iron gall Inks; Drawing media; Thin painted layers; time-domain