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

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.