Analysis of buried ink elements in library artefacts using pulsed thermography

Pulsed thermography is a well-established method for the non-destructive analysis of cultural heritage items. This technique has been recently applied by the authors of this paper for reading written scraps, used for the making of bookbinding of ancient manuscripts, located between the end papers and the covers. The readability of the hidden text depends on several geometrical, optical and thermal parameters characterizing the typology of paper and the ink employed. To this end, a comprehensive mathematical model was developed by the authors for analyzing the influence of the various involved parameters. In particular, two indices were introduced, namely the signal contrast and the distortion index, used to quantitatively characterize the hidden text readability. Several numerical simulations are reported for assessing the dependence of the contrast and distortion from various parameters appearing in the model. Finally, a preliminary application to the analysis of original books is also presented.