Optical methods for manuscript characterization

Because photons interact with parchment material in a non-invasive manner, light is an ideal probe for analytical studies on ancient manuscripts. Optical methods are developed in the laboratory for characterizing manuscripts in various aspects.

A non-invasive method combining optical spectrophotometry and principal component analysis was developed for the identification of parchment animal species (Alvarez et al., 2019). It was successfully validated by comparison with results of proteomic analyses performed on tens of historical parchments.

A non-invasive quantitative imaging method was developed for measuring birefringence (magnitude and axis orientation) in uniaxial optical media (Bouhy et al., 2022) and it is planned to apply it to mechanical stress as well as degradation characterization in parchments. The optical setup relies on a polarizing optical microscope combined with a laser diode and liquid-crystal devices. It operates in transmission mode.