Terahertz imaging

Terahertz (THz) spectroscopy and imaging is a non-destructive, non-contact, non-invasive technology emerging as a tool for the analysis of cultural heritage. THz Time-Domain Spectroscopy (TDS) techniques have the ability to retrieve information from different layers within a stratified sample. The most explored topics particularly using time-domain terahertz systems include stratigraphic examinations of wood panel paintings and plaster-covered wall paintings. However, investigations have expanded to include terahertz imaging of ceramic vessels, corroded metal objects and papyrus sheets. The data can be displayed through a series of parametric images mapping the imaging area with different arguments as parameters (maximum/minimum amplitude, peak to peak, frequency integration etc.) or as a cross-section. In this case, if no sample of the wall material is taken, an assumption must be made on the nature of the material constituting the under-layer to determine the thickness and approximate depth location of the different layers.