Reflection terahertz time-domain imaging for analysis of an 18th century neoclassical easel painting

In this study, the 18C easel painting The Dying Messalina and her Mother, by Nicolai Abildgaard (Statens Museum for Kunst collection, Copenhagen, Denmark), has been investigated by Terahertz Time-Domain Imaging (THz-TDI) in reflection set-up. Despite the validity of traditional deconvolution and denoising methods used to resolve temporal features of THz reflected signals, they result impractical if applied to large images analysis. Therefore, we presented a simple, fast and effective method to separate single THz pulses of interest from the entire signal recorded at each spatial coordinate of the acquired THz image. Interfaces between layers of the painting have been successfully imaged, contributing substantially to the understanding of the structure of the painting.