Conference Agenda

Hyperspectral imaging (HSI) is a very powerful tool to study artworks in a non-contact way. Nevertheless, typical HSI systems, which rely on spatial-scanning and dispersive spectrometers, suffer from high-light losses and are difficult to operate for analysing complex artworks. Here we review the capabilities of a HSI system based on TWINS, an innovative Fourier Tranform (FT) spectrometer, which allows wide-field imaging. We demonstrate how, by coupling the TWINS to different imaging systems, it is possible to achieve multi-scalar configurations from very large field-of-view (FOV) acquisition to microscopy. Further, we show how the high-collection throughput of the device allows for the sequential and fast detection of multi-modal signals’, as diffuse reflectance, transmittance, photoluminescence (PL) and Raman.

The characterization of deterioration processes in wooden artifacts is crucial for assessing their state of conservation and ensuring their preservation. Advanced imaging techniques are currently being explored to study the effect of chemical changes on the structural and mechanical properties of wood. Combined second harmonic generation and two-photon excited fluorescence (SHG/TPEF) imaging is a recently introduced non-destructive method for the analysis of cellulose-based samples. The study of age-related wood degradation based on nonlinear signal variation is a promising avenue. This work involves nonlinear multimodal analysis of naturally aged and dendrochronologically dated spruce samples. SHG/TPEF imaging and fluorescence lifetime imaging microscopy (FLIM) were used to demonstrate the influence of molecular deterioration and rearrangement of biopolymers on the fluorescence emitted by lignin and the second harmonic signal generated by cellulose. Imaging based on spectral filter detection and time-resolved analysis of the nonlinear fluorescence signal was used to delineate and potentially quantify ageing-induced morpho-chemical changes in the ultrastructure of wood cells. The analysis of cell structures by optical sectioning revealed variations between wood samples of different ages and different cell structures.

This work introduces a novel method to multivariate analysis applied to fused hyperspectral datasets in the field of Cultural Heritage (CH). Hyperspectral Imaging is a well-established approach for the non-invasive examination of artworks, offering insights into their composition and conservation status. In CH field, a combination of hyperspectral techniques is usually employed to reach a comprehensive understanding of the artwork. To deal with hyperspectral data, multivariate statistical methods are essential due to the complexity of the data. The process involves factorizing the data matrix to highlight components and reduce dimensionality, with techniques such as Non-negative Matrix Factorization (NMF) gaining prominence. To maximize the synergies between multimodal datasets, the fusion of hyperspectral datasets can be coupled with multivariate analysis, with potential applications in CH. In this work, I will show examples of this approach with different combinations of datasets, including reflectance and transmittance spectral imaging, Fluorescence Lifetime Imaging and Time-Gated Hyperspectral Imaging, and Raman and fluorescence spectroscopy micro-mapping.

The discovery of the Herculaneum papyri in the 18th century at the Villa dei Papiri has captivated scholars due to their preservation from the 79 A.D. eruption of Vesuvius and their rich historical content. These papyri, containing knowledge from Greek philosophical schools, present significant challenges for readability and interpretation due to their carbonized condition. The ERC Advanced Grant “GreekSchools” project aims to develop new protocols using optical methods to enhance text analysis, facilitating a new critical edition of Philodemus’ "Arrangement of the Philosophers." To uncover hidden texts and locate overlapping layers, we employ advanced non-invasive techniques across various spectral regions, including Macro X-Ray Fluorescence Imaging (MA-XRF), Shortwave-Infrared Hyperspectral Imaging (SWIR HSI), technical photography in the visible (VIS), ultraviolet (UV), and infrared (IR) regions and high-resolution digital microscopy in the VIS and NIR. This contribution compares various acquisition methods and image processing techniques in the NIR and SWIR regions to enhance the visualization of the writing patterns.

Throughout the 20th Century, plastics found extensive use in fashion, art, and design due to their versatile nature. However, their degradation over time poses challenges, impacting material integrity, particularly in museum collections. To tackle this issue, different scientific techniques have been employed to study polymers. In this work, a complementary multi-analytical approach is proposed to investigate the light stability of ABS compounds, selecting LEGO® bricks as reference material. The method is based on fluorescence emission and lifetime integrating point-like analysis and imaging systems to corroborate chemical and spatial information specifically addressed at the surface level. The latter has shown promising results in studying ABS objects, offering insights into degradation and aiding conservation efforts.