Multimodal optical approach for cultural heritage characterisation: 3D scanning and spectral mapping techniques

In recent years, an increasing number of advanced instruments has been employed for the scientific investigation of cultural heritage artefacts, triggering the development of sophisticated processing tools for data analysis. The growing complexity and diversity of materials, along with the need for non-invasive and highly accurate measurement techniques, have driven significant advancements in optical metrology. This field now plays a crucial role in developing innovative solutions that combine precision, efficiency, and adaptability to diverse challenges in the documentation, conservation, and restoration of cultural heritage. A robust methodology for the detailed morphologic and compositional characterization across extensive surface areas relies on the combination of 3D surface scanning and chemical mapping techniques. This approach provides a multi-scale understanding of artefacts, capturing both topographical and chemical features critical for conservation and restoration purposes. Among the various optical methods and instruments developed at the National Institute of Optics (CNR-INO, Florence, Italy), macro-Raman mapping has proven to be a valuable tool for spatially resolved chemical analysis. The coupling of spectral mapping with tailored 3D-scanning technologies not only enhances the spatial registration of chemical data but also facilitates the correlation with other optical modalities, such as multispectral and hyperspectral imaging. These integrated methodologies contribute to a more comprehensive and data-driven approach to cultural heritage diagnostics, enabling tailored conservation strategies that consider the characteristics and complexity of artefacts. Here, we demonstrate how such multimodal, hardware-registered data, when further processed using advanced univariate analytical methods, provide comprehensive insights into the material composition and degradation processes of cultural heritage objects.