Nowadays, there is an increased demand to develop alternative non-plastic packaging to be used in the food industry. The most popular biodegradable films are cellulose and poly(lactic acid) (PLA); however, there is still the need to increase their UV absorption to protect the packaging content. In this work, we have covered those biodegradable films with thin coatings based on carbon dots (CDs) dispersed in polyvinyl alcohol (PVA) deposited by spin- or spray-coating techniques. We report a strong increase in the UV light-absorbing properties, together with a detailed morphological characterization; moreover, we show the results of a new microscopy and spectral imaging technique applied to the coated samples. The scientific and technological novelty of this approach is the possibility of characterizing large areas of the material surface by the simultaneous detection of PL spectra in all the pixels of a highly spatially-resolved two-dimensional (2D) map of the surface. We report UV-excited PL maps whose detailed information allows us to clearly identify regions with different spectral behaviors and to compare their characteristic signals for different CDs:PVA deposition techniques.

Scientific investigation in the cultural heritage field is generally aimed at the characterization of the constituent materials and the conservation status of artworks. Since the 1990s, reflectance spectral imaging proved able to map pigments, reveal hidden details and evaluate the presence of restorations in paintings. Over the past two decades, hyperspectral imaging has further improved our understanding of paints and of its changes in time. In this work, we present an innovative hyperspectral camera, based on the Fourier transform approach, utilising an ultra-stable interferometer and we describe its advantages and drawbacks with respect to the commonly used line- and spectral-scanning methods. To mitigate the weaknesses of the Fourier transform hyperspectral imaging, we propose a strategy based on the virtual extension of the dynamic range of the camera and on the design of an illumination system with a balanced emission throughout the spectral range of interest. The hyperspectral camera was employed for the analysis of a painting from the “Album of Nasir al-din Shah”. By applying analysis routines based on supervised spectral unmixing, we demonstrate the effectiveness of our camera for pigment mapping. This work shows how the proposed hyperspectral imaging camera based on the Fourier transform is a promising technique for robust and compact in situ investigation of artistic objects in conditions compatible with museum and archaeological sites. Graphic

SignificanceHyperspectral imaging (HSI) is a promising real-time, non-invasive, non-ionizing optical imaging technique. In surgical oncology, HSI can capture both structural and functional tissue information, allowing the characterization of tumor lesions both intraoperatively and on a histopathological level.AimWe review the latest technological and clinical advancements of HSI as a guidance tool for tumor resection.ApproachFollowing the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we systematically searched MEDLINE, Embase, and Web of Science using logical keyword combinations related to “hyperspectral imaging” and “surgical oncology.” Eighty-five articles published between January 1, 2014, and April 30, 2024, were selected based on predefined inclusion and exclusion criteria. Technical and clinical data were extracted and analyzed.ResultsThe reviewed studies include preclinical and clinical investigations involving various tumor models and 2163 patients, including 24 pediatric cases. HSI has demonstrated broad applicability across various anatomical regions in both ex vivo and in vivo settings, with its most valuable application being tumor tissue delineation.ConclusionsHSI remains in its early technological stages, requiring high-quality evidence and multidisciplinary collaboration to support clinical adoption. A deeper understanding and improved characterization of biological tissue hyperspectral properties are essential to better inform and orient future hardware and software designs.

Raman microscopy is a powerful technique to determine the chemical composition of a sample. The main challenge of the state-of-the-art spontaneous Raman microscopes, based on point-scanning frequency-domain detection, is the acquisition of Raman maps of large areas due to typically long pixel dwell times (0.1-1 s). The wide-field Fourier-transform (FT) microscope presented here allows rapid measurement of extended samples with ~1-µm spatial and ~23-cm-1 spectral resolution. It is based on an ultra-stable and compact common-path birefringent interferometer, added along the detection path of a commercial microscope, which enables the parallel acquisition of spectra for all pixels of a 2D detector, significantly reducing the measurement time (10-100x faster). The time-domain approach effectively addresses another limitation of the frequency-domain technique, which is disentangling the Raman signal from the photoluminescence background, in which the Raman signal may be buried. This protocol describes how to perform hyperspectral measurements with an upgraded commercial microscope: the alignment of the illumination scheme, the criteria to choose measurement parameters, and the data analysis to retrieve and investigate spectra.

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.