Nonlinear imaging techniques as non-destructive, high-resolution diagnostic tools for cultural heritage studies

Filippidis, George; Tserevelakis, George J.; Selimis, Alexandros; Fotakis, C.

doi:10.1007/s00339-014-8357-8

Cited by 30 publications

(30 citation statements)

References 20 publications

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“…In biomedical researches, SHG microscopy has emerged as a powerful technique to quantify collagen 3D organization in tissues, in particular in skin dermis 11,12 . NLO microscopy has recently been applied to the field of cultural heritage [13][14][15][16][17][18] but never to examine collagen-based objects. Nevertheless, this technique cannot resolve nanometer structural features of collagen and the image interpretation may be difficult on materials.…”

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confidence: 99%

Correlative nonlinear optical microscopy and infrared nanoscopy reveals collagen degradation in altered parchments

Robinet

Dazzi

Portier

et al. 2016

European Microscopy Congress 2016: Proceedings

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This paper presents the correlative imaging of collagen denaturation by nonlinear optical microscopy (NLO) and nanoscale infrared (IR) spectroscopy to obtain morphological and chemical information at different length scales. Such multiscale correlated measurements are applied to the investigation of ancient parchments, which are mainly composed of dermal fibrillar collagen. The main issue is to characterize gelatinization, the ultimate and irreversible alteration corresponding to collagen denaturation to gelatin, which may also occur in biological tissues. Key information about collagen and gelatin signatures is obtained in parchments and assessed by characterizing the denaturation of pure collagen reference samples. A new absorbing band is observed near the amide I band in the IR spectra, correlated to the onset of fluorescence signals in NLO images. Meanwhile, a strong decrease is observed in Second Harmonic signals, which are a structural probe of the fibrillar organization of the collagen at the micrometer scale. NLO microscopy therefore appears as a powerful tool to reveal collagen degradation in a non-invasive way. It should provide a relevant method to assess or monitor the condition of collagen-based materials in museum and archival collections and opens avenues for a broad range of applications regarding this widespread biological material.In museums, libraries and archives, skin is largely present in collections as rawhide, parchment or leather since it has been used for utilitarian purposes, for example in clothes, vessels, writing supports and musical instruments or for decorative purposes. In Western Europe, parchment was the main writing support in the Middle Ages up to the growth of paper production in the 14-15 th centuries. Made from an untanned animal skin, it was preserved by liming, scraping and drying the skin under tension 1 . Compared to skin, parchment retains only the dermis layer, made mostly of fibrillar collagen (type I).Among conservators and scientists involved in the preservation of cultural heritage, gelatinization is a term commonly used for parchment alteration. It refers to the collagen denaturation to gelatin, where the triple helix is dissociated. Nevertheless, little is known about the actual transformation process in parchments and the influencing factors. UV radiation, heat or pH can cause perturbations in the bonding within and in-between collagen molecules but this might not be apparent unless water comes into contact with the material. In such a damaged structure, called a "pre-gelatinized" state, the access of water to the collagen molecules is considered to cause the loss of the hydrogen bonds holding the triple helix, resulting in the unfolding of the molecule. The gelatinization resulting from the action of water is accelerated by the additional energy provided by heating 2,3 . Given that gelatinization is irreversible, the major challenge for the conservation of parchment is to identify collagen in the "pre-gelatinized" state 2,3 so that suitable treatments or cons...

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mentioning

confidence: 99%

Correlative nonlinear optical microscopy and infrared nanoscopy reveals collagen degradation in altered parchments

Robinet

Dazzi

Portier

et al. 2016

European Microscopy Congress 2016: Proceedings

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“…These techniques under different modalities provide new insights for the assessment of appropriate conservation methods that have to be applied for various CH objects of high artistic or cultural significance [79,115]. Recent studies have demonstrated the potential of these techniques for depth resolved imaging of materials in cultural heritage, such as varnishes [79], lining glues [80,81], paintings [75], historical coatings [82], and corrosion layers on metal-based artifacts [84]. Fruitful key information concerning the determination of the different layers, precise thickness or surface topography, nature of the different materials, and cracks in the layers has been extracted.…”

Section: Non-linear Microscopymentioning

confidence: 99%

Non-Linear Microscopy: A Well-Established Technique for Biological Applications towards Serving as a Diagnostic Tool for in situ Cultural Heritage Studies

Mari

Filippidis

2020

Sustainability

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A range of sophisticated imaging techniques have been developed in recent years that can reveal the surface structure of cultural heritage objects with varying precision. In combination with various spectroscopic methods, they allow the study of the chemical composition of the object; thus, conclusions can be drawn about the origin of the object or its initial components, method, or time of creation, authenticity, mechanisms of degradation, and ways of further conservation. At present, different techniques can be applied to a wide range of cultural heritage objects, such as varnishes, paintings, archaeological objects, binding media, paper-based documents, parchments, marbles, frescoes, as well as various objects made of leather, fabric, stone, ceramics and glass, wood, or metal. One of the main needs in the study of cultural heritage (CH) is the transportability/portability of the research equipment, since many pieces under investigation cannot be moved to the laboratory, either because of their size, inseparability (for example, frescoes on walls, mural paintings in caves), or the threat of damage. In this work, we briefly overview the main optical- and laser-based methods used for the study of cultural heritage objects indicating the scope of their application, and we focus on the applications of non-linear microscopic methods for the investigation of a series of artifacts. We also discuss all the requirements for the construction of a prototype transportable non-linear optical system that will be used as a novel diagnostic tool for in situ studies of CH assets. The availability of such a transportable workstation will significantly improve the study and characterization of various types of CH objects and will constitute an extremely useful diagnostic tool for heritage scientists dealing with a variety of investigations.

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“…On the other hand, THG allows to resolve transparent interfaces, on the basis of local differences in refractive index and dispersion [8]. In Two-Photon-Excited Fluorescence (TPEF) the detection of fluorescence emitted after the simultaneous absorption of two infrared photons [9] yields to the identification of chromophores. Finally, fluorescence lifetime imaging microscopy (FLIM) measures time-decay of the fluorescence intensity exhibited by fluorescent emitting molecules [10], yielding information on the molecular microenvironment of a molecule and on its energy exchanges.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear optical imaging techniques (NLO) for painting investigation

Fovo¹,

Fontana²,

Striová³

et al. 2017

Proceedings of the International Conference LACONA XI

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Nonlinear optical imaging techniques (NLO imaging), i.e. multiphoton excitation fluorescence (MPEF), second and third harmonic generation (SHG, THG), are high-resolution imaging modalities which may provide non-destructive determination of thickness and composition within multi-layer objects as a function of depth. NLO techniques have been recently introduced into artworks analyses, giving promising results. As regards paintings, the guiding idea is to exploit the low absorption in the near-infrared (NIR) of most materials, using a laser light in this spectral region which may generate non-linear interactions within materials. The objective is to make feasible the in-depth profiling of thin films on the basis of refractive index changes, variation of optical activity and presence of fluorophores. Such information is definitely useful for the analysis of painted objects and can be also crucial for the monitoring of restoring operations. In this study, we present the preliminary results obtained through the application of NLO imaging techniques on a series of single-and multi-layers systems simulating real egg-tempera wood panel paintings. This research is part of the wider Iperion CH Project, whose WP6 entails the evaluation of NLO-imaging to obtain highly resolved en-face and 3D images of small areas on paintings. To that purpose, a set of multi-layer painted samples, simulating real paintings, was designed and realized. They are currently under analysis with different operating systems and modalities within the partnership. In order to assess the reliability of NLO measurements, data were complemented with other well-established techniques, such as Fourier Transform Infrared Spectroscopy (FTIR) and X-Ray Fluorescence (XRF) for the chemical characterization of materials, Optical Coherence Tomography (OCT) for the determination of layers thickness and laser scanning micro-profilometry for the study of surface morphology. In addition, colorimetric analyses, i.e. reflectance spectroscopy in the visible region, were performed in order to chromatically characterize pigments and lakes. Finally, the transparency of the different materials was investigated by means of Scanning Multispectral VIS-NIR Reflectography. The preliminary results suggest that the 740 nm wavelength, while enabling the visualization of the painting surfaces micromorphology, is not effective for the determination of thickness through the detection of the non-linear signals.

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Nonlinear imaging techniques as non-destructive, high-resolution diagnostic tools for cultural heritage studies

Cited by 30 publications

References 20 publications

Correlative nonlinear optical microscopy and infrared nanoscopy reveals collagen degradation in altered parchments

Correlative nonlinear optical microscopy and infrared nanoscopy reveals collagen degradation in altered parchments

Non-Linear Microscopy: A Well-Established Technique for Biological Applications towards Serving as a Diagnostic Tool for in situ Cultural Heritage Studies

Nonlinear optical imaging techniques (NLO) for painting investigation

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