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The present study discusses the experimental physicochemical results obtained from the historical vaulted ceilings of an ancient church located in central Italy. Infrared thermography (IRT) in the active configuration was used to map subsurface defects caused by a seismic event and to discover buried structures, while the visible and near-infrared (VIS-NIR) fibreoptics diffuse reflectance spectroscopy (FORS) technique was applied to identify the pigments of wall paintings decorating the vault. Historical photographs are useful to readers in order to clarify the state of conservation before and after the earthquake that took place in 2009. The combination of the experimental results can be useful in restoration processes. [ABSTRACT FROM AUTHOR]

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Infrared (IR) reflectography has been used for many years for the detection of underdrawings on panel paintings. Advances in the fields of IR sensors and optics have impelled the wide spread use of IR reflectography by several recognized Art Museums and specialized laboratories around the World. The transparency or opacity of a painting is the result of a complex combination of the optical properties of the painting pigments and the underdrawing material, as well as the type of illumination source and the sensor characteristics. For this reason, recent researches have been directed towards the study of multispectral approaches that could provide simultaneous and complementary information of an artwork. The present work relies on non−simultaneous multispectral inspection using a set of detectors covering from the ultraviolet to the terahertz spectra. It is observed that underdrawings contrast increases with wavelength up to 1700 nm and, then, gradually decreases. In addition, it is shown that IR thermography, i.e., temperature maps or thermograms, could be used simultaneously as an alternative technique for the detection of underdrawings besides the detection of subsurface defects. [ABSTRACT FROM AUTHOR]

In this work, the combined effect of indentation damage and of manufacturing defects of a hybrid laminate including jute hessian cloth (plain weave) and hemp fibres in an epoxy matrix has been investigated. With this aim, various non-destructive evaluation (NDE) techniques have been employed, such as near-infrared (NIR) reflectography, infrared thermography (IRT), holographic interferometry (HI) and digital speckle photography (DSP). In particular, two different methods of heating were applied during IRT data collection: pulse thermography and square pulse thermography (SPT). The first one using a mid-wave infrared (IR) camera, while the second one using a long-wave IR camera. In the same way, two different cameras working into the near- and short-wave IR spectra were used, to compare different results from ∼ 0.74 to 14 μm. Data were processed applying principal component thermography (PCT), correlation and the robust second-order blind identification (SOBI-RO) algorithms. The latter is used for the first time to our knowledge in this work. The defects found were enhanced by image subtraction between the reflectogram and the transmittogram, distance transform and image fusion. In particular, data fusion from IRT and DPS images allowed clearly defining the extension of the indentation damage. [ABSTRACT FROM AUTHOR]

The increasing deterioration of panel paintings can be due to the physical processes that take place during exhibition or transit, or as a result of temperature and humidity fluctuations within a building, church or museum. In response to environmental alterations, a panel painting can expand or contract and a new equilibrium state is eventually reached. These adjustments, though, are usually accompanied by a change in shape in order to accommodate the new conditions. In this work, a holographic method for detecting detached regions and micro-cracks is described. Some of these defects are confirmed by the thermographic signal reconstruction (TSR) technique. In addition, pulsed phase thermography (PPT) and principal component thermography (PCT) allow two artificial defects in Mylar to be identified with greater contrast, which is crucial to understand the topic of interest: the discrimination between defect materials. Finally, traditional contact ultrasound applications are widely applied for the evaluation of the wood quality in several characterisation procedures. Inspecting the specimen from the front side, the natural and artificial defects of the specimen are confirmed. Experimental results derived by the application of the integrated methods on an Italian panel painting reproduction, called The Angel specimen, are presented. The main advantages that these techniques can offer to the conservation and restoration of artworks are emphasised. [ABSTRACT FROM AUTHOR]

In this paper, fundamental theory of the pulsed phase thermography (PPT) processing method is presented including notes on thermal waves, pulsed thermography and lockin thermography. Moreover, advances in signal inversion for PPT using wavelets are included along with discussions about pulse shaping and polynomial fitting for signal improvement (synthetic data). Results are presented as well. [Copyright &y& Elsevier]

Infrared thermography in nondestructive testing provides images (thermograms) in which zones of interest (defects) appear sometimes as subtle signatures. In this context, raw images are not often appropriate since most will be missed. In some other cases, what is needed is a quantitative analysis such as for defect detection and characterization. In this paper, presentation is made of various methods of data analysis required either at preprocessing and/or processing images. References from literature are provided for briefly discussed known methods while novelties are elaborated in more details within the text which include also experimental results. [Copyright &y& Elsevier]