Square pulse thermography in frequency domain as adaptation of pulsed phase thermography for qualitative and quantitative applications in cultural heritage and civil engineering

Holographic Interferometry (HI), Infrared Vision and X-Ray Fluorescence (XRF) spectroscopy for the assessment of painted wooden statues: a new integrated approach

“…The integration of near-infrared (NIR) reflectography [7], square pulse thermography (SPT) [8], holographic contouring [9] and sandwich holography (SH) [10] techniques have been used for the non-destructive testing (NDT) of the wooden statue. An unusual fringes pattern appeared over the area covered by the nose, mouth and chin of the Child.…”

“…In the square pulse configuration [8], [51], the specimen surface is submitted to a long pulse (from a few seconds to several minutes), and the temperature rise and decay is registered using an infrared camera and stored as a 3D matrix composed by N thermograms, where x and y are the spatial coordinates, and t is the time.…”

Non-destructive testing of works of art by stimulated by infrared thermography: PPT interest

“…In this work, we aim to reduce this disadvantage. With this objective, we have associated a PPT analyze (Pulse Phase Thermography [55][56][57][58][59][60][61][62][63][64]) to the stimulated infrared thermography. Indeed, we believe that this disruptive optical effect is rather of energy nature while those due to the presence of defects are also of temporal nature.…”

Experimental IRT applications in building elements with 3D thin defects

“…The interpretation of phase contrast curves (representation of phase contrast in the frequency spectrum) enables the quantitative characterization of defects. Namely, defect depth retrieval techniques based on phase contrast curves by relating the defect's depth with the blind frequency (frequency at which the defect is no longer visible in terms of phase contrast images) or with the characteristic frequency (frequency at which the defect is most visible in terms of phase contrast images) have been proposed by authors [3], [4].…”

“…It has been suggested that pulse phase thermography, which is a combination of pulse thermography and lockin thermography, may be the most suited technique for Civil Engineering applications, since it allows enhanced defect detectability, better definition of the defect's geometry and inspections at greater depths [4]. For many years, the majority of thermographic studies in buildings have been performed with the buildings in their natural state, without making use of active IRT, and have been focused on evaluating energy efficiency and performing a qualitative assessment of the building envelope [5].…”