An Experimental Study on the Defect Detectability of Time- and Frequency-Domain Analyses for Flash Thermography

A defect’s detectability in flash thermography is highly dependent on the applied post-processing methodology. The majority of the existing analysis techniques operate either on the time-temperature data or on the frequency-phase data. In this paper, we compare the efficiency of time- and frequency-domain analysis techniques in flash thermography for obtaining good defect detectability. Both single-bin and integrated-bin evaluation procedures are considered: dynamic thermal tomography and thermal signal area for the time-domain approach, and frequency domain tomography and adaptive spectral band integration for the frequency-domain approach. The techniques are applied on various carbon fiber reinforced polymer samples having a range of defect sizes and defect types. The advantages and drawbacks of the different post-processing techniques are evaluated and discussed. The best defect detectability is achieved using the integrated procedure in frequency domain.

New methods for art object conservation and restoration – practical experience in the field: the experience of The True Image Solution Ltd

Previously, scientific examination of works of art was almost exclusively carried out in a specialist laboratory, major gallery or institution. Moving the artwork nearly always involved associated risks and transportation and insurance costs. Founded in 2009, The True Image Solution (TIS) had a vision to bring non-destructive technology to the artwork and to extend the possible range of evaluation by applying other imaging techniques, including ultrasound, flash thermography, X-ray spectroscopy and microwave imaging. In conjunction with English Heritage, these techniques were applied to a wide variety of objects. The results demonstrated that all of these techniques could be successfully carried out in situ and the risk of transportation damage, as well as associated transport and insurance costs, could be eliminated.

Flash Thermography Mapping of Degradation Patterns in Archaeological Glass

The process of degradation in artefacts subjected to centuries of burial can be of great relevance above all in archaeological glass. Infrared thermography is a non-destructive method allowing to map the defects of the glass substrate, both produced during its manufacturing (e.g., bubbles and inclusions) and due to ageing. This research is focused on the use of different flash thermography methods for the mapping of superficial flakes on Roman glasses dating back to the I and II century A.D. The effectiveness of active thermography methods is evaluated to map degraded portions of archaeological glass considering their semitransparency and specific optical absorption.