NDT inspection of plastered mosaics by means of transient thermography and holographic interferometry

In this research work, experimental procedures by means of Transient Thermography and Holographic Interferometry were performed in order to detect subsurface tesserae areas of plastered mosaics. A mosaic sample consisted of various types of tesserae and covered with hydraulic lime mortar was evaluated in the laboratory with various transient thermal processing techniques such as Pulsed Phase Thermography, Thermographic Signal Reconstruction and Principal Component Thermography, as well as Holographic Interferometry in both real-time and double-exposure configurations. Results from the non-invasive investigation are presented and discussed, revealing that the above approaches can obtain a seeing through investigation of plastered mosaics.

► A plastered mosaic was tested by various thermographic and interferometric methods.
► Pulsed thermographic inspection was performed by means of PPT, TSR and PCT.
► Interferometric test was performed in Real Time and Double Exposure configurations.
► Subsurface tesserae areas and their borders were possible to be detected.
► Above techniques combination can be used as a diagnostic NDT tool.