Thermographic nondestructive evaluation: overview of recent progress

This paper presents a summary of recent research activities carried out at our laboratory in the field of Infrared Thermography for Nondestructive Evaluation (TNDE). First, we explore the latest developments in signal improvement. We describe three approaches: multiple pulse stimulation [1]; the use of Synthetic Data for de-noising of the signal [2]; and a new approach derived from the Fourier diffusion equation called the Differentiated Absolute Contrast method (DAC) [3]. Secondly, we examine the advances carried out in inverse solutions. We describe the use of the Wavelet Transform [4] to manage pulsed thermographic data, and we present a summary on Neural Networks for TNDE [5]. Finally, we look at the problem of complex geometry inspection. In this case, due to surface shape, heat variations might be incorrectly identified as flaws. We describe the Shape-from-Heating approach [6] and we propose some potential research avenues to deal with this problem.