The Complex Wavelet Transform is applied to analyse thermographic data (in a similar way as the ‘classical’ Fourier transform but with the advantage of preserving time information of the signal). This information can be correlated e.g. to defect depth, allowing a quantitative evaluation of defects. Based on these results we determine the ‘phase velocity’ of thermal diffusion waves by application of Complex Wavelets (dispersion relation).
The acquisition system represents a combination of a thermal imaging system and a 3D surface measurement. It will link the depth information and the color image of a low-cost sensor with the information of a thermography camera to support and extend the non-destrutive testing method.