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).
![](http://www.thermo-ndt.com/wordpress/wp-content/uploads/2018/01/Wavelet001-300x250.jpg)
![](http://www.thermo-ndt.com/wordpress/wp-content/uploads/2018/01/Wavelet002-300x227.jpg)