Lockin and burst-phase induction thermography for NDE

Eddy current activated thermography uses resistive losses inside the sample for heating. This heating is done in a modulated way (Induction-Lockin-Thermography: ILT) or as a burst with a subsequent Fourier transformation of the temperature image sequence (Induction-Burst-Phase thermography: IBP). The phase evaluation of ILT and IBP has significant advantages as compared to inductive heating with visual inspection of the thermographic sequence: Phase angle images are independent of most artefacts like reflections, variation in emission coefficient, or inhomogeneous heating. Also the signal-tonoise ratio in the amplitude and phase images is significantly better than in single temperature images.