Figure 12From: Application of the topological derivative to post-processing infrared time-harmonic thermograms for defect detectionTopological derivative on \(\varGamma _{\mathrm{front}}\) combining three different lamp locations. Left: lamps linearly spaced along the z axis at a frequency of 2 Hz. Right: counterpart at 0.2 Hz. Combining different lamp locations is a great way to improve the reconstruction of several defects at the same time, but we still have to choose the adequate frequencyBack to article page