Photoinductive imaging is a unique dual-mode NDE technique that combines eddy current and thermal wave methods. The photoinductive effect, upon which this method is based, is the thermally induced change in the impedance of an eddy current probe in proximity to a conducting surface that is illuminated with a modulated light source. The change in probe impedance is caused by the temperature-induced change in the conductivity of the specimen. Typical changes in probe impedance are small, on the order of a few ppm, but because they are synchronous with the light-beam modulation, lock-in techniques can be used to detect the signals, which can then be used to image surface or near-surface defects, voids, inclusions, or other thermal or structural inhomogeneities