High-Resolution Thermal-Wave Imaging Using the Photoinductive Effect
Photoinductive imaging is a newly devised technique for photothermal imaging based on eddy-current detection of thermal waves . Thermal waves produce a localized modulation in the specimen’s electrical conductivity, which can be detected by its effect on the impedance of a nearby eddy-current coil. This photoinductive effect can be used to image surface or near-surface cracks, voids, or inclusions. The method is limited in practice to conducting specimens, but it can be used to inspect thin, nonconducting coatings on metallic substrates, as we demonstrate here. One promising feature of photoinductive imaging is its potential for high resolution, especially when compared with the resolution possible with eddy-current probes alone. The objective of the present study was to exploit the high resolution capability inherent in this technique by adapting a photoinductive sensor developed for a fiber optic probe  to an existing photoacoustic microscope. In this paper we explore using this technique for typical applications in nondestructive evaluation.
KeywordsFatigue Crack Thermal Wave Fiber Optic Probe Magnitude Image Photoinductive Phase
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- 2.J. C. Moulder, M. W. Kubovich, J. M. Mann, M. S. Hughes, and N. Nakagawa, “Applications of Photoinductive Imaging,” this volume.Google Scholar