Holographic Principles Applied To Low Frequency Electromagnetic Imaging In Conductors

B. P. Hildebrand; A. J. Boland; T. J. Davis

doi:10.1117/12.936127

15 April 1983 Holographic Principles Applied To Low Frequency Electromagnetic Imaging In Conductors

B. P. Hildebrand, A. J. Boland, T. J. Davis

Proceedings Volume 0422, 10th Intl Optical Computing Conf; (1983) https://doi.org/10.1117/12.936127
Event: 10th International Optical Computing Conference, 1983, Cambridge, United States

Abstract

Low frequency electromagnetic methods for non-destructive testing have been interpreted in terms of the eddy current or inductive phenomenon. In this scenario the flaw distorts the flow of eddy currents, which in turn, results in a change of impedance of the sensing coil. This change of complex impedance can be analyzed in terms of phase an amplitude, and inferences about the depth and size of the flaw made by observing the impedance plane plot on an oscilloscope as the coil is scanned across the flaw. A great deal of operator experience is required, although attempts at automating the decision making process have recently been made. In this paper we explore an alternate view-point; that the change in sensing coil impedance is due to the interference of a reflected electromag-netic wave (by the flaw) with the outgoing wave. This allows us to utilize those properties of wave theory which form the basis for holographic imaging. In this paper we show theoretically and experimentally that such is indeed the case.

Citation Download Citation

B. P. Hildebrand, A. J. Boland, and T. J. Davis "Holographic Principles Applied To Low Frequency Electromagnetic Imaging In Conductors", Proc. SPIE 0422, 10th Intl Optical Computing Conf, (15 April 1983); https://doi.org/10.1117/12.936127

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