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Liftoff Correction Based on the Spatial Spectral Behavior of Eddy-Current Images

Ribeiro, A. L. ; Alegria, F. ; Postolache, O. ; Ramos, H.

IEEE Trans. on Instrumentation and Measurement Vol. 59, Nº 5, pp. 1362 - 1367, May, 2010.

ISSN (print): 0018-9456
ISSN (online): 0018-9456

Journal Impact Factor: 1,790 (in 2014)

Digital Object Identifier: 10.1109/TIM.2010.2043981

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Abstract
In this paper a new processing scheme to compensate the liftoff effect is proposed to increase the SNR of measurements carried out when a duralumin plate with artificially manufactured defects was scanned with eddy current probes. The mathematical algorithm is based on the spatial frequency behavior of the output signals with the liftoff distance (distance between the probe used for inspection and the sample) and its equivalent form (deconvolution) in the spatial domain. Results are presented for measurements performed at three different distances for the same defect of the duralumin plate.