1 Transfusion of Time - Domain and Frequency - Domain Eddy Current Signals

Conventional eddy current using single-frequency excitation has limited material characterization capabilities. Enrichment of the spectral information of the signal with techniques such as multifrequency or swept frequency inspection could be employed to improve the inspection process. Broadband excitation is also implemented with time-domain inspection using pulsed eddy current PEC. The spectrum of PEC however has decayed energy corresponding to higher frequencies. This paper addresses the implementation of a technique, termed transfusion; to fuse partial eddy current information obtained from measurements in the time domain with PEC with inspection results that could be available at fixed points in the frequency domain, obtained with conventional eddy current inspection. The technique is based on image fusion methods, in accordance with increased interest in c-scan representation of eddy current signals. The developed algorithm depends on packing multi-spectral and multi-temporal data into the values of color components of transfusion image. Further enhancement could be obtained by fusing this image with a high quality image of the object under test, which could be acquired using high frequency eddy current inspection or another NDE modality. Results based on the proposed technique, based on finite element simulation of eddy current inspection are presented, along with suggested image quality measures to test the spectral as well as spatial information of the transfusion image.