Multifrequency eddy current testing of steam generator tubes using optimal affine transformation

An alternative technique was developed for the implementation of multifrequency/multiparameter concepts for extracting defect signal information from complex measured eddy current data. The approach uses affine transformations which appropriately shape and rotate the basic frequency response similar to procedures used in image registration. Vector subtraction of the auxiliary frequency signals is then performed to obtain the relevant eddy current defect signal. The mathematics of the technique are discussed. The experimental setup for reactor steam generator tube imaging is described and results are graphed.