The inverse problems of eddy current nondestructive evaluation are reviewed and the techniques that have been used to find solutions are described. As well as considering the theory of flaw reconstruction, including the determination of crack shape from eddy current data, the status of the one-dimensional eddy current inverse "problem is discussed. The emphasis throughout is on inversion schemes that are capable of giving quantitative estimates of the material properties or the dimensions of flaws or structural features from a set of observations. The account of what has already been achieved is supplemented by an attempt to indicate the direction of future developments in the hope that this may assist researchers to choose fruitful paths of enquiry.
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