Hall sensor arrays for rapid large-area transient eddy current inspection

There is an ongoing requirement for scanning large areas of metallic structures to detect and characterise small defects. This has led to the development of a new type of eddy current probe that incorporates a sparse linear array of Hall sensors. This probe has been evaluated with the TRECSCAN((R)) system using transient excitation. It is shown that coherent images of defects can be formed with notable reductions in inspection time. Although the inherent resolution of the probe is not high, it can rapidly scan large areas that are relatively featureless. When a feature requires more detail, repeated over-scanning produces an image with as much resolution as required.