Lift-Off Point of Intercept (LOI) Behavior

In Pulsed Eddy Current it was previously shown that there is a point where probe responses are independent of the lift‐off distance for a given material condition. It was effectively used previously to detect corrosion, cracks and map first and second layer defects independently of lift‐off variations. In this paper, the behavior of the LOI was investigated experimentally under a wide variety of conditions. The results show that the LOI points follow a unique curve for a given probe. The results also lead to a method of selecting a probe, based on its electrical properties, for a given pulsed eddy current inspection and evaluation.