What is a "lift-off correction" in Eddy Current Testing?

A "lift-off correction" in Eddy Current Testing refers to adjustments made to account for variations in the distance between the probe and the surface of the material being tested. This is crucial because changes in lift-off—a term used to describe the separation between the probe and the surface—can significantly affect the amplitude of the eddy current signals detected by the probe. If lift-off varies, it can lead to inaccurate readings, as the strength of the eddy currents can diminish with increased distance. By implementing lift-off corrections, technicians can ensure that the data obtained from the testing process accurately reflects the condition of the material, rather than the effects of distance variations. This correction is essential for maintaining the reliability and accuracy of the inspection results, especially in applications where precision is critical.