Abstract
Eddy current (EC) testing has been selected as a standard candidate for detecting defects in conductive materials in the past few decades. Nevertheless, inventing EC probes capable of detecting minor defects has always been challenging for researchers due to the tradeoff between the probe dimensions and the strength of the EC generated on the surface of the test piece. Here, we use a copper core with a sophisticated design to converge the rotating EC at the tip of the copper core to detect small cracks in all directions in conductive materials. In this method, we can arbitrarily accommodate a large excitation coil so that a larger rotating uniform EC is generated in a small area of the test piece. Hence, the probe can detect cracks in all directions in conductive materials.