Patent ID: 8890517

Claim:
An eddy current measuring sensor comprising a probe configured in regular polygon, the probe comprising an excitation unit for applying a predetermined alternating current excitation signal to an object to be measured and a detection unit for detecting a detection signal generated in the object in response to the alternating current excitation signal, wherein the excitation unit comprises multiple exciting coils arranged along the each side of the probe, wherein the detection unit comprises multiple detection coils arranged at the each vertex of the probe, wherein locating the probe in the proximity of the object, an alternating voltage as the excitation signal is applied to at least one of the exciting coils, whereby a magnetic field is produced at a portion of the object facing the detection coil and an eddy current is generated by the magnetic field, wherein an inductive voltage generated by the eddy current is detected as the detection signal by means of at least one of the detection coils, whereby the eddy current measuring is performed on a basis of the detection signal, and the detection unit further comprises a balance coil arranged at the center of the probe for cancelling the electromotive forces generated by the detection coils.