Abstract: If surface defects, near surface defects, or internal defects of a ferromagnetic substance object, a paramagnetic substance object, or a mixture object of ferromagnetic and paramagnetic substances are not quantitatively analyzed, the detected results can be differently analyzed depending on the knowledge or skill of an inspector. A defect detection apparatus according to an exemplary embodiment of the present invention includes an induced current applier, a magneto-electric converter, a signal processor, a signal converter, and a data processor. The induced current applier applies a line or surface current to an object that is to be measured by using an alternating current (AC) having a frequency varying depending on a depth to be measured. The magneto-electric converter senses a magnetic field generated from the object by the Hn e or surface current and generates a magnetic field sensing signal corresponding to a strength of the sensed magnetic field.

Abstract: If surface defects, near surface defects, or internal defects of a ferromagnetic substance object, a paramagnetic substance object, or a mixture object of ferromagnetic and paramagnetic substances are not quantitatively analyzed, the detected results can be differently analyzed depending on the knowledge or skill of an inspector. A defect detection apparatus according to an exemplary embodiment of the present invention includes an induced current applier, a magneto-electric converter, a signal processor, a signal converter, and a data processor. The induced current applier applies a line or surface current to an object that is to be measured by using an alternating current (AC) having a frequency varying depending on a depth to be measured. The magneto-electric converter senses a magnetic field generated from the object by the Hn e or surface current and generates a magnetic field sensing signal corresponding to a strength of the sensed magnetic field.