| 摘要 |
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. The signal processor filters and amplifies the magnetic field sensing signal and outputs a signal corresponding to amplitude of the filtered and amplified signal. The signal converter converts the signal output from the signal processor into a digital signal. The data processor quantitatively converts an intensity of a magnetic field generated from the object into a numerical value based on the digital signal output from the signal converter. |
