| 摘要 |
PROBLEM TO BE SOLVED: To shorten the time required for obtaining a three-dimensional image in a nondestructive inspection for inspecting defects through the use of a highly sensitive magnetic sensor. SOLUTION: A saw-tooth wave generating device 6 generates an electric signal of saw-tooth waveform containing modes of a large number of different frequency components from a low frequency to a high frequency and outputs the electric signal to an exciting coil 5. A magnetic field generated from an eddy current induced to a sample is measured by a highly sensitive magnetic sensor (SQUID flux meter 1). By performing FET on a time-domain signal value of the magnetic field obtained by the measurement, a frequency-domain signal value is obtained and stored in a storage part of a computer 4. The frequency-domain signal value of the magnetic field is stored as a function of a location on the sample. From the stored signal value, the three-dimensional image of a defect present in the sample is obtained by software, etc.
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