| 摘要 |
Inspection apparatus utilises one or more probes (10) each comprising a coil (12) and associated ferritic core (14) in parallel with a capacitance (16) to form an LC circuit. This circuit (12, 14, 16) is driven by a square wave signal to produce a substantially sinusoidal output. Test piece defects are detected by examination of the harmonic content of the sine waveform, preferably the third harmonic. |
