| 摘要 |
PURPOSE:To improve the inspection accuracy by emitting simultaneously ultrasonic waves of plural sequences of each difference frequency, from a probe having plural vibrators of each different resonance frequency, receiving a reflected wave from a defect in a measuring object, bringing an output signal of a form which is superposed plural echo signals, to a frequency analysis, and detecting the defect. CONSTITUTION:When an ultrasonic wave of (3f/2) of a frequency (f), which is emitted from vibrators 3a, 3b is reflected by a defect 1a, it becomes a reflected wave having some band width centering around the frequency (f) (3f/2), and it is received mainly by the vibrators 3a, 3b, and received secondarily by the vibrators 3b, 3a. In such a way, an output signal S which is obtained in an output terminal of a pulser receiver unit 5 becomes a signal of a form which is superposed an echo signal Sa which is outputted from the vibrator 3a, and an echo signal Sb which is outputted from the vibrator 3b. The output signal S is supplied to a frequency analyzer 6, and converted to a frequency area from a time area. Subsequently, a data which has been converted to the frequency area is supplied to a data processing system 7, and the defect 1a is detected.
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