| 摘要 |
PURPOSE:To perform the measurement of a flaw dimension with good accuracy, by applying frequency analysis to the time difference of the surface echo and flaw echo from the surface of a material to be inspected. CONSTITUTION:When the ultrasonic oscillation pulse T from the vibrator 2 in a probe 1 is allowed to be incident to the surface of a material to be inspected, said pulse T is reflected not only from a flaw 4 to generate a flaw echo F but also from the surface 31 of the material to be inspected to generate a surface echo S and both echoes are received by a vibrator 2. Signals of the oscillation pulse T, the surface echo S and the flaw echo F are also inputted to an oscilloscope 8. The signals of the surface echo S and the flaw echo F are taken out from the signals inputted to a gate circuit 7 and the time different t2 of both echoes is processed by a frequency analyser 9. The signals from the circuit 7 are simultaneously inputted to an ultrasonic frequency interval measuring circuit 10 where the frequency interval of the max. value in a frequency spectrum is measured and a flaw dimension d1 is calculated by a flaw dimension operation circuit 11. |
