| 摘要 |
PURPOSE:To make a handling easy and to enable the measurement with high accuracy by removing the component of the ultrasonic beam around the center axis in a converging ultrasonic transducer and by making so as to draw an interference curve by the detected leak elastic surface wave signal. CONSTITUTION:The high frequency signal transmitted from a high frequency transmitter 18 excites a converging ultrasonic transducer 20 for transmission with a pulse modulation 19. On the other hand the electrical output of the converging ultrasonic transducer 24 of a leak elastic surface wave is subjected to a phase detection 23 with the high frequency signal branched from the transmitter 18 as the reference signal and the detected output is fed to an oscilloscope 11 as a display signal. And when the stand 5 holding the body to be inspected is moved to the direction vertical with the surface of the sample by a moving device 10 in the direction (z), the phase difference between the detecting signal of the leak elastic surface wave and the reference signal is changed gradually. Consequently the top of a peak is caused in case of the phase being the same and the root is caused in case of a reverse phase in the output of a phase detector 23 and the interference curve showing a periodical dip is drawn on the display face of the oscilloscope 11. The information only of the leak elastic wave of the sample can be extracted accordingly. |
