Abstract: An apparatus for detecting flaws using supersonic waves measures a thickness of a test object or a position of a cavity inside the test object by employing a pair of ultrasonic probes. By, changing a relative position of one ultrasonic probe to that of the other ultrasonic probe, a plurality of waveform data of ultrasonic reception signals is acquired. Each of the acquired waveform data is added together. Because a surface wave component of each waveform data has a shifted phase due to a difference in arrival times, a level of the surface wave component is offset and thus minimized through addition of the waveform data.

Abstract: An apparatus for detecting flaws using supersonic waves measures a thickness of a test object or a position of a cavity inside the test object by employing pair of ultrasonic probes. By changing a relative position of one ultrasonic probe to that of the other ultrasonic probe, a plurality of waveform data of ultrasonic reception signals is acquired. Each acquired waveform data is added per corresponding unit of time. Since a surface wave component of each waveform data has a shifted phase due to the difference in arrival time, a level of the surface wave component is offset and thus minimized through addition of the waveform data.

Abstract: An ultrasonic transducer is provided with an ultrasonic transmitter; an ultrasonic receiver; and a propagation-delay-time calculating device for calculating a propagation delay time from the time when an ultrasonic wave is transmitted by the transmitter until the time when the ultrasonic wave is received by the receiver.