| 摘要 |
PURPOSE:To obtain the title apparatus improved in inspection efficiency and accuracy by forming a reference wave having the same frequency band as the reflected wave of the ultrasonic signal projected on a specimen and allowing the phases of both signals to coincide and mix to obtain output and detecting the level of the output. CONSTITUTION:An ultrasonic signal is generated from a burst wave generator 50 and applied to a probe 4 to generate an ultrasonic wave which is, in turn, projected on a specimen 3. The projected ultrasonic wave is reflected to be received by the probe 3 and enters a detector 13 and a mixer 15 as a reflected wave RS. A reference wave generator 12 inputs a reference wave having the same frequency band as the reflected wave RS to a phase shifter 14 and the shifter 14 allows the rising of a detection output signal to coincide with that of the reference wave. Since the reflected wave RS rises from a negative phase when a flaw is present in the specimen 3 to be inspected, the reflected wave RS is shifted by 180 deg. in phase from the reference wave after phase shifting and an output level becomes opposite to that in case of no flaw and, therefore, the output level is subjected to calculation processing by a CPU 18 to make it possible to display a judgement result and inspection can be automatically performed with high accuracy without relying on the visual check of an inspector. |
