| 摘要 |
PROBLEM TO BE SOLVED: To calculate sonic speed V in a material by irradiating an ultrasonic wave into the material to detect the ultrasonic wave reflected with a reflecting plate as a delayed electric signal. SOLUTION: A longitudinal wave is irradiated into a material and reflected with a reflecting plate 7 when an input electric signal from a signal generator 4 is applied between a comblike electrode 2A and a facing electrode 3 in sequence. Then a distance Z<SB>i</SB>(i=1, 2,..., n) between one interface of the material and the other interface thereof is gradually controlled with a means 6 for controlling the distance, and the reflected longitudinal wave is detected as a delayed electric signal D<SB>i</SB>(i=1, 2,..., n) corresponding to the distance Z<SB>i</SB>(i=1, 2,..., n) between a comblike electrode 2B and the facing electrode 3. On the other hand, a combined signal from the input electric signal between the comblike electrode 2B and the facing electrode 3 is detected, and the delayed signal D<SB>i</SB>and the combined signal are interfered. Consequently, an interference signal R<SB>i</SB>(i=1, 2,..., n) is generated. The sonic speed V in the material is calculated from the interference signal R<SB>i</SB>. COPYRIGHT: (C)2004,JPO
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