| 摘要 |
<P>PROBLEM TO BE SOLVED: To realize an apparatus and a method for measuring the ultrasonic waves at the measuring point present in a liquid, using an optical means, such as, an optical interferometer, or the like, without being affected by acousto-optical effects. Ž<P>SOLUTION: This ultrasonic measuring instrument 1 is equipped with an ultrasonic wave detecting cell 6, installed in the liquid and having a film 5 vibrated by the ultrasonic wave to detect the ultrasonic waves and an optical interferometer, or the like, for optically detecting the ultrasonic signal caused by the vibration of the film 5 and the cell 6 is constituted, by providing a gas layer 8, which has an acoustic impedance (the product of density and sonic velocity) sufficiently smaller than the film 5 or liquid, on the back side of the film 5. Propagation of the ultrasonic waves to the back of the film 5 is prevented by the gas layer 8, while the production of the ultrasonic signal caused by acousto-optical effects is inhibited, and only the ultrasonic signal produced by the vibration of the film 5 is detected optically. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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