| 摘要 |
PURPOSE:To enable an underwater ultrasonic wave to be detected with a high sensitiveness by constituting a sound detector for radiating light from part of the signal light path of an optical interference system onto a sound medium through which a detected sound wave is transmitted and leading light transmitted through or reflected from the sound medium to an optical wave guide path. CONSTITUTION:An optical wave guide path for leading light from a coherent light source 11 is connected to a Mach-Zehnder optical interference system 23. Part of an optical fiber bundle 13 is constituted as a sound wave detector 31. Light from the optical fiber bundle 13 is radiated onto a sound medium 15 and light transmitted therethrough is led to the optical fiber bundle 13. That is, the optical fiber bundle 13 is cut to optical fiber bundles 13a and 13b. Sound wave 17 from a sound source 16 passes between the cut optical fiber bundles 13a and 13b in the detector 31 and the refractive index of the medium 15 between the bundles 13a and 13b changes according to the sound pressure of the sound wave 17. Accordingly, a light path difference is produced between reference light and signal light reaching an optical synthesizer 19 and interference light in accordance with the sound pressure of the sound wave 17 is obtained. The degree of an interference thus obtained is displayed on a display 22 as the sound pressure.
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