| 摘要 |
PURPOSE:To obtain an optical fiber type underwater sound detector having high performance by adhering an optical fiber wound in the inside wall of a sheet metal case thereby forming a detecting element. CONSTITUTION:An optical fiber 12 wound in multiple turns is adhered on the inside surface of a resonating cylindrical case 11 consisting of a nickel sheet thereby forming an underwater sound detecting element 6. The light from a laser light source 1 is passed through a beam expander 2, is split by a semitransparent film 3 and is made incident to an optical fiber 5 for measurement and an optical fiber 5' for reference. A sound wave detector 6 is inserted in the fiber 5 and when a sound wave is applied on the fiber, a distortion arises in the fiber 12 and a phase difference arises between the light transmitted in the fiber 5 and the light transmitted in the fiber 5'. An interference fringe 7 is generated in an interferometer by said phase difference. The sound in the water is detected with high sensitivity by the displacement of the fringe 7. |
