| 摘要 |
PROBLEM TO BE SOLVED: To provide a quartz pressure sensor capable of performing sure water level measurement by preventing a damage of an oscillation circuit caused by thunderbolt. SOLUTION: Optical cables 17a, 17b are laid up to an underwater quartz pressure sensor 10 to thereby input pulse modulated light, and output light whose phase is shifted by vibration of a reflecting mirror 15c fixed on a vibration beam part of a doublet tuning fork vibrator 14 of the quartz pressure sensor 10 is taken out, and the phase difference between input light and output light is detected. Hereby, the water level can be detected. COPYRIGHT: (C)2005,JPO&NCIPI
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