Invention Grant
- Patent Title: Fiber laser pressure sensor
- Patent Title (中): 光纤激光压力传感器
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Application No.: US09623048Application Date: 2000-11-20
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Publication No.: US06630658B1Publication Date: 2003-10-07
- Inventor: Klaus Bohnert , Hubert Brandle
- Applicant: Klaus Bohnert , Hubert Brandle
- Priority: DE19807891 19980225
- Main IPC: G01J104
- IPC: G01J104

Abstract:
The invention relates to a frequency-coded fiber laser pressure sensor (1) which is especially suitable for measuring isotropic pressures in oil wells. The sensor principle provided for in the invention is based on the fact that in a fiber laser (2) doped with Er3+ a monomode or bimodal sensor fiber (5, 5a, 5b) is positioned whose pressure-related birefraction results in a frequency shift and beat frequencies between the orthogonal linear polarisation modes x, y or the spatial modes LP01 and LP11straight line. The beat frequencies are easily measured using a frequency counter (19). Temperature-related variations in birefraction are compensated in a differential arrangement of two sensor fiber segments (5a, 5b). Fiber-integrated Bragg gratings (4a, 4b) with low bandwidths (0.2 nm) are especially suitable as laser end reflectors. The pressure sensor (1) is characterized by a large measurement range (100 Mpa) and a high triggering capacity , (kPa), is readily multiplexed and can be housed in a very compact, light-weight and robust pressure-resistant housing (25).
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