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Proceedings Paper

High Pressure Fiber-Optic Sensor With Side-Hole Fiber
Author(s): K. Jansen; Ph. Dabkiewicz
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Paper Abstract

Experiments are performed toward the development of a fiber optic pressure sensor which uses the elasto-optic birefringence in a single-mode fiber. The 'side-hole' fiber-structure may be viewed as a PANDA-structure with open channels instead of the stress generating rods in its cross-section. The use of the side-hole fiber exploits the high reproducibility of silica serving as the elastic reference. By the side-hole geometry external hydrostatic pressure is converted into an anisotropic stress in the core region. Additionally, a stress concentration by a factor of 3 to 5 can be achieved by suitable choice of the geometry of the channels. In the experimental setup, the fiber is exposed in a pressure chamber directly to the pressure to be measured. The chamber is designed for a pressure range of 0 to 1000 bars.The induced birefringence is determined by passing a polarized laser beam through the fiber and by bi-directional counting the periods of phase delay between the two polarization-eigenstates of the fiber at the output. Thus, the sensor operates in an incremental mode. Using a fiber length of 10 cm, a pressure induced birefringence of 7.78 rad/(bar-m) was measured at a wavelength of 1300 nm. The resolution of optical phase evaluation is ni2, corresponding to a pressure resolution of approx. 2 bars. The overall accuracy of the sensor is better than ± 0.5% in the pressure range of 100-1000 bars where unambiguous phase evaluation was possible. Below 100 bars, in one fiber problems were caused near the point where the the birefringence vanishes. The experimental sensor-head is connected to the evaluation unit by a polarization-maintaining single-mode fiber, supplying the laser light, and three electrical leads for the detector signals. A version without any electrical lead to the sensor head is planned, in which the light source and the signal detectors are connected by optical fibers.

Paper Details

Date Published: 14 October 1987
PDF: 5 pages
Proc. SPIE 0798, Fiber Optic Sensors II, (14 October 1987); doi: 10.1117/12.941085
Show Author Affiliations
K. Jansen, Technische Universitat Hamburg-Harburg (Germany)
Ph. Dabkiewicz, Technische Universitat Hamburg-Harburg (Germany)

Published in SPIE Proceedings Vol. 0798:
Fiber Optic Sensors II
Anna Maria Verga Scheggi, Editor(s)

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