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Proceedings Paper

Fiber optic pressure sensor based on vibrating-quartz-crystal technology
Author(s): Kenneth A. Wickersheim; Mei H. Sun
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Paper Abstract

The pressure sensor described in this paper is an optical adaptation of a high performance commercial pressure sensor that measures the resonant frequency of a double-ended quartz tuning fork as modified by the force applied. The shift in resonant frequency is used to determine the pressure. In this device the tines of the crystal are forced into transverse oscillation by an electrical microcircuit powered by a photodiode array illuminated by an LED via an optical fiber. The crystal oscillation frequency is determined using a second light beam from a separate LED also transmitted by a fiber. (The light beam is interrupted by the two oscillating tines, generating an AC signal at the crystal oscillation frequency.) Since the measured frequency is independent of intensity variations, the sensor is unaffected by light source degradation or by fiber bending. In a recently-developed prototype device, force is applied to the crystal via a balanced Bourdon tube assembly. Increasing the pressure inside the tubes increases the force exerted on the crystal. The prototype exhibits an accuracy, linearity, and stability of better than 0.1 psi over a 100 psi range when operated in air and without any temperature compensation. The sensor also shows good immunity to shock and vibration.

Paper Details

Date Published: 1 August 1990
PDF: 8 pages
Proc. SPIE 1267, Fiber Optic Sensors IV, (1 August 1990); doi: 10.1117/12.20317
Show Author Affiliations
Kenneth A. Wickersheim, Luxtron Corp. (United States)
Mei H. Sun, Luxtron Corp. (United States)

Published in SPIE Proceedings Vol. 1267:
Fiber Optic Sensors IV
Ralf Th. Kersten, Editor(s)

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