Michael CAMPBELL, Gang ZHENG, Peter A. WALLACE and A. Sheila HOLMES-SMITH

Department of Physical Sciences, Glasgow Caledonian University, Cowcaddens Road, Glasgow, G4 OBA, UK

(Received July 2, 1996; Accepted September 12, 1996)

A new distributed stress sensor, based on a birefringent fiber Sagnac ring configuration and frequency modulation continuous wave technology, has been investigated. The two forward-coupled mode beams in the Sagnac ring, induced by an applied stress at any given point along the fiber length, produce a beat frequency which can be analysed to determine, simultaneously, the magnitude and position of the stress. The system has a reasonable spatial resolution of 1 m in a dynamic sensing range of 50 m.

Key words : stress sensor, fiber sensor, distributed sensor, polarimetric, frequency modulated continuous wave technology