Simultaneous strain and temperature measurement using an integrated fibre Bragg grating/extrinsic Fabry-Perot sensor

Abstract

This paper reports on a novel optical fiber sensor configuration for conducting simultaneous strain and temperature measurements. The sensor consisted of an optical fiber-based extrinsic Fabry-Perot interferometer (EFPI) with an integrated fiber Bragg grating (FBG). The FBG was located within a glass capillary which housed the EFPI sensor and was thus in a strain-free condition. The FBG is primarily sensitive to temperature, while the EFPI was sensitive to both strain and temperature. The integrated FBG/EFPI sensor was embedded in a carbon fiber reinforced composite and evaluated. The standard deviation of strain measurement was 36 (mu) e in the range 0 to 1200 (mu) e, and the temperature measurement had a standard deviation of 3.5 degrees C in the range 30 degrees to 70 degrees C. The thermal expansion of the cross-ply composite was investigated and was found approximately 4.05 X 10-6 degrees C.