Real time angular velocity and vibration monitoring using fiber Bragg grating interrogation system

We present a fiber Bragg grating sensing system which combined with fiber Bragg grating (FBG) vibration sensors and fiber optic gyroscope (FOG) in a fiber loop to achieve the ability of real time angular velocity measurement and mechanical monitoring. The FBG sensing system is consisted by a fiber ring laser structure which is pumped by an erbium doped fiber amplifier (EDFA). The FBG which its wavelength can be perturbed by physical vibration and is used for the reflective filter of the fiber ring laser. The principle of the angular velocity measurement is based on Sagnac effect to form the interference due to two counter-propagating propagation, CW and CCW along the fiber loops. Real time vibrational measurement as high as 1 kHz with accuracy of 1 Hz, and minimum angular velocity measurement of 0.105 rad/s (1 rpm) was achieved. It shows that this FBG sensing system is efficient to real time safety monitoring for the civil engineering object and geodesic landscape.