A FIBER OPTIC SENSOR FOR MEASURING DISTRIBUTED FORCES

A fiber optic sensor system for measuring distributed forces is presented in this paper. A high-birefringent fiber is chosen as a sensing element. Based on the coupling effects of polarization modes in high-birefringence fibers, the distribution of the force points along the sensing fiber can be measured by detecting mode couplings in the fiber which are caused by external force disturbance. The location and magnitude of the measured forces are determined by interferometry with phase modulation and the technique of optical path scanning. The spatial resolution of the sensor system is better than 0.15 m for a 50 m testing fiber. This distributed sensor has many applications, such as detecting tact forces and in smart structures.