Two-Dimensional Displacement Sensor Based on Plastic Optical Fibers

An inexpensive fiber-based displacement sensor for two-dimensional crack monitoring is proposed and analyzed. The device is packaged as conventional crack monitoring gages based on sliding plates and exploits the dependence of the transmitted power between facing optical fibers with the displacement. The use of multi-core polymeric fibers with high numerical aperture allows a compact form factor and simplifies the sensor assembly. The position detection algorithm has been optimized through simulations; then experimental tests have shown a good agreement with simulations and have proved that even with simplified layout and artisanal realization the sensor can measure displacements in a square area of 3 mm by 3 mm with an uncertainty better than 0.05 mm