Low-cost 2D fiber-based displacement sensor

A displacement sensor for two-dimensions crack monitoring, based on plastic optical fibers, is analyzed. The device, resembling a conventional crack gage based on sliding plates, exploits the power attenuation of facing fibers with displacement. The use of multi-core fibers allows for a compact form factor and easy assembling of the packaged sensor. Simulations have been carried out to validate the detection algorithm, which retrieves the displacement from the power collected by three receiving fibers. Experimental tests, performed on a prototype made by 980 μm-core fibers, exhibit good agreement with the simulations and prove the sensor can measure displacements on an area of 1 mm² with an uncertainty better than 40 μm.