Low-cost, non-contact displacement sensor based on plastic fiber bundle

The article presents the state-of-the-art realization of a low-cost, non-contact displacement sensor based on plastic optical fibers. The sensor head makes use of 7 fibers, arranged in a bundle configuration, to detect small displacements on a moving target; the sensing systems can compensate variations to target reflectivity. Two advanced features have been implemented: an optimization of the fiber bundle enables to improve the accuracy up to 2.7 times, and a Monte Carlo simulation provides a detailed description of the system and enables surface mapping. Experimental result show an accuracy of 7.5 μm on a range of 2.5 mm with reflectivity compensation, and of 2.4 μm on a range of 5 mm without compensation.