A fluorescent linear optical fiber position sensor

Abstract

This paper describes a fluorescent long-line optical fiber position sensor to satisfy an industrial need for measuring position over a wide range of distances, varying from centimeters to many meters, where high resolution is not required. As is well-known, the light power transmitted by an optical fiber decreases with distance. By measuring the light power collected at both ends of a fluorescent long-line optical fiber, a position sensor has been developed. The position of the point where a light beam enters the fiber can be determined by comparing the light power collected at its two ends. In addition to their low cost and easiness of handling, plastic optical fibers present the advantages common to all multimode optical fibers such as flexibility, small size, and a good behaviour against electromagnetic interferences. Besides, sensors based on optical fiber eliminate the risk of electrical sparks in explosive environments, and they can be read from remote positions. In this work, several fluorescent optical fibers with different diameters, wavelengths, and light sources have been tested.