Polymer-optical-fiber-based sensor system for simultaneous measurement of angle and temperature

This paper presents a polymer-optical-fiber (POF)-based sensor system for simultaneous measurement of angle and temperature. The main contribution is obtaining a sensor with higher temperature sensitivity and lower hysteresis on the angle measurements. The annealing was made on the fibers under the conditions of low relative humidity and under water, and a third set of samples without any heat treatment was applied for comparison with the annealed ones. Results of temperature and angle characterization show that the fibers annealed under water presented higher temperature sensitivity and lower errors when compared with the fibers annealed with low humidity or the fibers without annealing. Furthermore, the fibers annealed under water also presented lower hysteresis on the angle characterization. For these reasons, such fibers were employed for the temperature and angle measurements, which results in a sensor system capable of simultaneously measuring the angle and temperature with root-mean-squared error of 0.82 degrees C for temperature and 2.20 degrees for angle, which is further reduced to 1.20 degrees after the application of a dynamic compensation technique for POF curvature sensors. (C) 2018 Optical Society of America.