Fiber optic displacement sensor used in railway turnout contact monitoring system

In order to measure the distance between switch point and stock rail in railway system high precision, a wide range and high precision fiber Bragg grating (FBG) displacement sensor is designed. The sensitivity as well as the measurement range of the senor is increased through the effective cooperation of the spring and equal strength beam. At the same time, differential compensation method is exploited for eliminating temperature effects, which brings further improvement of the sensitivity as well. Test results show that, in the range of 160 mm, the precision of the sensor is 0.017 mm.