Development of a multi-interval displacement sensor using Fiber Bragg Grating technology

Abstract

We have developed a multi-interval displacement sensor using Fiber Bragg Grating (FBG) technology, which has potential for the long-term durability, high accuracy and ability to transmit data over long distances. Field trials in the Horonobe Underground Research Laboratory (URL) of the multi-interval displacement sensor developed using FBG technology are described. Laboratory tests were carried out to obtain the relational expression computed from the interrelationship of the variation in the Bragg wavelength, temperature and displacement. From the results of laboratory tests, accuracy of the sensor was evaluated to be better than ±0.5% of the measurement range. In situ monitoring at the Horonobe URL using the developed sensor was carried out in parallel with nearby monitoring using a conventional extensometer, which is an electrical signal system type, for verification of the developed sensor. The results of the in situ test indicate that the displacement values from both the sensor developed and the conventional extensometer are almost equivalent. One of the advantages of the developed sensor is the absence of noise in the monitoring data, in contrast to the data from a conventional extensometer.