Development of Optical Fiber Stress Sensor Based on OTDR

Abstract

In this paper, an OTDR-wide full dispersion fiber stress sensor is used to sensing the signal of strain, and the geometrical bending of the optical fiber can be generated by the strain of stress, and the variation characteristic of the optical conduction modal. When stress is produced in single-mode fibers, the optical energy of a part of the optical fiber is transformed into a radiant mode, so that an OTDR can accurately identify the location of the signal source, and the OTDR uses the time-domain analysis of the optical pulse wave technique, which can simultaneously sensing the accurate energy loss and position of the source of stress signals [1].

The single-mode optical fiber is used to simulate two different practical environments. One is the soil, the other is the sand, and uses two different material protection casing, one is the plastic casing, the other is the silicone casing, carries on the real measure, and compares the different light wave pulse width, the measured result to the different average time to the stress influence. Finally, the material elasticity and deformation characteristics of two kinds of protective casing are tested. The experimental results are that the selection of silicone protective casing is ideal, while the length of 150 m multi-point monitoring, the light pulse width of the choice of 100 ns, so the results obtained in the experiment can prove the ratio of stress to elastic modulus of relationship. On the other hand, because the quality of sand and soil of different problems, so the hardness of different, the same weight trample on the specific stresses of the rendering, in different substrate materials reflect different stress changes, because the sand soft and then greatly enhance the sensitivity of stress [2].