Performance Evaluation of BOTDR-based Distributed Fiber Optic Sensors for Crack Monitoring

In this paper, the measurement behavior of BOTDR (Brillouin Optical Time Domain Reflectometry) in different sensing lengths and different strain levels is investigated theoretically and validated by experiments. Moreover, the relationship between measured strain distribution and actual strain distribution is derived in theory and validated by experiment. Based on these investigations, a standard method for evaluating the measurement performance of distributed or long gauge fiber optic sensors for monitoring cracks is proposed. The performance evaluation of BOTDR-based distributed fiber optic sensors are then performed based on the proposed method, and applicable conditions of different fiber optic installation methods for monitoring cracks or localized deformations are clarified, and the measurement accuracy of BOTDR is evaluated.