Multipoint displacement measurement based on low intracavity-loss FLRD method

In this paper, we propose a method of multipoint displacement measurement using fiber-loop ring-down (FLRD) technology. We demonstrated the feasibility of multipoint displacement measurement using three cascaded FLRDs. Single-mode optical fiber wrapped around the cylinder airbag surface (CA-SMF) is used as the displacement sensor. Due to the low insertion loss of CA-SMF and the high-power modulated signal output of OTDR, it is not necessary to add any device for compensating the pulse signal power in FLRD. Finally, we also consider the errors that arise in the engineering manufacturing process. We have experimentally demonstrated that the length and intrinsic losses of FLRD do not affect the sensing performance of displacement sensors in a reasonable range, which is extremely helpful for practical engineering applications.