We present a technique to overcome the random transfer function of fiber-optic direct detection coherent optical time-domain reflectometry (C-OTDR). For this purpose, a standard optical fiber was treated by UV light in order to introduce local strongly scattering segments of definite size and distance to each other. Dynamic strain measurements were performed to demonstrate the sensory benefit in comparison to a non-manipulated fiber section. Our results show, that the modified fiber section exhibits a significant boost in strain sensitivity and in addition reduces the sensor dead time in a temperature-unstable environment as compared to a standard fiber.
Distributed fibre optic acoustic sensing (DAS) can serve as an excellent tool for real-time condition monitoring of a variety of industrial and civil infrastructures. In this paper, we portray a subset of our current research activities investigating the usability of DAS based on coherent optical time-domain reflectometry (C-OTDR) for innovative and demanding condition monitoring applications. Specifically, our application-oriented research presented here aims at acoustic and vibrational condition monitoring of pipelines and piping systems, of rollers in industrial heavy-duty conveyor belt systems and of extensive submarine power cable installations, respectively.