A high-performance miniaturized time division multiplexed sensor system for remote structural health monitoring

We report for the first time the design, implementation and commercial application of a hand-held optical time division multiplexed, distributed fibre Bragg grating sensor system. A unique combination of state-of-the art electronic and optical components enables system miniaturization whilst maintaining exceptional performance. Supporting more than 100 low-cost sensors per channel, the battery-powered system operates remotely via a wireless GSM link, making it ideal for real-time structural health monitoring in harsh environments. Driven by highly configurable timing electronics, an off-the-shelf telecommunications semiconductor optical amplifier performs combined amplification and gating. This novel optical configuration boasts a spatial resolution of less than 20cm and an optical signal to noise ratio of better than 30dB, yet utilizes sensors with reflectivity of only a few percent and does not require RF speed signal processing devices. This paper highlights the performance and cost advantages of a system that utilizes TDM-style mass manufactured commodity FBGs. Created in continual lengths, these sensors reduce stock inventory, eradicate application-specific array design and simplify system installation and expansion. System analysis from commercial installations in oil exploration, wind energy and vibration measurement will be presented, with results showing kilohertz interrogation speed and microstrain resolution.