Radio telemetry interrogation of multiple fiber sensors in civil structures

We have examined various fiber sensor multiplexing techniques, e.g., frequency-, time-, coherence-multiplexing, in an attempt to ascertain the method best suited for interrogation of multiple sensors scattered throughout a modern civil structure. Based on our embedded fiber sensor results conducted at the Stafford Biotechnology Complex at the University of Vermont, a 65,000 square foot, multistory reinforced concrete structure, where more than fifty single-mode and multimode fiber optic sensors have been embedded into the structure, we have determined that in many instances a radio telemetry method of interrogating the sensors is optimal. Many real-world factors such as architectural details, lighting, power, and HVAC design requirements influence the overall nature of the use of multiplexed fiber sensors in civil structures. In instances where we have multiplexed intensity-modulating fiber sensors onto a single transmit/receive fiber, radio telemeterized command and data acquisition from the fiber sensor `network' may be achieved. The development of the interrogation of the multiplexed fiber optic sensors is presented, as are experimental results obtained from fiber optic vibration sensors.