Aircraft structural-health monitoring using optical fiber distributed BOTDR sensors

We conducted theoretical and practical studies for applying the Brillouin optical timedomain reflectometer (BOTDR) to an aircraft structural-health-monitoring system. First, we measured strain and temperature independently and simultaneously using a combined system of the BOTDR and fiber Bragg grating (FBG) with wavelength division multiplexing (WDM). Second, we used Brillouin spectrum analysis and processing to enhance up to 0.5 m the spatial resolution of the distributed strain measured by the BOTDR. Finally, we verified the proposed improvement of the BOTDR measurement by manufacturing and testing a composite structure.