Fiber optic sensors focus on smart systems

Materials with structurally integrated fiber-optic sensors, the first step toward smart structures, which continuously monitor their own vibration, internal strain and deformation, temperature, and structural integrity are described. It is shown that the Fabry-Perot fiber-optic strain sensor has capabilities that far exceed those of conventional foil strain gauges, which holds the promise of responding to acoustic emission signals while simultaneously tracking the high loads likely to be encountered in practical structures such as aircraft wings. The same sensing system may be able to monitor the degree of cure during fabrication of thermoset composite structures. The fabrication and characterization of such all-fiber, intrinsic Fabry-Perot strain sensors are discussed. Passive and active homodyne signal recovery techniques used in the fiber-optic sensor systems are also described.<>