Distributed grating sensors using low-coherence reflectometry

Distributed grating sensors have recently been interrogated with low-coherence reflectometry. Initial results have been enhanced using two new and versatile configurations. The first system tracks the wavelength using a closed-loop scheme, while the second system scans the distance using an open-loop approach. Arbitrary strain and temperature profiles along gratings have been examined with 300 μm spatial resolution and 5.4 με/√Hz accuracy. A theoretical model of the interrogation technique is derived and the predicted performance limits are examined experimentally