Surface-mounted optical fiber strain sensor design.

We develop the theory of surface-mounted interferometric optical fiber strain sensor design for arbitrarily configured fiber paths and present design techniques to select the path of a curved fiber-optic sensor required to isolate predetermined strain components. Several of these gauges are combined to form a rosette that directly measures the state of strain without the need to solve a set of simultaneous equations. We also use the design procedures to develop an optical fiber sensor that measures a single arbitrary stress component in an isotropic body. The design process is guided by a fundamental relationship among path, strain, and phase change for an arbitrarily configured optical fiber. The design theory is restricted to small strains and flat surfaces. All fiber sensor designs are validated with experiments.