Developments in sensor technology have enabled measurement of strain in composite materials by means of embedded fiber optic interferometric sensors. Often the intent is to measure and then actively control vibration and position. This paper describes novel Bend Enhanced Fiber (BEF) sensors used to make continuous, linear, real-time measurements of curvatures, which often relate more directly than strains to the control of vibration and position. BEF sensors are made by treating optical fibers to have an optically absorptive zone along a thin axial stripe a few millimeters long. Light transmission through the fiber past this zone then becomes a robust function of curvature, three orders of magnitude more sensitive to bending than in the untreated fiber. Directionality and polarity of curvature are preserved in the transmission function, over a linear range covering 5 orders of magnitude, centered about zero curvature. Thus, BEF sensors are curvature-measuring optical analogs of elongation-measuring resistance strain gauges, with similar sensitivity. BEF sensors add little or no thickness to the fiber, can be instrumented with simple analog electronics, and have been successfully embedded in composites. Results of dynamic curvature measurements are included, along with characterization data for BEF sensors made with plastic and silica fibers as small as 125 microns.