Fiber optic strain sensors are designed to measure strain, but they can be changed to measure temperature, acceleration or displacement. They employ Fiber Bragg Grating (FBG) to measure the strain. FBG is created by a periodic variation in the refractive index of the fiber core, which reflects specific wavelengths based on the properties of the gratings. An applied strain makes a relative shift in the Bragg wavelength which can be used to measure it.
