Abstract: A temperature sensor is disclosed. The sensor includes an optical fiber and at least one twin-grating structure formed on the optical fiber. Each twin-grating structure includes a first optical grating structure, a second optical grating structure adjacent the first optical grating structure, and a sensing cavity disposed between the first and second optical grating structures. Each twin-grating structure is selectively responsive to a unique wavelength of light to generate an optical interference fringe signal. For each twin-grating structure, an optical property of the twin-grating structure and a phase of the optical interference fringe signal generated by the twin-grating structure are determined by a temperature of the twin-grating structure.

Abstract: A fiber optic strain and temperature sensor is disclosed. The fiber can directly measure strain and temperature or the fiber can be coated with a magnetostrictive coating to measure magnetic flux, or coated with a hydroscopic coating to measure humidity or moisture content. The optical fiber sensors can be embedded in different locations in a generator to provide real time measurement of operating conditions.