Fiber Optic Demodulation Method for Fiber Grating Corrosion Detection

Physical Optics Corporation proposes to develop a new fiber optic corrosion detection system capable of measuring the location and progress of corrosion in an aging aluminum aircraft structure. The proposed system will give aircraft maintainers and designers important quantitative information about corrosion kinetics. The proposed system uses a corrosion sensitive fiber Bragg gratings, which can easily be embedded into structural members and lap joints, as sensing elements. The fiber provides distributed sensing over the entire area covered by the fiber. The fiber optic corrosion detection system will focus on the development of fiber Bragg grating sensors with aluminum metal coatings and the development of a novel demodulation method based on tapped fiber Bragg gratings. The sensor can be used to detect the average state of corrosion at specific points along the fiber. The tapped Bragg grating demodulator dispersively scatters light out of the optical fiber and is then imaged on to linear photodiode array. In Phase I POC proposes to demonstrate the feasibility of using corrosion sensitive fiber Bragg gratings with the novel tapped Bragg grating demodulation system to detect the presence of aluminum corrosion.