Simple low-frequency optical fiber accelerometer with large rotating machine monitoring applications

A simple fiber optic accelerometer with large rotating equipment monitoring applications is presented. The sensor is optimized for detection of mechanical vibrations in the frequency range 0.2-140 Hz. The minimum detectable acceleration is 0.025 m/s² root mean square (rms), and it has low transverse sensitivity. The transducer operating principle, based on a fiber optic cantilever beam without any selamic mass on it, is simple and easy to construct, and the intensity-modulation and compensation techniques developed require simple electronic processing and provide very good stability and accuracy. Other advantages of the system are its robustness, compact size, and cost-effectiveness, which make it appropriate for industrial applications, specially for those where harsh environments are involved. The complete process of research and development of the sensor has been carried out, from the theoretical study of its operation principles, through the design, fabrication, experimental characterization and enhancement, to its starting up in a high-power electric station for hydrogenerator monitoring