Issues concerning intensity-based fiber sensors for non-contact vibration monitoring

The paper describes a simple fiber optic sensor for non-contact vibration measurements. The sensor is based on a couple of optical fibers placed in front of a vibrating target and derives the vibration amplitude from the changes of the reflected light intensity. A model of the optical sensor is introduced to predict the sensor behavior in different working conditions and for different sensor configurations. Then, issues concerning the sensor calibration in the presence of arbitrary targets, the choice of the sensor working distance, the strategies for sensitivity enhancement and the noise effects are investigated.