An intensiometric contactless vibration sensor with bundle optical fiber for real time vibration monitoring

In this paper a low-cost fiber-optic intensity based vibration sensor is presented. As sensing element a bundle optical fiber was used. The sensor is based on changes of the reflected light intensity in bundle fiber which is placed near the vibrating element. As the vibrating element loudspeaker cone was used. The sensor was tested in the range of frequencies from 10 Hz to 1 kHz. The minimum detectable amplitude of vibration achieved is 1 μm. An application for real time vibration monitoring in LabVIEW software package was developed. The advantages of the proposed sensor are its simplicity, low-cost, immunity to electromagnetic interference, and the possibility of distributed and long term vibration monitoring over a single optical fiber link.