A fibre optic position sensor is used to enhance the performance of conventional stream flow meters. Non-contact optic detection allows operation in polluted or salt water. In addition, the small size of the optical detector allows a sixteen-fold increase in resolution.
Terence M. Dwyer,
Barry E. Paton,
"A Fibre Optic Sensor For Remote Rotation Sensor", Proc. SPIE 0661, Optical Testing and Metrology, (25 November 1986); doi: 10.1117/12.938613; https://doi.org/10.1117/12.938613