The fibre-optic Doppler anemometer

A laser Doppler anemometer is described in which an optical fibre is used to transmit the light to and from the measurement zone. An account is given of the various types of measurement that have been made with the instrument, particularly those involving Brownian motion. An analysis is made of backscattering into a fibre which shows that the back-scattered power is confined to a region extending only a few tens of core diameters from the fibre end.