A single laser all fibre based optical sensor and switching system and method for measuring velocity in atmospheric air flow

摘要

A system for measuring a velocity of tracerparticle motion in a fluid comprising at least one laser emitterconfigured to emit a continuous wave laser beam and a plurality of optical devices being configured to alternately receivea laser beam, focusing the laser beam onto a same probevolume comprising tracer particles, and receiving backscatteredlight from the tracer particles. The optical deviceshave a common optical input/output port for transmitting thereceived continuous-wave laser beam and for receiving thebackscattered radiation. The optical devices are provided tohave mutual pointing angles so that each of the plurality ofoptical devices points at the probe volume under a differentangle. A processor is configured to receive a part of the trans -mitted laser beam and the received backscattered radiationbeam to calculate a Doppler shift, and thereby determine aplurality of velocity components of the tracer particles usingcoherent detection.