Anemometer for e.g. helicopter, has optical amplifier receiving light beam from laser and delivering pre-amplified light beam to optical coupler which provides light beams to light reference medium and detect Doppler shift

摘要

The anemometer has an optical amplifier (52) with an input receiving a light beam from a laser (50) and an output delivering pre-amplified light beam to an input of an optical coupler (54). The coupler has two outputs providing a light beam to light a reference medium and a reference light beam to detect Doppler shift, from the pre-amplified beam. Aircraft speed is determined by frequency deviation between the beams of the coupler.