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2-D Profile Laser Doppler Anemometer

With two pairs of beams of different colours the velocity vector in the plane of the beams is measured. Depending on the trajectory there is a time delay between the green and blue velocity signal. By knowing the geometry (angle between the two measuring volumes) and velocity of the scatterer its momentary location is also well known. Spatial resolution is increased up to two orders of magnitude compared with size of the cross section. Such a type of 2D-LDA (usually part of commercial 3-D LDAs) is able to measure velocity profiles.