Vector velocimeter

Abstract

A vector velocimeter includes a laser emitting a measurement beam with a wavelength λ, for illumination of an object in a measurement volume to create a signal beam, a reference beam generator generating a reference beam, and a first detector arranged such that the signal beam and the reference beam, propagating at a first angle θ relative to the signal beam, are incident thereon. The first detector includes an array of first detector elements to convert the intensity of the interfering signal beam and reference beam incident thereon into an oscillating electronic detector element signal when the fringe pattern formed thereby moves across the first detector array. A signal processor generates a velocity signal corresponding to a first velocity component of movement of the object in the measurement volume in the longitudinal direction thereof based on the electronic detector element signals from each of the first detector elements.