Patent ID: 6297878
Filing Date: 2001-10-02
Classification: G01P,G01S

Abstract:
A method of measuring relative velocity of a base with respect to a fluid containing particles comprising the steps of:providing a plurality of fixed non-scanning separate beams of light along separate non parallel axes that are fixed relative to each other and the base;focusing the non-scanning beams of light with optical elements fixed relative to the base at locations forming separate volumes of space, each volume of space comprising particle detection regions, said particle detection regions being exposed to fluid containing particles, whereby when a particle passes through one or more of the particle detection regions light is reflected along the axis of the beam forming the respective particle detection region at a shifted frequency due to the relative velocity of the particle;determining the difference in velocity of particles in each of the separate axes with respect to the base; and resolving the difference in velocity in the three axes into velocity coordinates in three mutual perpendicular axes.