Patent ID: 7812950
Filing Date: 2010-10-12
Classification: G01P,G01S

Abstract:
1. A method for measuring the direction and velocity of a target in a measurement volume in a laser Doppler velocimetry system comprising: selecting a discrete number of grating positions for an electrically switchable grating; placing the electrically switchable grating in a light path of a laser source, wherein the laser source outputs a laser beam along the light path; switching the electrically switchable grating sequentially through the discrete number of grating positions at a grating frequency to generate diffracted light beams from the laser; directing the diffracted light beams through a lens; focusing the diffracted light beams on a measurement volume; passing a target through the measurement volume in a target direction at a target velocity; and receiving scattered light in a detector and calculating the power spectrum of light intensity fluctuations, wherein the power spectrum includes a maximum peak, wherein the maximum peak occurs at a frequency shifted from the grating frequency an amount corresponding to the target velocity and in a direction corresponding to the target direction.