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Optical doppler radar system using a conically scanned laser beam

  • US 4,340,299 A
  • Filed: 03/13/1980
  • Issued: 07/20/1982
  • Est. Priority Date: 03/13/1980
  • Status: Expired due to Term
First Claim
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1. A method for generating indicia of movement relative to a surface at a position above the surface comprising the steps:

  • scanning a first laser beam and synchronously receiving, during the scan, the first laser beam scattered from the surface to produce a return laser beam,generating a frequency difference electrical signal from the frequency difference between the return laser beam and the first laser beam after mixing it with a reference frequency,generating movement signals that indicate electrical movement and horizontal movement in selected horizontal directions by splitting said frequency difference signal into its components that vary in proportion to movement in selected directions and that component which varies independently of the position of the scan, characterized by;

    generating a scan position signal indicative of of the position of the scan from a reference position,comparing the phase of said scan position signal with the phases of said frequency difference signals at quadrature phase angles the correspond to the quadrature angular positions of the scan to produce indicia of horizontal movements in selected directions resulting in signals proportional to the phase differences,producing an indicia of elevational movement comprising a signal whose magnitude is proportional to the average level of the frequency difference signal.

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