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Remote Sensing of Atmospheric Winds by Utilizing Speckle-Turbulence Interaction and Optical Heterodyne Detection.

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Final rept. 1 Jun 83-30 Sep 85,

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Speckle turbulence interaction has the potential for allowing single ended remote sensing of the path averaged vector crosswind in a plane perpendicular to the line of sight to a target. If a laser transmitter is used to illuminate a target, the resultant speckle field generated by the target is randomly perturbed by the atmospheric turbulence as it propagates back to the location of the transmitter-receiver. When a crosswind is present, this scintillation pattern will move with time across the receiver aperture and consequently, the time delayed statistics of the speckle field at the receiver are dependent on the crosswind velocity. A continuous wave laser transmitter of modest power level a watt or two in conjunction with optical heterodyne detection has been used to exploit the speckle-turbulence interaction and measure the crosswind. The use of a cw transmitter at 10.6 microns and optical heterodyne detection has many advantages over direct detection and a double pulsed source in the visible or near infrared. These advantages include the availability of compact, reliable and inexpensive transmitters better penetration of smoke, dust and fog stable output power low beam pointing jitter and considerably reduced complexity in the receiver electronics. In addition, with a cw transmitter, options exist for processing the received signals for the crosswind that do not require a knowledge of the strength of turbulence.

Subject Categories:

  • Meteorology
  • Jet and Gas Turbine Engines

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