Accession Number : AD0634886

Title :   DESIGN STUDY OF LASER RADAR FOR DETEDTION OF CLEAR AIR TURBULENCE.

Descriptive Note : Final rept. 1 Apr 65-15 Apr 66,

Corporate Author : SPACE AND INFORMATION SYSTEMS DIV NORTH AMERICAN AVIATION INC DOWNEY CALIF

Personal Author(s) : BREECE, R. C. ; Fried,D. L. ; Munick,R. J.

Report Date : JUN 1966

Pagination or Media Count : 170

Abstract : The objective of the research was to perform a design study and feasibility demonstration of a Doppler laser radar system for use in detection of clear air turbulence. Both CW and pulsed radar techniques were investigated to determine applicability to analysis of laser light backscattered from atmospheric molecules and aerosol particles in order to measure macroscopic motion of the air. It was desired to detect wind gusts in excess of 25 feet per second while operating in a jet aircraft at an altitude of approximately 30,000 feet. The program included analysis of design requirements, analysis of light scattering by the atmosphere, a design trade-off study, and an experimental demonstration. It was concluded that, if particulate matter exists at flight altitudes in sufficient concentration and if advances in the laser state of the art permit fabrication of a laser with the required performance, a system with a range of up to 50 nautical miles is feasible. The analysis showed that the system must depend on scattering from aerosol particles and that a pulsed system has significant advantages over a CW system. A system concept is described which employs detection of beat frequencies in the output current of a photodetector resulting from photo-mixing of the backscattered light from two laser pulses illuminating separated volumes of air. An experimental demonstration was attempted which optically combined the light scattered from two streams of smoke moving at different velocities. The scattering volumes were illuminated by focusing the expanded output beam of an argon laser. (Author)

Descriptors :   (*CLEAR AIR TURBULENCE, RADAR SCANNING), (*DOPPLER RADAR, *LASERS), (*METEOROLOGICAL RADAR, LASERS), AEROSOLS, LIGHT, BACKSCATTERING, DEMODULATORS, PHOTOTUBES, AIRCRAFT EQUIPMENT

Subject Categories : Meteorology
      Lasers and Masers
      Active & Passive Radar Detection & Equipment

Distribution Statement : APPROVED FOR PUBLIC RELEASE