Preliminary design study of a laser Doppler velocimeter for remote probing of the atmosphere

Thesis (M.S.)--University of Rochester. College of Engineering and Applied Science. Institute of Optics.This thesis presents a preliminary design study of a laser Doppler velocimeter for measurement of atmospheric wind velocities. The particular configuration chosen for study consists of a collimated C.W. laser transmitter and a receiver which is physically separated from the transmitter. The receiver collects light scattered by the naturally occurring clear air aerosols and employs optical heterodyning as a spectroscopic tool to measure the Doppler shift in the light scattered from the moving particles. The detection system is analyzed in order to determine the optimum receiver field of view. Signal to noise ratios are derived in terms of parameters of the system and of the atmosphere. By analyzing the scattering process it is possible to estimate the amount of spectral broadening to be expected. A model of the atmosphere is chosen and used to estimate the intensity of the scattered light. With reasonable estimates of other system parameters it is possible to calculate numerical values for the expected signal to noise ratio. These values are presented for daylight operation for various ranges, wavelengths, and scattering angles