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Proceedings Paper

Simulation and theory of speckle noise for an annular aperture frequency-modulation differential-absorption LIDAR (FM-DIAL) system
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Paper Abstract

This paper presents theory of speckle noise for a frequency-modulation differential-absorption LIDAR system along with simulation results. These results show an unexpected relationship between the signal-to-noise ratio (SNR) of the speckle and the distance to the retro-reflector or target. In simulation, the use of an annular aperture in the system results in a higher SNR at midrange distances than at short or long distances. This peak in SNR occurs in the region where the laser's Gaussian beam profile approximately fills the target. This was unexpected since it does not occur in the theory or simulations of the same system with a circular aperture. By including the autocorrelation of this annular aperture and expanding the complex correlation factor used in speckle models to include conditions not generally covered, a more complete theoretical model is derived for this system. Obscuration of the center of the beam at near distances is also a major factor in this relationship between SNR and distance. We conclude by comparing the resulting SNR as a function of distance from this expanded theoretical model to the simulations of the system over a double-pass horizontal range of 10 meters to 10 km at a wavelength of 1.28 micrometers.

Paper Details

Date Published: 30 April 2009
PDF: 12 pages
Proc. SPIE 7324, Atmospheric Propagation VI, 732404 (30 April 2009); doi: 10.1117/12.817698
Show Author Affiliations
Paul E. Keller, Pacific Northwest National Lab. (United States)
Michael T. Batdorf, Pacific Northwest National Lab. (United States)
Jana D. Strasburg, Pacific Northwest National Lab. (United States)
Warren W. Harper, Pacific Northwest National Lab. (United States)

Published in SPIE Proceedings Vol. 7324:
Atmospheric Propagation VI
Linda M. Wasiczko Thomas; G. Charmaine Gilbreath, Editor(s)

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