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Proceedings Paper

Beam shape of coherently-combined optical arrays
Author(s): Irl W. Smith
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Paper Abstract

In many applications, the utility of coherently-driven arrays of spatially distributed optical apertures is highly dependent on the "power in the bucket", i.e., power in the main lobe of the beam. This depends on the illumination pattern of the individual apertures (e.g., truncated-Gaussian) via a geometric efficiency η of order unity. It depends more strongly on the areal fill factor FA, i.e., the degree to which the emitting apertures (exclusive of the support structure between the apertures) cover the entire array face. Starting from first principles, we derive rigorous formulations of certain measures of array beam shape and extract a small set of heuristically-motivated but robust performance measures. At a range R, the peak irradiance Ip is PtotAarrayFAη/λ2R2. In terms of the effective diameter Deff, which depends on the second moment <x2> of the emitted amplitude and is equal to the actual diameter for a uniformly illuminated ("top-hat") circular emitter, we find for a wide range of near-field irradiance distributions that the power in the bucket PB is given by (1.05±0.05)×(λR/Deff)2Ip.

Paper Details

Date Published: 13 May 2011
PDF: 15 pages
Proc. SPIE 8052, Acquisition, Tracking, Pointing, and Laser Systems Technologies XXV, 80520P (13 May 2011); doi: 10.1117/12.883402
Show Author Affiliations
Irl W. Smith, Raytheon Co. (United States)

Published in SPIE Proceedings Vol. 8052:
Acquisition, Tracking, Pointing, and Laser Systems Technologies XXV
William E. Thompson; Paul F. McManamon, Editor(s)

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