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Proceedings Paper

Evaluation of cone tracking for free-space optical communication with a retro-modulator
Author(s): Eric Saint Georges
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Paper Abstract

Cone tracking is a well known method to optimize the pointing of a beam, and has been previously reported in the case of direct mode free-space optical communication (FSOC) links, using a beacon or a dedicated wavelength to carry the feed-back. In a retro link, because the beam is reflected back to the transmitter, feedback data is locally available. We present here the results of an evaluation (both simulation and experiments) of the cone tracking technique applied to a retro link and how the implementation can be optimized for this specific case. We show that using only a small number of samples (as low as 16 with 625 Hz modulation frequency) we can retrieve the beam offset. We also show how the technique can be used to estimate the beam wander. We finally demonstrate cone tracking (closed loop maintaining the beam center on the retro-reflector) with modulation amplitude as low as 1% of the beam divergence.

Paper Details

Date Published: 25 September 2007
PDF: 12 pages
Proc. SPIE 6709, Free-Space Laser Communications VII, 670903 (25 September 2007); doi: 10.1117/12.731624
Show Author Affiliations
Eric Saint Georges, NovaSol (United States)

Published in SPIE Proceedings Vol. 6709:
Free-Space Laser Communications VII
Arun K. Majumdar; Christopher C. Davis, Editor(s)

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