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Optical Engineering

Evaluation and implementation of cone tracking for free-space optical communication with a retromodulator
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 reported previously in the case of direct-mode free-space optical communication links, using a beacon or a dedicated wavelength to carry the feedback. In a retro link, because the beam is reflected back to the transmitter, feedback data are 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 few as 16 with 625-Hz modulation frequency), we can retrieve the pointing error. We finally demonstrate cone tracking (a closed loop maintaining the beam center on the retroreflector) with modulation amplitude as low as 1% of the beam divergence.

Paper Details

Date Published: 1 November 2010
PDF: 9 pages
Opt. Eng. 49(11) 115002 doi: 10.1117/1.3509365
Published in: Optical Engineering Volume 49, Issue 11
Show Author Affiliations
Eric Saint-Georges, NovaSol (United States)

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