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Proceedings Paper

Free-space optical data link to a small robot using modulating retroreflectors
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Paper Abstract

Small robots are finding increasing use for operations in areas that may be dangerous to humans. These robots often have needs for high bandwidth communications to return video and other data. While radio frequency (RF) links can be used in may cases, in some circumstances they may be impractical due to frequency congestion, reflections off surfaces, jamming or other RF noise. In these cases an optical link may be advantageous, particularly when a clear line of sight exists. However, a conventional optical link has limitations for this application. For example, a conventional optical link operating at rates of megabits per second at ranges of 1 Km requires about a 1 degree pointing accuracy. This implies a need for active pointing and tracking, which maybe be unacceptable for a small platform. We explored an optical modulating retroreflector (MRR) link for these cases. An array of 6 MRRs and photodetectors with a field of view of 180 degrees (azimuth)x 30 degrees (elevation) was constructed and mounted a small robot, the iRobot PackbotTM. An Ethernet modem designed to work with MRR links was also part of the system. Using a tracking laser interrogator at the other end of the link, a 1.5 Mbps free space optical Ethernet link was established that completely replaced the normal RF Ethernet link. The link was demonstrated out to ranges of 1 Km down a road, exceeding the range of the RF link. Design issues and measurements of performance will be described.

Paper Details

Date Published: 21 August 2009
PDF: 9 pages
Proc. SPIE 7464, Free-Space Laser Communications IX, 746408 (21 August 2009); doi: 10.1117/12.828869
Show Author Affiliations
William S. Rabinovich, Naval Research Lab. (United States)
James L. Murphy, Naval Research Lab. (United States)
Michele Suite, Naval Research Lab. (United States)
Mike Ferraro, Naval Research Lab. (United States)
Rita Mahon, Naval Research Lab. (United States)
Peter Goetz, Naval Research Lab. (United States)
Kurt Hacker, Naval Explosive Ordnance Disposal Technology Div. (United States)
Wade Freeman, SmartLogic, Inc. (United States)
Eric Saint Georges, Novasol, Inc. (United States)
Stan Uecke, Novasol, Inc. (United States)
John Sender, Novasol, Inc. (United States)

Published in SPIE Proceedings Vol. 7464:
Free-Space Laser Communications IX
Arun K. Majumdar; Christopher C. Davis, Editor(s)

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