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

William S. Rabinovich; James L. Murphy; Michele Suite; Mike Ferraro; Rita Mahon; Peter Goetz; Kurt Hacker; Wade Freeman; Eric Saint Georges; Stan Uecke; John Sender

doi:10.1117/12.828869

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21 August 2009 Free-space optical data link to a small robot using modulating retroreflectors

William S. Rabinovich, James L. Murphy, Michele Suite, Mike Ferraro, Rita Mahon, Peter Goetz, Kurt Hacker, Wade Freeman, Eric Saint Georges, Stan Uecke, John Sender

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Proceedings Volume 7464, Free-Space Laser Communications IX; 746408 (2009) https://doi.org/10.1117/12.828869
Event: SPIE Optical Engineering + Applications, 2009, San Diego, California, United States

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 Packbot^TM. 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.

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William S. Rabinovich, James L. Murphy, Michele Suite, Mike Ferraro, Rita Mahon, Peter Goetz, Kurt Hacker, Wade Freeman, Eric Saint Georges, Stan Uecke, and John Sender "Free-space optical data link to a small robot using modulating retroreflectors", Proc. SPIE 7464, Free-Space Laser Communications IX, 746408 (21 August 2009); https://doi.org/10.1117/12.828869

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