Free Space Optical Communications on US Navy Carriers

We are currently in development of an eye-safe free space optical communication system for use aboard US Navy aircraft carriers. This system using infra red LEDs permits instantaneous two way optical communications from anywhere on the carrier flight deck to a 190 degree transceiver mounted on the ship's island. The technology uses a hand held PDA for data collection (via speech capture) and transmits the data to the ADMACS data system aboard the carrier at data rates of 1Mbps. Operations take place during all lighting and weather conditions and operate interference free from crowded RF and radar generated EMI environment.

Currently we are operating at 1Mbit data rates and have sucessfully tested at 10Mhz. We anticipate reaching 50Mhz using our new proprietary LED drive solutions and with a revision of our current receiver. Our extremely low noise optical receivers are capable of detecting as little as 10nA of radiant output from the emitter, are capable of operating in the brightest sunlight conditions, and operate at distances exceeding 2500 feet using hand pointed emitters. At lower data rates (10kbits) we can operate at up to 2.4km.

Sample image Photo shows location of the single island based optical transciever and the optical communication coverage where multiple 20 degree fields permit multiple optical data transfers simultaneously.

Sample image Carrier personnel use hand held optical transceiver to carry out two-way communcations with the island mounted receiver.

GPS-less optical localization

For a DARPA application we developed a method for localizing remote data sensors that are dropped randomly into an area of interest. The exact position of these devices cannot always be determined from GPS based reading and an alternative approach was needed. We developed an optically based localization system that included a 360 degree camera and free space optical communications device (left photo) which coexisted with the data sensor.

Together with a second device (right photo) that operates like a lighthouse, and communicates with the remote sensor via an infrared laser-based free space optical communications beam directed by a rotating mirror and gimbal system, we were able to provide accurate positioning of the remote sensors to within +/-2.5 inches.

Using the 360 degree camera system, the remote sensors were also able to self-locate based on observations of airborne optical signals from passing aircraft.

Sample image Sample image Left photo is 360 degree optical communications sensor that talks to other sensors via free-space optical communications at distances of up to 1000 ft. Right photo shows optical position device that provides precise localization data to the remote sensors via a laser based optical communications scheme.