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The Defense Advanced Research Projects Agency said a project team testing new optical wireless energy receiver technology was able to transfer 800 W of power to a receiver 8.6 km away in a 30 second transmission. It claims is a distance and power record amongst optical power beaming demonstration results. The U.S. Defense Advanced Research Projects Agency (DARPA) announced record results in a test campaign of a new optical power-beaming receiver. “The team recorded more than 800 watts of power delivered during a 30-second transmission from a laser 8.6 kilometers (5.3 miles) away,” said DARPA. The results represent distance and power records for this type of wireless energy transfer amongst reported demonstrations, according to the researchers, and that until now the greatest reported distance for an “appreciable amount” of optical power, greater than one microwatt, was 230 watts of average power at 1.7 kilometers for 25 seconds. It also referred to a transfer of energy over 3.7 kilometers of an undisclosed amount. “It is beyond a doubt that we absolutely obliterated all previously reported optical power beaming demonstrations for power and distance,” said Paul Jaffe of the DARPA Tactical Technology Office in a statement. Describing how the new optical power-beaming receiver works, DARPA said that the laser beam enters an aperture, strikes a parabolic mirror, and reflects onto dozens of photovoltaic cells arranged around the inside of the device, which convert the energy back to usable power. No further technical details about the emitter, transmitter, or laser technologies were disclosed. Both the transmitter and optical receiver were on the ground for the experiments. “It’s a lot easier to send a power beam directly up or down relative to the ground because there is so much less atmosphere to fight through,” said Jaffe. The work was completed within the DARPA Persistent Optical Wireless Energy Relay (POWER) program, a multi-phase initiative that envisions a network of optical transmitters and receivers that act as a relay system to “instantly beam power from a location where it can be easily generated to wherever it is needed.” For example, providing power to devices in remote and risky locations where the ability to deliver fuel is limited, such as battlefields and disaster zones. While the focus of the demonstration was to “rapidly validate the capability of a new design” to extend the potential distance and not efficiency, the team reported that at “shorter distances” the receiver achieved 20% efficiency. “Over the course of the test campaign, more than a megajoule of energy was transferred,” it added. |
