It was the second day of a 3-day-long tech demonstration at the David Taylor Model Basin at the Naval Surface Warfare Center in Bethesda, MD, where attendees had gathered to stand around in the dark to look at something they mostly couldn't see.
It was a long-range, free-space power beaming system—the first of its kind. Attendees that day, May 23, could see the system itself—the two 13-foot-high towers, one a 2-kW laser transmitter, the other a receiver of specially designed photovoltaics. But the important part—the laser that was beaming 400 W of power across 325 m from the transmitter to the receiver—was invisible to the naked eye.
On one end of the of the testing facility—one of the largest test facilities for model ships in the world—the receiver was converting the laser energy to DC power, which an inverter turned into AC power to run lights, several laptops, and a coffeemaker that the organizers were using to make coffee for the attendees (laser lattes)." As more than one person there had noted, it wasn't exactly an exciting scene. But when you're transmitting hundreds of watts of power with a laser beam "exciting" is not what you're aiming for. You want it quiet, boring and, most importantly, safe. And so it was.