In a demonstration at Northwestern Polytechnical University in Xianyang, China, researchers showed off a special type of laser-charged drone. It can be recharged remotely using a ground-based adaptive laser that tracks targets.
The energy from the laser is collected by the system through a photoelectric converter that is mounted on the underside of the drone. Even though they aren’t very efficient, these sorts of devices do a rather good job of wirelessly transmitting electricity to their intended destinations. At the point of transmission, power-to-laser efficiency may range anywhere from 50 to 85%, depending on how sophisticated your laser is; but at the point of reception, you are likely to lose something in the neighborhood of 50 percent of your energy once again.
But energy is cheap, and if your surveillance drone is always connected to a power source, you should consider these losses tolerable if they keep the drone from ever having to be taken offline.
An identical wireless charging system for drones was demonstrated in 2012 by a company based in Washington called PowerLight, which was formerly known as LaserMotive. During the demonstration, the company kept a big drone in the air for 2 days inside a wind tunnel. They also powered a Lockheed Martin Stalker drone outside at ranges of up to 600 meters.
The NPU team came up with a “smart visual tracking algorithm” in order to keep their beam focused on the surface of the drone. They also came up with a way to shape the beam so that it could adapt to changes in the density of the air around it. In addition, it came up with a way to find obstacles and quickly lower the intensity of the beam to a level that was safe. They used a tiny quadcopter to test it and proved that it worked both indoors when the lights were on or off as well as outside at night, with footage displaying the laser-charged drone reaching heights of around 10 meters or so.
Due to their long range, laser systems could make it possible for drones to fly at higher altitudes, creating permanent platforms in the air that can act like low-altitude satellites. But, the deployment of platforms like multicopters is likely to depend on the weather.
Since these devices would send lasers up, you should expect some pushback from the government. NPU hasn’t said how far the system can reach, how powerful the laser is, or how well the device works, saying that the gadget could be used by the military. But it’s quite obvious that this is just an early prototype from the lab.
On the other hand, Power Light seems to be much closer to commercial use. The company says it’s working on a small, lightweight, long-range, cordless laser transmission with effective safety shutdown mechanisms and the ability to work no matter the weather.
Aside from how it could be used in the military, it’s interesting to think about how wireless power has the ability to affect other types of electric aircraft, like eVTOL electric aircraft, which have problems with battery capacity and range. It is possible that a city grid with laser chargers that provide energy as they fly above may help them make more financial sense. However, there is a significant amount of work that has to be done before a laser-charged drone or other aircraft is legally permitted and suitable for urban usage.