Researchers charge a smartphone using a laser from across the room

Researchers from the University of Washington have devised a new way to charge a smartphone from across the room using lasers. The team says that the method of charging is safe and uses a narrow invisible beam from a laser emitter to deliver a charge the smartphone battery. The system is also designed with multiple safety features.

The researchers say that the laser system could potentially charge a smartphone as quickly as a USB cable does. To enable the laser charging, the team mounted a thin power cell to the back of the smartphone that is able to receive the power from the laser. A metal, flat-plate heatsink is also on the back of the smartphone to help dissipate excess heat from the laser. A reflector that shuts the laser off if a person moves into the path of the beam.

The team says that safety was the focus when designing this system. The researchers say the safety systems are robust enough to apply this charging system to "a variety of commercial and home settings." The charging beam used is generated by a laser emitter that produces a focused beam in the near-infrared spectrum.

The safety beams that shut the system down if a person moves into the beam are dubbed "guard beams" and they are low-power and harmless. The guard beams are unable to deliver power to the phone, but they reflect to the laser emitter allowing function as a safety system. The team says since the guard beams are sent to the emitter at the speed of light the system reacts faster than any human.

The beam can deliver a steady 2W of power to a 15 square inch area for a distance of up to 14-feet. The emitter can be modified to charge from up to 40-feet away and can be wide enough to charge anything placed on a counter or tabletop. The red lasers used in the image here were just for demonstration purposes, the guard beams and charging beam are invisible to the human eye.