Using Lasers to Recharge Your Phone

Laser Beam

A team of researchers from the University of Washington has come up with a system to wirelessly charge a phone from anywhere in the room using lasers. Once the phone is placed in a stationary position within the room, the laser finds it and beams a collimated light into a photovoltaic cell. Although this is not a new idea, the team has found a way to address the primary obstacle – safety.

The use of concentrated light to provide power has been pitched for a number of applications, but the problem is that the laser could also impose series damage. In this application, that potentially means having a laser hitting human beings in the eye.

A solution came in mounting retroreflectors around the photovoltaic cell on the phone. These reflectors essentially work like those found on road signs, with their three-sided, cubed corners with mirrored inner surfaces reflecting light back at the same angle as it hits them. This reflection concept forms a harmless tube of light around the more powerful laser beam. So, if anything breaks that outer barrier of reflected light, the power to the laser is cut. The signal charged with this safety function moves at the speed of light, so a human being moving fast enough to penetrate the outer light layer and make contact with the laser is nearly impossible.

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