Telescopes often have a ring-shaped primary mirror to concentrate light onto a secondary mirror, which, in turn, reflects it through the hole in the primary. The same principle informs a new design for backlit screens.
In the 'telescopic pixels' described by Anna Pyayt of the University of Washington in Seattle and her team, the shape of the primary mirrors is under electronic control. When their shape is near-parabolic, they bounce light onto the secondaries, illuminating the holes in the primaries. When they are flat, no light hits the secondaries and the holes remain dark.
The prototype pixels transmit more than three times as much light as comparable liquid crystal displays. At present, the contrast they achieve is low, but models suggest that this can be improved. The technology may be suited to large, energy-efficient flat panels.