A revolutionary type of 3-D display could provide a new look to moving images.
David Fattal, a French-born quantum physicist who is now a researcher at HP Labs, is a master of nanoscale light tricks, and the feat he unveiled this year is his most impressive yet. It’s a new kind of display that can project colorful moving images, viewable in three dimensions from multiple angles without any special glasses.
Fattal’s invention, which he calls a “multidirectional backlight,” consists of a thin piece of glass (or plastic) with light-emitting diodes mounted on its edge. Thanks to its particular design, which governs the angle at which the light is propagated, the device takes advantage of total internal reflection—the same optical phenomenon used in fiber optics.
Light from the LEDs doesn’t escape from the material until it hits nanoscale features etched or imprinted on the surface—what Fattal calls “directional pixels.” Composed of grooves smaller than the wavelength of the light, the pixels allow for precise control over the direction in which individual rays are scattered, shooting the different colors of light in specific directions. The result is colorful images that “seem to come from nowhere,” says Fattal.
In a paper published in Nature in March, Fattal and colleagues presented prototypes capable of projecting static and moving images viewable from 200 angles. They performed the trick by overlaying their novel backlight with an ink-printed mask that blocked certain colors and allowed others through. One of the first images they produced was that of a turtle hovering immediately above the glass. Fattal has also used a modified liquid crystal display to produce simple moving images.
Since the setup creates realistic, hologram-like 3-D images without the need for bulky optical equipment, it could be attractive for use in smartphones, tablets, smart watches, and other mobile devices.
Projecting high-quality images, however, will require much larger and more complicated pixel arrays and advanced mechanisms for handling a huge number of data-rich images quickly. And creating 3-D content that can be enjoyed from all the many vantage points accommodated by this technology will be no small task either. But in his ingenious use of nanotechnology, Fattal has given us the possibility of seeing images and videos in a whole new light.
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