The Beam in Your Eye

By Gregory T PopeSep 1, 1992 5:00 AM


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A television image is hard to take seriously. Trapped in two dimensions on the surface of a bulky piece of hardware, it insults the resolving power of your eyes. But what if you could banish the screen altogether and have the images beamed straight into your brain?

At the University of Washington’s Human Interface Technology Lab, research engineer Joel Kollin isn’t far from doing that. His pet project is the virtual retinal display (VRD), a device that uses lasers to create pictures on the back of your eye. And if Kollin has his druthers, the VRD will someday render present television--including the much-vaunted high- definition TV--obsolete.

The VRD was once just the dream of Thomas Furness, a pioneer in interface technology. Its best-known product is virtual reality, which can transport you to alternate computer worlds when you strap on goggles with two miniature video monitors inside. In the mid-eighties at Wright- Patterson Air Force Base, Furness ran the Super Cockpit program, in which researchers tried to figure out how to let a pilot see panoramic computer images superimposed on the real world. Now that he’s director of the Human Interface Technology Lab, Furness is still trying to realize his vision and has gotten Kollin to build a prototype.

The VRD has a lot in common with an ordinary television screen. In the latter a beam of electrons sweeps back and forth across the screen, tickling a phosphorescent coating into emitting light. The VRD also uses a scanning beam: a low-powered laser that stimulates photoreceptor cells on the retina. In each case the image created is composed of cells called pixels; the more pixels, the finer the resolution.

Kollin’s hardware has so far reached a modest resolution of 400 by 300 pixels, a little under that of normal television. The computer- guided laser can create 66 images a second, which is fast enough for realistic animation. Still, the VRD has a long way to go. The images all come in red, and they fill only 35 degrees of your field of view. If your eye wanders too far, the edge of your pupil cuts off part of the picture. Kollin plans to build a gaze tracker that will readjust the image based on where you’re looking. That should spare images from amputation. And as laser technology gets more sophisticated, Kollin will be able to add more colors to his palette.

Lasers peppering your eyeballs are a lot safer than they sound, according to Kollin. You could stare into this thing all day, he claims. I have. His laser puts out less than a ten-millionth of a watt, well below government-prescribed safety limits, and Kollin has developed a safety mechanism to clip off freak surges in light intensity before they cause any damage.

Kollin’s immediate goal is to get the resolution of the VRD up to 1,280 by 1,024 pixels. But that’s just the starting point for him and Furness. They want to shrink the hardware--the lasers and the scanning mechanisms and other electronics--so that it can all fit on a single microchip. Then engineers could put the chip into the earpiece of a pair of eyeglasses. The lasers would strike the lens and reflect into the eye. Images might occupy just a part of your field of view, or, if you wished, block out the exterior world altogether.

With a chip and lasers for each eye, the VRD could produce three- dimensional images. The plan is to push the resolution to 3,000 by 2,000 pixels, with a 120 degree field of view. Theoretically, the only limit on the VRD’s sharpness is the resolving power of the human eye. And if all the equipment can be consolidated on a single chip, the manufacturing costs will shrivel up dramatically.

Given healthy funding, Kollin and Furness believe a full- performance VRD is at least five years away. Should the lab’s corporate sponsors pounce on this technology, the commercial potential is vast. We hope this will replace TV or video games, says Kollin.

Computer images overlaid on the real world could also guide surgeons performing operations, construction workers putting together airplanes, and pilots engaged in dogfights. And for escapists, entering a psychedelic virtual world would be as simple as putting on a pair of Ray- Bans.

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