Lasers Get In Your Eye In New Screen

Computers are so small now that a system with all the power of a desktop model can fit in a Walkman-sized packet. But where does the screen go?

MicroVision has gotten around the problem by beaming images directly into the eye.

With the new system, there could be, perhaps in the next decade, three-dimensional video games in which the players themselves move through the images.

Virtual retinal display works because sight is the brain’s interpretation of the light that comes in through the pupil and falls on the retina. MicroVision’s system mimics the way the eye works.

First, an image comes out of a computer and is broken down into its constituent parts, color and brightness.

Then, the system’s electronics transform the image into picture elements, or pixels. They are conveyed by fiber optic cable to a pair of tiny, rapidly moving mirrors that paint the pixel stream onto the back of the eye, just as a cathode ray tube paints an image across a TV screen.

What’s remarkable is the speed at which the scanners project the individual points of light - about 18 million times a second. It’s so fast the eye perceives it as a stable image, rather than a series of consecutive dots.

“You already have this very high performance, very dynamic screen built into your head - it’s called the eye,” said Todd MacIntyre, the company’s vice president of business development. “Why not take advantage of that?”

“We’re just leveraging the eye’s response to light, only instead of reflected light we’re using directed light,” he said.

Virtual retinal display holds amazing possibilities for computer-generated images that users would perceive as real as the real world. Because the images are created in the same way as human sight, the only limit on the sharpness of the picture is the power of the computer behind it.

“We can potentially approximate the visual acuity of a human,” said MacIntyre. “Potentially, this is as good or better than film.”

The technology is complex, but the feeling is simple.

Anyone who has looked into a microscope and seen the image go from black to the bright, invisible world sent up the scope knows the feeling. But rather than seeing something real, with MicroVision the user sees an image created by a computer.

The virtual retinal display images appear to hang a few feet in front of the viewer, strangely solid, though translucent. The viewer can look at objects beyond. And that will be the first use of the system, MicroVision believes.

Surgeons using minute cameras to guide their work inside the body would have the images float in front of them. They wouldn’t have to turn toward monitors.

Looking out over enemy terrain, soldiers would be able to call up detailed maps with locations of hidden mines marked out and overlaying the ground before them.

“Imagine looking at an aircraft and trying to work out how to fix it,” said analyst Jackie Fenn of the Gartner Group in Burlington, Mass.

“You could have the schematics beamed into your eye in a way that doesn’t affect your vision,” she said. “You can see through the image and see what’s beyond. It’s completely unique.”

Prior to MicroVision’s system, so-called “heads up” computing used small matchbook-sized screens attached to visors. They usually used liquid-crystal displays, which are easily washed out by the ambient light of a sunny day.

Virtual retinal display doesn’t have that problem. It projects light directly into the eye, allowing about 60 percent of the original light from the image to be used. Liquid-crystal displays are only about 2 percent efficient, said senior researcher David Melville.

“You can’t use (liquid-crystal displays) on a sunny day, which means (soldiers) can only clean up mines when it rains,” said president and chief executive officer Richard Rutkowski.

Although some might worry about having lasers beamed into their eyes, MacIntyre said the light photons emitted by the display are just like the light coming off a computer screen.

“The American National Standards Institute has published guidelines for exposure to visible light,” he said. “We operate anywhere from 10,000 to 100,000 times below that safe threshold.”

For now, MicroVision, a publicly held corporation founded in 1993, is putting together color prototypes of its system.

Officials hope to have working systems available in roughly 18 months, costing between $5,000 and $50,000 each. MacIntyre expects the first contracts to be mostly for military and medical uses.