Our window into the digital universe has long been a glowing screen perched on a desk. It's called a computer monitor, and as you stare at it, light is focused into a dime-sized image on the retina at the back of your eyeball. The retina converts the light into signals that percolate into your brain via the optic nerve.
Here's a better way to connect with that universe: eliminate that bulky, power-hungry monitor altogether by painting the images themselves directly onto your retina. To do so, use tiny semiconductor lasers or special light-emitting diodes, one each for the three primary colors--red, green, and blue--and scan their light onto the retina, mixing the colors to produce the entire palette of human vision. Short of tapping into the optic nerve, there is no more efficient way to get an image into your brain.
The advantages, at least for some viewing situations, would be overwhelming. Scanning the light into only one of your eyes, for instance, would allow images to be laid over your view of real objects, giving you an animated, X-raylike glimpse of the simulated innards of something--a car's engine, say, or a human body. Alternatively, scanning slightly different images into each eye could render grippingly vivid three-dimensional scenes with pure, jewel-like spectral colors. Gamers could experience a heightened sense of reality that liquid-crystal-display goggles could never provide, because the laser or light-emitting diode system could dynamically refocus to simulate near and distant objects with utter realism.
Best of all, the system would waste essentially no photons, so it would be fantastically efficient and very well suited to the low-power requirements of mobile devices. In round numbers, lasers or LEDs would use hundreds of times less power than a small LCD screen typical of a subnotebook or handheld personal digital assistant. Imagine a cellphone or a PDA with a small, cameralike viewfinder that, by stimulating your retina when peered into, would show you an image rich in color and detail. The image would appear to your brain as a large, brightly lit display screen perhaps 65 centimeters away, which could be reconfigured quickly from, say, a traditional, boxy 4:3 format to the widescreen 16:9 format.
The forerunners of such systems, known as scanned-beam displays, are just now hitting the market. They are moving into several industries, including automotive service, to help service technicians keep track of the huge and ever-changing reams of repair data and display it precisely where and when they need it--in the service bay, while they are working on a car. This first-generation system, from the company I work for, Microvision Inc. of Bothell, Wash., was introduced to auto dealers earlier this year at the National Automobile Dealers Association Convention and Exposition in Las Vegas. The system is built around a lightweight display mounted on a baseball cap or visor [see diagram, Direct View]. In the current version, a wireless computer with a touch-pad control is worn on the belt.
Like a high-tech monocle, a clear, flat window angled in front of the technician's eye reflects scanned laser light to the eye. That lets the user view automobile diagnostics, as well as repair, service, and assembly instructions superimposed onto the field of vision. The information that the device displays comes from an automaker's service-information Web site through a computer running Microsoft Windows Server 2003 in the dealership or repair shop. The data gets to the display via an ordinary IEEE 802.11b Wi-Fi network, and all the technicians in the service center are able to access different information simultaneously from one server.
Those of you who remember the stern warnings printed on the side of the lasers in your school physics lab are probably wondering about the safety of aiming laser light directly into the eye. To ensure that its device is safe, Microvision applied rigorous safety standards from the American National Standards Institute, Washington, D.C., and the International Electrotechnical Commission, Geneva, derived from years of studying the effects of light on the eye. Laser light can be harmful because its beam is intense, capable of concentrating its power in a tiny area of incidence. This could be a problem if a fixed beam--as opposed to a scanned beam--were allowed to dwell on just one spot. We ensure that the retina is never overwhelmed by limiting the power of the laser light entering the eye to about a thousandth of a watt and using a high-reliability interlock circuit that turns on the laser only when the beam is scanning. Furthermore, because this very low-power light is continuously scanned onto the retina, its energy is dispersed over an area hundreds of thousands of times larger than a single spot of an incident beam.
Even at this very low power level, the monochrome system now being marketed, called the Nomad Expert Technician System, delivers images that are bright enough, and in a color distinct enough--a vivid red--that they can easily be seen over the background, even outdoors [see Direct View]. A test of the Nomad at the American Honda Motor Co. training center in Torrance, Calif., showed that skilled service technicians performed complex repair procedures in 39 percent less time, on average. Even at half that efficiency gain, a dealership would realize a net return on investment of US $2292 per technician per month, according to the Honda study. Honda has announced its intention to buy 3800 Nomad systems, which retail for $3995 each. Microvision has held trials with dealerships of many other leading automakers, including GM, DaimlerChrysler, and Volvo.