WINDOWS ON THE VIRTUAL WORLD: HEAD-MOUNTED DISPLAYS

If Alice Through the Looking Glass were written today, the heroine might have used a head-mounted display to go through to the other side, instead of a mirror. Inside head-mounted displays, explains Walter Robinett, director of the head-mounted display project at the University of North Carolina, "are two 3-inch- square liquid crystal display television screens. In front of them are some lenses so that the image portrayed on the television screen doesn't seem two inches in front of the viewer, but 10 feet off. It creates the illusion that you are in a life-size, 3-D world. Each screen has a different view so you see a stereoscopic, wide-angle view of this computer-simulated place."

"On the head-mounted display," Robinett goes on, "is a device called a Polhemus that measures your head position and can detect where...