Chances are you can't remember the last time you hauled a projector out of the attic to look at slides or movies. But, says Ramesh Raskar, you may soon carry one with you everywhere you go. Raskar, a research scientist at Cambridge, MA's Mitsubishi Electric Research Laboratories, sees tiny projectors as the solution to one of the fundamental problems with our ever shrinking cell phones, PDAs, digital cameras, and other portable devices. The gizmos carry more and more of our data, but they are running out of room to display it to us. Build a tiny projector into each of those devices, though, and the world becomes your display. Raskar's team has developed hardware and software that can project digital images onto whatever surface is handy -- the wall, say, or a desktop -- and make them look good even if the impromptu screen isn't nice and smooth. And "once you buy into this notion that people would like to have this kind of an attachment," he asks, "what will they do beyond just looking at those images?" Raskar envisions projectors as the heart of a whole new way of interacting with the world, and he shared his vision with Technology Review senior editor Rebecca Zacks.

1-2. Aiming at portability. In a dimly lit lab, Raskar describes his vision of pencil-size projectors that are standard components in mobile devices. Then Jeroen van Baar, who along with Paul Deitz and Paul Beardsley works with Raskar on the project, picks up one of the team's prototypes. It's bigger than a pencil, to be sure, but the researchers are confident they will be able to shrink it down. Van Baar takes aim at a spot in the middle of four red lights taped to the wall. As the projector beams out a video game, four lasers, two on each side of the device, shine red dots onto the wall just beyond each corner of the projected image. A camera atop the device, Raskar explains, "is looking at all eight lights and finding the relationship between the wall and the projector." That way, the computer can adjust the image on the fly to keep it stable even as van Baar moves his hand to point and click. In the future, Beardsley believes, the system will use landmarks such as cracks or grout lines for reference, eliminating the need for the taped-on markers.