3-D Technology Laboratories Inc.Mountain View, Calif.

Three-dimensional display

At a time when the display market seems preoccupied with CRTs vs flat panels, Elizabeth Downing sees a different future for computer monitors, TVs, and other equipment relying on an image to present information. While a student at Stanford University, her dreams -- and her research -- centered on the advantages that a three-dimensional display might offer if it didn't have to contend with special glasses, holograms, or virtual-reality gear. Recently, she demonstrated how the concept could produce a 3-D color image inside a cube of clear glass. The cube is surrounded by lasers, scanners, and the other components of a prototype video display that creates images a whole new way -- by creating actual 3-D images inside the solid piece of glass. In that demonstration, the glass was about the size of a sugar cube, but Downing is confident that the concept can be scaled up to handle a variety of commercial applications. To pursue that potential, she has founded 3-D Technology Labs. Among the early possibilities to be explored are applications in medicine, air traffic control, and design engineering. For example, physicians could use it to gain a fuller view of images of internal organs via magnetic-resonance imaging, computer-aided tomography, or ultrasound. For air traffic controllers, the 3-D display could be used to track aircraft in three dimensions. In product design, engineers could find the technology useful for viewing products created with computer-aided tools. Eventually the display could make 3-D TV a reality. (As a graduate student at Stanford, Downing worked with Prof. Lambertus Hesselink who has been a leader in the study of 3-D video systems.) In all those applications, there would be few if any restrictions on the viewing angle. Not only could groups of people view the display, but they could walk around it and see it in any perspective, says Downing. "There are a number of different 3-D display technologies, but this technology has some unique features," adds Downing. "For one thing, it doesn't create an image that only appears to be three-dimensional, it actually produces an image that is drawn in three dimensions. Also, the images are emissive -- they glow -- rather than being reflective in nature. They can easily be seen in ordinary room light." Another characteristic is the transparent appearance of the object being shown, although computer processing can alter that appearance. Downing says she got the basic idea for the novel display while working at FMC Corp.'s Technology Center in Santa Clara, Calif. When she came to Stanford in 1988 and began researching the concept, however, she discovered that she wasn't the first to think of it. "There was a group at Battelle Memorial Institute in Columbus that worked on this in the early 1970s without success. The right components weren't available then. They didn't have semiconductor lasers, and they didn't have the variety of fluorescent glasses that are available today." The fluorescent-glass display is based on a scientific principle called "upconversion." Certain atoms in the rare-earth family emit visible light when struck in rapid succession by two infrared laser beams of slightly different wavelengths. Different kinds of atoms emit different colors of light when stimulated in this way. To make the display, small amounts of these atoms are mixed (doped) into the glass as impurities. When the two infrared laser beams that are invisible to the naked eye are directed through the glass, a point of visible light is created where the two beams intersect. To generate color images, the rare-earth impurities that create red, green, and blue are mixed into the glass in separate layers that are very close together. When the laser beams stimulate adjacent layers at nearly the same time, the different colors fuse into a single color. Downing considers medical imaging to be the most natural application. She estimates a 10-in. prototype display would cost about $80,000, but expects that price to fall rapidly once the concept is commercialized.

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