Micromirrors reflect 3-D display

With the help of tiny mirrors, a general-purpose 3-D display may be one step closer to reality. Using a micromirror array, Jun Yan, recent Ph.D. graduate from the College of Engineering at the University of Cincinnati (Cincinnati, OH), and associates demonstrated a real-time, full-color, autostereoscopic, 3-D display. This display provides time-multiplexed views that are scanned to the correct viewing zones by the micromirror array.

A test image of a target (top) consists of the image for the left eye (lower left) and the image for the right eye (lower right).

3-D display systems are hot research projects for use in 3-D workstations and virtual-reality systems. "The challenge has been to make a larger screen display while maintaining color and high resolution," says Yan. The autostereoscopic 3-D displays (no glasses required) that exist today are highly specialized. "They automatically create a cone of viewing with a number of discrete zones, generating a choppy image," says Chris Chinnock, president of Insight Media (Norwalk, CT). "This approach appears to eliminate the choppiness, creating a continuous viewing zone," he says.

The researchers fabricated the micromirror array, which consists of 400 µm X 400 µm display with a center-to-center spacing of 568.5 µm. The display uses 400 micromirrors--200 for left viewing and 200 for the right. The collecting lens collects the light in the viewing zones according to the tilting of the micromirrors, which are uniformly and horizontally actuated.

Previously, the researchers experimented with using gratings to redirect light from an observer's right and left eyes. But gratings change after fabrication and are also wavelength dependent. "Micromirrors can be moved so one can scan from left to right through most of the viewing zone," says Yan. "Also, they are not wavelength dependent."

"It is an interesting concept," Chinnock observes. "While there are 3-D displays out there, a lot of people are eyeing the general consumption market, and the low-price killer 3-D monitor isn't there yet."

The patent-pending prototype display is for a single person only. "We built the design around the known position of viewer's right and left eyes," says Yan. The researchers are currently working on a multiview version of a similar design.