While the 3-D video image would not actually be projected into the air, that’s how it would appear to a person looking into the screen.

Other possibilities, Peyghambarian said, including eye-catching ads at shopping malls and a technique to enable designers of cars or airplanes to make changes more quickly. Live 3-D video also could help the military train troops, he said.

We see objects by perceiving the light that bounces off them. Peyghambarian’s technology uses holograms, two-dimensional images that reconstruct the light that would have bounced off a physical object, making it look 3-D.

In contrast, technology used for 3-D movies like “Avatar” or the election-night “hologram” of a CNN reporter in 2008 produces images that don’t show different views from different angles, as a genuine hologram or a real object does, Peyghambarian said.

Many people have seen holograms of still images. The Arizona group is one of maybe half a dozen around the world that are trying to move that technology into 3-D video, said V. Michael Bove Jr. of the MIT Media Lab.

Bove said several groups, including his own, have in fact produced such videos, achieving the magic rate of 30 frames a second. But those displays are only about the size of a postcard or smaller, he said, and one big challenge is how to make the display bigger.