Lasers Project the Big Picture

Lasers Project the Big Picture

People love tiny gadgets like the iPod or Motorola Q. But they don't like staring at tiny screens, especially now that handhelds have the power to run 3-D games and display television-quality video.

Tiny, laser-based projectors could transform these pocket-size devices into full-blown entertainment systems by shining images onto walls, tabletops or the backs of airplane seats. In a bright room, the handheld projectors would produce images about as bright and big as a 10-inch laptop screen, said Greg Niven, the vice president of marketing at laser maker Novalux. "If you turn the lights out, you could make the projection 10 feet," he said.

And the quality could be stunning. Lasers generate richer hues than LCD screens, which produce images by passing white light from a bulb through color filters in the screen. (Novalux is also making lasers for giant-screen rear-projection TVs, including a model from Mitsubishi expected in late 2007.) And unlike other projectors, laser-based units don't require focusing: The pinpoint beams of light form a sharp image from any distance.

Laser projection is not new. The Corporation for Laser Optics Research, for example, has been building big-screen -- and big-cost -- video systems since the late '90s.

But newly developed miniature lasers and mirrors make it possible to build cheap projectors about the size of a thumb. The systems use mini lasers and a tiny pivoting mirror called a micro scanner, which is smaller than a pinhead. Lasers fire at the mirror, which reflects the light onto a surface one pixel at a time but so quickly that the entire screen appears to be lit at once.

These exotic technologies have roots in humble devices.

The laser bar-code scanners found in most supermarkets use a pivoting mirror to spread the beam over a wide swath. A company called Microvision has re-imagined that concept in a silicon-chip-size micro-electromechanical system, or MEMS, with a mirror that can move quickly accurately. The system is capable of creating an 800-by-600 image at a 60-hertz refresh rate, which requires projecting 28.8 million pixels per second.

The color lasers are the progeny of simple read heads found in now-ubiquitous CD and DVD players. Harnessing that laser technology for video displays posed challenges, though.

"Display lasers have almost nothing in common with the lasers used by anybody else for anything else," said Matt Brennesholtz, an analyst with the research firm Insight Media. The key difference, he said, is color.

All color displays form images by mixing red, blue and green light. And everyday semiconductor lasers don't produce the right hues. CD lasers, in fact, don't produce any color: They make infrared light. DVDs use red lasers, but not the right shade for a good picture. And the lasers in high-def Blu-ray DVD players aren't actually blue; they are violet.

Novalux tweaked gallium arsenide crystals found in traditional DVD-player lasers to get a better shade of red. And it modified the gallium nitride crystals for "blue" laser DVDs to get true-blue wavelengths. But green is trickier. "There is no way to directly generate green with a semiconductor laser," said Novalux's Niven.

So the company uses a so-called nonlinear, or "frequency doubling," crystal. An infrared laser fires into the crystal, which causes every two infrared photons to merge into one green photon. Frequency doubling is an old trick, but Novalux cut costs by using crystals of lithium niobate, which is found in all cell phones. "There's hundreds of millions of pieces of this stuff being made each year," said Niven.

Novalux hopes to ship its primary-color lasers by mid-2007. And Microvision has developed a projector system it is showing off at this week's Society for Information Display conference in San Francisco. Matt Nichols, Microvision's director of communications, said the company is considering using lasers from Novalux but hasn't picked a supplier yet. Nor has it set a date for when it will ship projectors to customers such as cell-phone makers.

Nichols confirmed that green lasers, though getting better, are still the sticking point for the company's projector. "It's a pretty darn good image right now," he said. "But there's some work to be done."