Portable Optoma, 3M 'pico' projectors put on a big show

— -- You're lying in bed, staring in the dark up at a movie, music video, or slideshow that's been projected on the ceiling. If you didn't know better, you might assume the image was projected by one of those heavy-duty projectors common to conference rooms, school auditoriums and home theaters. Instead, the little projector is much closer in size and weight to the iPhone or iPod from which you are playing the video. It's tiny enough to stuff in your pocket.

That, in a nutshell, is what makes a new class of small digital micro or "pico" projectors so darn cool. You can easily schlep them wherever you go and turn virtually any light, blank surface into a screen. With some variation, such projectors can connect to iPods, phones, digital cameras, PCs and PDAs.

I've been testing two of these mini marvels: the Optoma Pico Pocket Projector PK101 and the 3M Micro Professional Projector MPro110.

The projectors don't have noisy fans or bulbs that are likely to need replacing. 3M claims the LED (light-emitting diode) light source in its unit will last more than 10,000 hours; Optoma says its LED will go twice as long. The projectors work off tiny chips, DLP (from Texas Instruments) in Optoma's case, and LCoS (liquid crystal on silicon) with 3M.

Easy as it is to get seduced by all this, it's important to recognize the limitations. Resolutions are limited. None of these small projectors can produce an image as bright as large, heavy corporate or home theater projectors you may be familiar with.

In projector-speak, the 3M operates at 8 lumens, a common brightness measure; in its brightest mode, the Optoma is at 9 lumens. By contrast, the projector in your office might have 2,000 lumens.

This results in dim images, especially in well-lit rooms. These are not, suffice to say, ideal projectors for delivering a presentation to a large gathering.

All that said, these pocket projectors deliver decent enough results in a home or hotel. It beats having the family crowd around a video iPod screen; now, you can all gaze at the movie on the wall.