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Digital Movie Projection

How digital movie projectors work.

Digital action, sound and computer-animated graphics have become as much a cinema staple as the dancing soft drink and fries. Yet although motion-picture production is turning digital, in most theaters, projection is still a distinctly old-fashioned analog affair. Recently, Texas Instruments developed technology to keep the movie digital all the way to the screen. In 1996, it unveiled a projector that assembles the moving image not from film but from a stream of bits. The bit stream controls an array of micromirrors inside the device that manipulate beams of colored light and turn them into moving pictures.

The heart of the system is a network of over one million moveable mirrors on a silicon chip two centimeters wide. Each mirror measures a scant 16 micrometers square and teeters diagonally on a pivot to reflect light in one of two directions. Digital data controls where and how fast a pulse of light is reflected. The mirrors are nimble enough to handle a new light pulse every five to 10 microseconds. With this rapid switching rate, and a gap of only one micrometer between mirrors, a seamless image is produced that lacks the pixel effects marring some computer graphics or the familiar flicker of film. Like CDs, so-called digital light processing also avoids the wear and tear that causes analog information to deteriorate over time.

Digital projection debuted in 1999, when Texas Instruments teamed with Lucasfilm to present Star Wars: Episode I-The Phantom Menace. Since then, more than 30 cinemas worldwide have used the technology to present Toy Story 2, Bicentennial Man, Dinosaur, Tarzan, Mission to Mars, Fantasia 2000 and The Emperor’s New Groove. While these computer-generated movies are well suited for digital projection, the technology is not restricted to them. Conventional film can be converted to data and then displayed with a digital light processor. For this technology to really come into its own, however, moving pictures must be produced digitally from start to finish-an industrywide change still in its infancy.

Got a new technology you’d like to see explained in Visualize? Send your ideas to visualize@technologyreview.com.

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