Moving images into the future

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: cut James Bond in half. That problem has gone away as compact and inexpensive semiconductor lasers have become commercially available. The second problem, though, is that laser light can ‘speckle’, which is to say that when it scatters off a rough surface, a random shimmering and sparkling pattern is produced. Speckle, a consequence of the narrow range of light that a laser produces, degrades the sharpness of the projected image. It is this problem that Bi and his colleagues have overcome. They use several red, green and blue lasers and feed the light from these into an optical-fibre cable to produce white light. Because the operation of each laser is independent of the others, their speckles cancel each other out. That done, the white laser light is filtered back into red, green and blue light and projected using the DLP system.

Bi has, however, gone further than just eliminating speckle. He notes that if the red laser light used is made redder and the blue laser light made bluer, the gamut increases. Indeed, the theoretical maximum gamut of a laser-based system is almost 90% of what humans can experience.

The disadvantage of this increased redness and blueness is that higher-power lasers are required. But that may not matter too much. Lasers are more efficient than xenon lamps, which waste a lot of energy as heat. Bi and his colleagues calculate that even with the boosted lasers their projector needs only 35% of the power required to run a normal digital projector. On top of that, lasers last for a long time, whereas xenon lamps burn out and need to be replaced periodically. Running costs should therefore be lower.

The initial cost will still be higher, though, at least to start with. When launched, Phoebus’s projector is expected to be ten to 20 times more expensive than those that use a xenon lamp. But that, no doubt, will change as the cost of lasers drops.

Just as they have done with countless other areas, from telecom to compact-disc players, lasers could thus end up making going to the cinema even better than it is now.