Fraunhofer researchers have unveiled a video projector no larger than a sugar cube, which uses a single mirror rotated around two axes instead of conventional microarrays.
Some previous attempts at miniaturising projectors came up against physical restrictions. The core piece of a classic projector is a micromirror array comprising a million mirrors which can be tilted in one plane and are evenly illuminated. By turning towards or away from the light source, they produce light or dark pixels that together form the projected image. But not only do the arrays preclude true miniaturisation, their high price makes it difficult for projectors to enter the consumer goods market.
The scientists from the Fraunhofer Institute for Photonic Microsystems and the Fraunhofer Institute for Applied Optics and Precision Engineering have come up with an alternative to the micromirror arrays.
‘We use just one single mirror,’ said Andreas Bräuer, director of the Micro-optic Systems division at IOF. ‘This mirror can be tilted around two axes.’
The next target in the miniaturisation process is the light source. To fit the entire projector mechanism into the tiny case, the standard high-pressure lamp will have to be replaced by small diode lasers. While red and blue diode lasers are already small enough, green lasers are still too bulky.