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Laser pointer that thinks its a projector

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Beamer for the vest pocket

A projector in the pocket size is in range: In it a mobile micro mirror develops the picture line for line. In laboratory prototypes researchers could increase its frequency of oscillation and dissolution so far that diagrams and texts appear clearly readable.

Not much more largely than a piece wuerfelzucker could be the Beamer of the future. Built into Handys would always participate the mini projector - approximately for a PowerPoint presentation in the small circle or the fast view into an on-line journal. In strange cities it could facilitate orientation, by projecting simply a city plan to the next house wall. Still is this future music. Researchers of the institute for Fraunhofer for silicon technology ISIT in Itzehoe however already built a demonstrator for such a tiny equipment. It projects texts and diagrams with a dissolution of 320 x 240 pixels. Heart is a mobile mirror with a diameter of 1,5 millimeters, which can be manufactured as mass product on a chip. It directs a laser beam by speedy changing of its tilting angle, and develops so the picture pixel for pixels.

"the special at the mirror is its suspension", stresses Ulrich Hofmann. "by a special attachment at two torsion bars the mirror can be tilted around two axles. Thus it can divert a laser beam horizontal and vertically." After each deflection the feathers/springs withdraw the mirror so fast into its initial position that it can be tilted several thousands times per second. Suitably the high mobility the researchers accelerated electronics. It decides within the range of nanoseconds, how it must modulate the laser light, so that each pixel in the correct brightness appears. In order to avoid errors in the projection, a second laser serves as control. It radiates likewise on the mobile mirror; the reflected light meets however a photodiode, which locates, as the mirror tilted. "the mirror changes its position for example by vibrations inadvertently, notices control this", explains Hofmann. "electronics can react then flexibly to it and adapt the picture information accordingly." The system is thereby to a large extent insensitively in relation to disturbances from the outside.

Still the demonstrator fits into no mobile telephone. "for the test we had not made, say electronics smaller yet to a minimum" Hofmann. That is however one of the next goals of the researchers, who in addition the frequency of the mirror movement and so the dissolution would like to increase. Also in other place it hooks still: As tiny source of light with sufficient life span and leuchtstaerke there are so far only red laser diodes. Within this range the researchers wait now for developments of their colleagues. They however already prepared their system for the multi-color enterprise.