New laser scanning technology may enable higher resolution pico projectors

The Fraunhofer IPMS developed a new laser scanner technology called LinScan that features a quick switching of the target positions of the laser beam and a dynamic adjustment of the scanning speed. This technology may enable higher resolution pico projectors and 3D cameras (the image below shows an optical scan head of a 3D-TOF-camera with integrated MEMS scanning mirror array).

3D-TOF-camera optical scan head

The Fraunhofer says that unlike the double-resonant scanning principle used so far for pico-projectors, where the mirror oscillates in a sinusoidal manner with a frequency predefined by the geometry of the component, LinScan makes it possible for the laser beam to jump from line to line with a flexible scanning speed.

Fraunhofer sent the following technology explanation: LinScan is based on the manufacturing technology developed by Fraunhofer IPMS for resonant microscanners. The idea is to tilt the drive combs of the hitherto existing resonant scanner toward each other. This makes the linear drive of the mirror plate on one axis possible. Furthermore, a resonant drive with a defined frequency on the fast horizontal axis can be combined with a variable quasi-static oscillation on the vertical axis. The components are manufactured in the Fraunhofer IPMS cleanroom in a bulk micromachining manufacturing process. All of the micro-mechanical components are manufactured as two-dimensional structures in a layer of monocrystalline silicon. The vertical comb electrodes are realized in an adhesive wafer bonding process with a second planar-structured silicon wafer. Mechanical solid state structures on the second wafer tilt or stagger the in-plane comb drive, the whole device is fixed by and subsequent wafer-bonding fusing. Given the small tolerances of micromachining processes, the structures on the two wafers are optimal aligned to each other. This component concept is extremely flexible and makes it possible to realize a broad spectrum of component characteristics.

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