Ultra compact laser projection systems based on two-dimensional resonant micro scanning mirrors
Recently, there has been substantial progress in the development of ultra-compact image projection systems with dimensions clearly below the size of products based on DMDTM technology. This has been enabled by the availability of electrically modulated laser sources for all three elementary colors and a two-dimensional resonant micro scanning mirror as MOEMS device for light deflection. The laser beam formed by collimator optics is directed onto the micro scanning mirror. Then, the reflected beam describes a highly complicated Lissajous figure on the projection screen with flare angles of up to 20 degrees. By driving the mirror and electrically modulating the intensity of the laser beam in a synchronous manner, projection of images can be achieved. In this contribution we will present the theoretical background of the projection system as well as the latest achievements in system design. Both monochrome and full color systems are currently available. The latter use a separate laser bank as RGB light source, which is coupled with the projection head comprising the micro-optics and the micro scanning mirror. For monochrome red systems, the laser diode can be integrated into the projection head as well, whose volume could be reduced to 15mm x 7 mm x 5mm. All systems have VGA (640 x 480 pixels) resolution and operate with 8 bit color depth per pixel and 50 frames per second. This degree of miniaturization makes laser projection systems attractive for integration into mobile devices and overcomes limitations of display size in such appliances.