Wafer-level vacuum-packaged two-axis MEMS scanning mirror for pico-projector application

Hermetic wafer level packaging of optical MEMS scanning mirrors is essential for mass-market applications. It is the key to enable reliable low-cost mass producible scanning solutions. Vacuum packaging of resonant MEMS scanning mirrors widens the parameter range specifically with respect to scan angle and scan frequency. It also allows extending the utilizable range of mirror aperture size based on the fact that the energy of the high-Q oscillator can be effectively conserved and accumulated. But there are also some drawbacks associated with vacuum packaging. This paper discusses the different advantageous and disadvantageous aspects of vacuum packaging of MEMS scanning mirrors with respect to laser projection displays. Improved MEMS scanning mirror designs are being presented which focus on overcoming previous limitations. Finally an outlook is presented on the suitability of this technology for very large aperture scanning mirrors to be used in high power laser applications.