Laser beam scanning based AR-display applying resonant 2D MEMS mirrors

Abstract

Presented is a high-resolution AR micro display based on Laser Beam Scanning (LBS) applying a two-dimensional resonantly operated vacuum packaged MEMS mirror with large mirror diameter, high scan frequencies, high Q-factor and large field-of-view (FoV). The image is projected to the retina using a diffractive waveguide leading to a comfortably large eyebox. Advanced control algorithms and image processing methods are implemented to accurately drive, sense and control the biaxial resonant MEMS mirror as well as to optimize image projection quality. Due to a sufficiently large mirror diameter this micro display does not need any beam expansion optics between MEMS mirror and waveguide enabling an ultra-compact projection unit. Resonant operation of the MEMS mirror in both axes and exploiting the significant advantage of a hermetic vacuum package effectively reduces energy loss by damping and thus minimizes drive voltage and power consumption. The display setup demonstrates the successful realization of a small form factor high resolution micro projector that meets important requirements for enabling fashionable AR smartglasses.