Optical simulation for an optimized wafer level optopackage for 2D-micromirrors

The Fraunhofer Institute for Silicon Technology in Itzehoe has developed vacuum encapsulated dual-axis scanning micro-mirrors, for high-resolution laser projections [1]. Sinceparallel orientation of the glass cover to the micro-mirror results in a bright laser spot in the projected image, a wafer level packaging with an inclined glass lid was developed to eliminate the reflex in the image. To determine the quality requirements and the design specifications of the new package, optical simulations were performed in Zemax®. For this purpose, the influence of the surface curvatures on the laser beam was examined. A further study was focused on the avoidance of secondary reflections, resulting in a disturbing ghost images superimposing the projected image.