A Self-Aligned 45°-Tilted Two-Axis Scanning Micromirror for Side-View Imaging

This paper presents a two-axis electrothermal single-crystal-silicon micromirror that is tilted 45° out of plane on a silicon optical bench (SiOB). The SiOB provides mechanical support and electrical wiring to the tilted two-axis scanning mirror, as well as aligned trenches for assembling other optical components, such as optical fibers and GRIN lens. The preset tilting of the mirror plate is achieved via the bending of a set of stressed bimorph cantilevers. A stopper connected on the bending bimorphs reaches and is stopped by the adjacent silicon sidewall. The tilt angle can be precisely controlled by properly choosing the distance from the stopper to the silicon sidewall and the flexure bimorph length. The fabricated mirror plate is 0.72 mm × 0.72 mm and the footprint of the entire MEMS device is 2.22 mm × 1.25 mm. The measured maximum total optical scan angle of the mirror is approximately 40° in both x-axis and y-axis at only 5.5 Vdc. This technology will enable a new class of more compact microendoscopic optical imaging probes for in vivo early cancer detection.