Design and Fabrication of a Forward View Scanner on SiOB with Latch Structure for Improved Vertical Orientation

摘要

MEMS mirror based forward-view optical scanning typically requires a second mirror to direct the optical beam forward, which increases the size and weight of the scanner drastically. This paper reports a compact forward-view laser scanner with two vertically oriented scanning micromirrors integrated on a silicon optical bench. This concept was previously explored, but the bending angles of the vertical mirrors had large deviations (typically ±15°) from 90°. In this work, a new latch structure is proposed to secure the mirror frame at its vertical position and an array of meander thin-film stripes is proposed to ensure the latching. The new design has been successfully fabricated and shows much-improved verticality with a maximum deviation of less than ± 2° from 90°. The measured forward field of view (FoV) of the vertical micromirror reaches 20° in both axes at non-resonance with the voltage amplitude less than 3.5 V. The first-order resonant frequency of the micromirror is about 630 Hz. A forward scanning LiDAR has been built with this new MEMS scanner and 3D point clouds have been achieved.