Low Power Electromagnetic Scanning Micromirror for LiDAR System
Jeong-Yeon Hwang, Jong‐Uk Bu, Chang‐Hyeon Ji
Abstract
In this article, a low power and compact scanning micromirror for LiDAR (light detection and ranging) system is designed, fabricated, and characterized. A 5 mm-diameter scanning micromirror is electromagnetically actuated with multi-turn copper winding formed on the gimbal and magnet assembly formed under the silicon substrate. A unique magnetic circuit that generates an asymmetric radial magnetic field has been designed and analyzed. A series-connected double spring-mass system consisting of a gimbal and a mirror plate has been used to amplify the deflection angle. An analytic model of the system has been developed and verified with finite element analysis. Also, a reinforcement rim structure is utilized to reduce the dynamic deformation of the reflective surface down to 19.3 nm <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rms</sub> . An optical scan angle of 30 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sup> is obtained at 690 Hz, 17.4 mA <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rms</sub> input, and corresponding power consumption is 7.8 mW <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rms</sub> . A prototype scanning system with 180 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sup> x 30 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sup> field-of-view has been demonstrated with fabricated scanning micromirror as the vertical scanner. The proposed approach provides a simple and compact design for a large diameter scanning micromirror, which can potentially be utilized in various LiDAR applications.