Low Power Electromagnetic Scanning Micromirror for LiDAR System

• Published in: IEEE sensors journal Vol. 21; no. 6; pp. 7358 - 7366
• Main Authors: Hwang, Jeong-Yeon, Bu, Jong-Uk, Ji, Chang-Hyeon
• Format: Journal Article
• Language: English
• Published: New York IEEE 15.03.2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Circuit design; dynamic deformation; electromagnetic actuation; Field of view; Finite element analysis; Finite element method; Laser radar; Lidar; light detection and ranging (LiDAR) system; Magnetic circuits; Magnetic resonance; Mass-spring systems; Micromirrors; Power consumption; Scanning; Scanning micromirror; Silicon substrates; Springs; Strain; Torque
• ISSN: 1530-437X; 1558-1748
• DOI: 10.1109/JSEN.2020.3048710

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 rms . An optical scan angle of 30° is obtained at 690 Hz, 17.4 mA rms input, and corresponding power consumption is 7.8 mW rms . A prototype scanning system with <inline-formula> <tex-math notation="LaTeX">180^{\circ } \times 30^{\circ } </tex-math></inline-formula> 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.