Low Power Electromagnetic Scanning Micromirror for LiDAR System

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
^o
is obtained at 690 Hz, 17.4 mA
_rms
input, and corresponding power consumption is 7.8 mW
_rms
. A prototype scanning system with 180
^o
x 30
^o
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.