Research on MEMS Biaxial Electromagnetic Micromirror Based on Radial Magnetic Field Distribution

An electromagnetically actuated dual-axis MEMS scanning micromirror for lidar applications is introduced, besides a novel radial magnetic field actuation system is designed. The dual-axis scanning micromirror with large aperture which the plate size of 2.6 mm in diameter was realized utilizing patterned single-turn electroplated copper coils, which combined with a concentric permanent magnet assembly forming radial magnetic field. Based on the basic of this working principle, the displacement response outputs of different torsion beam structures were compared by theoretical analysis and finite element simulation. The serpentine elastic beam was chosen as the external torsion axis of the micromirror device because of its large displacement output. The coupling magnetic field of the permanent magnet assembly was analyzed and simulated to achieve the maximum magnetic field intensity at the coils. Horizontal resonance frequency of the presented micromirror was 3376.2 Hz and vertical resonance frequency was 419.46 Hz, in addition, maximum deflection angle of approximately ±25.2°in horizontal direction and about ±17.4°in vertical direction were achieved at resonance. The design of the micromirror meets the requirements of MEMS lidar for large mirror size and wide scanning field of view.