Two-axis asymmetric electrothermal MEMS micromirror for decoupled resonant scanning

Electrothermally-actuated two-axis scanning microelectromechanical system (MEMS) micromirrors have gained significant attention in the field of optical endomicroscopy for their large scan range at low driving voltages. However, significant coupling between the two axes when actuated at resonance poses a challenge. In this work, an asymmetric two-axis electrothermal MEMS micromirror design is proposed to realize decoupled two-axis resonant scanning. The decoupled micromirror has been successfully fabricated. Experiments show that this new electrothermal micromirror can generate a distortion-free Lissajous pattern, achieving a frame rate of 30 fps and an optical field of view (FOV) larger than 21°×22° driven at only 2 V_pp. Compared to its symmetric counterparts, this decoupled micromirror reduces the degree of coupling by one order of magnitude, making it a great fit in advanced endoscopic medical imaging applications that demand high imaging speed, large FOV, and safe driving voltage.