MEMS 3-D Scan Mirror With SU-8 Membrane and Flexures for High NA Microscopy

We demonstrate a micro-electro-mechanical systems (MEMS) beam scanner capable of biaxial scanning with simultaneous focus control, for integration into a handheld confocal microscope for skin imaging. The device is based on a dual-axis gimbal structure with an integrated large-stroke deformable mirror. SU-8 polymer is used to construct both the deformable membrane as well as the torsional hinges for biaxial scanning. The 4-mm-diameter mirror can perform raster pattern scanning with a range of +/-1.5° and Lissajous scanning with a range of +/-3° (mechanical scan angle), and has a maximum deflection of 9 μm for focus control. The design, fabrication, and characterization of the opto-mechanical performance of the MEMS device are presented in this paper.