High Mechanical Bandwidth Polysilicon Micromirrors for Large Area / High Deflection Angle Micromirror Arrays

We demonstrate a new design for micromirror arrays that allow for high tilt angles (0.75deg) of mirror elements in arbitrary directions, large actuated areas (0.64 mm
²
), and high actuation bandwidth (measured resonant frequencies range from 100 to 450 kHz). This is achieved by subdividing each actuated mirror into several small submirrors that are addressed simultaneously, so that they behave as one large composite mirror. Submirrors increase the resonance frequency, surface area, and tilt angle of each composite mirror, at the expense of a slight reduction in fill factor. Different designs for the individual micromirrors were fabricated from polysilicon using standard surface micromachining technology (MUMPs) and characterized; a 5 x 5 array of composite mirrors was also fabricated and tested.