Micromachined polysilicon microscanners for barcode readers

We describe the design and fabrication of micromachined resonant scanners that have large scan angles at fast scan speeds. Driven by an electrostatic combdrive actuator, these 200 μm×250 μm micromirrors have a maximum scan angle of 28/spl deg/ (optical) at a resonant frequency of 3 kHz when driven by a sinusoidal voltage of 9.5 V (amplitude) superimposed on a 30-V dc bias. Fabricated with a four-layer polysilicon-surface-micromachining process, these resonant scanners are compact, extremely light in weight, potentially very low in cost, and operate at very low power levels. Using the scanner as a laser-beam deflector, we have demonstrated a barcode reader system.