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Simple Fabrication Process for Self-Aligned, High-Performance Microscanners—Demonstrated Use to Generate a 2-D Ablation Pattern

Choo, Hyuck and Garmire, David and Demmel, James and Muller, Richard S. (2007) Simple Fabrication Process for Self-Aligned, High-Performance Microscanners—Demonstrated Use to Generate a 2-D Ablation Pattern. Journal of Microelectromechanical Systems, 16 (2). pp. 260-268. ISSN 1057-7157.

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A new, straightforward, complementary metal–oxide–semiconductor (CMOS)-compatible, three-mask process is used to fabricate high-performance torsional microscanners driven by self-aligned, vertically offset comb drives. Both the moving and fixed combs are defined using the same photolithography mask and fabricated in the same device layer, a process allowing the minimum gap between comb fingers to be as small as twice the alignment accuracy of the photolithography process. Our fabricated microscanners have torsional resonant frequencies between 58 Hz and 24 kHz and maximum optical-scanning angles between 8° and 48° with actuation voltages ranging from 14.1 to 67.2 V_(ac-rms). The yields on two separate fabrication runs have been better than 70%. To demonstrate an application for these scanners, we used them to generate laser-ablation patterns suitable for ocular cornea surgery. We assembled a 2-D scanning system by orienting two identical microscanners at right angles to one another. When driven by two 90° out-of-phase 6.01-kHz sine waves, the cross-coupled scanners produce circular patterns having radii fixed by the amplitude of the driving voltage. Then, we emulated a small pattern from the surface topography found on a U.S. Roosevelt dime and built up an ablation pattern that compares favorably with similar emulations reported by earlier researchers who used larger, more complicated ablation systems.

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Choo, Hyuck0000-0002-8903-7939
Additional Information:© 2007 IEEE. Manuscript received August 31, 2006; revised November 22, 2006. Parts of this paper were presented orally at the 2005 IEEE/LEOS Optical MEMS Conference, Technical Digest 21-22, Oulu, Finland, August 1-4, 2005. This work was supported by the National Science Foundation under the Grants NSFEEC0318642 and CITRIS-NSF-TR22325. Subject Editor H. Fujita.
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Subject Keywords:Complementary metal–oxide–semiconductor (CMOS)-compatible, ocular refractive surgery, self-aligned vertical offset combs, torsional microscanners, 2-D scanning system
Record Number:CaltechAUTHORS:20150731-104702779
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:59106
Deposited By: Kristin Buxton
Deposited On:06 Aug 2015 18:52
Last Modified:08 May 2017 23:03

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