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Micromachines 2016, 7(4), 57;

Resonant Varifocal Micromirror with Piezoresistive Focus Sensor

Department of Nanomechanics, Tohoku University, Aramaki-aza Aoba 6-6-01, Aoba-ku, Sendai 980-8579, Japan
Research & Development Center, Panasonic Industrial Devices SUNX Co., Ltd.; Ushiyama-cho 2431-1, Kasugai 486-0901, Japan
Author to whom correspondence should be addressed.
Academic Editors: Pei-Cheng Ku and Jaeyoun (Jay) Kim
Received: 14 February 2016 / Revised: 17 March 2016 / Accepted: 25 March 2016 / Published: 30 March 2016
(This article belongs to the Special Issue Micro/Nano Photonic Devices and Systems)
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This paper reports a microelectromechanical systems (MEMS) resonant varifocal mirror integrated with piezoresistive focus sensor. The varifocal mirror is driven electrostatically at a resonant frequency of a mirror plate to obtain the wide scanning range of a focal length. A piezoresistor is used to monitor the focal length of the varifocal mirror. The device is made of a silicon-on-insulator (SOI) wafer and a glass wafer. A mirror plate and a counter electrode are fabricated by a top silicon layer of the SOI wafer and on the glass wafer, respectively. The piezoresistor is fabricated by ion implantation on a supporting beam of the mirror plate. The stress variation of the beam, which is detected by the piezoresistor, correspond the focal length of the varifocal mirror. The focus length varies from −41 to 35 mm at the resonant frequency of 9.5 kHz. The focal length of the varifocal mirror is monitored by the piezoresistor in real time. View Full-Text
Keywords: varifocal mirror; piezoresistor; resonant vibration; microelectromechanical systems varifocal mirror; piezoresistor; resonant vibration; microelectromechanical systems

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Nakazawa, K.; Sasaki, T.; Furuta, H.; Kamiya, J.; Sasaki, H.; Kamiya, T.; Hane, K. Resonant Varifocal Micromirror with Piezoresistive Focus Sensor. Micromachines 2016, 7, 57.

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