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1 October 2009 Feedback-stabilized deformable membrane mirrors for focus control
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This paper describes a method to extend the range of motion of a deformable, continuous membrane mirror beyond the limit of open-loop electrostatic instability through feedback control. The feedback scheme employs capacitive sensing directly at the mirror actuation electrodes and is based on frequency modulation of a coupled ring oscillator using a differential measurement technique. Analysis of the system shows that the range of stable deflection depends on the relative dynamics of the device and the feedback control circuitry. Experimental results demonstrate stable closed-loop deflection of our silicon nitride membrane test device to 69% of the air gap and confirm the dependence of the maximum stable displacement on overall loop dynamics.
©(2009) Society of Photo-Optical Instrumentation Engineers (SPIE)
Sarah J. Lukes, Phillip A. Himmer, Eric J. Moog, Steven R. Shaw, and David L. Dickensheets "Feedback-stabilized deformable membrane mirrors for focus control," Journal of Micro/Nanolithography, MEMS, and MOEMS 8(4), 043040 (1 October 2009).
Published: 1 October 2009

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