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Proceedings Paper

Stroboscopic phase-shifting interferometry for dynamic characterization of optical MEMS
Author(s): Matthew Richard Hart; Robert A. Conant; Kam Y. Lau; Richard S. Muller
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Paper Abstract

Macro-scale optical components with surface flatness better than 25 nm over large areas (more than 1 X 1 mm) are widely available. However, the flatness of optical MEMS devices (for example micro-mirrors and -diffraction gratings) is often considerably worse. In addition to static deformation caused by film stresses and stress gradients, dynamic mechanical effects, such as air drag and excitation of higher-order resonant modes, cause surface deformations that are difficult to predict using theoretical or finite- element models. These deformations can cause significant degradation to optical performance. Dynamic measurements of nanometer-scale displacements across the entire surface of a micro-mirror are difficult or impossible to perform with conventional MEMS metrology techniques such as SEM, AFM, and optical microscopy. Stroboscopic interferometry, however, can be used to measure time-slice images that show 3D motion of fast-moving MEMS devices, with vertical resolution better than 1 nm. In this paper, we report the application of this technique to dynamic characterization of fold-up surface- micromachined structures and show how the method can be used to provide new insights into the optical and mechanical behavior of scanning micro-mirror devices.

Paper Details

Date Published: 19 July 1999
PDF: 2 pages
Proc. SPIE 3749, 18th Congress of the International Commission for Optics, (19 July 1999); doi: 10.1117/12.354838
Show Author Affiliations
Matthew Richard Hart, Univ. of California/Berkeley (United States)
Robert A. Conant, Univ. of California/Berkeley (United States)
Kam Y. Lau, Univ. of California/Berkeley (United States)
Richard S. Muller, Univ. of California/Berkeley (United States)

Published in SPIE Proceedings Vol. 3749:
18th Congress of the International Commission for Optics
Alexander J. Glass; Joseph W. Goodman; Milton Chang; Arthur H. Guenther; Toshimitsu Asakura, Editor(s)

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