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Proceedings Paper

Optical readout of microaccelerometer code features
Author(s): Scott C. Holswade; Fred M. Dickey; Charles T. Sullivan; Marc A. Polosky; Richard N. Shagam
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Paper Abstract

Micromachine accelerometers offer a way to enable critical functions only when a system encounters a particular acceleration environment. This paper describes the optical readout of a surface micromachine accelerometer containing a unique 24-bit code. The readout uses waveguide-based optics, which are implemented as a photonic integrated circuit (PIC). The PIC is flip-chip bonded over the micromachine, for a compact package. The shuttle moves 500 micrometer during readout, and each code element is 17 micrometer wide. The particular readout scheme makes use of backscattered radiation from etched features in the accelerometer shuttle. The features are etched to create corner reflectors that return radiation back toward the source for a 'one' bit. For a 'zero' bit, the shuttle is not etched, and the radiation scatters forward, away from the detector. This arrangement provides a large signal difference between a 'one' and 'zero' signal, since the 'zero' signal returns virtually no signal to the detector. It is thus superior to schemes that interrogate the code vertically, which have a limited contrast between a 'one' and a 'zero.' Experimental results are presented for mock shuttle features etched into a silicon substrate. To simulate the shuttle moving under a fixed PIC, a commercially available waveguide source was scanned over the mock code.

Paper Details

Date Published: 2 September 1999
PDF: 8 pages
Proc. SPIE 3878, Miniaturized Systems with Micro-Optics and MEMS, (2 September 1999); doi: 10.1117/12.361267
Show Author Affiliations
Scott C. Holswade, Sandia National Labs. (United States)
Fred M. Dickey, Sandia National Labs. (United States)
Charles T. Sullivan, Sandia National Labs. (United States)
Marc A. Polosky, Sandia National Labs. (United States)
Richard N. Shagam, Sandia National Labs. (United States)

Published in SPIE Proceedings Vol. 3878:
Miniaturized Systems with Micro-Optics and MEMS
M. Edward Motamedi; Rolf Goering, Editor(s)

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