Optical readout of microaccelerometer code features

Scott C. Holswade; Fred M. Dickey; Charles T. Sullivan; Marc A. Polosky; Richard N. Shagam

doi:10.1117/12.361267

2 September 1999 Optical readout of microaccelerometer code features

Scott C. Holswade, Fred M. Dickey, Charles T. Sullivan, Marc A. Polosky, Richard N. Shagam

Proceedings Volume 3878, Miniaturized Systems with Micro-Optics and MEMS; (1999) https://doi.org/10.1117/12.361267
Event: Symposium on Micromachining and Microfabrication, 1999, Santa Clara, CA, United States

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.

Citation Download Citation

Scott C. Holswade, Fred M. Dickey, Charles T. Sullivan, Marc A. Polosky, and Richard N. Shagam "Optical readout of microaccelerometer code features", Proc. SPIE 3878, Miniaturized Systems with Micro-Optics and MEMS, (2 September 1999); https://doi.org/10.1117/12.361267

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