| Vol. 3, No. 1, August 2006- Art. 7 |
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| Optical Detection of the Coriolis Force on a Silicon Micromachined
Gyroscope |
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by
Valerio Annovazzi-Lodi, Sabina Merlo, Michele Norgia - University
of Pavia, Guido Spinola, Benedetto Vigna, and Sarah Zerbini-
STMicroelectronics
Copyright
Copyright © IEEE, 2003. Reprinted from Optical Detection
of the Coriolis Force on a Silicon Micromachined Gyroscope,
by Valerio Annovazzi-Lodi, Sabina Merlo, Michele Norgia Guido
Spinola, Benedetto Vigna, and Sarah Zerbini, IEEE JOURNAL
OF MICROELECTROMECHANICAL SYSTEMS, VOL. 12, NO. 5, OCTOBER
2003 |
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Abstract
In this paper we report on the optical characterization of a micromachined
gyroscope prototype for automotive applications by means of feedback
interferometry. In order to detect the rotation-induced Coriolis
force directly, we have developed a compact and stable interferometric
setup which has been positioned inside a small vacuum bell mounted
on a rotating table. By using this setup, which has a noise limit
of the order of 10-11 m/(Hz)1/2, we have measured the gyro responsivity
curve, demonstrating the feasibility of the optical interferometric
detection of the in-plane response of a MEMS sensor. In addition,
we have carried out the full mechanical characterization of the
device at different pressures, and we have performed the matching
of the gyro resonance frequencies by the interferometric monitoring.
Our gyro had a resonance frequency of 3986 Hz for both axes after
tuning; at a pressure of 710-2 Torr, the quality factors were
Q = 18000 for the driving axis and Q=1800 for the sensing axis,
while the measured responsivity was 7 10-10 m/(°/s). The optical
characterization represents an important feedback to the designer
and is especially powerful in the case of prototypes for which
the on-board electronics is not yet available.
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