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Proceedings Paper

Digital demodulation scheme for wide-dynamic-range measurements with a fiber optic interferometer
Author(s): Lisa C. Giulianelli; A. Bruce Buckman; Rodger M. Walser; Michael F. Becker
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Paper Abstract

We model and experimentally demonstrate a Hilbert Transform-based signal processing scheme that maps optical phase shifts in a fiber optic interferometer into electrical phase shifts in the harmonics of an imposed modulation frequency. The interferometer is a two-loop Mach- Zehnder with only one loop exposed to the measurand. A phase modulation at a convenient carrier frequency is applied to the first loop, and its second harmonic is applied to the second loop. A 30 Hz measurand test signal is applied, upshifted, and demodulated using a simple digital signal processing algorithm. In contrast to the nonlinear dependence of transmittance on phase shift of conventional interferometric sensors, this digital signal processing scheme yields a demodulated output that is linear with phase shift, and is capable of extracting measurands with dynamic ranges much greater than 2 (pi) radians.

Paper Details

Date Published: 1 May 1994
PDF: 10 pages
Proc. SPIE 2191, Smart Structures and Materials 1994: Smart Sensing, Processing, and Instrumentation, (1 May 1994); doi: 10.1117/12.173961
Show Author Affiliations
Lisa C. Giulianelli, Univ. of Texas/Austin (United States)
A. Bruce Buckman, Univ. of Texas/Austin (United States)
Rodger M. Walser, Univ. of Texas/Austin (United States)
Michael F. Becker, Univ. of Texas/Austin (United States)

Published in SPIE Proceedings Vol. 2191:
Smart Structures and Materials 1994: Smart Sensing, Processing, and Instrumentation
James S. Sirkis, Editor(s)

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