Simultaneous interrogation of interferometric and Bragg grating sensors.
We propose a new method for the simultaneous interrogation of conventional two-beam interferometers and Bragg grating sensors. The technique employs an unbalanced Mach-Zehnder interferometer illuminated by a single low-coherence source, which acts as a wavelength-tunable source for the grating and as a path-matched f ilter for the Fizeau interferometer, thus providing a high phase resolution output for each sensor. The grating sensor demonstrates a dynamic strain resolution of ~0.05 microepsilon/ radicalHz at 20 Hz, while the interferometric phase resolution is better than 1 mrad/ radicalHz at 20 Hz, corresponding to an rms mirror displacement of 0.08 nm.
Brady
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G
Kalli
K
K
Webb
D J
DJ
Jackson
D A
DA
Reekie
L
L
Archambault
J L
JL