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Proceedings Paper

Insight into fiber Bragg sensor response at 100-MHz interrogation rates under various dynamic loading conditions
Author(s): George Rodriguez; Marcelo Jaime; Chuck H. Mielke; Fedor F. Balakirev; Abul Azad; Richard L. Sandberg; Bruce Marshall; Brandon M. La Lone; Bryan F. Henson; Laura Smilowitz; Mark Marr-Lyon; Tom Sandoval
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Paper Abstract

A 100 MHz fiber Bragg grating (FBG) interrogation system is described and applied to strain, pressure, and shock position sensing. The approach relies on coherent pulse illumination of the FBG sensor with a broadband short pulse from a femtosecond modelocked erbium fiber laser. After interrogation of the FBG sensor, a long multi-kilometer run of single mode fiber was used for chromatic dispersion to temporally stretch the spectral components of the reflected pulse from the FBG sensor. Dynamic strain or pressure induced spectral shifts in the FBG sensor were detected as a pulsed time domain waveform shift after encoding by the chromatic dispersive line. Signals were recorded using a single 35 GHz photodetector and a 25 GHz bandwidth digitizing oscilloscope. Application of this approach to high-speed strain sensing of magnetic materials in pulsed magnetic fields to ~150 T is demonstrated. The FBG wavelength shifts were used to study magnetic field driven magnetostriction effects in LaCoO3. A sub-microsecond temporal shift in the FBG sensor wavelength attached to the sample under first order phase change appears as a fractional length change (strain: ΔL/L<10-4) in the material. A second application to FBG sensing of pressure dynamics to nearly 2 GPa in the thermal ignition of the high explosive PBX-9501 is also demonstrated. Then, as final demonstration, we use a chirped FBG (CFBG) to resolve shock propagation dynamics in 1-D from an explosive detonation that produces fragmentation in an inert confinement vessel. These applications demonstrate the use of this FBG interrogation system in dynamical extreme conditions that would otherwise not be possible using traditional FBG interrogation approaches that are deemed too slow to resolve such events.

Paper Details

Date Published: 13 May 2015
PDF: 15 pages
Proc. SPIE 9480, Fiber Optic Sensors and Applications XII, 948004 (13 May 2015); doi: 10.1117/12.2086707
Show Author Affiliations
George Rodriguez, Los Alamos National Lab. (United States)
Marcelo Jaime, Los Alamos National Lab. (United States)
Chuck H. Mielke, Los Alamos National Lab. (United States)
Fedor F. Balakirev, Los Alamos National Lab. (United States)
Abul Azad, Los Alamos National Lab. (United States)
Richard L. Sandberg, Los Alamos National Lab. (United States)
Bruce Marshall, National Security Technologies, LLC (United States)
Brandon M. La Lone, National Security Technologies, LLC (United States)
Bryan F. Henson, Los Alamos National Lab. (United States)
Laura Smilowitz, Los Alamos National Lab. (United States)
Mark Marr-Lyon, Los Alamos National Lab. (United States)
Tom Sandoval, Los Alamos National Lab. (United States)


Published in SPIE Proceedings Vol. 9480:
Fiber Optic Sensors and Applications XII
Gary Pickrell; Eric Udd; Henry H. Du, Editor(s)

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