Title :
Position determination of an acoustic burst along a Sagnac interferometer
Author :
Hoffman, Paul R. ; Kuzyk, Mark G.
Author_Institution :
Aculight Corp., Bothell, WA, USA
Abstract :
We report on a method to measure the longitudinal position of an acoustic burst, or spark, using an all-fiber Sagnac interferometer (SI). A focused pulsed ∼10 ns laser is used to ionize air creating the spark. This ionization point is situated near a coil of test fiber connected to the SI but acoustically separated from the bulk of the SI. A fast Fourier transform (FFT) performed on the temporal signal of the SI shows a series of s from which the position of the acoustic signal is determined. Over an SI length of ∼35 km, longitudinal positions are determined to within tens of meters, corresponding to a best run percent uncertainty of 0.07%.
Keywords :
Sagnac interferometers; acoustic signal detection; fast Fourier transforms; fibre optic sensors; high-speed optical techniques; ionisation; optical focusing; optical signal detection; position measurement; sparks; Sagnac interferometer; acoustic burst; acoustic signal; air ionization; fast Fourier transform; fiber sensor; focused pulsed laser; ionization point; longitudinal positions; photoacoustic detection; position determination; spark; temporal signal; test fiber; Acoustic measurements; Acoustic pulses; Acoustic testing; Coils; Fiber lasers; Ionization; Optical pulses; Position measurement; Sagnac interferometers; Sparks;
Journal_Title :
Lightwave Technology, Journal of
DOI :
10.1109/JLT.2004.824455
