Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2007 · 17 citations · 2 references
Natural SciencesMaterials SciencePhysicsOpticsPhotonicsSensorsFiber OpticsInterferometryOptical FibersPressure SensorsShock WavesBragg Grating SensorsDetonationDynamic Pressure MeasurementFiber Bragg Grating SensorsFiber-optic Pressure SensorsFiber-optic SensingMach-zehnder InterferometersShock Wave Measurement
A new technique for the dynamic measurement of detonation pressures by use of a Fibre Bragg Grating (FBG) sensor is reported. A variation in pressure changes the wavelength of the FBG reflected light. In a detonation, the shock wave passes the explosive with a velocity of ca. 7 km/s and the pressure builds up to ca. 20 GPa within 100 ns, so huge differences in pressure exist in a small area. To prevent measuring the average pressure in a few mm, short FBG with a length of about 0.5mm is developed by Hongkong PolyU and is inserted in the explosive. The light reflected by the FBG is sent to a fibre optic Mach-Zehnder interferometer with a 3x3 beam combiner. Pressure induced wavelength shift will cause a phase change of the interferometric signal. Using the 3 output signals of the interferometer, the phase can be calculated. Interaction between the FBG and the ionization light generated by the shockwave is also demonstrated.
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