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The effect of acoustic noise on optical fibre based laser Doppler velocimetry systems

C.N.Pannell
Optoelectronics Research Centre, University of Southampton, UK

J.D.C.Jones
Department of Optoelectronics and Laser Engineering, Heriot Watt University, Riccarton, Edinburgh, UK

D.A.Jackson
Department of Physics, University of Kent, Canterbury, Kent, UK

Abstract

The potentially serious problem of acoustic noise pick-up in fibre-based LDV systems is addressed both theoretically and experimentally. A new broadening mechanism, called phase noise broadening, is discussed and the magnitude of this effect is estimated for typical LDV systems. This broadening leads to an overestimate of the turbulence index which is more serious for low speed flows. In a representative situation the magnitude of the error in the turbulence index is of the order of 5%.


6th International Symposium on Applications of Laser Techniques to Fluid Mechanics Lisbon 20-23 Jul (1992)

Southampton ePrint id: 77346

 

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Copyright University of Southampton 2006