Two-Component Directional Laser Doppler Anemometer Based on a Frequency Modulated Nd: YAG Ring Laser and Fiber Delay Lines

  • J. W. Czarske
  • H. Müller
Conference paper


A novel method for the directional multicomponent laser Doppler anemometry, LDA, based on the generation of different carrier frequencies, one for each velocity component, is presented. The carrier frequencies are generated by a chirp laser frequency modulation in conjunction with fiber delay lines of different lengths. Since the carrier frequency generation is realized without involving additional frequency shift elements like Bragg cells the LDA arrangement can be significantly simplified. Accurate velocity measurements without influence of carrier frequency fluctuations are accomplished by correlating the generated measuring Doppler signal with reference signals, given by the same carrier frequencies. The employed quadrature demodulation signal processing technique enables the measurement of the momentary Doppler frequency in the baseband. This novel LDA system is demonstrated by a directional measurement of two orthogonal velocity components of fluid flows


Fiber-optic laser Doppler anemometry Heterodyne technique Frequency multiplexing Quadrature demodulation technique 


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Copyright information

© Springer-Verlag Berlin Heidelberg 1997

Authors and Affiliations

  • J. W. Czarske
    • 1
  • H. Müller
    • 2
  1. 1.Laser Zentrum Hannover e.V.Department of DevelopmentHannoverGermany
  2. 2.Physikalisch-Technische BundesanstaltLaboratory for Fluid Flow Measuring TechniquesBraunschweigGermany

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