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Journal of the Optical Society of America A

Journal of the Optical Society of America A


  • Vol. 18, Iss. 3 — Mar. 1, 2001
  • pp: 696–703

Measurements of the instantaneous velocity difference and the local velocity with a fiber-optic coupler

Sheng-Hong Yao, Viktor K. Horváth, Penger Tong, Bruce J. Ackerson, and Walter I. Goldburg  »View Author Affiliations

JOSA A, Vol. 18, Issue 3, pp. 696-703 (2001)

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New optical arrangements with two single-mode input fibers and a fiber-optic coupler are devised to measure the instantaneous velocity difference and the local velocity. The fibers and the coupler are polarization-preserving to guarantee a high signal-to-noise ratio. When the two input fibers are used to collect the scattered light with the same momentum-transfer vector but from two spatially separated regions in a flow, the obtained signals interfere when combined via the fiber-optic coupler. The resultant light received by a photomultiplier tube contains a cross-beat frequency proportional to the velocity difference between the two measuring points. If the two input fibers are used to collect the scattered light from a common scattering region but with two different momentum-transfer vectors, then the resultant light contains a self-beat frequency proportional to the local velocity at the measuring point. The experiment shows that both the cross-beat and the self-beat signals are large and that the standard laser Doppler signal processor can be used to measure the velocity difference and the local velocity in real time. The new technique will have various applications in the general area of fluid dynamics.

© 2001 Optical Society of America

OCIS Codes
(030.7060) Coherence and statistical optics : Turbulence
(060.1810) Fiber optics and optical communications : Buffers, couplers, routers, switches, and multiplexers
(060.2420) Fiber optics and optical communications : Fibers, polarization-maintaining
(120.7250) Instrumentation, measurement, and metrology : Velocimetry

Original Manuscript: June 5, 2000
Revised Manuscript: September 28, 2000
Manuscript Accepted: September 28, 2000
Published: March 1, 2001

Sheng-Hong Yao, Viktor K. Horváth, Penger Tong, Bruce J. Ackerson, and Walter I. Goldburg, "Measurements of the instantaneous velocity difference and the local velocity with a fiber-optic coupler," J. Opt. Soc. Am. A 18, 696-703 (2001)

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  1. U. Frisch, Turbulence: The Legacy of A. N. Kolmogorov (Cambridge U. Press, Cambridge, UK, 1995).
  2. K. R. Sreenivasan, “Fluid turbulence,” Rev. Mod. Phys. 71, S383–395 (1999). [CrossRef]
  3. G. I. Taylor, “The spectrum of turbulence,” Proc. R. Soc. London Ser. A 164, 476–490 (1938). [CrossRef]
  4. T. Narayanan, C. Cheung, P. Tong, W. I. Goldburg, X.-L. Wu, “Measurement of the velocity difference by photon correlation spectroscopy: an improved scheme,” Appl. Opt. 36, 7639–7644 (1997). [CrossRef]
  5. Y. Du, B. J. Ackerson, P. Tong, “Velocity difference measurement with a fiber-optic coupler,” J. Opt. Soc. Am. A 15, 2433–2439 (1998). [CrossRef]
  6. B. J. Berne, R. Pecora, Dynamic Light Scattering (Wiley, New York, 1976).
  7. P. Tong, W. I. Goldburg, C. K. Chan, A. Sirivat, “Turbulent transition by photon correlation spectroscopy,” Phys. Rev. A 37, 2125–2133 (1988). [CrossRef] [PubMed]
  8. H. K. Pak, W. I. Goldburg, A. Sirivat, “Measuring the probability distribution of the relative velocities in grid-generated turbulence,” Phys. Rev. Lett. 68, 938–941 (1992). [CrossRef] [PubMed]
  9. P. Tong, Y. Shen, “Relative velocity fluctuations in turbulent Rayleigh–Bénard convection,” Phys. Rev. Lett. 69, 2066–2069 (1992). [CrossRef] [PubMed]
  10. H. Kellay, X.-L. Wu, W. I. Goldburg, “Experiments with turbulent soap films,” Phys. Rev. Lett. 74, 3975–3978 (1995). [CrossRef] [PubMed]
  11. Oz Optics Ltd, 219 Westbrook Road, Carp, Ontario, Canada, K0A 1LO ( http://ozoptics.com ).
  12. P. Tong, K.-Q. Xia, B. J. Ackerson, “Incoherent cross-correlation spectroscopy,” J. Chem. Phys. 98, 9256–9264 (1993). [CrossRef]
  13. J. W. Daily, D. R. F. Harleman, Fluid Dynamics (Addison–Wesley, Reading, Mass., 1966), p. 421.
  14. F. M. White, Viscous Fluid Flow, (McGraw-Hill, New York, 1991), p. 470.
  15. F. Durst, J. H. Whitelaw, “Optimization of optical anemometers,” Proc. R. Soc. London Ser. A 324, 157–181 (1971).
  16. L. E. Drain, The Laser Doppler Technique (Wiley, New York, 1980).
  17. M. A. Rutgers, X.-L. Wu, R. Bagavatula, A. A. Peterson, W. I. Goldburg, “Two-dimensional velocity profiles and laminar boundary layers in flowing soap films,” Phys. Fluids 8, 2847 (1997). [CrossRef]
  18. W. I. Goldburg, A. Belmonte, X.-L. Wu, I. Zusman, “Flowing soap films: a laboratory for studying two-dimensional hydrodynamics,” Physica A 254, 231–247 (1998). [CrossRef]
  19. V. K. Horváth, R. Crassman, W. I. Goldburg, X.-L. Wu, “Hysteresis at low Reynolds number: onset of two-dimensional vortex shedding,” Phys. Rev. E 61, R4702–4705 (2000). [CrossRef]
  20. For a full description of the correlator board, see http://karman.phyast.pitt.edu/horvath/corr/ . The total cost for the correlator board is less than $100. The device can be duplicated for nonprofit applications without permission.
  21. See, e.g., W. H. Press, B. P. Flannery, S. A. Teukolsky, W. T. Vetterling, Numerical Recipes, 2nd ed. (Cambridge U. Press, UK, 1992).
  22. J. D. Scargle, “Studies in astronomical time series analysis III,” Astrophys. J. 343, 874–887 (1989). [CrossRef]
  23. S. H. Yao, P. Tong, B. J. Ackerson, “Instantaneous vorticity measurements using fiber-optic couplers,” manuscript available from the authors, c/o P. Tong at Oklahoma State University, Physics Department, Stillwater, Okla. 74078-3072.

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