Abstract

A method is described to measure the speed of sound and the temperature in the sea as functions of depth. Backscattered laser light is analyzed with an interferometric spectrometer. The speed of sound at very short acoustic wavelengths is obtained directly from the wavelength shift of the Brillouin scattered light, and the temperature is deduced from the speed of sound together with auxiliary information on depth and salinity. Experiments are described.

© 1984 Optical Society of America

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References

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  1. Stommel Report, “The Role of the Oceans in Climate Production,” Ocean Science Committee, U.S. National Academy of Sciences(1975).
  2. F. D. Tappert, U. Miami; private communication (1982).
  3. G. E. Walrafen, “Raman Spectral Studies of the Effects of Temperature on Water Structure,” J. Chem. Phys. 47, 114 (1967).
    [CrossRef]
  4. R. L. Schwiesow, “Raman Scattering from Pollutant Gases and Air–Water Interfaces,” AIAA J. 11, 87 (1973).
    [CrossRef]
  5. C. H. Chang, L. A. Young, Avco-Everett Research Laboratory Research note 960, Everett, Mass. (1974).
  6. C. H. Chang, L. A. Young, D. A. Leonard, U.S. Pat.3,986,775 (Dec.1974).
  7. D. A. Leonard, B. Caputo, R. L. Johnson, F. E. Hoge, “Experimental Remote Sensing of Subsurface Temperature in Natural Ocean Water,” Geophys. Res. Lett. 4, 279 (1977).
    [CrossRef]
  8. D. A. Leonard, B. Caputo, F. E. Hoge, “Remote Sensing of Subsurface Water Temperature by Raman Scattering,” Appl. Opt. 18, 1732 (1979).
    [CrossRef] [PubMed]
  9. D. A. Leonard, “Remote Raman Measurement Techniques,” Opt. Eng. 20, 91 (1981).
    [CrossRef]
  10. D. A. Leonard, B. Caputo, J. D. Fridman, “Remote Sensing of Subsurface Water Temperature by Raman Polarization Spectroscopy,” Proc. Soc. Photo-Opt. Instrum. Eng. 307, 76 (1981).
  11. J. G. Hirschberg, A. W. Wouters, F. N. Cooke, K. M. Simon, J. D. Byrne, “Laser Application to Measure Vertical Sea Temperature and Turbidity,” NASA Report CR-139184 (Jan.1975).
  12. J. G. Hirschberg, A. W. Wouters, J. D. Byrne, “Laser Measure of Salinity, Temperature and Turbidity in Depth,” in Remote Sensing Energy Related Studies, N. Veziroglu, Ed. (Wiley, New York, 1975).
  13. J. G. Hirschberg, “The Use of Brillouin and Raman Scattering to Measure Temperature and Salinity Below the Water Surface,” in Proceedings, Waste Heat Management and Utilization Conference, Miami Beach, Fla. (1977).
  14. J. G. Hirschberg, A. W. Wouters, J. D. Byrne, “Ocean Parameters Using the Brillouin Effect,” in Ocean Remote Sensing Using Lasers, NOAA Tech. Memo. ERL PMEL-18, H. R. Gordon, Ed. (1980).
  15. P. O. Cervenka, “Brillouin Remote Sensing,” J. Opt. Soc. Am. 67, 1410 (1977).
  16. J. L. Guagliardo, H. L. Dufilho, “Range Resolved Brillouin Scattering Using a Pulsed Laser,” Rev. Sci. Instrum. 51, 79 (1980).
    [CrossRef]
  17. J. B. Breckenridge, C. A. Sepulveda, D. J. Collins, H. B. Hotz, Jet Propulsion Laboratory, Optical Physics Group; personal communication (Mar.1982).
  18. C. L. O’Connor, J. P. Schlupf, “Brillouin Scattering in Water: the Landau-Placzek Ratio,” J. Chem. Phys. 47, 31 (1967).
    [CrossRef]
  19. I. G. Fabelinskii, Molecular Scattering of Light (Plenum, New York, 1968).
    [CrossRef]
  20. A. R. Maret, E. Yeager, “Rayleigh-Brillouin Intensity Ratios in Aqueous Electrolyte Solutions,” J. Chem. Phys. 59, 206 (1973).
    [CrossRef]
  21. L. Brillouin, “Scattering of Light,” C. R. Acad. Sci. 158, 1331 (1914).
  22. H. R. Gordon, “Interpretation of Airborne Oceanic Lidar: Effects of Multiple Scattering,” Appl. Opt. 211, 2996 (1982).
    [CrossRef]
  23. R. W. Fairbridge, Encyclopedia of Oceanography (Reinhold, New York, 1966).
  24. H. U. Svedrup, M. W. Johnson, R. H. Fleming, The Oceans; Their Physics, Chemistry and General Biology (Prentice-Hall, New York, 1961).
  25. R. J. Urick, Principles of Underwater Sound for Engineers (McGraw-Hill, New York, 1967).
  26. R. Y. Chiao, P. A. Fleury, “Brillouin Scattering and the Dispersion of Hypersonic Waves,” in Physics of Quantum Electronics, P. L. Kelley, B. Lax, P. E. Tannerwald, Eds. (McGraw-Hill, New York, 1965).
  27. L. D. Landau, E. M. Lifshiftz, Electrodynamics of Continuous Media (Addison-Wesley, Reading, Mass., 1960).
  28. R. D. Mountain, J. M. Deutch, “Light Scattering for Binary Solutions,” J. Chem. Phys. 50, 1103 (1969).
    [CrossRef]
  29. K. H. Langley, N. C. Ford, “Interferometric Attenuation of Scattering,” J. Opt. Soc. Am. 59, 281 (1969).
    [CrossRef]
  30. A. S. Monin, V. M. Kamenkovich, V. G. Kort, Variability of the Oceans (Wiley, New York, 1977).

1982 (1)

H. R. Gordon, “Interpretation of Airborne Oceanic Lidar: Effects of Multiple Scattering,” Appl. Opt. 211, 2996 (1982).
[CrossRef]

1981 (2)

D. A. Leonard, “Remote Raman Measurement Techniques,” Opt. Eng. 20, 91 (1981).
[CrossRef]

D. A. Leonard, B. Caputo, J. D. Fridman, “Remote Sensing of Subsurface Water Temperature by Raman Polarization Spectroscopy,” Proc. Soc. Photo-Opt. Instrum. Eng. 307, 76 (1981).

1980 (1)

J. L. Guagliardo, H. L. Dufilho, “Range Resolved Brillouin Scattering Using a Pulsed Laser,” Rev. Sci. Instrum. 51, 79 (1980).
[CrossRef]

1979 (1)

1977 (2)

D. A. Leonard, B. Caputo, R. L. Johnson, F. E. Hoge, “Experimental Remote Sensing of Subsurface Temperature in Natural Ocean Water,” Geophys. Res. Lett. 4, 279 (1977).
[CrossRef]

P. O. Cervenka, “Brillouin Remote Sensing,” J. Opt. Soc. Am. 67, 1410 (1977).

1973 (2)

A. R. Maret, E. Yeager, “Rayleigh-Brillouin Intensity Ratios in Aqueous Electrolyte Solutions,” J. Chem. Phys. 59, 206 (1973).
[CrossRef]

R. L. Schwiesow, “Raman Scattering from Pollutant Gases and Air–Water Interfaces,” AIAA J. 11, 87 (1973).
[CrossRef]

1969 (2)

K. H. Langley, N. C. Ford, “Interferometric Attenuation of Scattering,” J. Opt. Soc. Am. 59, 281 (1969).
[CrossRef]

R. D. Mountain, J. M. Deutch, “Light Scattering for Binary Solutions,” J. Chem. Phys. 50, 1103 (1969).
[CrossRef]

1967 (2)

G. E. Walrafen, “Raman Spectral Studies of the Effects of Temperature on Water Structure,” J. Chem. Phys. 47, 114 (1967).
[CrossRef]

C. L. O’Connor, J. P. Schlupf, “Brillouin Scattering in Water: the Landau-Placzek Ratio,” J. Chem. Phys. 47, 31 (1967).
[CrossRef]

1914 (1)

L. Brillouin, “Scattering of Light,” C. R. Acad. Sci. 158, 1331 (1914).

Breckenridge, J. B.

J. B. Breckenridge, C. A. Sepulveda, D. J. Collins, H. B. Hotz, Jet Propulsion Laboratory, Optical Physics Group; personal communication (Mar.1982).

Brillouin, L.

L. Brillouin, “Scattering of Light,” C. R. Acad. Sci. 158, 1331 (1914).

Byrne, J. D.

J. G. Hirschberg, A. W. Wouters, J. D. Byrne, “Ocean Parameters Using the Brillouin Effect,” in Ocean Remote Sensing Using Lasers, NOAA Tech. Memo. ERL PMEL-18, H. R. Gordon, Ed. (1980).

J. G. Hirschberg, A. W. Wouters, J. D. Byrne, “Laser Measure of Salinity, Temperature and Turbidity in Depth,” in Remote Sensing Energy Related Studies, N. Veziroglu, Ed. (Wiley, New York, 1975).

J. G. Hirschberg, A. W. Wouters, F. N. Cooke, K. M. Simon, J. D. Byrne, “Laser Application to Measure Vertical Sea Temperature and Turbidity,” NASA Report CR-139184 (Jan.1975).

Caputo, B.

D. A. Leonard, B. Caputo, J. D. Fridman, “Remote Sensing of Subsurface Water Temperature by Raman Polarization Spectroscopy,” Proc. Soc. Photo-Opt. Instrum. Eng. 307, 76 (1981).

D. A. Leonard, B. Caputo, F. E. Hoge, “Remote Sensing of Subsurface Water Temperature by Raman Scattering,” Appl. Opt. 18, 1732 (1979).
[CrossRef] [PubMed]

D. A. Leonard, B. Caputo, R. L. Johnson, F. E. Hoge, “Experimental Remote Sensing of Subsurface Temperature in Natural Ocean Water,” Geophys. Res. Lett. 4, 279 (1977).
[CrossRef]

Cervenka, P. O.

P. O. Cervenka, “Brillouin Remote Sensing,” J. Opt. Soc. Am. 67, 1410 (1977).

Chang, C. H.

C. H. Chang, L. A. Young, Avco-Everett Research Laboratory Research note 960, Everett, Mass. (1974).

C. H. Chang, L. A. Young, D. A. Leonard, U.S. Pat.3,986,775 (Dec.1974).

Chiao, R. Y.

R. Y. Chiao, P. A. Fleury, “Brillouin Scattering and the Dispersion of Hypersonic Waves,” in Physics of Quantum Electronics, P. L. Kelley, B. Lax, P. E. Tannerwald, Eds. (McGraw-Hill, New York, 1965).

Collins, D. J.

J. B. Breckenridge, C. A. Sepulveda, D. J. Collins, H. B. Hotz, Jet Propulsion Laboratory, Optical Physics Group; personal communication (Mar.1982).

Cooke, F. N.

J. G. Hirschberg, A. W. Wouters, F. N. Cooke, K. M. Simon, J. D. Byrne, “Laser Application to Measure Vertical Sea Temperature and Turbidity,” NASA Report CR-139184 (Jan.1975).

Deutch, J. M.

R. D. Mountain, J. M. Deutch, “Light Scattering for Binary Solutions,” J. Chem. Phys. 50, 1103 (1969).
[CrossRef]

Dufilho, H. L.

J. L. Guagliardo, H. L. Dufilho, “Range Resolved Brillouin Scattering Using a Pulsed Laser,” Rev. Sci. Instrum. 51, 79 (1980).
[CrossRef]

Fabelinskii, I. G.

I. G. Fabelinskii, Molecular Scattering of Light (Plenum, New York, 1968).
[CrossRef]

Fairbridge, R. W.

R. W. Fairbridge, Encyclopedia of Oceanography (Reinhold, New York, 1966).

Fleming, R. H.

H. U. Svedrup, M. W. Johnson, R. H. Fleming, The Oceans; Their Physics, Chemistry and General Biology (Prentice-Hall, New York, 1961).

Fleury, P. A.

R. Y. Chiao, P. A. Fleury, “Brillouin Scattering and the Dispersion of Hypersonic Waves,” in Physics of Quantum Electronics, P. L. Kelley, B. Lax, P. E. Tannerwald, Eds. (McGraw-Hill, New York, 1965).

Ford, N. C.

Fridman, J. D.

D. A. Leonard, B. Caputo, J. D. Fridman, “Remote Sensing of Subsurface Water Temperature by Raman Polarization Spectroscopy,” Proc. Soc. Photo-Opt. Instrum. Eng. 307, 76 (1981).

Gordon, H. R.

H. R. Gordon, “Interpretation of Airborne Oceanic Lidar: Effects of Multiple Scattering,” Appl. Opt. 211, 2996 (1982).
[CrossRef]

Guagliardo, J. L.

J. L. Guagliardo, H. L. Dufilho, “Range Resolved Brillouin Scattering Using a Pulsed Laser,” Rev. Sci. Instrum. 51, 79 (1980).
[CrossRef]

Hirschberg, J. G.

J. G. Hirschberg, A. W. Wouters, J. D. Byrne, “Laser Measure of Salinity, Temperature and Turbidity in Depth,” in Remote Sensing Energy Related Studies, N. Veziroglu, Ed. (Wiley, New York, 1975).

J. G. Hirschberg, “The Use of Brillouin and Raman Scattering to Measure Temperature and Salinity Below the Water Surface,” in Proceedings, Waste Heat Management and Utilization Conference, Miami Beach, Fla. (1977).

J. G. Hirschberg, A. W. Wouters, F. N. Cooke, K. M. Simon, J. D. Byrne, “Laser Application to Measure Vertical Sea Temperature and Turbidity,” NASA Report CR-139184 (Jan.1975).

J. G. Hirschberg, A. W. Wouters, J. D. Byrne, “Ocean Parameters Using the Brillouin Effect,” in Ocean Remote Sensing Using Lasers, NOAA Tech. Memo. ERL PMEL-18, H. R. Gordon, Ed. (1980).

Hoge, F. E.

D. A. Leonard, B. Caputo, F. E. Hoge, “Remote Sensing of Subsurface Water Temperature by Raman Scattering,” Appl. Opt. 18, 1732 (1979).
[CrossRef] [PubMed]

D. A. Leonard, B. Caputo, R. L. Johnson, F. E. Hoge, “Experimental Remote Sensing of Subsurface Temperature in Natural Ocean Water,” Geophys. Res. Lett. 4, 279 (1977).
[CrossRef]

Hotz, H. B.

J. B. Breckenridge, C. A. Sepulveda, D. J. Collins, H. B. Hotz, Jet Propulsion Laboratory, Optical Physics Group; personal communication (Mar.1982).

Johnson, M. W.

H. U. Svedrup, M. W. Johnson, R. H. Fleming, The Oceans; Their Physics, Chemistry and General Biology (Prentice-Hall, New York, 1961).

Johnson, R. L.

D. A. Leonard, B. Caputo, R. L. Johnson, F. E. Hoge, “Experimental Remote Sensing of Subsurface Temperature in Natural Ocean Water,” Geophys. Res. Lett. 4, 279 (1977).
[CrossRef]

Kamenkovich, V. M.

A. S. Monin, V. M. Kamenkovich, V. G. Kort, Variability of the Oceans (Wiley, New York, 1977).

Kort, V. G.

A. S. Monin, V. M. Kamenkovich, V. G. Kort, Variability of the Oceans (Wiley, New York, 1977).

Landau, L. D.

L. D. Landau, E. M. Lifshiftz, Electrodynamics of Continuous Media (Addison-Wesley, Reading, Mass., 1960).

Langley, K. H.

Leonard, D. A.

D. A. Leonard, B. Caputo, J. D. Fridman, “Remote Sensing of Subsurface Water Temperature by Raman Polarization Spectroscopy,” Proc. Soc. Photo-Opt. Instrum. Eng. 307, 76 (1981).

D. A. Leonard, “Remote Raman Measurement Techniques,” Opt. Eng. 20, 91 (1981).
[CrossRef]

D. A. Leonard, B. Caputo, F. E. Hoge, “Remote Sensing of Subsurface Water Temperature by Raman Scattering,” Appl. Opt. 18, 1732 (1979).
[CrossRef] [PubMed]

D. A. Leonard, B. Caputo, R. L. Johnson, F. E. Hoge, “Experimental Remote Sensing of Subsurface Temperature in Natural Ocean Water,” Geophys. Res. Lett. 4, 279 (1977).
[CrossRef]

C. H. Chang, L. A. Young, D. A. Leonard, U.S. Pat.3,986,775 (Dec.1974).

Lifshiftz, E. M.

L. D. Landau, E. M. Lifshiftz, Electrodynamics of Continuous Media (Addison-Wesley, Reading, Mass., 1960).

Maret, A. R.

A. R. Maret, E. Yeager, “Rayleigh-Brillouin Intensity Ratios in Aqueous Electrolyte Solutions,” J. Chem. Phys. 59, 206 (1973).
[CrossRef]

Monin, A. S.

A. S. Monin, V. M. Kamenkovich, V. G. Kort, Variability of the Oceans (Wiley, New York, 1977).

Mountain, R. D.

R. D. Mountain, J. M. Deutch, “Light Scattering for Binary Solutions,” J. Chem. Phys. 50, 1103 (1969).
[CrossRef]

O’Connor, C. L.

C. L. O’Connor, J. P. Schlupf, “Brillouin Scattering in Water: the Landau-Placzek Ratio,” J. Chem. Phys. 47, 31 (1967).
[CrossRef]

Schlupf, J. P.

C. L. O’Connor, J. P. Schlupf, “Brillouin Scattering in Water: the Landau-Placzek Ratio,” J. Chem. Phys. 47, 31 (1967).
[CrossRef]

Schwiesow, R. L.

R. L. Schwiesow, “Raman Scattering from Pollutant Gases and Air–Water Interfaces,” AIAA J. 11, 87 (1973).
[CrossRef]

Sepulveda, C. A.

J. B. Breckenridge, C. A. Sepulveda, D. J. Collins, H. B. Hotz, Jet Propulsion Laboratory, Optical Physics Group; personal communication (Mar.1982).

Simon, K. M.

J. G. Hirschberg, A. W. Wouters, F. N. Cooke, K. M. Simon, J. D. Byrne, “Laser Application to Measure Vertical Sea Temperature and Turbidity,” NASA Report CR-139184 (Jan.1975).

Svedrup, H. U.

H. U. Svedrup, M. W. Johnson, R. H. Fleming, The Oceans; Their Physics, Chemistry and General Biology (Prentice-Hall, New York, 1961).

Tappert, F. D.

F. D. Tappert, U. Miami; private communication (1982).

Urick, R. J.

R. J. Urick, Principles of Underwater Sound for Engineers (McGraw-Hill, New York, 1967).

Walrafen, G. E.

G. E. Walrafen, “Raman Spectral Studies of the Effects of Temperature on Water Structure,” J. Chem. Phys. 47, 114 (1967).
[CrossRef]

Wouters, A. W.

J. G. Hirschberg, A. W. Wouters, J. D. Byrne, “Ocean Parameters Using the Brillouin Effect,” in Ocean Remote Sensing Using Lasers, NOAA Tech. Memo. ERL PMEL-18, H. R. Gordon, Ed. (1980).

J. G. Hirschberg, A. W. Wouters, J. D. Byrne, “Laser Measure of Salinity, Temperature and Turbidity in Depth,” in Remote Sensing Energy Related Studies, N. Veziroglu, Ed. (Wiley, New York, 1975).

J. G. Hirschberg, A. W. Wouters, F. N. Cooke, K. M. Simon, J. D. Byrne, “Laser Application to Measure Vertical Sea Temperature and Turbidity,” NASA Report CR-139184 (Jan.1975).

Yeager, E.

A. R. Maret, E. Yeager, “Rayleigh-Brillouin Intensity Ratios in Aqueous Electrolyte Solutions,” J. Chem. Phys. 59, 206 (1973).
[CrossRef]

Young, L. A.

C. H. Chang, L. A. Young, Avco-Everett Research Laboratory Research note 960, Everett, Mass. (1974).

C. H. Chang, L. A. Young, D. A. Leonard, U.S. Pat.3,986,775 (Dec.1974).

AIAA J. (1)

R. L. Schwiesow, “Raman Scattering from Pollutant Gases and Air–Water Interfaces,” AIAA J. 11, 87 (1973).
[CrossRef]

Appl. Opt. (2)

D. A. Leonard, B. Caputo, F. E. Hoge, “Remote Sensing of Subsurface Water Temperature by Raman Scattering,” Appl. Opt. 18, 1732 (1979).
[CrossRef] [PubMed]

H. R. Gordon, “Interpretation of Airborne Oceanic Lidar: Effects of Multiple Scattering,” Appl. Opt. 211, 2996 (1982).
[CrossRef]

C. R. Acad. Sci. (1)

L. Brillouin, “Scattering of Light,” C. R. Acad. Sci. 158, 1331 (1914).

Geophys. Res. Lett. (1)

D. A. Leonard, B. Caputo, R. L. Johnson, F. E. Hoge, “Experimental Remote Sensing of Subsurface Temperature in Natural Ocean Water,” Geophys. Res. Lett. 4, 279 (1977).
[CrossRef]

J. Chem. Phys. (4)

G. E. Walrafen, “Raman Spectral Studies of the Effects of Temperature on Water Structure,” J. Chem. Phys. 47, 114 (1967).
[CrossRef]

A. R. Maret, E. Yeager, “Rayleigh-Brillouin Intensity Ratios in Aqueous Electrolyte Solutions,” J. Chem. Phys. 59, 206 (1973).
[CrossRef]

R. D. Mountain, J. M. Deutch, “Light Scattering for Binary Solutions,” J. Chem. Phys. 50, 1103 (1969).
[CrossRef]

C. L. O’Connor, J. P. Schlupf, “Brillouin Scattering in Water: the Landau-Placzek Ratio,” J. Chem. Phys. 47, 31 (1967).
[CrossRef]

J. Opt. Soc. Am. (2)

P. O. Cervenka, “Brillouin Remote Sensing,” J. Opt. Soc. Am. 67, 1410 (1977).

K. H. Langley, N. C. Ford, “Interferometric Attenuation of Scattering,” J. Opt. Soc. Am. 59, 281 (1969).
[CrossRef]

Opt. Eng. (1)

D. A. Leonard, “Remote Raman Measurement Techniques,” Opt. Eng. 20, 91 (1981).
[CrossRef]

Proc. Soc. Photo-Opt. Instrum. Eng. (1)

D. A. Leonard, B. Caputo, J. D. Fridman, “Remote Sensing of Subsurface Water Temperature by Raman Polarization Spectroscopy,” Proc. Soc. Photo-Opt. Instrum. Eng. 307, 76 (1981).

Rev. Sci. Instrum. (1)

J. L. Guagliardo, H. L. Dufilho, “Range Resolved Brillouin Scattering Using a Pulsed Laser,” Rev. Sci. Instrum. 51, 79 (1980).
[CrossRef]

Other (16)

J. B. Breckenridge, C. A. Sepulveda, D. J. Collins, H. B. Hotz, Jet Propulsion Laboratory, Optical Physics Group; personal communication (Mar.1982).

I. G. Fabelinskii, Molecular Scattering of Light (Plenum, New York, 1968).
[CrossRef]

J. G. Hirschberg, A. W. Wouters, F. N. Cooke, K. M. Simon, J. D. Byrne, “Laser Application to Measure Vertical Sea Temperature and Turbidity,” NASA Report CR-139184 (Jan.1975).

J. G. Hirschberg, A. W. Wouters, J. D. Byrne, “Laser Measure of Salinity, Temperature and Turbidity in Depth,” in Remote Sensing Energy Related Studies, N. Veziroglu, Ed. (Wiley, New York, 1975).

J. G. Hirschberg, “The Use of Brillouin and Raman Scattering to Measure Temperature and Salinity Below the Water Surface,” in Proceedings, Waste Heat Management and Utilization Conference, Miami Beach, Fla. (1977).

J. G. Hirschberg, A. W. Wouters, J. D. Byrne, “Ocean Parameters Using the Brillouin Effect,” in Ocean Remote Sensing Using Lasers, NOAA Tech. Memo. ERL PMEL-18, H. R. Gordon, Ed. (1980).

Stommel Report, “The Role of the Oceans in Climate Production,” Ocean Science Committee, U.S. National Academy of Sciences(1975).

F. D. Tappert, U. Miami; private communication (1982).

R. W. Fairbridge, Encyclopedia of Oceanography (Reinhold, New York, 1966).

H. U. Svedrup, M. W. Johnson, R. H. Fleming, The Oceans; Their Physics, Chemistry and General Biology (Prentice-Hall, New York, 1961).

R. J. Urick, Principles of Underwater Sound for Engineers (McGraw-Hill, New York, 1967).

R. Y. Chiao, P. A. Fleury, “Brillouin Scattering and the Dispersion of Hypersonic Waves,” in Physics of Quantum Electronics, P. L. Kelley, B. Lax, P. E. Tannerwald, Eds. (McGraw-Hill, New York, 1965).

L. D. Landau, E. M. Lifshiftz, Electrodynamics of Continuous Media (Addison-Wesley, Reading, Mass., 1960).

A. S. Monin, V. M. Kamenkovich, V. G. Kort, Variability of the Oceans (Wiley, New York, 1977).

C. H. Chang, L. A. Young, Avco-Everett Research Laboratory Research note 960, Everett, Mass. (1974).

C. H. Chang, L. A. Young, D. A. Leonard, U.S. Pat.3,986,775 (Dec.1974).

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Figures (7)

Fig. 1
Fig. 1

Scattering in tap water showing Brillouin, Rayleigh, and Tyndall components. Δλ ≅ 1/5A. The spectrum was measured with a Fabry-Perot interferometer with a 1.00-cm spacer using light at 6328 Å from a He–Ne laser at a scattering angle of 135°.

Fig. 2
Fig. 2

Speed of sound at zero depth at various salinities for water in meters/sec is shown as a function of temperature (redrawn from Ref. 23).

Fig. 3
Fig. 3

Observations from natural seawater (averaged over seventeen Fabry-Perot orders) are fitted to theory. The crosses are observations, and the solid line is calculated.

Fig. 4
Fig. 4

Michelson interferometer showing collimating lens L1, 92% transmitting beam splitter S1, 50–50% beam splitter S3, compensating plate S2, mirrors M1 and M2, with path difference x, and focusing lenses L2 and L3. The interferometer is adjusted so that beam A (passing through L3) contains the Brillouin components, while beam B contains the central component. Since in ocean water the central component is strong, beam splitter S1 needs to reflect only a small percentage of the light, saving most of it for beam A going to the Fabry-Perot interferometers.

Fig. 5
Fig. 5

This shows calculated passbands of the two Fabry-Perot interferometers together with that of the Michelson, as they are adjusted for channel A of Fig. 6. The central peak has been eliminated. As the two Brillouin peaks move further apart (higher speed of sound) the channel C intensity increases and that of channel D decreases. As they move closer together the reverse occurs. The information is contained in the ratio C/D, which is thus proportional to the speed of sound.

Fig. 6
Fig. 6

Optical–electrical arrangement. Scattered light from the sea enters at T. The Michelson produces two beams as shown in Fig. 4. Backreflected beam B containing the central peak (turbidity information) is partially reflected by S1, and falls on photomultiplier Lb producing signal B. Beam A contains the Brillouin peaks and is separated into two equal parts by 50–50% beam splitter S4. The light then passes to the two Fabry-Perots C and D. Q is a signal processor which provides the ratios C/D proportional to the speed of sound and B/(C + D) proportional to turbidity.

Fig. 7
Fig. 7

Typical measurement made in the laboratory with the double Fabry-Perot method. Temperature in degrees Celsius, as measured with a standardized thermometer, is plotted against C/D, the ratio of the two Fabry-Perot photomultiplier signals.

Tables (1)

Tables Icon

Table I Characteristics of the Two Fabry-Perots Shown in Fig 6

Equations (3)

Equations on this page are rendered with MathJax. Learn more.

Δ ν B = ( 2 n v s / c ) ν 0 sin ( Θ / 2 ) cm - 1 ,
β ( 180 ) B = 2.4 × 10 - 4 m - 1 sr - 1 .
V s = 1449 + 4.6 T - 0.055 T 2 + 0.003 T 3 + ( S - 35 ) ( 1.39 - 0.012 T ) + 0.01 z + ,

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