Abstract

This paper describes the design and testing of a laboratory prototype dual He–Ne laser system for the detection of methane leaks from underground pipelines and solid-waste landfill sites using differential absorption of radiation backscattered from topographic targets. A laboratory-prototype dual cw carbon dioxide laser system also using topographic backscatter is discussed, and measurement results for methanol are given. With both systems, it was observed that the time-varying differential absorption signal was useful in indicating the presence of a gas coming from a nearby source. Limitations to measurement sensitivity, especially the role of speckle and atmospheric turbulence, are described. The speckle results for hard targets are contrasted with those from atmospheric aerosols. The Appendix gives appropriate laser lines and values of absorption coefficients for the hydrazine fuel gases.

© 1986 Optical Society of America

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  1. W. B. Grant, R. T. Menzies, “A Survey of Laser and Selected Optical Systems for Remote Measurement of Pollutant Gas Concentrations,” J. Air Pollut. Control Assoc. 33, 187 (1983).
    [CrossRef]
  2. D. K. Killinger, A. Mooradian, Eds. Laser Monitoring of the Atmosphere (Springer-Verlag, New York, 1983).
  3. R. M. Measures, Laser Remote Sensing (Wiley-Interscience, New York, 1984).
  4. H. J. Gerritsen, “Methane Gas Detection Using a Laser,” Trans. Am. Inst. Mining Eng. 235, 428 (1966).
  5. C. B. Moore, “Gas-laser Frequency Selection by Molecular Absorption,” Appl. Opt. 4, 252 (1965).
    [CrossRef]
  6. Z. Kucerovsky, E. Brannen, K. C. Paulekat, D. G. Rumbold, “Characteristics of a Laser System for Atmospheric Absorption and Air Pollution Experiments,” J. Appl. Meteorol. 12, 1387 (1973).
    [CrossRef]
  7. W. B. Grant, “Effect of Differential Spectral Reflectance on DIAL Measurements Using Topographic Targets,” Appl. Opt. 21, 2390 (1982).
    [CrossRef] [PubMed]
  8. R. M. Russ, “Detection of Atmospheric Methane Using a 2 Wavelength HeNe System,” Master's Thesis, MIT, Cambridge (1978).
  9. W. B. Grant, E. D. Hinkley, “Laser System for Natural Gas Detection—Phase I—Laboratory Feasibility Studies,” JPL Annual Report 5030-525 to the Gas Research Institute (1982).
  10. W. B. Grant, “Helium-Neon Laser Remote Measurement of Methane at Landfill Sites,” in Proceedings, Conference on Resource Recovery from Solid Wastes, S. Sengupta, K.-F. V. Wong, Eds. (Pergamon, London, 1982), p 265.
  11. I. Mendas, P. V. Cvijin, D. Ignjatijevic, “Conditions for the Harmonic-like and Efficient Amplitude Modulation of the cw Gaussian Laser Beam by Means of a Mechanical Chopper,” Appl. Phys. B 134, (1984).
  12. H. Ahlberg, S. Lundqvist, M. S. Shumate, U. Persson, “Analysis of Errors Caused by Optical Interference Effects in Wavelength-Diverse CO2 Laser Long-Path Systems,” Appl. Opt. 24, 3917 (1985).
    [CrossRef] [PubMed]
  13. J. W. Goodman, “Statistical Properties of Laser Speckle Patterns,” in Laser Speckle and Related Phenomena, J. C. Dainty, Ed. (Springer-Verlag, New York, 1975), Chap. 2.
    [CrossRef]
  14. P. H. Flamant, R. T. Menzies, M. J. Kavaya, “Evidence for Speckle Effects on Pulsed CO2 Lidar Signal Returns from Remote Targets,” Appl. Opt. 23, 1412 (1984).
    [CrossRef] [PubMed]
  15. G. Parry, “Speckle Patterns in Partially Coherent Light,” in Laser Speckle and Related Phenomena, J. C. Dainty, Ed. (Springer-Verlag, New York, 1975), Chap. 3.
    [CrossRef]
  16. P. H. Flamant, R. T. Menzies, “Mode Selection and Frequency Tuning by Injection in Pulsed TEA-CO2 Lasers,” IEEE J. Quantum Electron. QE-19, 821 (1983).
    [CrossRef]
  17. J. H. Shapiro, “Correlation Scales of Laser Speckle in Heterodyne Detection,” Appl. Opt. 24, 1883 (1985).
    [CrossRef] [PubMed]
  18. J. Y. Wang, P. A. Pruitt, “Laboratory Target Reflectance Measurements for Coherent Laser Radar Applications,” Appl. Opt. 23, 2559 (1984).
    [CrossRef] [PubMed]
  19. R. E. Hufnagel, “Propagation Through Atmospheric Turbulence,” in The Infrared Handbook, W. L. Wolfe, G. J. Zissis, Eds. (Office of Naval Research, Department of the Navy, Washington D. C., 1978), Chap. 6.
  20. M. L. Wesley, Z. I. Dersko, “Atmospheric Turbulence Parameters from Visual Resolution,” Appl. Opt. 14, 847 (1975).
    [CrossRef]
  21. R. S. Lawrence, G. R. Ochs, S. F. Clifford, “Measurements of Atmospheric Turbulence Relevant to Optical Propagation,” J. Opt. Soc. Am. 60, 826 (1970).
    [CrossRef]
  22. J. H. Churnside, H. T. Yura, “Velocity Measurement Using Laser Speckle Statistics,” Appl. Opt. 20, 3539 (1981).
    [CrossRef] [PubMed]
  23. J. H. Churnside, “Speckle from a Rotating Diffuse Object,” J. Opt. Soc. Am. 72, 1464 (1982).
    [CrossRef]
  24. J. F. Holmes, V. S. R. Gudimetla, “Variance of Intensity for a Discrete-Spectrum, Polychromatic Speckle Field After Propagation Through the Turbulent Atmosphere,” J. Opt. Soc. Am. 71, 1176 (1981).
    [CrossRef]
  25. R. R. Patty, G. M. Russwurm, W. A. McClenny, D. R. Morgan, “CO2 Laser Absorption Coefficients for Determining Ambient Levels of O3, NH3, and C2H4,” Appl. Opt. 13, 2850 (1974).
    [CrossRef] [PubMed]
  26. M. S. Shumate, R. T. Menzies, J. S. Margolis, L. G. Rosengren, “Water Vapor Absorption of Carbon Dioxide Laser Radiation,” Appl. Opt. 15, 2480 (1976).
    [CrossRef] [PubMed]
  27. N. Menyuk, D. K. Killinger, W. E. DeFeo, “Laser Remote Sensing of Hydrazine, MMH, and UDMH Using a Differential-Absorption CO2 Lidar,” Appl. Opt. 21, 2275 (1982).
    [CrossRef] [PubMed]
  28. E. R. Murray, J. E. van der Laan, “Remote Measurement of Ethylene Using a CO2 Differential-Absorption Lidar,” Appl. Opt. 17, 814 (1978).
    [CrossRef]
  29. D. K. Killinger, N. Menyuk, W. E. DeFeo, “Experimental Comparison of Heterodyne and Direct Detection for Pulsed Differential Absorption CO2 Lidar,” Appl. Opt. 22, 682 (1983).
    [CrossRef] [PubMed]
  30. P. Richter, I. Peczeli, “Signal Fluctuations in a cw Infrared Heterodyne Lidar,” Opt. Quantum Electron. 17, 93 (1985).
    [CrossRef]
  31. M. S. Shumate, R. T. Menzies, W. B. Grant, D. S. McDougal, “Laser Absorption Spectrometer: Remote Measurement of Troposperic Ozone,” Appl. Opt. 20, 545 (1981).
    [CrossRef] [PubMed]
  32. M. S. Shumate, W. B. Grant, R. T. Menzies, “Remote Measurement of Trace Gases with the JPL Laser Absorption Spectrometer,” in Optical and Laser Remote Sensing, D. K. Killinger, A. Mooradian, Eds. (Springer-Verlag, New York, 1983), p. 31.
  33. M. S. Shumate, S. Lundqvist, U. Persson, S. T. Eng, “Differential Reflectance of Natural and Man-made Materials at CO2 Laser Wavelengths,” Appl. Opt. 21, 2386 (1982).
    [CrossRef] [PubMed]
  34. K. Asai, T. Igarashi, “Interference from Differential Reflectance of Moist Topographic Targets in CO2 DIAL Ozone Measurement,” Appl. Opt. 23, 734 (1984).
    [CrossRef] [PubMed]
  35. W. Wiesemann, F. Lehmann, “Reliability of Airborne CO2 DIAL Measurements: Schemes for Testing Technical Performance and Reducing Interference from Differential Reflectance,” Appl. Opt. 24, 3481 (1985).
    [CrossRef] [PubMed]
  36. J. L. Bufton, T. Itabe, D. A. Grolemund, “Dual-Wavelength Correlation Measurements with an Airborne Pulsed Carbon Dioxide Lidar System,” Opt. Lett. 7, 584 (1982).
    [CrossRef] [PubMed]
  37. J. H. Churnside, H. T. Yura, “Speckle Statistics of Atmospherically Backscattered Laser Light,” Appl. Opt. 22, 2559 (1983).
    [CrossRef] [PubMed]
  38. T. Fukuda, Y. Matsuura, T. Mori, “Sensitivity of Coherent Range-Resolved Differential Absorption Lidar,” Appl. Opt. 23, 2026 (1984).
    [CrossRef] [PubMed]
  39. L. T. Molina, W. B. Grant, FTIR Spectrometer Determined Absorption Coefficients of Seven Hydrazine Fuel Gases: Implications for Laser Remote Sensing,” Appl. Opt. 23, 3893 (1984).
    [CrossRef] [PubMed]
  40. G. L. Loper, A. R. Calloway, M. A. Stamps, J. A. Gelbwachs, “Carbon Dioxide Laser Absorption Spectra and Low ppb Photoacoustic Detection of Hydrazine Fuels,” Appl. Opt. 19, 2726 (1980).
    [CrossRef] [PubMed]
  41. R. J. Brewer, C. W. Bruce, “Photoacoustic Spectroscopy of NH3 at the 9- and 10-μm 12C16O2 Laser Wavelengths” Appl. Opt. 17, 3746 (1978).
    [CrossRef] [PubMed]
  42. Also, turbulence can cause the beam to break up, expand, and contract.

1985 (4)

1984 (6)

1983 (4)

P. H. Flamant, R. T. Menzies, “Mode Selection and Frequency Tuning by Injection in Pulsed TEA-CO2 Lasers,” IEEE J. Quantum Electron. QE-19, 821 (1983).
[CrossRef]

W. B. Grant, R. T. Menzies, “A Survey of Laser and Selected Optical Systems for Remote Measurement of Pollutant Gas Concentrations,” J. Air Pollut. Control Assoc. 33, 187 (1983).
[CrossRef]

D. K. Killinger, N. Menyuk, W. E. DeFeo, “Experimental Comparison of Heterodyne and Direct Detection for Pulsed Differential Absorption CO2 Lidar,” Appl. Opt. 22, 682 (1983).
[CrossRef] [PubMed]

J. H. Churnside, H. T. Yura, “Speckle Statistics of Atmospherically Backscattered Laser Light,” Appl. Opt. 22, 2559 (1983).
[CrossRef] [PubMed]

1982 (5)

1981 (3)

1980 (1)

1978 (2)

1976 (1)

1975 (1)

1974 (1)

1973 (1)

Z. Kucerovsky, E. Brannen, K. C. Paulekat, D. G. Rumbold, “Characteristics of a Laser System for Atmospheric Absorption and Air Pollution Experiments,” J. Appl. Meteorol. 12, 1387 (1973).
[CrossRef]

1970 (1)

1966 (1)

H. J. Gerritsen, “Methane Gas Detection Using a Laser,” Trans. Am. Inst. Mining Eng. 235, 428 (1966).

1965 (1)

Ahlberg, H.

Asai, K.

Brannen, E.

Z. Kucerovsky, E. Brannen, K. C. Paulekat, D. G. Rumbold, “Characteristics of a Laser System for Atmospheric Absorption and Air Pollution Experiments,” J. Appl. Meteorol. 12, 1387 (1973).
[CrossRef]

Brewer, R. J.

Bruce, C. W.

Bufton, J. L.

Calloway, A. R.

Churnside, J. H.

Clifford, S. F.

Cvijin, P. V.

I. Mendas, P. V. Cvijin, D. Ignjatijevic, “Conditions for the Harmonic-like and Efficient Amplitude Modulation of the cw Gaussian Laser Beam by Means of a Mechanical Chopper,” Appl. Phys. B 134, (1984).

DeFeo, W. E.

Dersko, Z. I.

Eng, S. T.

Flamant, P. H.

P. H. Flamant, R. T. Menzies, M. J. Kavaya, “Evidence for Speckle Effects on Pulsed CO2 Lidar Signal Returns from Remote Targets,” Appl. Opt. 23, 1412 (1984).
[CrossRef] [PubMed]

P. H. Flamant, R. T. Menzies, “Mode Selection and Frequency Tuning by Injection in Pulsed TEA-CO2 Lasers,” IEEE J. Quantum Electron. QE-19, 821 (1983).
[CrossRef]

Fukuda, T.

Gelbwachs, J. A.

Gerritsen, H. J.

H. J. Gerritsen, “Methane Gas Detection Using a Laser,” Trans. Am. Inst. Mining Eng. 235, 428 (1966).

Goodman, J. W.

J. W. Goodman, “Statistical Properties of Laser Speckle Patterns,” in Laser Speckle and Related Phenomena, J. C. Dainty, Ed. (Springer-Verlag, New York, 1975), Chap. 2.
[CrossRef]

Grant, W. B.

L. T. Molina, W. B. Grant, FTIR Spectrometer Determined Absorption Coefficients of Seven Hydrazine Fuel Gases: Implications for Laser Remote Sensing,” Appl. Opt. 23, 3893 (1984).
[CrossRef] [PubMed]

W. B. Grant, R. T. Menzies, “A Survey of Laser and Selected Optical Systems for Remote Measurement of Pollutant Gas Concentrations,” J. Air Pollut. Control Assoc. 33, 187 (1983).
[CrossRef]

W. B. Grant, “Effect of Differential Spectral Reflectance on DIAL Measurements Using Topographic Targets,” Appl. Opt. 21, 2390 (1982).
[CrossRef] [PubMed]

M. S. Shumate, R. T. Menzies, W. B. Grant, D. S. McDougal, “Laser Absorption Spectrometer: Remote Measurement of Troposperic Ozone,” Appl. Opt. 20, 545 (1981).
[CrossRef] [PubMed]

M. S. Shumate, W. B. Grant, R. T. Menzies, “Remote Measurement of Trace Gases with the JPL Laser Absorption Spectrometer,” in Optical and Laser Remote Sensing, D. K. Killinger, A. Mooradian, Eds. (Springer-Verlag, New York, 1983), p. 31.

W. B. Grant, E. D. Hinkley, “Laser System for Natural Gas Detection—Phase I—Laboratory Feasibility Studies,” JPL Annual Report 5030-525 to the Gas Research Institute (1982).

W. B. Grant, “Helium-Neon Laser Remote Measurement of Methane at Landfill Sites,” in Proceedings, Conference on Resource Recovery from Solid Wastes, S. Sengupta, K.-F. V. Wong, Eds. (Pergamon, London, 1982), p 265.

Grolemund, D. A.

Gudimetla, V. S. R.

Hinkley, E. D.

W. B. Grant, E. D. Hinkley, “Laser System for Natural Gas Detection—Phase I—Laboratory Feasibility Studies,” JPL Annual Report 5030-525 to the Gas Research Institute (1982).

Holmes, J. F.

Hufnagel, R. E.

R. E. Hufnagel, “Propagation Through Atmospheric Turbulence,” in The Infrared Handbook, W. L. Wolfe, G. J. Zissis, Eds. (Office of Naval Research, Department of the Navy, Washington D. C., 1978), Chap. 6.

Igarashi, T.

Ignjatijevic, D.

I. Mendas, P. V. Cvijin, D. Ignjatijevic, “Conditions for the Harmonic-like and Efficient Amplitude Modulation of the cw Gaussian Laser Beam by Means of a Mechanical Chopper,” Appl. Phys. B 134, (1984).

Itabe, T.

Kavaya, M. J.

Killinger, D. K.

Kucerovsky, Z.

Z. Kucerovsky, E. Brannen, K. C. Paulekat, D. G. Rumbold, “Characteristics of a Laser System for Atmospheric Absorption and Air Pollution Experiments,” J. Appl. Meteorol. 12, 1387 (1973).
[CrossRef]

Lawrence, R. S.

Lehmann, F.

Loper, G. L.

Lundqvist, S.

Margolis, J. S.

Matsuura, Y.

McClenny, W. A.

McDougal, D. S.

Measures, R. M.

R. M. Measures, Laser Remote Sensing (Wiley-Interscience, New York, 1984).

Mendas, I.

I. Mendas, P. V. Cvijin, D. Ignjatijevic, “Conditions for the Harmonic-like and Efficient Amplitude Modulation of the cw Gaussian Laser Beam by Means of a Mechanical Chopper,” Appl. Phys. B 134, (1984).

Menyuk, N.

Menzies, R. T.

P. H. Flamant, R. T. Menzies, M. J. Kavaya, “Evidence for Speckle Effects on Pulsed CO2 Lidar Signal Returns from Remote Targets,” Appl. Opt. 23, 1412 (1984).
[CrossRef] [PubMed]

P. H. Flamant, R. T. Menzies, “Mode Selection and Frequency Tuning by Injection in Pulsed TEA-CO2 Lasers,” IEEE J. Quantum Electron. QE-19, 821 (1983).
[CrossRef]

W. B. Grant, R. T. Menzies, “A Survey of Laser and Selected Optical Systems for Remote Measurement of Pollutant Gas Concentrations,” J. Air Pollut. Control Assoc. 33, 187 (1983).
[CrossRef]

M. S. Shumate, R. T. Menzies, W. B. Grant, D. S. McDougal, “Laser Absorption Spectrometer: Remote Measurement of Troposperic Ozone,” Appl. Opt. 20, 545 (1981).
[CrossRef] [PubMed]

M. S. Shumate, R. T. Menzies, J. S. Margolis, L. G. Rosengren, “Water Vapor Absorption of Carbon Dioxide Laser Radiation,” Appl. Opt. 15, 2480 (1976).
[CrossRef] [PubMed]

M. S. Shumate, W. B. Grant, R. T. Menzies, “Remote Measurement of Trace Gases with the JPL Laser Absorption Spectrometer,” in Optical and Laser Remote Sensing, D. K. Killinger, A. Mooradian, Eds. (Springer-Verlag, New York, 1983), p. 31.

Molina, L. T.

Moore, C. B.

Morgan, D. R.

Mori, T.

Murray, E. R.

Ochs, G. R.

Parry, G.

G. Parry, “Speckle Patterns in Partially Coherent Light,” in Laser Speckle and Related Phenomena, J. C. Dainty, Ed. (Springer-Verlag, New York, 1975), Chap. 3.
[CrossRef]

Patty, R. R.

Paulekat, K. C.

Z. Kucerovsky, E. Brannen, K. C. Paulekat, D. G. Rumbold, “Characteristics of a Laser System for Atmospheric Absorption and Air Pollution Experiments,” J. Appl. Meteorol. 12, 1387 (1973).
[CrossRef]

Peczeli, I.

P. Richter, I. Peczeli, “Signal Fluctuations in a cw Infrared Heterodyne Lidar,” Opt. Quantum Electron. 17, 93 (1985).
[CrossRef]

Persson, U.

Pruitt, P. A.

Richter, P.

P. Richter, I. Peczeli, “Signal Fluctuations in a cw Infrared Heterodyne Lidar,” Opt. Quantum Electron. 17, 93 (1985).
[CrossRef]

Rosengren, L. G.

Rumbold, D. G.

Z. Kucerovsky, E. Brannen, K. C. Paulekat, D. G. Rumbold, “Characteristics of a Laser System for Atmospheric Absorption and Air Pollution Experiments,” J. Appl. Meteorol. 12, 1387 (1973).
[CrossRef]

Russ, R. M.

R. M. Russ, “Detection of Atmospheric Methane Using a 2 Wavelength HeNe System,” Master's Thesis, MIT, Cambridge (1978).

Russwurm, G. M.

Shapiro, J. H.

Shumate, M. S.

Stamps, M. A.

van der Laan, J. E.

Wang, J. Y.

Wesley, M. L.

Wiesemann, W.

Yura, H. T.

Appl. Opt. (22)

C. B. Moore, “Gas-laser Frequency Selection by Molecular Absorption,” Appl. Opt. 4, 252 (1965).
[CrossRef]

R. R. Patty, G. M. Russwurm, W. A. McClenny, D. R. Morgan, “CO2 Laser Absorption Coefficients for Determining Ambient Levels of O3, NH3, and C2H4,” Appl. Opt. 13, 2850 (1974).
[CrossRef] [PubMed]

M. L. Wesley, Z. I. Dersko, “Atmospheric Turbulence Parameters from Visual Resolution,” Appl. Opt. 14, 847 (1975).
[CrossRef]

M. S. Shumate, R. T. Menzies, J. S. Margolis, L. G. Rosengren, “Water Vapor Absorption of Carbon Dioxide Laser Radiation,” Appl. Opt. 15, 2480 (1976).
[CrossRef] [PubMed]

E. R. Murray, J. E. van der Laan, “Remote Measurement of Ethylene Using a CO2 Differential-Absorption Lidar,” Appl. Opt. 17, 814 (1978).
[CrossRef]

R. J. Brewer, C. W. Bruce, “Photoacoustic Spectroscopy of NH3 at the 9- and 10-μm 12C16O2 Laser Wavelengths” Appl. Opt. 17, 3746 (1978).
[CrossRef] [PubMed]

G. L. Loper, A. R. Calloway, M. A. Stamps, J. A. Gelbwachs, “Carbon Dioxide Laser Absorption Spectra and Low ppb Photoacoustic Detection of Hydrazine Fuels,” Appl. Opt. 19, 2726 (1980).
[CrossRef] [PubMed]

M. S. Shumate, R. T. Menzies, W. B. Grant, D. S. McDougal, “Laser Absorption Spectrometer: Remote Measurement of Troposperic Ozone,” Appl. Opt. 20, 545 (1981).
[CrossRef] [PubMed]

J. H. Churnside, H. T. Yura, “Velocity Measurement Using Laser Speckle Statistics,” Appl. Opt. 20, 3539 (1981).
[CrossRef] [PubMed]

N. Menyuk, D. K. Killinger, W. E. DeFeo, “Laser Remote Sensing of Hydrazine, MMH, and UDMH Using a Differential-Absorption CO2 Lidar,” Appl. Opt. 21, 2275 (1982).
[CrossRef] [PubMed]

M. S. Shumate, S. Lundqvist, U. Persson, S. T. Eng, “Differential Reflectance of Natural and Man-made Materials at CO2 Laser Wavelengths,” Appl. Opt. 21, 2386 (1982).
[CrossRef] [PubMed]

W. B. Grant, “Effect of Differential Spectral Reflectance on DIAL Measurements Using Topographic Targets,” Appl. Opt. 21, 2390 (1982).
[CrossRef] [PubMed]

D. K. Killinger, N. Menyuk, W. E. DeFeo, “Experimental Comparison of Heterodyne and Direct Detection for Pulsed Differential Absorption CO2 Lidar,” Appl. Opt. 22, 682 (1983).
[CrossRef] [PubMed]

J. H. Churnside, H. T. Yura, “Speckle Statistics of Atmospherically Backscattered Laser Light,” Appl. Opt. 22, 2559 (1983).
[CrossRef] [PubMed]

K. Asai, T. Igarashi, “Interference from Differential Reflectance of Moist Topographic Targets in CO2 DIAL Ozone Measurement,” Appl. Opt. 23, 734 (1984).
[CrossRef] [PubMed]

P. H. Flamant, R. T. Menzies, M. J. Kavaya, “Evidence for Speckle Effects on Pulsed CO2 Lidar Signal Returns from Remote Targets,” Appl. Opt. 23, 1412 (1984).
[CrossRef] [PubMed]

T. Fukuda, Y. Matsuura, T. Mori, “Sensitivity of Coherent Range-Resolved Differential Absorption Lidar,” Appl. Opt. 23, 2026 (1984).
[CrossRef] [PubMed]

J. Y. Wang, P. A. Pruitt, “Laboratory Target Reflectance Measurements for Coherent Laser Radar Applications,” Appl. Opt. 23, 2559 (1984).
[CrossRef] [PubMed]

L. T. Molina, W. B. Grant, FTIR Spectrometer Determined Absorption Coefficients of Seven Hydrazine Fuel Gases: Implications for Laser Remote Sensing,” Appl. Opt. 23, 3893 (1984).
[CrossRef] [PubMed]

J. H. Shapiro, “Correlation Scales of Laser Speckle in Heterodyne Detection,” Appl. Opt. 24, 1883 (1985).
[CrossRef] [PubMed]

W. Wiesemann, F. Lehmann, “Reliability of Airborne CO2 DIAL Measurements: Schemes for Testing Technical Performance and Reducing Interference from Differential Reflectance,” Appl. Opt. 24, 3481 (1985).
[CrossRef] [PubMed]

H. Ahlberg, S. Lundqvist, M. S. Shumate, U. Persson, “Analysis of Errors Caused by Optical Interference Effects in Wavelength-Diverse CO2 Laser Long-Path Systems,” Appl. Opt. 24, 3917 (1985).
[CrossRef] [PubMed]

Appl. Phys. B (1)

I. Mendas, P. V. Cvijin, D. Ignjatijevic, “Conditions for the Harmonic-like and Efficient Amplitude Modulation of the cw Gaussian Laser Beam by Means of a Mechanical Chopper,” Appl. Phys. B 134, (1984).

IEEE J. Quantum Electron. (1)

P. H. Flamant, R. T. Menzies, “Mode Selection and Frequency Tuning by Injection in Pulsed TEA-CO2 Lasers,” IEEE J. Quantum Electron. QE-19, 821 (1983).
[CrossRef]

J. Air Pollut. Control Assoc. (1)

W. B. Grant, R. T. Menzies, “A Survey of Laser and Selected Optical Systems for Remote Measurement of Pollutant Gas Concentrations,” J. Air Pollut. Control Assoc. 33, 187 (1983).
[CrossRef]

J. Appl. Meteorol. (1)

Z. Kucerovsky, E. Brannen, K. C. Paulekat, D. G. Rumbold, “Characteristics of a Laser System for Atmospheric Absorption and Air Pollution Experiments,” J. Appl. Meteorol. 12, 1387 (1973).
[CrossRef]

J. Opt. Soc. Am. (3)

Opt. Lett. (1)

Opt. Quantum Electron. (1)

P. Richter, I. Peczeli, “Signal Fluctuations in a cw Infrared Heterodyne Lidar,” Opt. Quantum Electron. 17, 93 (1985).
[CrossRef]

Trans. Am. Inst. Mining Eng. (1)

H. J. Gerritsen, “Methane Gas Detection Using a Laser,” Trans. Am. Inst. Mining Eng. 235, 428 (1966).

Other (10)

R. M. Russ, “Detection of Atmospheric Methane Using a 2 Wavelength HeNe System,” Master's Thesis, MIT, Cambridge (1978).

W. B. Grant, E. D. Hinkley, “Laser System for Natural Gas Detection—Phase I—Laboratory Feasibility Studies,” JPL Annual Report 5030-525 to the Gas Research Institute (1982).

W. B. Grant, “Helium-Neon Laser Remote Measurement of Methane at Landfill Sites,” in Proceedings, Conference on Resource Recovery from Solid Wastes, S. Sengupta, K.-F. V. Wong, Eds. (Pergamon, London, 1982), p 265.

J. W. Goodman, “Statistical Properties of Laser Speckle Patterns,” in Laser Speckle and Related Phenomena, J. C. Dainty, Ed. (Springer-Verlag, New York, 1975), Chap. 2.
[CrossRef]

G. Parry, “Speckle Patterns in Partially Coherent Light,” in Laser Speckle and Related Phenomena, J. C. Dainty, Ed. (Springer-Verlag, New York, 1975), Chap. 3.
[CrossRef]

Also, turbulence can cause the beam to break up, expand, and contract.

D. K. Killinger, A. Mooradian, Eds. Laser Monitoring of the Atmosphere (Springer-Verlag, New York, 1983).

R. M. Measures, Laser Remote Sensing (Wiley-Interscience, New York, 1984).

R. E. Hufnagel, “Propagation Through Atmospheric Turbulence,” in The Infrared Handbook, W. L. Wolfe, G. J. Zissis, Eds. (Office of Naval Research, Department of the Navy, Washington D. C., 1978), Chap. 6.

M. S. Shumate, W. B. Grant, R. T. Menzies, “Remote Measurement of Trace Gases with the JPL Laser Absorption Spectrometer,” in Optical and Laser Remote Sensing, D. K. Killinger, A. Mooradian, Eds. (Springer-Verlag, New York, 1983), p. 31.

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Figures (13)

Fig. 1
Fig. 1

Block diagram of the Ne–Ne laser system used for the long-path measurements of methane.

Fig. 2
Fig. 2

Time-varying absorptance by a methane plume measured using the 3.3913-μm (α = 8.2 atm−1 cm−1) and 3.3903-μm (α = 0.6 atm−1 cm−1) He–Ne laser lines using a 0.2-s time constant showing the rapid fluctuations associated with a small-diameter plume. (Reprinted from Ref. 10 with permission, Pergamon Press, Ltd.)

Fig. 3
Fig. 3

Methane measured in a landfill site using the He–Ne laser system placed in the back of a pickup truck and aimed at the ground 15 m away. (Reprinted from Ref. 10 with permission, Pergamon Press, Ltd.)

Fig. 4
Fig. 4

Methane measured at the same location in the landfill site using the He-Ne system aimed at a retroreflector along various lines of sight. (Reprinted from Ref. 10 with permission, Pergamon Press, Ltd.)

Fig. 5
Fig. 5

Graph of detected power vs target range for various values of K = PtAηρ/π for a He–Ne laser system. Also shown are detector noise equivalent power (NEP) levels for three time constants for the system discussed in the text as well as a measured value for K for that system aimed at a plywood target.

Fig. 6
Fig. 6

Block diagram of the optical subsystem for the dual cw CO2 laser system.

Fig. 7
Fig. 7

Block diagram of the electronics for the dual cw CO2 laser system.

Fig. 8
Fig. 8

Plots of signal vs time for four time constants for the cw CO2 laser system pointed at a FSA target at a distance of 80 m just down wind of a 6-cm diam beaker containing methanol showing the rapid fluctuations of the plume. The upper curves are for the 9P(34) line (α = 22.8 atm−1 cm−1) and are shown full scale. The lower curves are for the 9P(32) line (α = 2.2 atm−1 cm−1) and are shown with the zero displaced to about −60%.

Fig. 9
Fig. 9

Graph of detected power vs target distance for various values of K for a cw CO2 laser system. Detector NEPs are shown for the system described in the text for four time constants as well as the system response to a FSA (ρ = 0.75) (1) and concrete (ρ = 0.04) (2) target.

Fig. 10
Fig. 10

Graph showing a comparison of calculated vs measured values of peak-to-peak signal fluctuation 2 2 σ s / I due to speckle as the CO2 laser system is scanned across the 2-m wide FSA target for various receiver apertures.

Fig. 11
Fig. 11

Signal fluctuations for the dual cw CO2 laser system aimed over an asphalt roadway on a sunny day at a FSA target at a distance of 80 m for a receiver aperture of 115 cm2. The upper curve is for the 9P(34) line; the lower one is for the 9P(32) line. The two curves are shown displaced by 2 s. The first 40 s shows the signal fluctuation due primarily to speckle as the system is scanned across the 2-m wide target. Later traces show the signal fluctuations due to atmospheric turbulence modulation of the speckle pattern at the receiver and to oscillating the system.

Fig. 12
Fig. 12

Similar to Fig. 11 but with the system pointed at the asphalt road at a distance of 30 m showing that signal amplitude fluctuations are reduced with longer measurement times but that absolute measurement accuracy is reduced by the speckle effect.

Fig. 13
Fig. 13

Graph of normalized signal standard deviation (σs/I) vs receiver area for various values of effective speckle-lobe area As. Calculated values for two systems are shown as circles, while experimentally determined values for total system signal variation are shown as × or lines. The systems and conditions included are: 1–the He–Ne laser system; 2—the cw CO2 laser system; 3—a pulsed MM CO2 lidar system28; 4—a pulsed SLM CO2 lidar system29; 5a—pulsed MM CO2 lidar system with a hillside target; 5b—pulsed SLM CO2 lidar system with a treetop foliage target; 5c—pulsed SLM CO2 lidar system, sandblasted aluminum target; 5d—pulsed SLM CO2 lidar system, same target, heterodyne detection, all from Ref. 14.

Tables (4)

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Table I Components of the He–Ne Laser System

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Table II Differential Absorption Coefficients of the Components of Natural Gas Using the He-Ne Laser Lines Near 3.39 μm

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Table III Dual cw CO2 Laser Parameters

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Table IV Detection Sensitlvites Estimated for CO2 Laser Line Pairs Appropriate for Hydrazine Fuel Gas Detectiona

Equations (12)

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P r = P t A η ρ exp [ 2 ( α C + k ) R ] π R 2 ,
K = P t A η ρ / π
r = P 1 exp [ 2 ( Δ α ) C l ] P 2 ,
C l = 1 ln ( r P 2 / P 1 ) 2 Δ α .
t = 2 d tan ϕ ,
σ s / I M s 1 / 2 ,
d s = ( 2 λ R ) / D ,
f = [ 1 + ( 2 Δ ω σ z ) 2 ] 1 / 2 .
σ s = ( σ t 2 σ b 2 ) 1 / 2
β 2 = 1.53 C n 2 F 3 [ b 0 ( 0 ) ] 1 / 3 ,
σ x 2 = 0.124 C n 2 k 7 / 6 L 11 / 6 ,
τ = λ / ( 4 π σ ) ,

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