Abstract

This paper presents a new laser-based method of gas detection that permits real-time television images of gases to be produced. The principle of this technique [which is called backscatter absorption gas imaging (BAGI)] and the operation of two instruments used to implement it are described. These instruments use 5-W and 20-W CO2 lasers to achieve gas imaging at ranges of approximately 30 and 125 m, respectively. Derivations of relevant BAGI signal equations that can be used to predict the performance of a gas imager are provided. The predictions of this model and the measured range performance of an extended-range gas imager are compared. Finally, the results of gas sensitivity measurements and imaging tests on flowing gases are presented. These can be used to generate a realistic estimate of the BAGI sensitivity expected in detecting leaks of many different vapors.

© 1993 Optical Society of America

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  1. R. M. Measures, Laser Remote Sensing: Fundamentals and Applications (Wiley Interscience, New York, 1984), Chap. 7.
  2. L. C. Bradley, K. L. SooHoo, C. Freed, “Absolute frequencies of lasing transitions in nine CO2 isotopic species,” IEEE J. Quantum Electron. QE-22, 234–267 (1986).
    [CrossRef]
  3. T. G. McRae, “BAGI: A new concept for detecting and tracking hazardous gases,” presented at the 1984 Conference on Hazardous Material Spill, Nashville, Tenn., 9–12 April 1984.
  4. T. G. McRae, J. Stahovec, “The use of gas imaging as a means of locating leaks and tracking gas clouds,” in AIChE Petro Expo '86, EP-NO-96e-291 (microfiche) (American Institute of Chemical Engineering, New Orleans, La., 1986).
  5. T. J. Kulp, R. Kennedy, D. Garvis, T. G. McRae, “The development of an active imaging system and its application to the visualization of gas clouds,” in Laser Applications in Meteorology and Earth and Atmospheric Remote Sensing, Martin M. Sokoloski, ed. Proc Soc. Photo-Opt. Instrum. Eng.1062, 191–202 (1989).
  6. T. J. Kulp, R. Kennedy, D. Garvis, L. Seppala, D. Adomatis, J. Stahovec, “Further advances in gas imaging: Field testing of an extended-range gas imager,” in Proceedings of the International Conference on Lasers '90, D. G. Harris, J. Herbelin, eds. (Society for Optical and Quantum Electronics, McLean, Va., 1991), pp. 407–413.
  7. L. Carr, L. Fletcher, P. Holland, M. Althouse, “Characterization of filtered FLIR systems designed for chemical vapor detection and mapping,” in Infrared Imaging Systems: Design, Analysis, Modeling, and Testing, Gerald C. Hoist, ed. Proc. Soc. Photo-Opt. Instrum. Eng.1309, 90–103 (1990).
  8. C. T. Due, L. M. Peterson, Optical-Mechanical, Active/Passive Imaging Systems (Environmental Research Institute of Michigan, Ann Arbor, Mich., 1982), Vol. 1, No. 153200-2-T(I).
  9. W. B. Grant, “He–Ne and cw CO2 laser long-path system for gas detection,” Appl. Opt. 25, 709–719 (1986).
    [CrossRef] [PubMed]
  10. J. C. Dainty, ed., Laser Speckle and Related Phenomena (Springer-Verlag, New York, 1975).
  11. H. Henshall, J. Cruickshank, “Reflectance characteristics of selected materials for reference targets for 10.6 μm laser radars,” Appl. Opt. 27, 2748–2755 (1988).
    [CrossRef] [PubMed]
  12. Values were obtained from a report entitled “Threshold limit values and biological exposure indices—1988–9,” 2nd ed. (American Conference of Governmental Industrial Hygienists, Cincinnati, Ohio, 1988).
  13. 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, 2850–2854 (1974).
    [CrossRef] [PubMed]
  14. J. I. Steinfeld, B. D. Green, Monitoring Spacecraft Atmospheric Contaminants by Laser Absorption Spectroscopy, NASA-CR-148481 (NASA Ames Research Center, Moffet Field, Calif., 1976).
  15. A. Mayer, J. Comera, H. Charpentier, C. Jaussaud, “Absorption coefficients of various pollutant gases at CO2 laser wavelengths; application to the remote sensing of those pollutants,” Appl. Opt. 17, 391–393 (1978).
    [CrossRef] [PubMed]
  16. 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, 2726–2734(1980).
    [CrossRef] [PubMed]
  17. G. L. Loper, G. R. Sasaki, M. A. Stamps, “Carbon dioxide laser absorption spectra of industrial compounds,” Appl. Opt. 21, 1648–1653(1982).
    [CrossRef] [PubMed]
  18. P. Anderson, U. Persson, “Absorption coefficients at CO2 laser wavelengths for toluene, m-xylene, o-xylene, and p-xylene,” Appl. Opt. 23, 192–193 (1984).
    [CrossRef]
  19. J. A. Sell, “Photoacoustic and photothermal deflection spectroscopy of propane at CO2 laser wavelengths,” Appl. Opt. 24, 152–153 (1985).
    [CrossRef] [PubMed]
  20. W. B. Grant, “The mobile atmospheric pollutant mapping (MAPM) system: A coherent CO2 DIAL system,” in Laser Applications in Meteorology and Earth and Atmospheric Remote Sensing, M. M. Sokoloski, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1062, 172 (1989).

1988 (1)

1986 (2)

L. C. Bradley, K. L. SooHoo, C. Freed, “Absolute frequencies of lasing transitions in nine CO2 isotopic species,” IEEE J. Quantum Electron. QE-22, 234–267 (1986).
[CrossRef]

W. B. Grant, “He–Ne and cw CO2 laser long-path system for gas detection,” Appl. Opt. 25, 709–719 (1986).
[CrossRef] [PubMed]

1985 (1)

1984 (1)

1982 (1)

1980 (1)

1978 (1)

1974 (1)

Adomatis, D.

T. J. Kulp, R. Kennedy, D. Garvis, L. Seppala, D. Adomatis, J. Stahovec, “Further advances in gas imaging: Field testing of an extended-range gas imager,” in Proceedings of the International Conference on Lasers '90, D. G. Harris, J. Herbelin, eds. (Society for Optical and Quantum Electronics, McLean, Va., 1991), pp. 407–413.

Althouse, M.

L. Carr, L. Fletcher, P. Holland, M. Althouse, “Characterization of filtered FLIR systems designed for chemical vapor detection and mapping,” in Infrared Imaging Systems: Design, Analysis, Modeling, and Testing, Gerald C. Hoist, ed. Proc. Soc. Photo-Opt. Instrum. Eng.1309, 90–103 (1990).

Anderson, P.

Bradley, L. C.

L. C. Bradley, K. L. SooHoo, C. Freed, “Absolute frequencies of lasing transitions in nine CO2 isotopic species,” IEEE J. Quantum Electron. QE-22, 234–267 (1986).
[CrossRef]

Calloway, A. R.

Carr, L.

L. Carr, L. Fletcher, P. Holland, M. Althouse, “Characterization of filtered FLIR systems designed for chemical vapor detection and mapping,” in Infrared Imaging Systems: Design, Analysis, Modeling, and Testing, Gerald C. Hoist, ed. Proc. Soc. Photo-Opt. Instrum. Eng.1309, 90–103 (1990).

Charpentier, H.

Comera, J.

Cruickshank, J.

Due, C. T.

C. T. Due, L. M. Peterson, Optical-Mechanical, Active/Passive Imaging Systems (Environmental Research Institute of Michigan, Ann Arbor, Mich., 1982), Vol. 1, No. 153200-2-T(I).

Fletcher, L.

L. Carr, L. Fletcher, P. Holland, M. Althouse, “Characterization of filtered FLIR systems designed for chemical vapor detection and mapping,” in Infrared Imaging Systems: Design, Analysis, Modeling, and Testing, Gerald C. Hoist, ed. Proc. Soc. Photo-Opt. Instrum. Eng.1309, 90–103 (1990).

Freed, C.

L. C. Bradley, K. L. SooHoo, C. Freed, “Absolute frequencies of lasing transitions in nine CO2 isotopic species,” IEEE J. Quantum Electron. QE-22, 234–267 (1986).
[CrossRef]

Garvis, D.

T. J. Kulp, R. Kennedy, D. Garvis, L. Seppala, D. Adomatis, J. Stahovec, “Further advances in gas imaging: Field testing of an extended-range gas imager,” in Proceedings of the International Conference on Lasers '90, D. G. Harris, J. Herbelin, eds. (Society for Optical and Quantum Electronics, McLean, Va., 1991), pp. 407–413.

T. J. Kulp, R. Kennedy, D. Garvis, T. G. McRae, “The development of an active imaging system and its application to the visualization of gas clouds,” in Laser Applications in Meteorology and Earth and Atmospheric Remote Sensing, Martin M. Sokoloski, ed. Proc Soc. Photo-Opt. Instrum. Eng.1062, 191–202 (1989).

Gelbwachs, J. A.

Grant, W. B.

W. B. Grant, “He–Ne and cw CO2 laser long-path system for gas detection,” Appl. Opt. 25, 709–719 (1986).
[CrossRef] [PubMed]

W. B. Grant, “The mobile atmospheric pollutant mapping (MAPM) system: A coherent CO2 DIAL system,” in Laser Applications in Meteorology and Earth and Atmospheric Remote Sensing, M. M. Sokoloski, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1062, 172 (1989).

Green, B. D.

J. I. Steinfeld, B. D. Green, Monitoring Spacecraft Atmospheric Contaminants by Laser Absorption Spectroscopy, NASA-CR-148481 (NASA Ames Research Center, Moffet Field, Calif., 1976).

Henshall, H.

Holland, P.

L. Carr, L. Fletcher, P. Holland, M. Althouse, “Characterization of filtered FLIR systems designed for chemical vapor detection and mapping,” in Infrared Imaging Systems: Design, Analysis, Modeling, and Testing, Gerald C. Hoist, ed. Proc. Soc. Photo-Opt. Instrum. Eng.1309, 90–103 (1990).

Jaussaud, C.

Kennedy, R.

T. J. Kulp, R. Kennedy, D. Garvis, L. Seppala, D. Adomatis, J. Stahovec, “Further advances in gas imaging: Field testing of an extended-range gas imager,” in Proceedings of the International Conference on Lasers '90, D. G. Harris, J. Herbelin, eds. (Society for Optical and Quantum Electronics, McLean, Va., 1991), pp. 407–413.

T. J. Kulp, R. Kennedy, D. Garvis, T. G. McRae, “The development of an active imaging system and its application to the visualization of gas clouds,” in Laser Applications in Meteorology and Earth and Atmospheric Remote Sensing, Martin M. Sokoloski, ed. Proc Soc. Photo-Opt. Instrum. Eng.1062, 191–202 (1989).

Kulp, T. J.

T. J. Kulp, R. Kennedy, D. Garvis, L. Seppala, D. Adomatis, J. Stahovec, “Further advances in gas imaging: Field testing of an extended-range gas imager,” in Proceedings of the International Conference on Lasers '90, D. G. Harris, J. Herbelin, eds. (Society for Optical and Quantum Electronics, McLean, Va., 1991), pp. 407–413.

T. J. Kulp, R. Kennedy, D. Garvis, T. G. McRae, “The development of an active imaging system and its application to the visualization of gas clouds,” in Laser Applications in Meteorology and Earth and Atmospheric Remote Sensing, Martin M. Sokoloski, ed. Proc Soc. Photo-Opt. Instrum. Eng.1062, 191–202 (1989).

Loper, G. L.

Mayer, A.

McClenny, W. A.

McRae, T. G.

T. G. McRae, “BAGI: A new concept for detecting and tracking hazardous gases,” presented at the 1984 Conference on Hazardous Material Spill, Nashville, Tenn., 9–12 April 1984.

T. G. McRae, J. Stahovec, “The use of gas imaging as a means of locating leaks and tracking gas clouds,” in AIChE Petro Expo '86, EP-NO-96e-291 (microfiche) (American Institute of Chemical Engineering, New Orleans, La., 1986).

T. J. Kulp, R. Kennedy, D. Garvis, T. G. McRae, “The development of an active imaging system and its application to the visualization of gas clouds,” in Laser Applications in Meteorology and Earth and Atmospheric Remote Sensing, Martin M. Sokoloski, ed. Proc Soc. Photo-Opt. Instrum. Eng.1062, 191–202 (1989).

Measures, R. M.

R. M. Measures, Laser Remote Sensing: Fundamentals and Applications (Wiley Interscience, New York, 1984), Chap. 7.

Morgan, D. R.

Patty, R. R.

Persson, U.

Peterson, L. M.

C. T. Due, L. M. Peterson, Optical-Mechanical, Active/Passive Imaging Systems (Environmental Research Institute of Michigan, Ann Arbor, Mich., 1982), Vol. 1, No. 153200-2-T(I).

Russwurm, G. M.

Sasaki, G. R.

Sell, J. A.

Seppala, L.

T. J. Kulp, R. Kennedy, D. Garvis, L. Seppala, D. Adomatis, J. Stahovec, “Further advances in gas imaging: Field testing of an extended-range gas imager,” in Proceedings of the International Conference on Lasers '90, D. G. Harris, J. Herbelin, eds. (Society for Optical and Quantum Electronics, McLean, Va., 1991), pp. 407–413.

SooHoo, K. L.

L. C. Bradley, K. L. SooHoo, C. Freed, “Absolute frequencies of lasing transitions in nine CO2 isotopic species,” IEEE J. Quantum Electron. QE-22, 234–267 (1986).
[CrossRef]

Stahovec, J.

T. G. McRae, J. Stahovec, “The use of gas imaging as a means of locating leaks and tracking gas clouds,” in AIChE Petro Expo '86, EP-NO-96e-291 (microfiche) (American Institute of Chemical Engineering, New Orleans, La., 1986).

T. J. Kulp, R. Kennedy, D. Garvis, L. Seppala, D. Adomatis, J. Stahovec, “Further advances in gas imaging: Field testing of an extended-range gas imager,” in Proceedings of the International Conference on Lasers '90, D. G. Harris, J. Herbelin, eds. (Society for Optical and Quantum Electronics, McLean, Va., 1991), pp. 407–413.

Stamps, M. A.

Steinfeld, J. I.

J. I. Steinfeld, B. D. Green, Monitoring Spacecraft Atmospheric Contaminants by Laser Absorption Spectroscopy, NASA-CR-148481 (NASA Ames Research Center, Moffet Field, Calif., 1976).

Appl. Opt. (8)

IEEE J. Quantum Electron. (1)

L. C. Bradley, K. L. SooHoo, C. Freed, “Absolute frequencies of lasing transitions in nine CO2 isotopic species,” IEEE J. Quantum Electron. QE-22, 234–267 (1986).
[CrossRef]

Other (11)

T. G. McRae, “BAGI: A new concept for detecting and tracking hazardous gases,” presented at the 1984 Conference on Hazardous Material Spill, Nashville, Tenn., 9–12 April 1984.

T. G. McRae, J. Stahovec, “The use of gas imaging as a means of locating leaks and tracking gas clouds,” in AIChE Petro Expo '86, EP-NO-96e-291 (microfiche) (American Institute of Chemical Engineering, New Orleans, La., 1986).

T. J. Kulp, R. Kennedy, D. Garvis, T. G. McRae, “The development of an active imaging system and its application to the visualization of gas clouds,” in Laser Applications in Meteorology and Earth and Atmospheric Remote Sensing, Martin M. Sokoloski, ed. Proc Soc. Photo-Opt. Instrum. Eng.1062, 191–202 (1989).

T. J. Kulp, R. Kennedy, D. Garvis, L. Seppala, D. Adomatis, J. Stahovec, “Further advances in gas imaging: Field testing of an extended-range gas imager,” in Proceedings of the International Conference on Lasers '90, D. G. Harris, J. Herbelin, eds. (Society for Optical and Quantum Electronics, McLean, Va., 1991), pp. 407–413.

L. Carr, L. Fletcher, P. Holland, M. Althouse, “Characterization of filtered FLIR systems designed for chemical vapor detection and mapping,” in Infrared Imaging Systems: Design, Analysis, Modeling, and Testing, Gerald C. Hoist, ed. Proc. Soc. Photo-Opt. Instrum. Eng.1309, 90–103 (1990).

C. T. Due, L. M. Peterson, Optical-Mechanical, Active/Passive Imaging Systems (Environmental Research Institute of Michigan, Ann Arbor, Mich., 1982), Vol. 1, No. 153200-2-T(I).

Values were obtained from a report entitled “Threshold limit values and biological exposure indices—1988–9,” 2nd ed. (American Conference of Governmental Industrial Hygienists, Cincinnati, Ohio, 1988).

J. C. Dainty, ed., Laser Speckle and Related Phenomena (Springer-Verlag, New York, 1975).

J. I. Steinfeld, B. D. Green, Monitoring Spacecraft Atmospheric Contaminants by Laser Absorption Spectroscopy, NASA-CR-148481 (NASA Ames Research Center, Moffet Field, Calif., 1976).

R. M. Measures, Laser Remote Sensing: Fundamentals and Applications (Wiley Interscience, New York, 1984), Chap. 7.

W. B. Grant, “The mobile atmospheric pollutant mapping (MAPM) system: A coherent CO2 DIAL system,” in Laser Applications in Meteorology and Earth and Atmospheric Remote Sensing, M. M. Sokoloski, ed., Proc. Soc. Photo-Opt. Instrum. Eng.1062, 172 (1989).

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Figures (6)

Fig. 1
Fig. 1

Visible analogy to the BAGI technique is provided by a plume of nitrogen tetroxide.

Fig. 2
Fig. 2

(a) Design of the original scanner (hole-coupled optics), in which the laser and the IFOV share the same areas of the scan mirrors; (b) keyhole optics eliminates the cohabitation problem through the use of larger scan mirrors.

Fig. 3
Fig. 3

Operation of the shoulder-mounted BAGI system. A defective cylinder is simulated through the controlled emission of Freon 13B1. The image seen on the large TV screen is a real-time video picture of the gas leak, generated by the BAGI system. This image is visible to the operator through an ordinary camcorder eyepiece.

Fig. 4
Fig. 4

Diagram of the system parameters relevant to the BAGI performance mode. NEP, noise equivalent power.

Fig. 5
Fig. 5

Representative image obtained during the system range tests at LLNL with the extended-range imager.

Fig. 6
Fig. 6

Plot of the calculated return signal for the extended-range imager as a function of range (solid curve) and the measured return signal (open squares). Error bars indicate the magnitude of the variance in the signal intensity that resulted from laser speckle.

Tables (3)

Tables Icon

Table 1 System Parameter Values

Tables Icon

Table 2 Target Reflectivities

Tables Icon

Table 3 BAGI Detectable Gas Database

Equations (13)

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

P L = τ A L η T L P L ,
Ω = π d 2 / 4 R 2 .
P A = τ A L 2 P L Ω β η T L η R L .
τ A L = exp [ k ( λ L ) R ] ,
k ( λ L ) = σ ( λ L ) + C i α i ( λ L ) ,
τ g L = exp { 2 X [ σ g ( λ L ) + C g α g ( λ L ) ] } ,
P A = τ A L 2 τ g L P L Ω β η T L η R L [ 1 + K ] ,
P P = A t Ω L ( λ , T ) ( λ ) η R ( λ ) τ A ( λ ) τ g ( λ ) d λ ,
A t = π ( R θ R / 2 ) 2 .
P T = Ω { τ A L 2 τ g L P L β η T L η R L [ 1 + K ] + A t L ( λ , T ) ( λ ) η R ( λ ) τ A ( λ ) τ g ( λ ) d λ } .
P T = π d 2 τ A L 2 τ g L P L β η T L η R L 4 R 2 ,
d ( P T ) = π d 2 τ A L 2 P L η T L η R L 4 R 2 [ τ g L d ( β ) + β d ( τ g L ) ] ,
P L = 48 R 2 P N π d 2 τ A L 2 β η T L η R L ,

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