Abstract

A small scanning three-wavelength lidar system at NASA Langley Research Center in Hampton, Virginia, has been used since 1992 to make atmospheric measurements on stratospheric and upper tropospheric aerosols and on the evolution of aircraft exhaust plumes. Many of these measurements have been made away from the zenith, and, to reduce the hazard to air traffic produced by the laser beam, a radar safety device has been installed. The radar application is original in that the radar beam is made collinear with the laser beam by use of a dichroic mirror that transmits the laser radiation and reflects the microwaves. This mirror is inserted into the outgoing optical path prior to the radiation from both the radar and the laser passing through the independent scanning unit. Tests of the complete system show that the lidar and radar beams remain collocated as they are scanned and that the radar can be used to inhibit the laser prior to an aircraft passing through the beam.

© 1999 Optical Society of America

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References

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  1. P. J. Nessler, “Research lasers and air traffic safety: issues, concerns and responsibilities of the research community,” in Conference Abstracts, Nineteenth International Laser Radar Conference, U. N. Singh, S. Ismail, G. K. Schwemmer, eds. (National Aeronautics and Space Administration, Langley Research Center, Hampton, Virginia, 1998), pp. 975–978.
  2. American National Standards Institute, American National Standard for Safe Use of Lasers, (The Laser Institute of America, New York, 1993).
  3. J. P. Thayer, N. B. Nielsen, R. E. Warren, C. J. Heinselman, J. Sohn, “Rayleigh lidar system for middle atmosphere research in the arctic,” Opt. Eng. 36, 2045–2061 (1997).
    [CrossRef]
  4. J. D. Spinhirne, “Micro pulse lidar,” IEEE Trans. Geosci. Remote Sens. 31, 48–55 (1993).
    [CrossRef]
  5. D. C. Llewellen, W. S. Lewellen, L. R. Poole, R. J. DeCoursey, G. M. Hansen, C. A. Hostetler, G. S. Kent, “Large-eddy simulations and lidar measurements of vortex-pair breakup in aircraft wakes,” AIAA J. 36, 1439–1445 (1998).
    [CrossRef]
  6. G. S. Kent, G. M. Hansen, “Multiwavelength lidar observations of the decay phase of the stratospheric aerosol layer produced by the eruption of Mount Pinatubo in June 1991,” Appl. Opt. 37, 3861–3872 (1998).
    [CrossRef]
  7. J. M. Alvarez, W. H. Fuller, R. M. Lawrence, “A radar safety device for lidars probing the atmosphere,” in Conference Abstracts, Nineteenth International Laser Radar ConferenceU. N. Singh, S. Ismail, G. K. Schwemmer, eds. (National Aeronautics and Space Administration, Langley Research Center, Hampton, Virginia, 1998), pp. 983–986.
  8. R. D. Straw, ed., The ARRL Antenna Book (The American Radio League, Inc., Newington, Conn., 1997–1998).
  9. American Conference of Governmental Industrial Hygenists, 1998 TLVs and BEIs, Threshold Limit Values for Chemical Substances and Physical Agents, Biological Exposure Indices (ACGIH, Cincinnati, Ohio, 1998).

1998 (2)

D. C. Llewellen, W. S. Lewellen, L. R. Poole, R. J. DeCoursey, G. M. Hansen, C. A. Hostetler, G. S. Kent, “Large-eddy simulations and lidar measurements of vortex-pair breakup in aircraft wakes,” AIAA J. 36, 1439–1445 (1998).
[CrossRef]

G. S. Kent, G. M. Hansen, “Multiwavelength lidar observations of the decay phase of the stratospheric aerosol layer produced by the eruption of Mount Pinatubo in June 1991,” Appl. Opt. 37, 3861–3872 (1998).
[CrossRef]

1997 (1)

J. P. Thayer, N. B. Nielsen, R. E. Warren, C. J. Heinselman, J. Sohn, “Rayleigh lidar system for middle atmosphere research in the arctic,” Opt. Eng. 36, 2045–2061 (1997).
[CrossRef]

1993 (1)

J. D. Spinhirne, “Micro pulse lidar,” IEEE Trans. Geosci. Remote Sens. 31, 48–55 (1993).
[CrossRef]

Alvarez, J. M.

J. M. Alvarez, W. H. Fuller, R. M. Lawrence, “A radar safety device for lidars probing the atmosphere,” in Conference Abstracts, Nineteenth International Laser Radar ConferenceU. N. Singh, S. Ismail, G. K. Schwemmer, eds. (National Aeronautics and Space Administration, Langley Research Center, Hampton, Virginia, 1998), pp. 983–986.

DeCoursey, R. J.

D. C. Llewellen, W. S. Lewellen, L. R. Poole, R. J. DeCoursey, G. M. Hansen, C. A. Hostetler, G. S. Kent, “Large-eddy simulations and lidar measurements of vortex-pair breakup in aircraft wakes,” AIAA J. 36, 1439–1445 (1998).
[CrossRef]

Fuller, W. H.

J. M. Alvarez, W. H. Fuller, R. M. Lawrence, “A radar safety device for lidars probing the atmosphere,” in Conference Abstracts, Nineteenth International Laser Radar ConferenceU. N. Singh, S. Ismail, G. K. Schwemmer, eds. (National Aeronautics and Space Administration, Langley Research Center, Hampton, Virginia, 1998), pp. 983–986.

Hansen, G. M.

D. C. Llewellen, W. S. Lewellen, L. R. Poole, R. J. DeCoursey, G. M. Hansen, C. A. Hostetler, G. S. Kent, “Large-eddy simulations and lidar measurements of vortex-pair breakup in aircraft wakes,” AIAA J. 36, 1439–1445 (1998).
[CrossRef]

G. S. Kent, G. M. Hansen, “Multiwavelength lidar observations of the decay phase of the stratospheric aerosol layer produced by the eruption of Mount Pinatubo in June 1991,” Appl. Opt. 37, 3861–3872 (1998).
[CrossRef]

Heinselman, C. J.

J. P. Thayer, N. B. Nielsen, R. E. Warren, C. J. Heinselman, J. Sohn, “Rayleigh lidar system for middle atmosphere research in the arctic,” Opt. Eng. 36, 2045–2061 (1997).
[CrossRef]

Hostetler, C. A.

D. C. Llewellen, W. S. Lewellen, L. R. Poole, R. J. DeCoursey, G. M. Hansen, C. A. Hostetler, G. S. Kent, “Large-eddy simulations and lidar measurements of vortex-pair breakup in aircraft wakes,” AIAA J. 36, 1439–1445 (1998).
[CrossRef]

Kent, G. S.

D. C. Llewellen, W. S. Lewellen, L. R. Poole, R. J. DeCoursey, G. M. Hansen, C. A. Hostetler, G. S. Kent, “Large-eddy simulations and lidar measurements of vortex-pair breakup in aircraft wakes,” AIAA J. 36, 1439–1445 (1998).
[CrossRef]

G. S. Kent, G. M. Hansen, “Multiwavelength lidar observations of the decay phase of the stratospheric aerosol layer produced by the eruption of Mount Pinatubo in June 1991,” Appl. Opt. 37, 3861–3872 (1998).
[CrossRef]

Lawrence, R. M.

J. M. Alvarez, W. H. Fuller, R. M. Lawrence, “A radar safety device for lidars probing the atmosphere,” in Conference Abstracts, Nineteenth International Laser Radar ConferenceU. N. Singh, S. Ismail, G. K. Schwemmer, eds. (National Aeronautics and Space Administration, Langley Research Center, Hampton, Virginia, 1998), pp. 983–986.

Lewellen, W. S.

D. C. Llewellen, W. S. Lewellen, L. R. Poole, R. J. DeCoursey, G. M. Hansen, C. A. Hostetler, G. S. Kent, “Large-eddy simulations and lidar measurements of vortex-pair breakup in aircraft wakes,” AIAA J. 36, 1439–1445 (1998).
[CrossRef]

Llewellen, D. C.

D. C. Llewellen, W. S. Lewellen, L. R. Poole, R. J. DeCoursey, G. M. Hansen, C. A. Hostetler, G. S. Kent, “Large-eddy simulations and lidar measurements of vortex-pair breakup in aircraft wakes,” AIAA J. 36, 1439–1445 (1998).
[CrossRef]

Nessler, P. J.

P. J. Nessler, “Research lasers and air traffic safety: issues, concerns and responsibilities of the research community,” in Conference Abstracts, Nineteenth International Laser Radar Conference, U. N. Singh, S. Ismail, G. K. Schwemmer, eds. (National Aeronautics and Space Administration, Langley Research Center, Hampton, Virginia, 1998), pp. 975–978.

Nielsen, N. B.

J. P. Thayer, N. B. Nielsen, R. E. Warren, C. J. Heinselman, J. Sohn, “Rayleigh lidar system for middle atmosphere research in the arctic,” Opt. Eng. 36, 2045–2061 (1997).
[CrossRef]

Poole, L. R.

D. C. Llewellen, W. S. Lewellen, L. R. Poole, R. J. DeCoursey, G. M. Hansen, C. A. Hostetler, G. S. Kent, “Large-eddy simulations and lidar measurements of vortex-pair breakup in aircraft wakes,” AIAA J. 36, 1439–1445 (1998).
[CrossRef]

Sohn, J.

J. P. Thayer, N. B. Nielsen, R. E. Warren, C. J. Heinselman, J. Sohn, “Rayleigh lidar system for middle atmosphere research in the arctic,” Opt. Eng. 36, 2045–2061 (1997).
[CrossRef]

Spinhirne, J. D.

J. D. Spinhirne, “Micro pulse lidar,” IEEE Trans. Geosci. Remote Sens. 31, 48–55 (1993).
[CrossRef]

Thayer, J. P.

J. P. Thayer, N. B. Nielsen, R. E. Warren, C. J. Heinselman, J. Sohn, “Rayleigh lidar system for middle atmosphere research in the arctic,” Opt. Eng. 36, 2045–2061 (1997).
[CrossRef]

Warren, R. E.

J. P. Thayer, N. B. Nielsen, R. E. Warren, C. J. Heinselman, J. Sohn, “Rayleigh lidar system for middle atmosphere research in the arctic,” Opt. Eng. 36, 2045–2061 (1997).
[CrossRef]

AIAA J. (1)

D. C. Llewellen, W. S. Lewellen, L. R. Poole, R. J. DeCoursey, G. M. Hansen, C. A. Hostetler, G. S. Kent, “Large-eddy simulations and lidar measurements of vortex-pair breakup in aircraft wakes,” AIAA J. 36, 1439–1445 (1998).
[CrossRef]

Appl. Opt. (1)

IEEE Trans. Geosci. Remote Sens. (1)

J. D. Spinhirne, “Micro pulse lidar,” IEEE Trans. Geosci. Remote Sens. 31, 48–55 (1993).
[CrossRef]

Opt. Eng. (1)

J. P. Thayer, N. B. Nielsen, R. E. Warren, C. J. Heinselman, J. Sohn, “Rayleigh lidar system for middle atmosphere research in the arctic,” Opt. Eng. 36, 2045–2061 (1997).
[CrossRef]

Other (5)

P. J. Nessler, “Research lasers and air traffic safety: issues, concerns and responsibilities of the research community,” in Conference Abstracts, Nineteenth International Laser Radar Conference, U. N. Singh, S. Ismail, G. K. Schwemmer, eds. (National Aeronautics and Space Administration, Langley Research Center, Hampton, Virginia, 1998), pp. 975–978.

American National Standards Institute, American National Standard for Safe Use of Lasers, (The Laser Institute of America, New York, 1993).

J. M. Alvarez, W. H. Fuller, R. M. Lawrence, “A radar safety device for lidars probing the atmosphere,” in Conference Abstracts, Nineteenth International Laser Radar ConferenceU. N. Singh, S. Ismail, G. K. Schwemmer, eds. (National Aeronautics and Space Administration, Langley Research Center, Hampton, Virginia, 1998), pp. 983–986.

R. D. Straw, ed., The ARRL Antenna Book (The American Radio League, Inc., Newington, Conn., 1997–1998).

American Conference of Governmental Industrial Hygenists, 1998 TLVs and BEIs, Threshold Limit Values for Chemical Substances and Physical Agents, Biological Exposure Indices (ACGIH, Cincinnati, Ohio, 1998).

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Figures (3)

Fig. 1
Fig. 1

Scanning subsystem: (a) side view of the scan mirror housing showing the position of both mirrors and the motors and (b) schematic showing the locations of the radar and the dichroic mirror and the positions of the laser and radar beams. All dimensions are in inches.

Fig. 2
Fig. 2

Schematic showing the construction of the dichroic mirror.

Fig. 3
Fig. 3

Microwave radiation patterns at a distance of 2.9 m from the end of the radar horn. (a) Unimpeded direct beam, (b) through the scanning unit at 0° zenith angle, and (c) through the scanning unit at 20° zenith angle. In cases (b) and (c) the intersection of the dashed lines marks the location of the lidar beam.

Tables (4)

Tables Icon

Table 1 Specifications for the Scanning Unit

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Table 2 Specifications for the Radar Unit

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Table 3 Specifications and Design Performance of the Dichroic Mirror

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Table 4 Radiation Intensity Measurements for the Dichroic Mirrora

Metrics