Abstract

A time-dependent variable attenuator to reduce the dynamic range of lidar signals is introduced. The attenuator consists of a Pockels cell between two crossed polarizers that is incorporated into the receiving optic. The transmission is controlled electronically to attenuate the large signals from close ranges but to transmit far-range signal returns to their full extent. The signal dynamic range has been reduced by more than a factor of 100. Reproducibility and the effect of different rise times on the variable transmission are investigated. It is found that the attenuation is highly reproducible, and the associated statistical error remains below the detection limit of 10-3. Systematic errors in differential absorption lidar (DIAL) measurements are negligible for relative wavelength differences between on-line and off-line Δλ/λ < 0.1%. Otherwise it is shown how these can be corrected. We used the attenuator to adapt the measured range to the heights of interest by increasing the electronic gain or to extend the range considerably to lower heights. It is estimated that with this variable attenuator a height range of 0.2–10 km can be covered with one data-acquisition channel only.

© 1997 Optical Society of America

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References

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  1. R. M. Schotland, “Errors in the lidar measurement of atmospheric gases by differential absorption,” J. Appl. Meteorol. 13, 71–77 (1974).
    [CrossRef]
  2. R. T. H. Collis, P. B. Russel, “Lidar measurement of particles and gases by elastic backscattering and differential absorption,” in Laser Monitoring of the Atmosphere (Springer, New York, 1976), pp. 71–151.
    [CrossRef]
  3. E. E. Remsberg, L. L. Gordley, “Analysis of differential absorption lidar from the Space Shuttle,” Appl. Opt. 17, 624–628 (1978).
    [CrossRef] [PubMed]
  4. R. M. Measures, Laser Remote Sensing (Wiley, New York, 1984).
  5. G. J. Mégie, G. Ancellet, J. Pelon, “Lidar measurements of ozone vertical profiles,” Appl. Opt. 24, 3454–3463 (1985).
    [CrossRef] [PubMed]
  6. U. Kempfer, W. Carnuth, R. Lotz, T. Trickl, “A wide-range ultra-violet lidar system for tropospheric ozone measurements: development and application,” Rev. Sci. Instrum. 65, 3145–3164 (1994).
    [CrossRef]
  7. P. A. Wissel, “Design, construction, and performance evaluation of a gain-switched amplifier for lidar applications,” Ph.D. dissertation (University of Arizona, Tucson, 1983).
  8. J. Harms, W. Lahmann, C. Weitkamp, “Geometrical compression of lidar return signals,” Appl. Opt. 17, 1131–1135 (1978).
    [CrossRef] [PubMed]
  9. J. Harms, “Lidar return signals for coaxial and noncoaxial systems with central obstruction,” Appl. Opt. 18, 1559–1566 (1979).
    [CrossRef] [PubMed]
  10. Y. Zhao, R. M. Hardesty, M. J. Post, “Multibeam transmitter for signal dynamic range reduction in incoherent lidar systems,” Appl. Opt. 31, 7623–7632 (1992).
    [CrossRef] [PubMed]
  11. K. W. Rothe, H. Walther, J. Werner, “Differential-absorption measurements with fixed-frequency IR and UV lasers,” in Optical and Laser Remote Sensing (Springer, New York, 1983), pp. 10–16.
    [CrossRef]
  12. S. McDermid, D. A. Haner, M. M. Kleinman, T. D. Walsh, M. L. White, “Differential absorption lidar systems for tropospheric and stratospheric ozone measurements,” Opt. Eng. 30, 22–30 (1991).
    [CrossRef]
  13. D. P. J. Swart, J. Spakman, H. B. Bergwerff, “RIVM’s stratospheric ozone lidar for NDSC station Lauder: system description and first results,” in 17th International Laser Radar Conference Abstracts of Papers (1994), p. 405.
  14. S. Ismail, E. V. Browell, “Airborne and spaceborne lidar measurements of water vapour profiles: a sensitivity analysis,” Appl. Opt. 28, 3603–3615 (1989).
    [CrossRef] [PubMed]
  15. A. Ansmann, “Errors in ground-based water-vapor DIAL measurements due to Doppler-broadened Rayleigh backscattering,” Appl. Opt. 24, 3476–3480 (1985).
    [CrossRef] [PubMed]
  16. V. Wulfmeyer, J. Bösenberg, S. Lehmann, C. Senff, S. Schmitz, “Injection-seeded alexandrite ring laser: performance and application in a water vapor differential absorption lidar,” Opt. Lett. 20, 638–640 (1995).
    [CrossRef] [PubMed]
  17. A. Yariv, Optical Electronics (Holt-Saunders, New York, 1985), pp. 291–294.
  18. Pockels Electro-Optic Effect Information Sheet (Cleveland Crystals, Inc., Cleveland, Ohio, 1976).

1995

1994

U. Kempfer, W. Carnuth, R. Lotz, T. Trickl, “A wide-range ultra-violet lidar system for tropospheric ozone measurements: development and application,” Rev. Sci. Instrum. 65, 3145–3164 (1994).
[CrossRef]

1992

1991

S. McDermid, D. A. Haner, M. M. Kleinman, T. D. Walsh, M. L. White, “Differential absorption lidar systems for tropospheric and stratospheric ozone measurements,” Opt. Eng. 30, 22–30 (1991).
[CrossRef]

1989

1985

1979

1978

1974

R. M. Schotland, “Errors in the lidar measurement of atmospheric gases by differential absorption,” J. Appl. Meteorol. 13, 71–77 (1974).
[CrossRef]

Ancellet, G.

Ansmann, A.

Bergwerff, H. B.

D. P. J. Swart, J. Spakman, H. B. Bergwerff, “RIVM’s stratospheric ozone lidar for NDSC station Lauder: system description and first results,” in 17th International Laser Radar Conference Abstracts of Papers (1994), p. 405.

Bösenberg, J.

Browell, E. V.

Carnuth, W.

U. Kempfer, W. Carnuth, R. Lotz, T. Trickl, “A wide-range ultra-violet lidar system for tropospheric ozone measurements: development and application,” Rev. Sci. Instrum. 65, 3145–3164 (1994).
[CrossRef]

Collis, R. T. H.

R. T. H. Collis, P. B. Russel, “Lidar measurement of particles and gases by elastic backscattering and differential absorption,” in Laser Monitoring of the Atmosphere (Springer, New York, 1976), pp. 71–151.
[CrossRef]

Gordley, L. L.

Haner, D. A.

S. McDermid, D. A. Haner, M. M. Kleinman, T. D. Walsh, M. L. White, “Differential absorption lidar systems for tropospheric and stratospheric ozone measurements,” Opt. Eng. 30, 22–30 (1991).
[CrossRef]

Hardesty, R. M.

Harms, J.

Ismail, S.

Kempfer, U.

U. Kempfer, W. Carnuth, R. Lotz, T. Trickl, “A wide-range ultra-violet lidar system for tropospheric ozone measurements: development and application,” Rev. Sci. Instrum. 65, 3145–3164 (1994).
[CrossRef]

Kleinman, M. M.

S. McDermid, D. A. Haner, M. M. Kleinman, T. D. Walsh, M. L. White, “Differential absorption lidar systems for tropospheric and stratospheric ozone measurements,” Opt. Eng. 30, 22–30 (1991).
[CrossRef]

Lahmann, W.

Lehmann, S.

Lotz, R.

U. Kempfer, W. Carnuth, R. Lotz, T. Trickl, “A wide-range ultra-violet lidar system for tropospheric ozone measurements: development and application,” Rev. Sci. Instrum. 65, 3145–3164 (1994).
[CrossRef]

McDermid, S.

S. McDermid, D. A. Haner, M. M. Kleinman, T. D. Walsh, M. L. White, “Differential absorption lidar systems for tropospheric and stratospheric ozone measurements,” Opt. Eng. 30, 22–30 (1991).
[CrossRef]

Measures, R. M.

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

Mégie, G. J.

Pelon, J.

Post, M. J.

Remsberg, E. E.

Rothe, K. W.

K. W. Rothe, H. Walther, J. Werner, “Differential-absorption measurements with fixed-frequency IR and UV lasers,” in Optical and Laser Remote Sensing (Springer, New York, 1983), pp. 10–16.
[CrossRef]

Russel, P. B.

R. T. H. Collis, P. B. Russel, “Lidar measurement of particles and gases by elastic backscattering and differential absorption,” in Laser Monitoring of the Atmosphere (Springer, New York, 1976), pp. 71–151.
[CrossRef]

Schmitz, S.

Schotland, R. M.

R. M. Schotland, “Errors in the lidar measurement of atmospheric gases by differential absorption,” J. Appl. Meteorol. 13, 71–77 (1974).
[CrossRef]

Senff, C.

Spakman, J.

D. P. J. Swart, J. Spakman, H. B. Bergwerff, “RIVM’s stratospheric ozone lidar for NDSC station Lauder: system description and first results,” in 17th International Laser Radar Conference Abstracts of Papers (1994), p. 405.

Swart, D. P. J.

D. P. J. Swart, J. Spakman, H. B. Bergwerff, “RIVM’s stratospheric ozone lidar for NDSC station Lauder: system description and first results,” in 17th International Laser Radar Conference Abstracts of Papers (1994), p. 405.

Trickl, T.

U. Kempfer, W. Carnuth, R. Lotz, T. Trickl, “A wide-range ultra-violet lidar system for tropospheric ozone measurements: development and application,” Rev. Sci. Instrum. 65, 3145–3164 (1994).
[CrossRef]

Walsh, T. D.

S. McDermid, D. A. Haner, M. M. Kleinman, T. D. Walsh, M. L. White, “Differential absorption lidar systems for tropospheric and stratospheric ozone measurements,” Opt. Eng. 30, 22–30 (1991).
[CrossRef]

Walther, H.

K. W. Rothe, H. Walther, J. Werner, “Differential-absorption measurements with fixed-frequency IR and UV lasers,” in Optical and Laser Remote Sensing (Springer, New York, 1983), pp. 10–16.
[CrossRef]

Weitkamp, C.

Werner, J.

K. W. Rothe, H. Walther, J. Werner, “Differential-absorption measurements with fixed-frequency IR and UV lasers,” in Optical and Laser Remote Sensing (Springer, New York, 1983), pp. 10–16.
[CrossRef]

White, M. L.

S. McDermid, D. A. Haner, M. M. Kleinman, T. D. Walsh, M. L. White, “Differential absorption lidar systems for tropospheric and stratospheric ozone measurements,” Opt. Eng. 30, 22–30 (1991).
[CrossRef]

Wissel, P. A.

P. A. Wissel, “Design, construction, and performance evaluation of a gain-switched amplifier for lidar applications,” Ph.D. dissertation (University of Arizona, Tucson, 1983).

Wulfmeyer, V.

Yariv, A.

A. Yariv, Optical Electronics (Holt-Saunders, New York, 1985), pp. 291–294.

Zhao, Y.

Appl. Opt.

J. Appl. Meteorol.

R. M. Schotland, “Errors in the lidar measurement of atmospheric gases by differential absorption,” J. Appl. Meteorol. 13, 71–77 (1974).
[CrossRef]

Opt. Eng.

S. McDermid, D. A. Haner, M. M. Kleinman, T. D. Walsh, M. L. White, “Differential absorption lidar systems for tropospheric and stratospheric ozone measurements,” Opt. Eng. 30, 22–30 (1991).
[CrossRef]

Opt. Lett.

Rev. Sci. Instrum.

U. Kempfer, W. Carnuth, R. Lotz, T. Trickl, “A wide-range ultra-violet lidar system for tropospheric ozone measurements: development and application,” Rev. Sci. Instrum. 65, 3145–3164 (1994).
[CrossRef]

Other

P. A. Wissel, “Design, construction, and performance evaluation of a gain-switched amplifier for lidar applications,” Ph.D. dissertation (University of Arizona, Tucson, 1983).

D. P. J. Swart, J. Spakman, H. B. Bergwerff, “RIVM’s stratospheric ozone lidar for NDSC station Lauder: system description and first results,” in 17th International Laser Radar Conference Abstracts of Papers (1994), p. 405.

A. Yariv, Optical Electronics (Holt-Saunders, New York, 1985), pp. 291–294.

Pockels Electro-Optic Effect Information Sheet (Cleveland Crystals, Inc., Cleveland, Ohio, 1976).

R. T. H. Collis, P. B. Russel, “Lidar measurement of particles and gases by elastic backscattering and differential absorption,” in Laser Monitoring of the Atmosphere (Springer, New York, 1976), pp. 71–151.
[CrossRef]

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

K. W. Rothe, H. Walther, J. Werner, “Differential-absorption measurements with fixed-frequency IR and UV lasers,” in Optical and Laser Remote Sensing (Springer, New York, 1983), pp. 10–16.
[CrossRef]

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Figures (5)

Fig. 1
Fig. 1

(a) Electrical circuit diagram of the pulse generator for the Pockels cell. (b) Detector system including the variable attenuator.

Fig. 2
Fig. 2

(a) Variable transmission of the attenuator with various rise times k. (b) Expanded view to demonstrate the high contrast of <1:1000. (c) Expanded view showing the undulations in transmission that are due to crystal oscillations.

Fig. 3
Fig. 3

Relative statistical error in DIAL measurements ΔN/N caused by the variable attenuator and its detection limit (dotted curve).

Fig. 4
Fig. 4

Relative systematic error in DIAL measurements ΔN/N that is due to wavelength dependence of U λ/2 for different range resolutions and wavelength differences with LNP = 0.05 and k = 66760 s-1.

Fig. 5
Fig. 5

Backscatter lidar signals (a) with and (b) without the variable attenuator (250 shots and 10 samples averaged). The signal (a) was amplified by a factor of ≃ 10.

Equations (13)

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Pr=P0ζΔrr2βrexp(-20rγrdr).
Nr=const.lnPonr1Poffr2Poffr1Ponr2-lnTonr1Toffr2Toffr1Tonr2const.LNP-LNT.
Pr=PbrTr,
Tr=sin2π2UrUλ/2.
k=C+CPcCCPcR1+R2,
UtUλ/21-exp-kt.
I=I0 sin2πlno2-ne2sin2θ2λnone22l2ϑ4λ2,  ϑ1,
κ=16πlno2-ne2ϑ22λnone22l2ϑ4λ2,  ϑ1.
ϑ=ϑ0Dd.
Tr=sin2π2UrUλ/21+Δρ, α,
Δρ, α=Δρ, α0 exp-dtsinω0t.
ΔNN=LNTLNP-LNT,
LNT=lnTonr1Toffr2Toffr1Tonr2.

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