The Hull Coherent DIAL Programme

  • B. J. Rye
  • E. L. Thomas
Part of the Springer Series in Optical Sciences book series (SSOS, volume 39)


An experimental programme to exploit the advantages of coherent laser radars has been in progress at Hull since January, 1976. A 10 μm, coherent laser radar system has a much greater range capability along a near horizontal tropospheric path than either a uv-visible system or an infrared system employing direct detection. Further advantages of a coherent system operating at 10 μm include eye-safety, immunity to solar background radiation, good all-weather performance and the need to transmit relatively small amounts of energy. The inherent capability for high spectral resolution enables Doppler measurements to be made. Here we consider some problems in the application of these systems to differential absorption lidar (DIAL) and discuss briefly work in our laboratory.


Coherent System Unstable Resonator Fractional Bias Differential Absorption Lidar Lidar Equation 
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References and Footnotes

  1. (1).
    R. M. Schottland, Errors in the lidar measurement of atmospheric gases by differential absorption, J. Appl. Met. 13, 71 (1974).CrossRefGoogle Scholar
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    J. C. Petheram, Differential backscatter from the atmospheric aerosol: the implications for IR differential absorption lidar, Appl. Opt. 20, 3941 (1981).ADSCrossRefGoogle Scholar
  3. (3).
    M. J. Post, Experiemntal measurements of atmospheric aerosol inhomogeneities, Opt. Lett., 2, 166 (1978).ADSCrossRefGoogle Scholar
  4. (4).
    B. J. Rye, Primary aberration contribution to incoherent backscatter heterodyne lidar returns, Appl. Opt., 21, 839 (1982).ADSCrossRefGoogle Scholar
  5. (5).
    B. J. Rye, Refractive turbulence contribution to incoherent backscatter heterodyne lidar returns, J. Opt. Soc. Am., 71, 687 (1981).ADSCrossRefGoogle Scholar
  6. (6).
    Where the bandwidth of the pulse is large compared with atmospheric Doppler shifts the frequency-time correlation properties of the return are described by the radar ambiguity function. For simple pulses the correlation time is about the pulse duration; unfortunately except for chirp-free SLM operation laser pulses are not simple.Google Scholar
  7. (7).
    Ambiguity considerations suggest that the notion of obtaining temporally independent returns from essentially the same scatter volume is possible in principle provided the pulse bandwidth is much greater than the reciprocal pulse duration and pulse compression (matched) filters are not used. How closely the ideal can be realised in practice is not considered here. An alternative approach would of course be aperture (spatial) averagino which is demanding technically as use is made of a photodetector array; the conclusions here would be essentially unaffected.Google Scholar
  8. (8).
    R. M. Hardesty, A comparison of heterodyne and direct detection CO2 DIAL systems for ground based humidity profiling, NOAA Tech. Memo, ERL/WPL-64 (1980).Google Scholar
  9. (9).
    P. Brockman, R. V. Hess, L. D. Staton and C. H. Blair, DIAL with heterodyne detection including speckle noise, NASA Tech. Paper 1725 (1980).Google Scholar
  10. (10).
    G. Megie and R. T. Menzies, Complementarity of UV and IR differential absorption lidar for global measurements of atmospheric species, Appl. Opt. 19, 1173 (1980).ADSCrossRefGoogle Scholar
  11. (11).
    B. J. Rye, DIAL system sensitivity with heterodyne reception, Appl. Opt. 17, 3862 (1978).ADSCrossRefGoogle Scholar
  12. (12).
    E. L. Thomas, A coherent laser radar for trace gas and meteorological measurements, Topical Meeting on Coherent Laser Radar, Aspen, 1980.Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1983

Authors and Affiliations

  • B. J. Rye
    • 1
  • E. L. Thomas
    • 1
  1. 1.Department of Applied PhysicsUniversity of HullHullUK

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