Abstract

We have employed a two-dimensional multielement heterodyne detector array and demonstrated, for the first time to our knowledge, the enhanced detection efficiency of atmospheric-turbulence-distorted 1-μm coherent lidar returns. The heterodyne lidar signal intensity and statistical signal fluctuation were measured for both a 2 × 2 detector array and a single detector as a function of the atmospheric turbulence parameter Cn2. The detector array improved the lidar detection efficiency by a factor of approximately 4, and the statistical signal distribution changed from Rayleigh to Gaussian. This improvement is shown to be consistent with a first-order analysis.

© 1991 Optical Society of America

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References

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  1. V. I. Tatarski, IPST Catalog 5319 (National Technical Information Service, Springfield, Va., 1971).
  2. J. W. Strohbehn, ed., Laser Beam Propagation in the Atmosphere (Springer-Verlag, New York1978).
    [CrossRef]
  3. K. P. Chan, D. K. Killinger, Opt. Eng. 30, 49 (1991).
    [CrossRef]
  4. K. P. Chan, D. K. Killinger, N. Sugimoto, Appl. Opt. 30, 2617 (1991).
    [CrossRef] [PubMed]
  5. J. C. Dainty, ed., Laser Speckle and Related Phenomena (Springer-Verlag, New York, 1975).
  6. N. Sugimoto, K. P. Chan, D. K. Killinger, Appl. Opt. 30, 2609 (1991).
    [CrossRef] [PubMed]
  7. Owing to the limitation in our cw local oscillator power, in our experiments the lidar signal intensity was studied as opposed to the lidar signal-to-noise ratio. In heterodyne lidar detection in which the local oscillator-induced shot noise is the dominant noise source, the lidar signal-to-noise ratio is determined by the lidar signal intensity but not the local oscillator power. It is expected that the intensity signal-to-noise ratio will improve as the square root of the number of detector elements (see Ref. 6).
  8. R. H. Kingston, Detection of Optical and Infrared Radiation (Springer-Verlag, New York, 1978).
  9. S. F. Clifford, S. Wandzura, Appl. Opt. 20, 514, (1981) ,Appl. Opt. 20, 1502 (1981).
    [CrossRef] [PubMed]
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    [CrossRef] [PubMed]
  11. P. A. Pincus, M. E. Fossey, J. E. Holmes, J. R. Kerr, J. Opt. Soc. Am. 68, 760 (1978).
    [CrossRef]
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    [CrossRef]
  13. J. W. Goodman, Statistical Optics (Wiley, New York, 1985), Chaps. 1 and 2.

1991 (3)

1981 (2)

1980 (1)

1978 (1)

Capron, B. A.

Chan, K. P.

Clifford, S. F.

Fossey, M. E.

Goodman, J. W.

J. W. Goodman, Statistical Optics (Wiley, New York, 1985), Chaps. 1 and 2.

Harney, R. C.

Holmes, J. E.

Holmes, J. F.

Kerr, J. R.

Killinger, D. K.

Kingston, R. H.

R. H. Kingston, Detection of Optical and Infrared Radiation (Springer-Verlag, New York, 1978).

Lee, M. H.

Pincus, P. A.

Shapiro, J. H.

Sugimoto, N.

Tatarski, V. I.

V. I. Tatarski, IPST Catalog 5319 (National Technical Information Service, Springfield, Va., 1971).

Wandzura, S.

Appl. Opt. (4)

J. Opt. Soc. Am. (2)

Opt. Eng. (1)

K. P. Chan, D. K. Killinger, Opt. Eng. 30, 49 (1991).
[CrossRef]

Other (6)

Owing to the limitation in our cw local oscillator power, in our experiments the lidar signal intensity was studied as opposed to the lidar signal-to-noise ratio. In heterodyne lidar detection in which the local oscillator-induced shot noise is the dominant noise source, the lidar signal-to-noise ratio is determined by the lidar signal intensity but not the local oscillator power. It is expected that the intensity signal-to-noise ratio will improve as the square root of the number of detector elements (see Ref. 6).

R. H. Kingston, Detection of Optical and Infrared Radiation (Springer-Verlag, New York, 1978).

J. W. Goodman, Statistical Optics (Wiley, New York, 1985), Chaps. 1 and 2.

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

V. I. Tatarski, IPST Catalog 5319 (National Technical Information Service, Springfield, Va., 1971).

J. W. Strohbehn, ed., Laser Beam Propagation in the Atmosphere (Springer-Verlag, New York1978).
[CrossRef]

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Figures (4)

Fig. 1
Fig. 1

Schematic of a l-μm coherent Nd:YAG lidar system employing a 2 × 2 heterodyne detector array. B.S., 50/50 beam splitter.

Fig. 2
Fig. 2

Histograms of the received intensity of 600 heterodyne lidar pulses backscattered from a hard target at a range of 450 m for (a) a single-element heterodyne detector and (b) a 2 × 2 heterodyne detector array.

Fig. 3
Fig. 3

Heterodyne lidar signal intensity measured as a function of Cn2.

Fig. 4
Fig. 4

Statistical standard deviation of the heterodyne lidar signal measured as a function of Cn2.

Equations (5)

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F ( U ) = ( 1 + U 2 ) 1 ,
ρ 0 = [ 2.91 k 2 0 R C n 2 ( z ) ( 1 z / R ) 5 / 3 d z ] 3 / 5 ,
I 2 = α F ( U ) P S A r P o ,
I 2 = i = 1 N × N I i 2 = i = 1 N × N α i F ( U i ) P S A r i P o i ,
I 2 I 2 = N 2 ( d r d r ) 2 1 + ( d r / 3 ρ 0 ) 2 1 + ( d r / 3 ρ 0 ) 2

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