Abstract

Optical turbulence research contributes to improved laser communications, adaptive optics, and long-range imaging systems. This paper presents experimental measurements of scintillation and focal spot displacement to obtain optical turbulence information along a near-horizontal 2.33 km free-space laser propagation path. Calculated values for the refractive index structure constant (C 2 n) and Fried parameter (r 0) are compared to scintillometer-based measurements for several cases in winter and spring. Optical measurements were investigated using two different laser sources for the first and second parts of the experiment. Scintillation index estimates from recorded signal intensities were corrected to account for aperture averaging. As a result, we found that an earlier calculation algorithm based on analysis of log-amplitude intensity variance was the best estimator of optical turbulence parameters over the propagation path considered.

© 2008 Optical Society of America

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References

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  1. V. I. Tatarski, The Effects of the Turbulent Atmosphere on Wave Propagation (Israel Program for Scientific Translations, 1971).
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    [CrossRef] [PubMed]
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    [CrossRef]
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    [CrossRef]
  6. G. W. Carhart, M. A. Vorontsov, L. A. Beresnev, P. S. Paicopolis, and F. K. Beil, "Atmospheric laser communication system with wide-angle tracking and adaptive compensation," Proc. SPIE 5892 (2005).
  7. M. Vorontsov, G. Carhart, M. Banta, T. Weyrauch, J. Gowens, and J. Carrano, "Atmospheric Laser Optics Testbed (A_LOT): Atmospheric propagation characterization, beam control, and imaging results," Proc. SPIE 5162 (2003).
  8. Y. Han Oh, J. C. Ricklin, E. S. Oh, S. Doss-Hammel, and F. D. Eaton, "Estimating optical turbulence effects on free-space laser communication: modeling and measurements at ARL???s A_LOT facility," Proc. SPIE 5550, (2004).
  9. T. Weyrauch and M. A. Vorontsov, "Atmospheric compensation with a speckle beacon in strong scintillation conditions: directed energy and laser communication applications," Appl. Opt. 44, 6388-6401 (2005).
    [CrossRef] [PubMed]
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    [CrossRef] [PubMed]
  11. E. Polnau, M. A. Vorontsov, G. Carhart, T. Weyrauch, and L. A. Beresnev, "Adaptive compensation over a 2.33 km propagation path with retro reflectors under strong scintillation conditions," Proc. SPIE 6708 (2007).
  12. Tunick, "Statistical analysis of measured free-space laser signal intensity over a 2.33 km optical path," Opt. Express 17, 14115-14122 (2007).
    [CrossRef]
  13. Tunick, "Modeling microphysical influences on optical turbulence in complex areas," Meteorol. Atmos. Phys. 96, 293-304 (2007).
    [CrossRef]
  14. L. C. Andrews, R. L. Phillips, and C. Y. Hopen, Laser Beam Scintillation with Applications (SPIE Optical Engineering Press, Bellingham, 2001).
    [CrossRef]
  15. T-i Wang, G. R. Ochs, and S. F. Clifford, "A saturation-resistant optical scintillometer to measure Cn2," J. Opt. Soc. Am. 68, 334-338 (1978).
    [CrossRef]
  16. M. C. Roggemann and B. M. Welsh, Imaging Through Turbulence (CRC Press, Boca Raton, 1996).
  17. User???s Guide. LOA-004-xR Long Baseline Optical Anemometer and Atmospheric Turbulence Sensor. Revision 3/20/2003. Optical Scientific, Inc., Gaithersburg, MD (2003), http://www.opticalscientific.com/.
  18. Operating Instructions. Model 81000 Ultrasonic Anemometer. Revision 01/24/2007, R.M. Young Co., Traverse City, MI (2007), http://www.youngusa.com/.
  19. F. S. Vetelino, K. Grayshan, and C. Y. Young, "Inferring path average C2n values in the marine environment," J. Opt. Soc. Am. A 24, 3198-3206 (2007).
    [CrossRef]
  20. M. F. Stell, C. I. Moore, H. R. Burris, M. R. Suite, M. J. Vilcheck, M. A. Davis, R. Mahon, E. Oh, W. S. Rabinovich, G. C. Gilbreath, W. J. Scharpf, and A. E. Reed, "Passive optical monitor for atmospheric turbulence and windspeed," Proc. SPIE 5160, 422-431 (2004).
    [CrossRef]
  21. Tunick, "Toward increasing the accuracy and realism of future optical turbulence (Cn2) calculations," Meteorol. Atmos. Phys. 90, 159-164 (2005).
    [CrossRef]

2007 (4)

2005 (2)

2004 (1)

M. F. Stell, C. I. Moore, H. R. Burris, M. R. Suite, M. J. Vilcheck, M. A. Davis, R. Mahon, E. Oh, W. S. Rabinovich, G. C. Gilbreath, W. J. Scharpf, and A. E. Reed, "Passive optical monitor for atmospheric turbulence and windspeed," Proc. SPIE 5160, 422-431 (2004).
[CrossRef]

1981 (1)

G. Parry, "Measurement of atmospheric turbulence induced intensity fluctuation in a laser beam," Opt. Acta. 28, 715-728 (1981).
[CrossRef]

1978 (1)

1971 (1)

1967 (1)

Burris, H. R.

M. F. Stell, C. I. Moore, H. R. Burris, M. R. Suite, M. J. Vilcheck, M. A. Davis, R. Mahon, E. Oh, W. S. Rabinovich, G. C. Gilbreath, W. J. Scharpf, and A. E. Reed, "Passive optical monitor for atmospheric turbulence and windspeed," Proc. SPIE 5160, 422-431 (2004).
[CrossRef]

Chiba, T.

Davis, M. A.

M. F. Stell, C. I. Moore, H. R. Burris, M. R. Suite, M. J. Vilcheck, M. A. Davis, R. Mahon, E. Oh, W. S. Rabinovich, G. C. Gilbreath, W. J. Scharpf, and A. E. Reed, "Passive optical monitor for atmospheric turbulence and windspeed," Proc. SPIE 5160, 422-431 (2004).
[CrossRef]

Fried, D. L.

Gilbreath, G. C.

M. F. Stell, C. I. Moore, H. R. Burris, M. R. Suite, M. J. Vilcheck, M. A. Davis, R. Mahon, E. Oh, W. S. Rabinovich, G. C. Gilbreath, W. J. Scharpf, and A. E. Reed, "Passive optical monitor for atmospheric turbulence and windspeed," Proc. SPIE 5160, 422-431 (2004).
[CrossRef]

Grayshan, K.

Keister, M. P.

Mahon, R.

M. F. Stell, C. I. Moore, H. R. Burris, M. R. Suite, M. J. Vilcheck, M. A. Davis, R. Mahon, E. Oh, W. S. Rabinovich, G. C. Gilbreath, W. J. Scharpf, and A. E. Reed, "Passive optical monitor for atmospheric turbulence and windspeed," Proc. SPIE 5160, 422-431 (2004).
[CrossRef]

Mevers, G. E.

Moore, C. I.

M. F. Stell, C. I. Moore, H. R. Burris, M. R. Suite, M. J. Vilcheck, M. A. Davis, R. Mahon, E. Oh, W. S. Rabinovich, G. C. Gilbreath, W. J. Scharpf, and A. E. Reed, "Passive optical monitor for atmospheric turbulence and windspeed," Proc. SPIE 5160, 422-431 (2004).
[CrossRef]

Oh, E.

M. F. Stell, C. I. Moore, H. R. Burris, M. R. Suite, M. J. Vilcheck, M. A. Davis, R. Mahon, E. Oh, W. S. Rabinovich, G. C. Gilbreath, W. J. Scharpf, and A. E. Reed, "Passive optical monitor for atmospheric turbulence and windspeed," Proc. SPIE 5160, 422-431 (2004).
[CrossRef]

Parry, G.

G. Parry, "Measurement of atmospheric turbulence induced intensity fluctuation in a laser beam," Opt. Acta. 28, 715-728 (1981).
[CrossRef]

Rabinovich, W. S.

M. F. Stell, C. I. Moore, H. R. Burris, M. R. Suite, M. J. Vilcheck, M. A. Davis, R. Mahon, E. Oh, W. S. Rabinovich, G. C. Gilbreath, W. J. Scharpf, and A. E. Reed, "Passive optical monitor for atmospheric turbulence and windspeed," Proc. SPIE 5160, 422-431 (2004).
[CrossRef]

Reed, A. E.

M. F. Stell, C. I. Moore, H. R. Burris, M. R. Suite, M. J. Vilcheck, M. A. Davis, R. Mahon, E. Oh, W. S. Rabinovich, G. C. Gilbreath, W. J. Scharpf, and A. E. Reed, "Passive optical monitor for atmospheric turbulence and windspeed," Proc. SPIE 5160, 422-431 (2004).
[CrossRef]

Scharpf, W. J.

M. F. Stell, C. I. Moore, H. R. Burris, M. R. Suite, M. J. Vilcheck, M. A. Davis, R. Mahon, E. Oh, W. S. Rabinovich, G. C. Gilbreath, W. J. Scharpf, and A. E. Reed, "Passive optical monitor for atmospheric turbulence and windspeed," Proc. SPIE 5160, 422-431 (2004).
[CrossRef]

Stell, M. F.

M. F. Stell, C. I. Moore, H. R. Burris, M. R. Suite, M. J. Vilcheck, M. A. Davis, R. Mahon, E. Oh, W. S. Rabinovich, G. C. Gilbreath, W. J. Scharpf, and A. E. Reed, "Passive optical monitor for atmospheric turbulence and windspeed," Proc. SPIE 5160, 422-431 (2004).
[CrossRef]

Suite, M. R.

M. F. Stell, C. I. Moore, H. R. Burris, M. R. Suite, M. J. Vilcheck, M. A. Davis, R. Mahon, E. Oh, W. S. Rabinovich, G. C. Gilbreath, W. J. Scharpf, and A. E. Reed, "Passive optical monitor for atmospheric turbulence and windspeed," Proc. SPIE 5160, 422-431 (2004).
[CrossRef]

Tunick,

Tunick, "Modeling microphysical influences on optical turbulence in complex areas," Meteorol. Atmos. Phys. 96, 293-304 (2007).
[CrossRef]

Tunick, "Statistical analysis of optical turbulence intensity over a 2.33 km propagation path," Opt. Express 15, 3619-3628 (2007).
[CrossRef] [PubMed]

Tunick, "Statistical analysis of measured free-space laser signal intensity over a 2.33 km optical path," Opt. Express 17, 14115-14122 (2007).
[CrossRef]

Tunick, "Toward increasing the accuracy and realism of future optical turbulence (Cn2) calculations," Meteorol. Atmos. Phys. 90, 159-164 (2005).
[CrossRef]

Vetelino, F. S.

Vilcheck, M. J.

M. F. Stell, C. I. Moore, H. R. Burris, M. R. Suite, M. J. Vilcheck, M. A. Davis, R. Mahon, E. Oh, W. S. Rabinovich, G. C. Gilbreath, W. J. Scharpf, and A. E. Reed, "Passive optical monitor for atmospheric turbulence and windspeed," Proc. SPIE 5160, 422-431 (2004).
[CrossRef]

Vorontsov, M. A.

Wang, T-i

Weyrauch, T.

Young, C. Y.

Appl. Opt. (2)

J. Opt. Soc. Am. (2)

J. Opt. Soc. Am. A (1)

Meteorol. Atmos. Phys. (2)

Tunick, "Toward increasing the accuracy and realism of future optical turbulence (Cn2) calculations," Meteorol. Atmos. Phys. 90, 159-164 (2005).
[CrossRef]

Tunick, "Modeling microphysical influences on optical turbulence in complex areas," Meteorol. Atmos. Phys. 96, 293-304 (2007).
[CrossRef]

Opt. Acta. (1)

G. Parry, "Measurement of atmospheric turbulence induced intensity fluctuation in a laser beam," Opt. Acta. 28, 715-728 (1981).
[CrossRef]

Opt. Express (2)

Proc. SPIE (1)

M. F. Stell, C. I. Moore, H. R. Burris, M. R. Suite, M. J. Vilcheck, M. A. Davis, R. Mahon, E. Oh, W. S. Rabinovich, G. C. Gilbreath, W. J. Scharpf, and A. E. Reed, "Passive optical monitor for atmospheric turbulence and windspeed," Proc. SPIE 5160, 422-431 (2004).
[CrossRef]

Other (10)

Ishimaru, "The beam wave case and remote sensing," in Laser Beam Propagation in the Atmosphere, (Springer-Verlag, 1978), pp. 129-170

L. C. Andrews, R. L. Phillips, and C. Y. Hopen, Laser Beam Scintillation with Applications (SPIE Optical Engineering Press, Bellingham, 2001).
[CrossRef]

G. W. Carhart, M. A. Vorontsov, L. A. Beresnev, P. S. Paicopolis, and F. K. Beil, "Atmospheric laser communication system with wide-angle tracking and adaptive compensation," Proc. SPIE 5892 (2005).

M. Vorontsov, G. Carhart, M. Banta, T. Weyrauch, J. Gowens, and J. Carrano, "Atmospheric Laser Optics Testbed (A_LOT): Atmospheric propagation characterization, beam control, and imaging results," Proc. SPIE 5162 (2003).

Y. Han Oh, J. C. Ricklin, E. S. Oh, S. Doss-Hammel, and F. D. Eaton, "Estimating optical turbulence effects on free-space laser communication: modeling and measurements at ARL???s A_LOT facility," Proc. SPIE 5550, (2004).

V. I. Tatarski, The Effects of the Turbulent Atmosphere on Wave Propagation (Israel Program for Scientific Translations, 1971).

E. Polnau, M. A. Vorontsov, G. Carhart, T. Weyrauch, and L. A. Beresnev, "Adaptive compensation over a 2.33 km propagation path with retro reflectors under strong scintillation conditions," Proc. SPIE 6708 (2007).

M. C. Roggemann and B. M. Welsh, Imaging Through Turbulence (CRC Press, Boca Raton, 1996).

User???s Guide. LOA-004-xR Long Baseline Optical Anemometer and Atmospheric Turbulence Sensor. Revision 3/20/2003. Optical Scientific, Inc., Gaithersburg, MD (2003), http://www.opticalscientific.com/.

Operating Instructions. Model 81000 Ultrasonic Anemometer. Revision 01/24/2007, R.M. Young Co., Traverse City, MI (2007), http://www.youngusa.com/.

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Figures (8)

Fig. 1.
Fig. 1.

A schematic of the ARL A_LOT optical path

Fig. 2.
Fig. 2.

Schematic of the wave propagation geometry for this experiment, where laser signal data are collected at the focal plane of the receiving optics.

Fig. 3.
Fig. 3.

Photograph of the receiving optics (as detailed in the text). Note, aluminum plates and disks are placed on top of the breadboard to act as ballasts for the vibration isolation platform.

Fig. 4.
Fig. 4.

Optical turbulence (C 2 n ) calculations based on signal intensity data analysis for the data set collected during (a) winter and (b) spring. The dashed lines identify the boundary for estimates within a factor of two

Fig. 5.
Fig. 5.

IOL rooftop recorded wind velocity data (one-minute averaged) for the largest outliers shown in Fig. 4a. The vertical axis is the ratio of modeled C 2 n using Eq. (5) to scintillometer measured data.

Fig. 6.
Fig. 6.

Observed Rytov variance versus measured scintillation index for the data set collected in (a) winter and (b) spring. The dashed lines identify the boundary for estimates within a factor of two.

Fig. 7.
Fig. 7.

Optical turbulence (C 2 n ) calculations based on focal spot displacement data analysis for the data set collected during (a) winter and (b) spring. The dashed line identifies the boundary for estimates within a factor of ten.

Fig. 8.
Fig. 8.

Fried parameter (r 0) calculations based on different estimates C 2 n for the data set collected during (a) winter and (b) spring. The dashed lines identify the boundary for estimates within a factor of two.

Equations (9)

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

σ I 2 = I 2 I 2 I 2 .
σ I 2 ( D ) = A σ I 2 ( 0 ) ,
A = [ 1 + 0.33 ( k D 2 4 L ) 5 6 ] 7 5 .
σ I 2 = σ 1 2 = 0.5 C n 2 k 7 6 L 11 6 ,
C n 2 = C σ χ 2 D t 7 3 L 3 ,
σ F = F α 2 1 2 ,
α 2 = 1.093 C n 2 LD 1 3 .
β 2 = 1.093 C n 2 LD 1 3 .
r 0 = [ 0.158 k 2 LC n 2 ] 3 5 ,

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