Abstract

In high-resolution ultranarrow field-of-view thermal imagers, image quality over relatively long path lengths is typically limited by atmospheric degradation, especially atmospheric blur. We report our results and analyses of infrared images from two sites, Fort A. P. Hill and Aberdeen Proving Ground. The images are influenced by the various atmospheric phenomena: scattering, absorption, and turbulence. A series of experiments with high-resolution equipment in both the 3–5- and 8–13-μm regions at the two locations indicate that, as in the visible, image quality is limited much more by atmosphere than by the instrumentation for ranges even of the order of only a few kilometers. For paths close to the ground, turbulence is more dominant, whereas for paths involving higher average elevation, aerosol modulation transfer function (MTF) is dominant. As wavelength increases, turbulence MTF also increases, thus permitting aerosol MTF to become more dominant. A critical role in aerosol MTF in the thermal infrared is attributed to absorption, which noticeably decreases atmospheric transmission much more than in the visible, thereby reducing high-spatial-frequency aerosol MTF. These measurements indicate that atmospheric MTF should be a basic component in imaging system design and analysis even in the infrared, especially as higher-resolution hardware becomes available.

© 2004 Optical Society of America

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References

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  1. K. Krapels, R. G. Driggers, R. H. Vollmerhausen, N. S. Kopeika, C. E. Halford, “Atmospheric turbulence modulation transfer function for infrared target acquisition modeling,” Opt. Eng. 40, 1906–1913 (2001).
    [CrossRef]
  2. N. S. Kopeika, A System Engineering Approach to Imaging, Vol. 38 of the SPIE Press Monographs (SPIE, Bellingham, Wash., 1998).
  3. J. W. Goodman, Statistical Optics (Wiley, New York, 1985).
  4. D. Sadot, G. Kitron, N. Kitron, N. S. Kopeika, “Thermal imaging through the atmosphere: atmospheric MTF theory and validation,” Opt. Eng. 33, 880–887 (1994).
    [CrossRef]
  5. D. Sadot, A. Dvir, I. Bergel, N. S. Kopeika, “Restoration of thermal images distorted by the atmosphere, based upon measured and theoretical atmospheric modulation transfer function,” Opt. Eng. 33, 44–53 (1994).
    [CrossRef]
  6. D. Sadot, N. S. Kopeika, “Forecasting optical turbulence strength on the basis of macro scale meteorology and aerosols: models and validation,” Opt. Eng. 31, 200–212 (1992).
    [CrossRef]
  7. D. Sadot, N. S. Kopeika, “Effects of absorption on image quality through a particulate medium,” Appl. Opt. 33, 7101–7111 (1994).
    [CrossRef]
  8. W. R. Watkins, S. B. Crow, F. T. Kantrowitz, “Characterizing atmospheric effects on target contrast,” Opt. Eng. 30, 1563–1575 (1991).
    [CrossRef]
  9. J. Gottlieb, B. Fogel, I. Dror, Z. Y. Ofer, N. S. Kopeika, “Prediction of airborne particle statistics according to weather forecast: concentration and scattering area,” Opt. Eng. 34, 1208–1218 (1995).
    [CrossRef]

2001 (1)

K. Krapels, R. G. Driggers, R. H. Vollmerhausen, N. S. Kopeika, C. E. Halford, “Atmospheric turbulence modulation transfer function for infrared target acquisition modeling,” Opt. Eng. 40, 1906–1913 (2001).
[CrossRef]

1995 (1)

J. Gottlieb, B. Fogel, I. Dror, Z. Y. Ofer, N. S. Kopeika, “Prediction of airborne particle statistics according to weather forecast: concentration and scattering area,” Opt. Eng. 34, 1208–1218 (1995).
[CrossRef]

1994 (3)

D. Sadot, N. S. Kopeika, “Effects of absorption on image quality through a particulate medium,” Appl. Opt. 33, 7101–7111 (1994).
[CrossRef]

D. Sadot, G. Kitron, N. Kitron, N. S. Kopeika, “Thermal imaging through the atmosphere: atmospheric MTF theory and validation,” Opt. Eng. 33, 880–887 (1994).
[CrossRef]

D. Sadot, A. Dvir, I. Bergel, N. S. Kopeika, “Restoration of thermal images distorted by the atmosphere, based upon measured and theoretical atmospheric modulation transfer function,” Opt. Eng. 33, 44–53 (1994).
[CrossRef]

1992 (1)

D. Sadot, N. S. Kopeika, “Forecasting optical turbulence strength on the basis of macro scale meteorology and aerosols: models and validation,” Opt. Eng. 31, 200–212 (1992).
[CrossRef]

1991 (1)

W. R. Watkins, S. B. Crow, F. T. Kantrowitz, “Characterizing atmospheric effects on target contrast,” Opt. Eng. 30, 1563–1575 (1991).
[CrossRef]

Bergel, I.

D. Sadot, A. Dvir, I. Bergel, N. S. Kopeika, “Restoration of thermal images distorted by the atmosphere, based upon measured and theoretical atmospheric modulation transfer function,” Opt. Eng. 33, 44–53 (1994).
[CrossRef]

Crow, S. B.

W. R. Watkins, S. B. Crow, F. T. Kantrowitz, “Characterizing atmospheric effects on target contrast,” Opt. Eng. 30, 1563–1575 (1991).
[CrossRef]

Driggers, R. G.

K. Krapels, R. G. Driggers, R. H. Vollmerhausen, N. S. Kopeika, C. E. Halford, “Atmospheric turbulence modulation transfer function for infrared target acquisition modeling,” Opt. Eng. 40, 1906–1913 (2001).
[CrossRef]

Dror, I.

J. Gottlieb, B. Fogel, I. Dror, Z. Y. Ofer, N. S. Kopeika, “Prediction of airborne particle statistics according to weather forecast: concentration and scattering area,” Opt. Eng. 34, 1208–1218 (1995).
[CrossRef]

Dvir, A.

D. Sadot, A. Dvir, I. Bergel, N. S. Kopeika, “Restoration of thermal images distorted by the atmosphere, based upon measured and theoretical atmospheric modulation transfer function,” Opt. Eng. 33, 44–53 (1994).
[CrossRef]

Fogel, B.

J. Gottlieb, B. Fogel, I. Dror, Z. Y. Ofer, N. S. Kopeika, “Prediction of airborne particle statistics according to weather forecast: concentration and scattering area,” Opt. Eng. 34, 1208–1218 (1995).
[CrossRef]

Goodman, J. W.

J. W. Goodman, Statistical Optics (Wiley, New York, 1985).

Gottlieb, J.

J. Gottlieb, B. Fogel, I. Dror, Z. Y. Ofer, N. S. Kopeika, “Prediction of airborne particle statistics according to weather forecast: concentration and scattering area,” Opt. Eng. 34, 1208–1218 (1995).
[CrossRef]

Halford, C. E.

K. Krapels, R. G. Driggers, R. H. Vollmerhausen, N. S. Kopeika, C. E. Halford, “Atmospheric turbulence modulation transfer function for infrared target acquisition modeling,” Opt. Eng. 40, 1906–1913 (2001).
[CrossRef]

Kantrowitz, F. T.

W. R. Watkins, S. B. Crow, F. T. Kantrowitz, “Characterizing atmospheric effects on target contrast,” Opt. Eng. 30, 1563–1575 (1991).
[CrossRef]

Kitron, G.

D. Sadot, G. Kitron, N. Kitron, N. S. Kopeika, “Thermal imaging through the atmosphere: atmospheric MTF theory and validation,” Opt. Eng. 33, 880–887 (1994).
[CrossRef]

Kitron, N.

D. Sadot, G. Kitron, N. Kitron, N. S. Kopeika, “Thermal imaging through the atmosphere: atmospheric MTF theory and validation,” Opt. Eng. 33, 880–887 (1994).
[CrossRef]

Kopeika, N. S.

K. Krapels, R. G. Driggers, R. H. Vollmerhausen, N. S. Kopeika, C. E. Halford, “Atmospheric turbulence modulation transfer function for infrared target acquisition modeling,” Opt. Eng. 40, 1906–1913 (2001).
[CrossRef]

J. Gottlieb, B. Fogel, I. Dror, Z. Y. Ofer, N. S. Kopeika, “Prediction of airborne particle statistics according to weather forecast: concentration and scattering area,” Opt. Eng. 34, 1208–1218 (1995).
[CrossRef]

D. Sadot, N. S. Kopeika, “Effects of absorption on image quality through a particulate medium,” Appl. Opt. 33, 7101–7111 (1994).
[CrossRef]

D. Sadot, A. Dvir, I. Bergel, N. S. Kopeika, “Restoration of thermal images distorted by the atmosphere, based upon measured and theoretical atmospheric modulation transfer function,” Opt. Eng. 33, 44–53 (1994).
[CrossRef]

D. Sadot, G. Kitron, N. Kitron, N. S. Kopeika, “Thermal imaging through the atmosphere: atmospheric MTF theory and validation,” Opt. Eng. 33, 880–887 (1994).
[CrossRef]

D. Sadot, N. S. Kopeika, “Forecasting optical turbulence strength on the basis of macro scale meteorology and aerosols: models and validation,” Opt. Eng. 31, 200–212 (1992).
[CrossRef]

N. S. Kopeika, A System Engineering Approach to Imaging, Vol. 38 of the SPIE Press Monographs (SPIE, Bellingham, Wash., 1998).

Krapels, K.

K. Krapels, R. G. Driggers, R. H. Vollmerhausen, N. S. Kopeika, C. E. Halford, “Atmospheric turbulence modulation transfer function for infrared target acquisition modeling,” Opt. Eng. 40, 1906–1913 (2001).
[CrossRef]

Ofer, Z. Y.

J. Gottlieb, B. Fogel, I. Dror, Z. Y. Ofer, N. S. Kopeika, “Prediction of airborne particle statistics according to weather forecast: concentration and scattering area,” Opt. Eng. 34, 1208–1218 (1995).
[CrossRef]

Sadot, D.

D. Sadot, N. S. Kopeika, “Effects of absorption on image quality through a particulate medium,” Appl. Opt. 33, 7101–7111 (1994).
[CrossRef]

D. Sadot, A. Dvir, I. Bergel, N. S. Kopeika, “Restoration of thermal images distorted by the atmosphere, based upon measured and theoretical atmospheric modulation transfer function,” Opt. Eng. 33, 44–53 (1994).
[CrossRef]

D. Sadot, G. Kitron, N. Kitron, N. S. Kopeika, “Thermal imaging through the atmosphere: atmospheric MTF theory and validation,” Opt. Eng. 33, 880–887 (1994).
[CrossRef]

D. Sadot, N. S. Kopeika, “Forecasting optical turbulence strength on the basis of macro scale meteorology and aerosols: models and validation,” Opt. Eng. 31, 200–212 (1992).
[CrossRef]

Vollmerhausen, R. H.

K. Krapels, R. G. Driggers, R. H. Vollmerhausen, N. S. Kopeika, C. E. Halford, “Atmospheric turbulence modulation transfer function for infrared target acquisition modeling,” Opt. Eng. 40, 1906–1913 (2001).
[CrossRef]

Watkins, W. R.

W. R. Watkins, S. B. Crow, F. T. Kantrowitz, “Characterizing atmospheric effects on target contrast,” Opt. Eng. 30, 1563–1575 (1991).
[CrossRef]

Appl. Opt. (1)

D. Sadot, N. S. Kopeika, “Effects of absorption on image quality through a particulate medium,” Appl. Opt. 33, 7101–7111 (1994).
[CrossRef]

Opt. Eng. (6)

W. R. Watkins, S. B. Crow, F. T. Kantrowitz, “Characterizing atmospheric effects on target contrast,” Opt. Eng. 30, 1563–1575 (1991).
[CrossRef]

J. Gottlieb, B. Fogel, I. Dror, Z. Y. Ofer, N. S. Kopeika, “Prediction of airborne particle statistics according to weather forecast: concentration and scattering area,” Opt. Eng. 34, 1208–1218 (1995).
[CrossRef]

K. Krapels, R. G. Driggers, R. H. Vollmerhausen, N. S. Kopeika, C. E. Halford, “Atmospheric turbulence modulation transfer function for infrared target acquisition modeling,” Opt. Eng. 40, 1906–1913 (2001).
[CrossRef]

D. Sadot, G. Kitron, N. Kitron, N. S. Kopeika, “Thermal imaging through the atmosphere: atmospheric MTF theory and validation,” Opt. Eng. 33, 880–887 (1994).
[CrossRef]

D. Sadot, A. Dvir, I. Bergel, N. S. Kopeika, “Restoration of thermal images distorted by the atmosphere, based upon measured and theoretical atmospheric modulation transfer function,” Opt. Eng. 33, 44–53 (1994).
[CrossRef]

D. Sadot, N. S. Kopeika, “Forecasting optical turbulence strength on the basis of macro scale meteorology and aerosols: models and validation,” Opt. Eng. 31, 200–212 (1992).
[CrossRef]

Other (2)

N. S. Kopeika, A System Engineering Approach to Imaging, Vol. 38 of the SPIE Press Monographs (SPIE, Bellingham, Wash., 1998).

J. W. Goodman, Statistical Optics (Wiley, New York, 1985).

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Figures (22)

Fig. 1
Fig. 1

Short- and long-term exposure turbulence MTFs from measurements of C n 2 at APG at noon for 3600-m line of sight at a 4-μm wavelength on 22 August 2000 at 14:00.

Fig. 2
Fig. 2

Short- and long-term exposure turbulence MTFs from measurements of C n 2 at APG for a 3600-m line of sight at a 4-μm wavelength on 22 August 2000 at 19:00.

Fig. 3
Fig. 3

MTF right edge at APG for MWIR on 22 August 2000 at 11:58.

Fig. 4
Fig. 4

MTF left edge at APG for MWIR on 22 August 2000 at 11:58.

Fig. 5
Fig. 5

MTF left edge at APG for MWIR on 22 August 2000 at 14:08.

Fig. 6
Fig. 6

MTF right edge at APG for MWIR on 22 August 2000 at 14:08.

Fig. 7
Fig. 7

MTF left edge at APG for MWIR on 22 August 200 at 16:04.

Fig. 8
Fig. 8

MTF left edge at APG for LWIR on 22 August 2000 at 12:10.

Fig. 9
Fig. 9

MTF left edge at APG for LWIR on 22 August 2000 at 15:04.

Fig. 10
Fig. 10

MTF right edge at APG for LWIR on 22 August 2000 at 18:00.

Fig. 11
Fig. 11

MTF atmospheric left edge at APHill for LWIR on 16 August 2000 at 13:01.

Fig. 12
Fig. 12

MTF atmospheric right edge at APHill for LWIR on 16 August 2000 at 15:19.

Fig. 13
Fig. 13

MTF atmospheric right edge at APHill for LWIR on 16 August 2000 at 17:53.

Fig. 14
Fig. 14

MTF atmospheric left edge at APHill for MWIR on 16 August 2000 at 12:49.

Fig. 15
Fig. 15

MTF atmospheric right edge at APHill for MWIR on 16 August 2000 at 12:49.

Fig. 16
Fig. 16

MTF atmospheric right edge at APHill for MWIR on 16 August 2000 at 14:31.

Fig. 17
Fig. 17

MTF atmospheric left edge at APHill for MWIR on 16 August 2000 at 17:51.

Fig. 18
Fig. 18

MTF comparison at APHill and APG for LWIR.

Fig. 19
Fig. 19

(a) Image from APG, LWIR on 22 August 2000 at 15:03. (b) Image from APHill, LWIR on 16 August 2000 at 14:12.

Fig. 20
Fig. 20

Images from (a) APG on 22 August 2000 and (b) APHill on 16 August 2000 for LWIR for different hours of the day.

Fig. 21
Fig. 21

(a) APG for LWIR on 24 August 2000 at 09:05. (b) APG for LWIR on 23 August 2000 at 12:07. (c) APG for LWIR on 22 August 2000 at 19:04. (d) APHill for LWIR on 22 August 2000 at 11:00.

Fig. 22
Fig. 22

C n 2 comparison as a function of the time of day at APG and APHill.

Tables (1)

Tables Icon

Table 1 C n 2 Data at APG on 22 August 2000 and APHill on 16 August 2000

Equations (4)

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MTFLE=exp-57.4aξ5/3Cn2λ-1/3R,
MTFSE=exp-57.4aξ5/3Cn2λ-1/3R1-μξλ/D1/3,
MTFSEMTFA=MA.
ΔMTFA/MTFA=-ΔMTFSE/MTFSE,

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