Abstract

This paper will describe a state-of-the-art approach to real-time wavefront sensing and image enhancement. It will explore Boeing’s existing technology to realize a 50Hz frame rate (with a path to 1KHz and higher). At this higher rate, phase diversity will be readily applicable to compensate for distortions of large dynamic bandwidth such as those of the atmosphere. We will describe various challenges in aligning a two-camera phase diversity system. Such configurations make it almost impossible to process the captured images without additional upgrade in the algorithm to account for alignment errors. An example of an error is the relative misalignment of the two images, the “best-focus” and the diversity image, where it is extremely hard to maintain alignment to less than a fraction of 1 pixel. We will show that the algorithm performance increases dramatically when we account for these errors in the estimation process. Preliminary evaluation has assessed a National Imagery Interpretability Rating Scale increase of 3 from the best-focus to the enhanced image. Such a performance improvement would greatly increase the operating range (or, equivalently, decrease the weight) of many optical systems.

© 2008 Optical Society of America

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References

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    [CrossRef]
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  10. J. W. Goodman, Introduction to Fourier Optics (McGraw-Hill, 1968).
  11. S. M. Kay, (Prentice-Hall, 1993).
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  13. M. C. Roggemann and Byron Welsh, Imaging Through Turbulence (CRC Press, 1996).
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    [CrossRef]

2005 (1)

2003 (1)

1999 (1)

1994 (1)

M. G. Lofdahl and G. B. Scharmer, “Wave-front sensing and image restoration from focused and defocused solar images,” Astron. Astrophys. Suppl. Ser. 107, 243-264 (1994).

1993 (1)

1992 (1)

1988 (1)

1982 (1)

R. A. Gonsalves, “Phase retrieval and diversity in adaptive optics,” Opt. Eng. 21, 829-832 (1982).

1979 (1)

R. A. Gonsalves and R. Chidlaw, “Wavefront sensing by phase retrieval,” Proc. SPIE 207, 32--39 (1979).

1976 (1)

R. Noll, “Zernike polynomials and atmospheric turbulence,” J. Opt. Soc Am. 66, 207-211 (1976).
[CrossRef]

Black, K. A.

Chidlaw, R.

R. A. Gonsalves and R. Chidlaw, “Wavefront sensing by phase retrieval,” Proc. SPIE 207, 32--39 (1979).

Conan, J. M.

Cunningham, P. R.

Deville, Jana H.

Dolne, J. J.

Fienup, J. R.

Gonsalves, R. A.

R. A. Gonsalves, “Phase retrieval and diversity in adaptive optics,” Opt. Eng. 21, 829-832 (1982).

R. A. Gonsalves and R. Chidlaw, “Wavefront sensing by phase retrieval,” Proc. SPIE 207, 32--39 (1979).

Goodman, J. W.

J. W. Goodman, Introduction to Fourier Optics (McGraw-Hill, 1968).

Hammoud, A. M.

Idell, P. S.

Kay, S. M.

S. M. Kay, (Prentice-Hall, 1993).

Lofdahl, M. G.

M. G. Lofdahl and G. B. Scharmer, “Wave-front sensing and image restoration from focused and defocused solar images,” Astron. Astrophys. Suppl. Ser. 107, 243-264 (1994).

Meynadier, L.

Michau, V.

Mugnier, L. M.

Noll, R.

R. Noll, “Zernike polynomials and atmospheric turbulence,” J. Opt. Soc Am. 66, 207-211 (1976).
[CrossRef]

Papoulis, A.

A. Papoulis, Probability, Random Variables, and Stochastic Processes (McGraw-Hill, 1991).

Paxman, R. G.

Roggemann, M. C.

M. C. Roggemann and Byron Welsh, Imaging Through Turbulence (CRC Press, 1996).

Rousset, G.

Schall, H. B.

Scharmer, G. B.

M. G. Lofdahl and G. B. Scharmer, “Wave-front sensing and image restoration from focused and defocused solar images,” Astron. Astrophys. Suppl. Ser. 107, 243-264 (1994).

Schultz, T. J.

Snyder, D. L.

Tansey, R. T.

Velluet, M. T.

Welsh, Byron

M. C. Roggemann and Byron Welsh, Imaging Through Turbulence (CRC Press, 1996).

White, R. L.

Widen, K. C.

Appl. Opt. (3)

Astron. Astrophys. Suppl. Ser. (1)

M. G. Lofdahl and G. B. Scharmer, “Wave-front sensing and image restoration from focused and defocused solar images,” Astron. Astrophys. Suppl. Ser. 107, 243-264 (1994).

J. Opt. Soc Am. (1)

R. Noll, “Zernike polynomials and atmospheric turbulence,” J. Opt. Soc Am. 66, 207-211 (1976).
[CrossRef]

J. Opt. Soc. Am. A (3)

Opt. Eng. (1)

R. A. Gonsalves, “Phase retrieval and diversity in adaptive optics,” Opt. Eng. 21, 829-832 (1982).

Proc. SPIE (1)

R. A. Gonsalves and R. Chidlaw, “Wavefront sensing by phase retrieval,” Proc. SPIE 207, 32--39 (1979).

Other (4)

J. W. Goodman, Introduction to Fourier Optics (McGraw-Hill, 1968).

S. M. Kay, (Prentice-Hall, 1993).

A. Papoulis, Probability, Random Variables, and Stochastic Processes (McGraw-Hill, 1991).

M. C. Roggemann and Byron Welsh, Imaging Through Turbulence (CRC Press, 1996).

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Figures (5)

Fig. 1
Fig. 1

Experimental setup of the phase diversity system. The imaging path uses an incoherent light source; the interferometry path uses an He–Ne laser.

Fig. 2
Fig. 2

Example of the interference pattern of a typical optics used in this experiment. The rms value of the aberration is < 0.03 wave. The optics is considered diffraction limited.

Fig. 3
Fig. 3

Point pattern used to estimate the relative rotation and longitudinal misalignment of the PD system.

Fig. 4
Fig. 4

50 Hz PD processed image. There is clear improvement in contrast of the enhanced compared with the “best-focus” image. As an example, look at the corresponding encircled regions in the two images.

Fig. 5
Fig. 5

Images processed with the upgraded PD algorithm to account for noncommon path errors. Preliminary evaluation has assessed a NIIRS increase of 3 of the enhanced compared to the “best-focus” images.

Equations (2)

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E = | I ( u , v ) H ^ d ( u , v ) I d ( u , v ) H ^ ( u , v ) | 2 | H ^ ( u , v ) | 2 + | H ^ d ( u , v ) | 2 ,
O ^ ( u , v ) = H * ^ ( u , v ) I ( u , v ) + H d * ^ ( u , v ) I d ( u , v ) | H ^ ( u , v ) | 2 + | H d ^ ( u , v ) | 2 ,

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