Abstract

Ground-based optical searches for faint stellar or planetary companions about other stars may be limited by speckle noise, which is the rapid intensity fluctuations that are due to motions of remnant atmospheric speckles. Adaptive optics (AO) can reduce residual wave-front phase errors to low values, substantially reducing the unwanted power in the speckle halo. At high correction, however, the noise in the halo will be dominated by anomalously bright “pinned” speckles that have a number of unusual properties. They can have negative intensities and will appear in spatially antisymmetric patterns; they are spatially pinned to Airy rings and have zero mean in a sufficiently long integration. Some of these properties may be used to reduce the unanticipated effect of pinned speckles on companion searches, depending on details of the AO system. But, in short exposures, pinned speckles dominate speckle noise over much of the inner halo for Strehl ratios S as low as 0.6 and over much of the outer halo too as Strehl and deformable-mirror actuator densities increase. I show that these anomalously bright pinned speckles are not included in the traditional expression for speckle power in an image, 1-S, on which sensitivity estimates of future high-performance AO systems have been based.

© 2004 Optical Society of America

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References

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  1. M. Troy, R. G. Dekany, B. R. Oppenheimer, E. E. Bloemhof, T. Trinh, F. Dekens, F. Shi, T. L. Hayward, and B. Brandl, Proc. SPIE 4007, 31 (2000).
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    [CrossRef]
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    [CrossRef]
  9. E. E. Bloemhof, “Speckles in a highly corrected adaptive optics system,” Proc. SPIE5169 (to be published).
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    [CrossRef]

2003 (2)

E. E. Bloemhof, Astrophys. J. 582, L59 (2003).
[CrossRef]

A. Sivaramakrishnan, P. E. Hodge, R. B. Makidon, M. D. Perrin, J. P. Lloyd, E. E. Bloemhof, and B. R. Oppenheimer, Proc. SPIE 4860, 161 (2003).
[CrossRef]

2002 (1)

A. Sivaramakrishnan, J. P. Lloyd, P. E. Hodge, and B. A. Macintosh, Astrophys. J. 581, L59 (2002).
[CrossRef]

2001 (1)

E. E. Bloemhof, R. G. Dekany, M. Troy, and B. R. Oppenheimer, Astrophys. J. 558, L71 (2001).
[CrossRef]

2000 (2)

M. Troy, R. G. Dekany, B. R. Oppenheimer, E. E. Bloemhof, T. Trinh, F. Dekens, F. Shi, T. L. Hayward, and B. Brandl, Proc. SPIE 4007, 31 (2000).
[CrossRef]

D. Rouan, P. Riaud, A. Boccaletti, Y. Clénet, and A. Labeyrie, Publ. Astron. Soc. Pac. 112, 1479 (2000).
[CrossRef]

1999 (1)

R. Racine, G. A. H. Walker, D. Nadeau, R. Doyon, and C. Marois, Publ. Astron. Soc. Pac. 111, 587 (1999).
[CrossRef]

1994 (1)

J. R. P. Angel, Nature 368, 203 (1994).
[CrossRef]

1966 (1)

Angel, J. R. P.

J. R. P. Angel, Nature 368, 203 (1994).
[CrossRef]

Bloemhof, E. E.

E. E. Bloemhof, Astrophys. J. 582, L59 (2003).
[CrossRef]

A. Sivaramakrishnan, P. E. Hodge, R. B. Makidon, M. D. Perrin, J. P. Lloyd, E. E. Bloemhof, and B. R. Oppenheimer, Proc. SPIE 4860, 161 (2003).
[CrossRef]

E. E. Bloemhof, R. G. Dekany, M. Troy, and B. R. Oppenheimer, Astrophys. J. 558, L71 (2001).
[CrossRef]

M. Troy, R. G. Dekany, B. R. Oppenheimer, E. E. Bloemhof, T. Trinh, F. Dekens, F. Shi, T. L. Hayward, and B. Brandl, Proc. SPIE 4007, 31 (2000).
[CrossRef]

E. E. Bloemhof, “Speckles in a highly corrected adaptive optics system,” Proc. SPIE5169 (to be published).

Boccaletti, A.

D. Rouan, P. Riaud, A. Boccaletti, Y. Clénet, and A. Labeyrie, Publ. Astron. Soc. Pac. 112, 1479 (2000).
[CrossRef]

Brandl, B.

M. Troy, R. G. Dekany, B. R. Oppenheimer, E. E. Bloemhof, T. Trinh, F. Dekens, F. Shi, T. L. Hayward, and B. Brandl, Proc. SPIE 4007, 31 (2000).
[CrossRef]

Clénet, Y.

D. Rouan, P. Riaud, A. Boccaletti, Y. Clénet, and A. Labeyrie, Publ. Astron. Soc. Pac. 112, 1479 (2000).
[CrossRef]

Dekany, R. G.

E. E. Bloemhof, R. G. Dekany, M. Troy, and B. R. Oppenheimer, Astrophys. J. 558, L71 (2001).
[CrossRef]

M. Troy, R. G. Dekany, B. R. Oppenheimer, E. E. Bloemhof, T. Trinh, F. Dekens, F. Shi, T. L. Hayward, and B. Brandl, Proc. SPIE 4007, 31 (2000).
[CrossRef]

Dekens, F.

M. Troy, R. G. Dekany, B. R. Oppenheimer, E. E. Bloemhof, T. Trinh, F. Dekens, F. Shi, T. L. Hayward, and B. Brandl, Proc. SPIE 4007, 31 (2000).
[CrossRef]

Doyon, R.

R. Racine, G. A. H. Walker, D. Nadeau, R. Doyon, and C. Marois, Publ. Astron. Soc. Pac. 111, 587 (1999).
[CrossRef]

Fried, D. L.

Hayward, T. L.

M. Troy, R. G. Dekany, B. R. Oppenheimer, E. E. Bloemhof, T. Trinh, F. Dekens, F. Shi, T. L. Hayward, and B. Brandl, Proc. SPIE 4007, 31 (2000).
[CrossRef]

Hodge, P. E.

A. Sivaramakrishnan, P. E. Hodge, R. B. Makidon, M. D. Perrin, J. P. Lloyd, E. E. Bloemhof, and B. R. Oppenheimer, Proc. SPIE 4860, 161 (2003).
[CrossRef]

A. Sivaramakrishnan, J. P. Lloyd, P. E. Hodge, and B. A. Macintosh, Astrophys. J. 581, L59 (2002).
[CrossRef]

Labeyrie, A.

D. Rouan, P. Riaud, A. Boccaletti, Y. Clénet, and A. Labeyrie, Publ. Astron. Soc. Pac. 112, 1479 (2000).
[CrossRef]

Lloyd, J. P.

A. Sivaramakrishnan, P. E. Hodge, R. B. Makidon, M. D. Perrin, J. P. Lloyd, E. E. Bloemhof, and B. R. Oppenheimer, Proc. SPIE 4860, 161 (2003).
[CrossRef]

A. Sivaramakrishnan, J. P. Lloyd, P. E. Hodge, and B. A. Macintosh, Astrophys. J. 581, L59 (2002).
[CrossRef]

Macintosh, B. A.

A. Sivaramakrishnan, J. P. Lloyd, P. E. Hodge, and B. A. Macintosh, Astrophys. J. 581, L59 (2002).
[CrossRef]

Makidon, R. B.

A. Sivaramakrishnan, P. E. Hodge, R. B. Makidon, M. D. Perrin, J. P. Lloyd, E. E. Bloemhof, and B. R. Oppenheimer, Proc. SPIE 4860, 161 (2003).
[CrossRef]

Marois, C.

R. Racine, G. A. H. Walker, D. Nadeau, R. Doyon, and C. Marois, Publ. Astron. Soc. Pac. 111, 587 (1999).
[CrossRef]

Nadeau, D.

R. Racine, G. A. H. Walker, D. Nadeau, R. Doyon, and C. Marois, Publ. Astron. Soc. Pac. 111, 587 (1999).
[CrossRef]

Oppenheimer, B. R.

A. Sivaramakrishnan, P. E. Hodge, R. B. Makidon, M. D. Perrin, J. P. Lloyd, E. E. Bloemhof, and B. R. Oppenheimer, Proc. SPIE 4860, 161 (2003).
[CrossRef]

E. E. Bloemhof, R. G. Dekany, M. Troy, and B. R. Oppenheimer, Astrophys. J. 558, L71 (2001).
[CrossRef]

M. Troy, R. G. Dekany, B. R. Oppenheimer, E. E. Bloemhof, T. Trinh, F. Dekens, F. Shi, T. L. Hayward, and B. Brandl, Proc. SPIE 4007, 31 (2000).
[CrossRef]

Perrin, M. D.

A. Sivaramakrishnan, P. E. Hodge, R. B. Makidon, M. D. Perrin, J. P. Lloyd, E. E. Bloemhof, and B. R. Oppenheimer, Proc. SPIE 4860, 161 (2003).
[CrossRef]

Racine, R.

R. Racine, G. A. H. Walker, D. Nadeau, R. Doyon, and C. Marois, Publ. Astron. Soc. Pac. 111, 587 (1999).
[CrossRef]

Riaud, P.

D. Rouan, P. Riaud, A. Boccaletti, Y. Clénet, and A. Labeyrie, Publ. Astron. Soc. Pac. 112, 1479 (2000).
[CrossRef]

Rouan, D.

D. Rouan, P. Riaud, A. Boccaletti, Y. Clénet, and A. Labeyrie, Publ. Astron. Soc. Pac. 112, 1479 (2000).
[CrossRef]

Shi, F.

M. Troy, R. G. Dekany, B. R. Oppenheimer, E. E. Bloemhof, T. Trinh, F. Dekens, F. Shi, T. L. Hayward, and B. Brandl, Proc. SPIE 4007, 31 (2000).
[CrossRef]

Sivaramakrishnan, A.

A. Sivaramakrishnan, P. E. Hodge, R. B. Makidon, M. D. Perrin, J. P. Lloyd, E. E. Bloemhof, and B. R. Oppenheimer, Proc. SPIE 4860, 161 (2003).
[CrossRef]

A. Sivaramakrishnan, J. P. Lloyd, P. E. Hodge, and B. A. Macintosh, Astrophys. J. 581, L59 (2002).
[CrossRef]

Trinh, T.

M. Troy, R. G. Dekany, B. R. Oppenheimer, E. E. Bloemhof, T. Trinh, F. Dekens, F. Shi, T. L. Hayward, and B. Brandl, Proc. SPIE 4007, 31 (2000).
[CrossRef]

Troy, M.

E. E. Bloemhof, R. G. Dekany, M. Troy, and B. R. Oppenheimer, Astrophys. J. 558, L71 (2001).
[CrossRef]

M. Troy, R. G. Dekany, B. R. Oppenheimer, E. E. Bloemhof, T. Trinh, F. Dekens, F. Shi, T. L. Hayward, and B. Brandl, Proc. SPIE 4007, 31 (2000).
[CrossRef]

Walker, G. A. H.

R. Racine, G. A. H. Walker, D. Nadeau, R. Doyon, and C. Marois, Publ. Astron. Soc. Pac. 111, 587 (1999).
[CrossRef]

Astrophys. J. (3)

E. E. Bloemhof, R. G. Dekany, M. Troy, and B. R. Oppenheimer, Astrophys. J. 558, L71 (2001).
[CrossRef]

E. E. Bloemhof, Astrophys. J. 582, L59 (2003).
[CrossRef]

A. Sivaramakrishnan, J. P. Lloyd, P. E. Hodge, and B. A. Macintosh, Astrophys. J. 581, L59 (2002).
[CrossRef]

J. Opt. Soc. Am. (1)

Nature (1)

J. R. P. Angel, Nature 368, 203 (1994).
[CrossRef]

Proc. SPIE (2)

A. Sivaramakrishnan, P. E. Hodge, R. B. Makidon, M. D. Perrin, J. P. Lloyd, E. E. Bloemhof, and B. R. Oppenheimer, Proc. SPIE 4860, 161 (2003).
[CrossRef]

M. Troy, R. G. Dekany, B. R. Oppenheimer, E. E. Bloemhof, T. Trinh, F. Dekens, F. Shi, T. L. Hayward, and B. Brandl, Proc. SPIE 4007, 31 (2000).
[CrossRef]

Publ. Astron. Soc. Pac. (2)

R. Racine, G. A. H. Walker, D. Nadeau, R. Doyon, and C. Marois, Publ. Astron. Soc. Pac. 111, 587 (1999).
[CrossRef]

D. Rouan, P. Riaud, A. Boccaletti, Y. Clénet, and A. Labeyrie, Publ. Astron. Soc. Pac. 112, 1479 (2000).
[CrossRef]

Other (1)

E. E. Bloemhof, “Speckles in a highly corrected adaptive optics system,” Proc. SPIE5169 (to be published).

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Figures (2)

Fig. 1
Fig. 1

Simulations of the two kinds of speckle that arise from first-order expansion of the phase exponential appropriate to high-Strehl imaging. A random remnant phase screen with Strehl ratio S=0.6 and deformable-mirror actuator density D/a=64 is assumed. Upper left, exact image, AeiΦˆ2. Upper right, antisymmetric pattern of anomalously bright pinned speckles from the linear term, -2ImΦˆAˆ. (Here the negative peak is shown in black, and zero as gray; in the other parts of this figure, zero is black.) Lower left, symmetric pattern of unpinned speckles from the quadratic term Φˆ2. Lower right, sum of PSF, linear, and quadratic terms. Both linear- and quadratic-term speckles may be identified in the exact and sum images. The quadratic speckles are free to roam anywhere within a halo of diameter λ/a, but the anomalously bright linear-term speckles are pinned to Airy maxima and have nulls on every Airy null.

Fig. 2
Fig. 2

Simulated distribution over the speckle halo of rms fluctuations in image intensity over many realizations of the speckle halo. The largest fluctuations follow the rings of the PSF because the anomalous (linear-term) speckles occur only there. Top, current AO S=0.60,D/a=16; bottom (on a different spatial scale), advanced future AO S=0.99,D/a=100. This figure illustrates that the anomalous linear-term speckles, although they contribute no instantaneous speckle power, can be the dominant source of speckle noise, particularly at large Strehl ratio and deformable-mirror actuator density.5,9

Equations (2)

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Image intensity=AeiΦˆ2Aˆ2-2 ImΦAˆ+Φˆ2.
1-S=Φ2pupil=1ApupilΦ2dξdη=Φˆ2dxdy,

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