The Structure of High Strehl Ratio Point-Spread Functions

By M. Perrin, A. Sivaramakrishnan, R. Makidon, B. Oppenheimer, J. Graham. 2003

159 citations recorded by the source corpus.

We describe the symmetries present in the point-spread function (PSF) of an optical system either located in space or corrected by an adaptive optics (AO) system to Strehl ratios of about 70% and higher. We present a formalism for expanding the PSF to arbitrary order in terms of powers of the Fourier transform of the residual phase error over an arbitrarily shaped and apodized entrance aperture. For traditional unapodized apertures at high Strehl ratios, bright speckles pinned to the bright Airy rings are part of an antisymmetric perturbation of the perfect PSF, arising from the term that is first order in the residual phase error. There are two symmetric second-degree terms. One is negative at the center and, like the first-order term, is modulated by the perfect image's field strength—it reduces to the Maréchal approximation at the center of the PSF. The other is nonnegative everywhere, zero at the image center, and can be responsible for an extended halo—which limits the dynamic range of faint companion detection in the darkest portions of the image. In regimes where one or the other term dominates the speckles in an image, the symmetry of the dominant term can be exploited to reduce the effect of those speckles, potentially by an order of magnitude or more. We demonstrate the effects of both secondary obscuration and pupil apodization on the structure of residual speckles and discuss how these symmetries can be exploited by appropriate telescope and instrument design, observing strategies, and filter bandwidths to improve the dynamic range of high dynamic range AO and space-based observations. Finally, we show that our analysis is relevant to high dynamic range coronagraphy.

Subfields: Atomic and Molecular Physics, and Optics, Biomedical Engineering

View Paper: https://www.semanticscholar.org/paper/efd75b286e9d7756824c2841ac6ae081943dedd0

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Atomic and Molecular Physics, and Optics

1. Remi Soummer
2. L. Pueyo
3. Roger Davies
4. M. Kasper
5. C. Marois
6. B. Bowler

In Biomedical Engineering

1. Remi Soummer
2. Roger Davies
3. M. Kasper

Citations in the corpus

• A New High Contrast Imaging Program at Palomar Observatory (2010, background): “…in the incoming stellar wave front, arising from imperfections in the AO optics or the coronagraphic optics, can lead to a pattern of speckles that litter the image in the focal plane (e.g., Labeyrie 1995; Bloemhof et al. 2001; Boccaletti et al. 2002; Perrin et al. 2003; Aime & Soummer 2004).”
• Adaptive Optics for Astronomy (2012, background): “This is because the residual image intensity is proportional to the residual spatial power spectrum of the wavefront (e.g. Guyon 2005, Perrin et al. 2003) when aberrations are small.”
• FUNDAMENTAL LIMITATIONS OF HIGH CONTRAST IMAGING SET BY SMALL SAMPLE STATISTICS (2014, background): “Non-Gaussian speckle statistics, hopefully a rare occurrence when the data reduction is performed efficiently, therefore needs its own particular solution: in Sect.”
• Apodized Pupil Lyot Coronagraphs for Arbitrary Telescope Apertures (2004, methodology): “This can be approached with expansions or statistical methods (Sivaramakrishnan et al. 2002; Perrin et al. 2003; Aime & Soummer 2004b).”
• SPHERE: the exoplanet imager for the Very Large Telescope (2019, background): “…developments in coronagraphy and its interaction with adaptive optics in the early 2000s (Rouan et al. 2000; Sivaramakrishnan et al. 2001, 2002; Perrin et al. 2003; Soummer et al. 2003) as well as innovative observing strategies (Racine et al. 1999; Marois et al. 2006) quickly paved the way…”