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Proceedings Paper

The adaptive optics point-spread function at moderate and high Strehl ratios
Author(s): Anand Sivaramakrishnan; Philip E. Hodge; Russell B. Makidon; Marshall D. Perrin; James P. Lloyd; Eric E. Bloemhof; Ben R. Oppenheimer
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Paper Abstract

We describe the symmetries present in the monochromatic point-spread function (PSF) corrected by an adaptive optics (AO) system to Strehl ratios of about 60% or greater. We expand the PSF in powers of the Fourier transform of the phase disturbance over an arbitrarily shaped and apodized entrance aperture. We show that for traditional unapodized aperture geometries, bright speckles pinned to the bright Airy rings are part of an antisymmetric first order perturbation of the perfect PSF (we make no assumptions about the symmetries of the aperture). This first order term redistributes power within each bright ring, but contributes no power in regions where the perfect image would have no light because it is modulated by the square root of the perfectly corrected PSF. It also vanishes at the center of the image. There are two symmetric second degree terms, one is negative at the center, and is also modulated by the perfect Airy field strength--it reduces to the Marechal approximation at the center of the PSF. The other second degree term is non-negative everywhere, zero at the image center, and is responsible for the extended halo--it limits the dynamic range in the dark portions of the image. These features can be exploited by appropriate telescope and instrument design, observing strategies, and data reduction methods to improve the dynamic range of AO observations.

Paper Details

Date Published: 3 March 2003
PDF: 10 pages
Proc. SPIE 4860, High-Contrast Imaging for Exo-Planet Detection, (3 March 2003); doi: 10.1117/12.457668
Show Author Affiliations
Anand Sivaramakrishnan, Space Telescope Science Institute (United States)
Philip E. Hodge, Space Telescope Science Institute (United States)
Russell B. Makidon, Space Telescope Science Institute (United States)
Marshall D. Perrin, Univ. of California/Berkeley (United States)
James P. Lloyd, Univ. of California/Berkeley (United States)
Eric E. Bloemhof, Jet Propulsion Lab. (United States)
Ben R. Oppenheimer, American Museum of Natural History (United States)


Published in SPIE Proceedings Vol. 4860:
High-Contrast Imaging for Exo-Planet Detection
Alfred B. Schultz; Richard G. Lyon, Editor(s)

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