Understanding the statistics of remnant speckles in the halo of an adaptively-corrected point-spread function is critically important to using adaptive optics in high-dynamic-range searches for faint companions. It has been clear for some time that photon (Poisson) statistics alone do not adequately account for noise in the halo, as the coherent nature of speckles gives them a temporal persistence that leads to a much larger noise contribution, termed speckle noise. I consider in this paper the physical mechanism for speckle formation, and show that residual speckles, in the case of highly corrected adaptive optics systems, tend to be pinned to secondary maxima (Airy rings) in the underlying diffraction-limited point-spread function, affecting their spatial distribution in an important way. Further, in current practical adaptive optics systems, the structure of the Airy rings will shift over relatively short time scales in response to flexure-induced non-common-path errors, modifying the temporal evolution of the statistics of the speckle distribution as well.

Date Published: 4 February 2002
PDF: 6 pages
Proc. SPIE 4494, Adaptive Optics Systems and Technology II, (4 February 2002); doi: 10.1117/12.454811

Published in SPIE Proceedings Vol. 4494:
Adaptive Optics Systems and Technology II
Robert K. Tyson; Domenico Bonaccini; Michael C. Roggemann, Editor(s)