Institute of Astronomy

High sensitivity wavefront sensing for the AOLI Project

SpeakerTalk DateTalk Series
Jonathan Crass (IoA)30 January 2013Institute of Astronomy Seminars


Some of the highest resolution images ever taken in the visible were obtained by combining lucky imaging (LI) and low order adaptive optics (AO). In this talk I present a new instrument, the Adaptive Optics Lucky Imager (AOLI), under development for use on the 4.2m William Herschel Telescope. The instrument uses the proven combination of AO and LI, however it employs a non-linear curvature wavefront sensor (nlCWFS) as part of the AO system rather than more conventional Shack Hartmann wavefront sensors (SHWFS).

Many AO systems in use today require bright reference objects to determine the effects of atmospheric distortions on incoming wavefronts. This requirement is because of the use of SHWFS which distribute incoming light into a large number of sub-apertures. The nlCWFS as described by Guyon et al. has been shown to offer a significant increase in sensitivity when compared to a SHWFS, allowing greater sky coverage using natural guide stars. I present the nlCWFS method including the basic theory, intrinsic effects and how to reconstruct the wavefront from recorded data.