While single conjugated adaptive
optics delivers high Strehl ratios on axis, this method suffers
generally from angular anisoplanatism. Only a small field over the
isoplanatic patch is well corrected with the performance degrading
towards the edges quickly. Ground layer adaptive optics, utilizing
multiple laser guide stars is generally capable of correcting a larger
field of view. This technique has been demonstrated already with the
use of natural stars and recently with Rayleigh guide stars at the MMT.
Ground layer adaptive optics offers some general benefits which are not
associated with reaching the diffraction limit. The advantages here lie
in the enhanced resolution, the increased point source sensitivity and
slit coupling efficiency as well as the robustness against crowding.
Offering those advantages over a large field of view makes up the
uniqueness to enhance the scientific capabilities of the LBT.
Model calculations show the achievement that can be reached with laser guided ground layer adaptive optics.
(Left) Gain in FWHM with ARGOS GLAO correction. (Right) FWHM of the
corrected PSF (solid lines) and of the uncorrected one (dashed). Colours
identify the 4 different atmospheric profiles.
(Left) Gain in ensquared Energy with ARGOS GLAO correction.
(Right) Ensquared Energy in a 0.25’’ square pixel of the corrected PSF (solid
lines) and of the uncorrected one (dashed). Colors identify the 4 different
atmospheric profiles defined in [AD1]
© Infrared and Submillimeter Astronomy Group at MPE
03/02/2009, editor of this page: Julian Ziegleder