Adaptive Optics for GTC



The main scientific performance requirements for Day 1 are:

Mode Single-conjugate correction
Wavelength 1.0-2.5 micron, with a goal of 0.8-5 micron
Strehl Ratio SR>=0.65 at 2.2 micron for a bright NGS on axis
SR>=0.1 at 2.2 micron for a faint NGS (mR=14.5)
Range of operation Seeing better than 1.5 arcsec FWHM at 500 nm
Zenith angles 0º - 60º
Field of View (FoV) 1.5 arcmin available to the science instrument
1.5 arcmin accessible for wavefront sensing
Observation time At least 1 h exposure time on the science instrument
Non-sidereal operation Continuous tracking of objects which act as their own guide source at non-sidereal rates limited only by the telescope tracking
Dithering Offsets of 0.25 arcsec (goal 1.0 arcsec) without interrupting operation
Nodding Ability to keep the loop closed while nodding the telescope at 1 arcsec per second (TBC)
Throughput Throughput of wavefront corrector shall be at least 70% in the wavelength range from 1.0 to 2.5 micron with a goal of 70% in the range 0.8 to 5 micron
Emissivity < 20% at 3.8 micron
Ghost images Defocused ghosts: <1e-5 (except dichroic 1e-4)
Focused ghosts: <1e-3 and located within 0.2 arcsec)
Upgrades Facilitate upgrade to a multi-conjugate system having two deformable mirrors.
Facilitate upgrade to the use of a single LGS and upgrade to the use of multiple LGS