WIde-field adaptive optics correction using a single rotating laser guide star.

The problem of providing Adaptive Optics (AO) correction over a wide field of view is one that can be alleviated by using multiple conjugate AO (MCAO), or a low-altitude Laser Guide Star (LGS) that is projected to an altitude below any high layer turbulence. A low-altitude LGS can only sense wavefront distortions induced by low-altitude turbulence, which is dominated by a strong boundary layer at the ground. Sensing only the wavefront from this layer provides an AO system with a more spatially invariant performance over the telescope field of view at the expense of overall correction. An alternative method for measuring a ground-layer biased wavefront using a single rotating LGS is presented together with a numerical analysis of the wide-field performance of an AO system utilizing such a LGS. System performance in H and K bands is predicted in terms of system Strehl ratio, which shows that uniform correction can be obtained over fields of view of 200 arcsec in diameter. The simulations also show that the on-axis performance of a LGS utilizing Rayleigh backscattered light will be improved.

[1]  T. Kármán Progress in the Statistical Theory of Turbulence , 1948 .

[2]  Christopher D. Saunter,et al.  Acceleration of adaptive optics simulations using programmable logic , 2005, ArXiv.

[3]  R. Ragazzoni,et al.  No Laser Guide Stars for adaptive optics in giant telescopes , 1999 .

[4]  C. Froehly,et al.  Coherent combination of four laser beams in a multi-axis Fourier cavity using a diffractive optical element , 2001 .

[5]  Richard W. Wilson,et al.  Adaptive optics for astronomy: theoretical performance and limitations , 1996 .

[6]  Ray M. Sharples,et al.  MOSAIC: a multi-object spectrograph with adaptive image correction , 2000, Astronomical Telescopes and Instrumentation.

[7]  Roberto Ragazzoni,et al.  Adaptive-optics corrections available for the whole sky , 2000, Nature.

[8]  Robert K. Tyson,et al.  Adaptive Optical System Technologies , 1998 .

[9]  Bernhard Delabre,et al.  MAPS: a turbulence simulator for MCAO , 2004, SPIE Astronomical Telescopes + Instrumentation.

[10]  Brooke Gregory,et al.  Design of ground-layer turbulence compensation with a Rayleigh beacon , 2004, SPIE Astronomical Telescopes + Instrumentation.

[11]  C. Baranec,et al.  First Tests of Wavefront Sensing with a Constellation of Laser Guide Beacons , 2005 .

[12]  R. Noll Zernike polynomials and atmospheric turbulence , 1976 .

[13]  Brian J. Bauman,et al.  MCAO for Gemini South , 2003, SPIE Astronomical Telescopes + Instrumentation.

[14]  Andrei Tokovinin,et al.  Seeing Improvement with Ground‐Layer Adaptive Optics , 2004 .