First light AO (FLAO) system for LBT: final integration, acceptance test in Europe, and preliminary on-sky commissioning results

In this paper we present the laboratory characterization and performance evaluation of the First Light Adaptive Optics (FLAO) the Natural Guide Star adaptive optics system for the Large Binocular Telescope (LBT). The system uses an adaptive secondary mirror with 672 actuators and a pyramid wavefront sensor with adjustable sampling of the telescope pupil from 30×30 down to 4×4 subapertures. The system was fully assembled in the Arcetri Observatory laboratories, passing the acceptance test in December 2009. The performance measured during the test were closed to goal specifications for all star magnitudes. In particular FLAO obtained 83% Strehl Ratio (SR) in the bright end (8.5 magnitudes star in R band) using H band filter and correcting 495 modes with 30×30 subapertures sampling. In the faint end (16.4 magnitude) a 5.0% SR correcting 36 modes with 7×7 subapertures was measured. The seeing conditions for these tests were 0.8" (r0 = 0.14m @ 550 nm) and an average wind speed of 15m/s. The results at other seeing conditions up to 1.5" are also presented. The system has been shipped to the LBT site, and the commissioning is taking place since March to December 2010. A few on sky results are presented.

[1]  J. M. Hill,et al.  The Large Binocular Telescope , 2008, Astronomical Telescopes + Instrumentation.

[2]  R. Biasi,et al.  The adaptive secondary mirror for the Large Binocular Telescope: results of acceptance laboratory test , 2008, Astronomical Telescopes + Instrumentation.

[3]  Armando Riccardi,et al.  MMT adaptive secondary: first AO closed-loop results , 2003, SPIE Optics + Photonics.

[4]  Roberto Ragazzoni,et al.  LINC-NIRVANA: the Fizeau interferometer for the Large Binocular Telescope , 2008, Astronomical Telescopes + Instrumentation.

[5]  Tom Herbst,et al.  An Infrared Test Camera for LBT adaptive optics commissioning , 2008, Astronomical Telescopes + Instrumentation.

[6]  R. Ragazzoni,et al.  Sensitivity of a pyramidic Wave Front sensor in closed loop Adaptive Optics , 1999 .

[7]  Armando Riccardi,et al.  The adaptive secondary mirror for the Large Binocular Telescope: optical acceptance test and preliminary on-sky commissioning results , 2010, Astronomical Telescopes + Instrumentation.

[8]  Armando Riccardi,et al.  The adaptive secondary mirrors for the Large Binocular Telescope: a progress report , 2004, SPIE Astronomical Telescopes + Instrumentation.

[9]  Joe Kraus,et al.  Status of the LBT interferometer , 2008, Astronomical Telescopes + Instrumentation.

[10]  Armando Riccardi,et al.  Adaptive secondary mirrors for the Large binocular telescope , 2003, SPIE Optics + Photonics.

[11]  J. Bahcall,et al.  Models for the Galaxy and the Predicted Star Counts , 1979 .

[12]  Simone Esposito,et al.  The double pyramid wavefront sensor for LBT , 2008, Astronomical Telescopes + Instrumentation.

[13]  Armando Riccardi,et al.  Observer-Based Control Techniques for the LBT Adaptive Optics under Telescope Vibrations , 2011, Eur. J. Control.

[14]  S. Esposito,et al.  Pyramid Wavefront Sensor behavior in partial correction Adaptive Optic systems , 2001 .

[15]  Armando Riccardi,et al.  First light AO (FLAO) system for LBT: performance analysis and optimization , 2010, Astronomical Telescopes + Instrumentation.

[16]  Walter Seifert,et al.  LUCIFER: a Multi-Mode NIR Instrument for the LBT , 2003, SPIE Astronomical Telescopes + Instrumentation.

[17]  Lorenzo Busoni,et al.  First light AO system for LBT: toward on-sky operation , 2006, SPIE Astronomical Telescopes + Instrumentation.

[18]  S. Rabien,et al.  The laser guide star program for the LBT , 2008, Astronomical Telescopes + Instrumentation.