Alfio Puglisi

Large Binocular Telescope Adaptive Optics System: new achievements and perspectives in adaptive optics

The Large Binocular Telescope (LBT) is a unique telescope featuring two co-mounted optical trains with 8.4m primary mirrors. The telescope Adaptive Optics (AO) system uses two innovative key components, namely an adaptive secondary mirror with 672 actuators and a high-order pyramid wave-front sensor. During the on-sky commissioning such a system reached performances never achieved before on large ground-based optical telescopes. Images with 40mas resolution and Strehl Ratios higher than 80% have been acquired in H band (1.6 μm). Such images showed a contrast as high as 10-4. Based on these results, we compare the performances offered by a Natural Guide Star (NGS) system upgraded with the state-of-the-art technology and those delivered by existing Laser Guide Star (LGS) systems. The comparison, in terms of sky coverage and performances, suggests rethinking the current role ascribed to NGS and LGS in the next generation of AO systems for the 8-10 meter class telescopes and Extremely Large Telescopes (ELTs).

MAGELLAN ADAPTIVE OPTICS FIRST-LIGHT OBSERVATIONS of the EXOPLANET β PIC b. II. 3-5 μm DIRECT IMAGING with MagAO+Clio, and the EMPIRICAL BOLOMETRIC LUMINOSITY of A SELF-LUMINOUS GIANT PLANET

We thank the Magellan and Las Campanas Observatory staff for making this well-engineered, smoothly operated telescope and site possible. We would especially like to thank Povilas Palunas for help over the entire MagAO commissioning run. Juan Gallardo, Patricio Jones, Emilio Cerda, Felipe Sanchez, Gabriel Martin, Maurico Navarrete, Jorge Bravo, Victor Merino, Patricio Pinto, Gabriel Prieto, Mauricio Martinez, Alberto Pasten, Jorge Araya, Hugo Rivera, and the whole team of technical experts helped perform many exacting tasks in a very professional manner. Glenn Eychaner, David Osip, and Frank Perez all gave expert support which was fantastic. The entire logistics, dining, housekeeping, and hospitality staff provide for an excellent, healthy environment that ensured the wellness of our team throughout the commissioning runs. It is a privilege to be able to commission an AO system with such a fine staff and site. The MagAO system was developed with support from the NSF, MRI and TSIP programs. The VisAO camera was developed with help from the NSF ATI program. K.M.M. and J.R.M. were supported under contract with the California Institute of Technology, funded by NASA through the Sagan Fellowship Program. J.R.M. is grateful for the generous support of the Phoenix ARCS Foundation. L.M.C.s and Y.-L.W.s research were supported by NSF AAG and NASA Origins of Solar Systems grants. V.B. was supported in part by the NSF Graduate Research Fellowship Program (DGE-1143953). We thank the anonymous referee for a careful, timely review that significantly improved the manuscript. Facility: Magellan:Clay (MagAO+Clio) .

Pyramid sensor for segmented mirror alignment

We report what is to our knowledge the first laboratory experiment that shows the use of a pyramid wavefront sensor to cophase and align segmented mirrors having three degrees of freedom per segment, i.e., piston, tip, and tilt. In the laboratory the iterative alignment procedure reached a wavefront residual error of about 10 nm. The residual error was equally distributed between piston, tip, and tilt. These results demonstrate that the pyramid can successfully simultaneously sense the piston, tip, and tilt of a segmented mirror. This last feature makes this technique very attractive in phasing and aligning astronomical segmented telescopes such as extremely large telescopes currently under extensive studies.

The adaptive secondary mirror for the Large Binocular Telescope: optical acceptance test and preliminary on-sky commissioning results

The Large Binocular Telescope (LBT) has two adaptive secondary mirrors based on 672 voice-coil force actuators. The shape of the mirror is controlled using internal metrology based on co-located capacitive sensors. The first mirror unit is currently mounted on LBT for on-sky commissioning as part of the First Light Adaptive Optics System (FLAO). During spring-time 2009 the optical acceptance test was performed using the 14-m optical test tower at the Osservatorio Astrofisico di Arcetri (INAF) showing the capability of flattening the shell at the level of 14nm rms residual surface error. This paper reports the optical layout, calibration procedures and results of the optical acceptance test. Moreover we report the first results obtained during the early runs of FLAO commissioning showing the ability of the mirror to compensate for atmospheric turbulence with extremely high Strehl ratio values (better than 80% in H-band) as permitted by the largest number of correcting degrees of freedom currently available on-sky for astronomical telescopes.

The Giant Magellan Telescope adaptive optics program

The Giant Magellan Telescope (GMT) adaptive optics (AO) system will be an integral part of the telescope, providing laser guidestar generation, wavefront sensing, and wavefront correction to every instrument currently planned on the 25.4 m diameter GMT. There will be three first generation AO observing modes: Natural Guidestar, Laser Tomography, and Ground Layer AO. All three will use a segmented adaptive secondary mirror to deliver a corrected beam directly to the instruments. The Natural Guidestar mode will provide extreme AO performance, with a total wavefront error less than 185 nm RMS using bright guidestars. The Laser Tomography mode uses 6 lasers and a single off-axis natural guidestar to deliver better than 290 nm RMS wavefront error at the science target, over 50% of the sky at the galactic pole. The Ground Layer mode uses 4 natural guidestars on the periphery of the science field to tomographically reconstruct and correct the ground layer AO turbulence, improving the image quality for wide-field instruments. A phasing system maintains the relative alignment of the primary and secondary segments using edge sensors and continuous feedback from an off-axis guidestar. We describe the AO system preliminary design, predicted performance, and the remaining technical challenges as we move towards the start of construction.

Laboratory MCAO test-bed for developing wavefront sensing concepts

An experimental optical bench test-bed for developing new wavefront sensing concepts for Multi-Conjugate Adaptive Optics (MCAO) systems is described. The main objective is to resolve imaging problems associated with wavefront sensing of the atmospheric turbulence for future MCAO systems on Extremely Large Telescopes (ELTs). The test-bed incorporates five reference sources, two deformable mirrors (DMs) and atmospheric phase screens to simulate a scaled version of a 10-m adaptive telescope operating at the K band. A recently proposed compact tomographic wavefront sensor is employed for star-oriented DMs control in the MCAO system. The MCAO test-bed is used to verify the feasibility of the wavefront sensing concept utilizing a field lenslet array for multi-pupil imaging on a single detector. First experimental results of MCAO correction with the proposed tomographic wavefront sensor are presented and compared to the theoretical prediction based on the characteristics of the phase screens, actuator density of the DMs and the guide star configuration.

Natural guide star adaptive optics systems at LBT: FLAO commissioning and science operations status

This paper summarizes the activities and the principal results achieved during the commissioning of the two Natural Guide Star (NGS) AO systems called FLAO#1 & 2 installed at the bent Gregorian focal stations of the 2x8.4m Large Binocular Telescope (LBT). The commissioning activities of FLAO#1 took place in the period February 2010 - October 2011, while FLAO#2 commissioning started in December 2011 and should be completed by November 2012. The main results of the commissioning campaign are presented in terms of the H-band Strehl Ratio values achieved under different observing conditions. We will also describe the automatic procedures to configure and set-up the FLAO systems, and in particular the modal gain optimization procedure, which has been proven to be a very important one in achieving the nominal performance. Finally, some of the results achieved in two science runs using the near infra-red camera PISCES are briefly highlighted.

ON THE MORPHOLOGY AND CHEMICAL COMPOSITION OF THE HR 4796A DEBRIS DISK

[abridged] We present resolved images of the HR 4796A debris disk using the Magellan adaptive optics system paired with Clio-2 and VisAO. We detect the disk at 0.77 \microns, 0.91 \microns, 0.99 \microns, 2.15 \microns, 3.1 \microns, 3.3 \microns, and 3.8 \microns. We find that the deprojected center of the ring is offset from the star by 4.76

Nulling Data Reduction and On-sky Performance of the Large Binocular Telescope Interferometer

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First light AO (FLAO) system for LBT: performance analysis and optimization

1.6 AU and that the deprojected eccentricity is 0.06