Multiple sodium laser beacons are a crucial development in multi-conjugate adaptive optics systems that offers wide-field diffraction limited adaptive optics correction to the astronomical community. This correction is strongly dependent on the laser beam power and quality, so a beam shaping concept is currently being developed to speed-up calibration and alignment of the laser before every run. A method previously reported, has now been implemented on a laboratory bench using MEMS deformable mirrors. Necessary calibration and characterization of the deformable mirrors are described and the results for experimental amplitude correction are presented.
The Beam Transfer Optics (BTO) is a sub-system of the Gemini Multi-Conjugate Adaptive Optics System (GeMS). The main purpose of the BTO is to relay the laser light from the laser service enclosure up to the Laser Launch Telescope (LLT), located behind the telescope secondary mirror, where the five laser beams are propagated to the sky. Other functionalities besides relaying the laser light from the laser to the LLT, is the laser polarization control, which is crucial to any AO related system. The polarization state of the laser output beam influences the photon return flux. It is proven that the backscattering efficiency is higher when exciting the sodium layer with a circular polarized beam than one with linear polarization. For this reason circular polarization of our five laser beams that exit the LLT is desired for any telescope position. The paper reviews the current status of the Gemini South Beam Transfer Optics polarization and its control scheme. It reports on the improvements already done on the polarization control and measurement data of the polarization state at different BTO sections. In addition we discuss further optimization and upgrade ideas of the system.
The newly commissioned Gemini Planet Imager (GPI) combines extreme adaptive optics, an advanced coronagraph, precision wavefront control and a lenslet-based integral field spectrograph (IFS) to measure the spectra of young extrasolar giant planets between 0.9-2.5 μm. Each GPI detector image, when in spectral model, consists
of ~37,000 microspectra which are under or critically sampled in the spatial direction. This paper demonstrates
how to obtain high-resolution microlens PSFs and discusses their use in enhancing the wavelength calibration,
flexure compensation and spectral extraction. This method is generally applicable to any lenslet-based integral field spectrograph including proposed future instrument concepts for space missions.
An Atmospheric Dispersion Corrector (ADC) uses a double-prism arrangement to nullify the vertical chromatic
dispersion introduced by the atmosphere at non-zero zenith distances.
The ADC installed in the Gemini Planet Imager (GPI) was first tested in August 2012 while the instrument was
in the laboratory. GPI was installed at the Gemini South telescope in August 2013 and first light occurred later
that year on November 11th.
In this paper, we give an overview of the characterizations and performance of this ADC unit obtained in the
laboratory and on sky, as well as the structure of its control software.
The Gemini Multi-Conjugate Adaptive Optics System (GeMS) began its on-sky commissioning in January 2011.
The system provides high order wide field corrections using a constellation of five Laser Guide Stars. In December 2011, commissioning culminated in images with a FWHM of 80±2mas at 1.65 microns (H band) over an 87 x 87 arcsecond field of view. The first images have already demonstrated the scientific potential of GeMS, and after more than a year of commissioning GeMS is finally close to completion and ready for science. This paper presents a general status of the GeMS project and summarizes the achievements made during more than a year of commissioning. The characterization of GeMS performance is presented in a companion paper: “GeMS on-sky results”, Rigaut et al. Here we report on the sub-systems' performance, discuss current limitations and present proposed upgrades. The integration of GeMS into the observatory operational scheme is detailed. Finally, we present the plans for next year's operations with GeMS.
GeMS, the Gemini Laser Guide Star Multi-Conjugate Adaptive Optics facility system, has seen first light in December 2011, and has already produced images with H band Strehl ratio in excess of 35% over fields of view of 85x85 arcsec, fulfilling the MCAO promise. In this paper, we report on these early results, analyze trends in performance, and concentrate on key or novel aspects of the system, like centroid gain estimation, on-sky non common path aberration estimation. We also present the first astrometric analysis, showing very encouraging results.
With two to three deformable mirrors, three Natural Guide Stars (NGS) and five sodium Laser Guide Stars (LGS), the
Gemini Multi-Conjugate Adaptive Optics System (Gemini MCAO a.k.a. GeMS) will be the first facility-class MCAO
capability to be offered for regular science observations starting in 2013A. The engineering and science commissioning
phase of the project was kicked off in January 2011 when the Gemini South Laser Guide Star Facility (GS LGSF)
propagated its 50W laser above the summit of Cerro Pachón, Chile. GeMS commissioning has proceeded throughout
2011 and the first half of 2012 at a pace of one 6- to 10-night run per month with a 5-month pause during the 2011
This paper focuses on the LGSF-side of the project and provides an overview of the LGSF system and subsystems, their
top-level specifications, design, integration with the telescope, and performance throughout commissioning and beyond.
Subsystems of the GS LGSF include: (i) a diode-pumped solid-state 1.06+1.32 micron sum-frequency laser capable of
producing over 50W of output power at the sodium wavelength (589nm); (ii) Beam Transfer Optics (BTO) that transport
the 50W beam up the telescope, split the beam five-ways and configure the five 10W beams for projection by the Laser
Launch Telescope (LLT) located behind the Gemini South 8m telescope secondary mirror; and (iii) a variety of safety
systems to ensure safe laser operations for observatory personnel and equipment, neighbor observatories, as well as
passing aircrafts and satellites.
The Gemini Multi-Conjugate Adaptive Optics System (GeMS} began its on-sky commissioning in January 20ll. The system provides high order wide-field corrections using a constellation of five Laser Guide Stars. In December 20ll, commissioning culminated in images with a FWHM of 80±2mas at 1.65 microns (H band} over an 87 x 87 arcsccond field of view. The first images have already demonstrated the scientific potential of GeMS, and after more than a year of commissioning GeMS is finally close to completion and ready for science. This paper presents a general status of the GeMS project and summarizes the achievements made during more than a year of commissioning. The characterization of GeMS performance is presented in a companion paper: "GeMS on-sky results" , R.igaut ct al. Here we report on the sub-systems' performance, discuss current limitations and present proposed upgrades. The integration of GeMS into the observatory operational scheme is detailed. Finally, we present the plans for next year's operations with GeMS.
GeMS (the Gemini Multi-conjugated adaptive optics System) is a facility instrument for the Gemini-South
telescope. It will deliver a uniform, diffraction-limited image quality at near-infrared (NIR) wavelengths over an
extended FoV or more than 1 arcmin across. GeMS is a unique and challenging project from the technological
point of view and because of its control complexity. The system includes 5 laser guide stars, 3 natural guide
stars, 3 deformable mirrors optically conjugated at 0, 4.5 and 9km and 1 tip-tilt mirror. After 10 years since
the beginning of the project, GeMS is finally reaching a state in which all the subsystems have been received,
integrated and, in the large part, tested. In this paper, we report on the progress and current status of the
different sub-systems with a particular emphasis on the calibrations, control and optimization of the AO bench.
We report on the successful delivery of a 30 W solid-state sodium Guide Star Laser System (GLS) to the W. M. Keck
Observatory in 2009, and the demonstration of a 55 W GLS delivered to the Gemini South Observatory in 2010. This
paper describes the GLS performance results of both the Keck I and Gemini South GLSs with an emphasis on the system
design and delivered performance. The 589 nm output was generated via Sum Frequency Mixing (SFM) of 1064 nm
and 1319 nm Nd:YAG lasers in a LBO (Lithium Triborate) nonlinear crystal. The Keck GLS underwent extensive
testing and has demonstrated consistent performance with a CW mode-locked output of > 30 W and measured beam
quality of M<sup>2</sup> < 1.2 while locked to the sodium D2a transition. The Keck GLS was installed on the telescope in late 2009
and first light on the sky was achieved in early 2010. Factory testing of the Gemini South GLS shows a CW modelocked
output of > 55 W and measured M<sup>2</sup> ~1.2 while locked to the sodium D2a line center. The Gemini South GLS has
produced a maximum power of 76 W at 589 nm with 85 W of 1319 nm and 110 W of 1064 nm as inputs to the SFM,
representing a single-pass conversion efficiency of 39%.
The Gemini North telescope has been providing Laser Guide Star Adaptive Optics (LGS AO) regular science queue
observations for worldwide astronomers since February 2007. In this paper we comment on the reliability of the Laser
Guide Star Facility high-power solid-state laser during normal operations, and discuss progress made on various issues
that will enable a "turn-key" operation mode for the laser system. In this effort to produce consistent, stable and
controlled laser parameters (power, wavelength and beam quality) we completed a failure mode effect analysis of the
laser system and sub systems that initiated a campaign of hardware upgrades and procedural improvements to the routine
maintenance operations. These upgrades are discussed, including pump laser diode replacements, as well as sum
frequency generation (SFG) crystal degradation along with our detailed plans to improve overall laser reliability, and
availability. Finally, we provide an overview of normal operation procedures during LGS runs and present a snapshot of
data accumulated over several years that describes the overall LGS AO observing efficiency at the Gemini North