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.
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.
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
Chilean winter.
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.
Laser-induced breakdown (LIB) has long been used in ophthalmic microsurgery as a mechanism for disruption of tissue. The goal of this surgery has been precise tissue cutting by plasma formation and a minimization of collateral damage due to shock wave and cavitation bubble formation. We investigate the strength of the shock wave emission, the size of the cavitation bubble, and the amount of plasma shielding to determine the efficacy of using femtosecond pulses in surgery to reduce collateral photoacoustic damage. A pump-probe technique is used to image the time-resolved evolution of the cavitation bubble produced by focused laser pulses with pulsewidths of 130 fs, 300 fs, 3 ps, and 60 ps. Simultaneously, a hydrophone is used to measure the pressure response generated by the initial plasma shock wave and subsequent shock waves generated by the collapse and rebound of the cavitation bubbles. In addition, transmission measurements are made which indicate the amount of energy shielded beyond the focus by the plasma. These measurements give a good indication of the degree to which collateral damage may be reduced as the pulsewidths is decreased from the picosecond to the femtosecond time regime.
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