&lt;title&gt;Multiconjugate adaptive optics with hybrid laser beacon systems&lt;/title&gt;

Rue, Imelda A. De La; Ellerbroek, Brent L.

doi:10.1117/12.454803

Cited by 6 publications

(1 citation statement)

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“…Such a scheme overcomes a limitation of MCAO systems in which the beacons are all at a common range that leads to a requirement for three well separated tip-tilt stars. 6,7 This is the case, for example, with the Gemini South MCAO system 8 which uses five sodium LGS, but will be somewhat limited in its sky coverage by the need for multiple tip-tilt stars of magnitude ~18 or brighter within 1 arc min.…”

Section: Introductionmentioning

confidence: 99%

Status report on the Large Binocular Telescope's ARGOS ground-layer AO system

et al. 2011

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ARGOS, the laser-guided adaptive optics system for the Large Binocular Telescope (LBT), is now under construction at the telescope. By correcting atmospheric turbulence close to the telescope, the system is designed to deliver high resolution near infrared images over a field of 4 arc minute diameter. Each side of the LBT is being equipped with three Rayleigh laser guide stars derived from six 18 W pulsed green lasers and projected into two triangular constellations matching the size of the corrected field. The returning light is to be detected by wavefront sensors that are range gated within the seeing-limited depth of focus of the telescope. Wavefront correction will be introduced by the telescope's deformable secondary mirrors driven on the basis of the average wavefront errors computed from the respective guide star constellation. Measured atmospheric turbulence profiles from the site lead us to expect that by compensating the ground-layer turbulence, ARGOS will deliver median image quality of about 0.2 arc sec across the JHK bands. This will be exploited by a pair of multi-object near-IR spectrographs, LUCIFER1 and LUCIFER2, with 4 arc minute field already operating on the telescope. In future, ARGOS will also feed two interferometric imaging instruments, the LBT Interferometer operating in the thermal infrared, and LINC-NIRVANA, operating at visible and near infrared wavelengths. Together, these instruments will offer very broad spectral coverage at the diffraction limit of the LBT's combined aperture, 23 m in size.

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Section: Introductionmentioning

confidence: 99%

Status report on the Large Binocular Telescope's ARGOS ground-layer AO system

et al. 2011

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First Tests of Wavefront Sensing with a Constellation of Laser Guide Beacons

Lloyd‐Hart

Baranec

Milton

et al. 2005

ApJ

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Adaptive optics to correct current telescopes over wide fields, or future very large telescopes over even narrow fields, will require real-time wavefront measurements made with a constellation of laser beacons. Here we report the first such measurements, made at the 6.5 m MMT with five Rayleigh beacons in a 2 ′ pentagon. Each beacon is made with a pulsed beam at 532 nm, of 4 W at the exit pupil of the projector. The return is range-gated from 20-29 km and recorded at 53 Hz by a 36-element Shack-Hartmann sensor. Wavefronts derived from the beacons are compared with simultaneous wavefronts obtained for individual natural stars within or near the constellation. Observations were made in seeing averaging 1. ′′ 0 with 2/3 of the aberration measured to be from a ground layer of mean height 380 m. Under these conditions, subtraction of the simple instantaneous average of the five beacon wavefronts from the stellar wavefronts yielded a 40% rms reduction in the measured modes of the distortion over a 2 ′ field. We discuss the use of multiple Rayleigh beacons as an alternative to single sodium beacons on 8 m telescopes, and the impact of the new work on the design of a multi-sodium beacon system for the 25 m Giant Magellan Telescope.

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