Co-phasing the Large Binocular Telescope: status and performance of LBTI/PHASECam

Defrère, Denis; Hinz, Philip M.; Downey, E.; Ashby, David S.; Bailey, Vanessa P.; Brusa, Guido; Christou, Julian C.; Danchi, W. C.; Grenz, P.; Hill, John M.; Hoffmann, W. F.; Leisenring, Jarron; Lozi, Julien; McMahon, Thomas J.; Mennesson, Bertrand; Millan-Gabet, R.; Montoya, Manny; Powell, Keith; Skemer, Andrew J.; Vaitheeswaran, Vidhya; Vaz, Amali; Veillet, Christian

doi:10.1117/12.2057178

Cited by 20 publications

(26 citation statements)

References 9 publications

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“…ARGOS users a pair of three Rayleigh laser guide star constellations from each side of the LBT to provide ground layer adaptive optics corrections for the two near-infrared LUCI spectrometers. ARGOS is described in these proceedings by Raab et al 3 Finally, the first stabilized fringes of the two 8.4 m telescopes and nulling interferometric observations were obtained with the LBT Interferometer (LBTI) in December 2013 and January 2014 respectively and are described in these proceedings by Hinz et al 4 and Defrère et al 5 In this contribution, we present a summary of the scientific instruments for the LBT that have been commissioned for partner science observations and are now in regular use, those instruments that are being commissioned at the present time, or are currently under development in partner laboratories for the LBT.…”

Section: Introductionmentioning

confidence: 99%

An overview and the current status of instrumentation at the Large Binocular Telescope Observatory

et al. 2014

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An overview of instrumentation for the Large Binocular Telescope (LBT) is presented. Optical instrumentation includes the Large Binocular Camera (LBC), a pair of wide-field (24 ′ × 24 ′ ) mosaic CCD imagers at the prime focus, and the Multi-Object Double Spectrograph (MODS), a pair of dual-beam blue-red optimized long-slit spectrographs mounted at the left and right direct F/15 Gregorian foci incorporating multiple slit masks for multi-object spectroscopy over a 6 ′ field and spectral resolutions of up to 2000. Infrared instrumentation includes the LBT Near-IR Spectrometer (LUCI), a modular near-infrared (0.9-2.5 µm) imager and spectrograph pair mounted at the left and right front-bent F/15 Gregorian foci and designed for seeing-limited (FOV: 4 ′ × 4 ′ ) imaging, long-slit spectroscopy, and multi-object spectroscopy utilizing cooled slit masks and diffraction limited (FOV: 0 ′ .5 × 0 ′ .5) imaging and long-slit spectroscopy. Strategic instruments under development that can utilize the full 23 m baseline of the LBT include an interferometric cryogenic beam combiner with near-infrared and thermal-infrared instruments for Fizeau imaging and nulling interferometry (LBTI) and an optical bench nearinfrared beam combiner utilizing multi-conjugate adaptive optics for high angular resolution and sensitivity (LINC-NIRVANA). LBTI is currently undergoing commissioning and performing science observations on the LBT utilizing the installed adaptive secondary mirrors in both single-sided and two-sided beam combination modes. In addition, a fiber-fed bench spectrograph (PEPSI) capable of ultra high resolution spectroscopy and spectropolarimetry (R = 40,000-300,000) will be available as a principal investigator instrument. Installation and testing of the bench spectrograph will begin in July 2014. Over the past four years the LBC pair, LUCI1, and MODS1 have been commissioned and are now scheduled for routine partner science observations. Both LUCI2 and MODS2 passed their laboratory acceptance milestones in the summer of 2013 and have been installed on the LBT. LUCI2 is currently being commissioned and the data analysis is well underway. Diffraction-limited commissioning of its adaptive optics modes will begin in the 2014B semester. MODS2 commissioning began in May 2014 and will completed in the 2014B semester as well. Binocular testing and commissioning of both the LUCI and MODS pairs will begin in 2014B with the goal that this capability could be offered sometime in 2015. The availability of all these instruments mounted simultaneously on the LBT permits unique science, flexible scheduling, and improved operational support.

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Section: Introductionmentioning

confidence: 99%

An overview and the current status of instrumentation at the Large Binocular Telescope Observatory

et al. 2014

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“…The tertiary mirrors can be turned to move the focus to any of the instruments in the middle of the telescope. For the LBT, two of these center-positioned instruments are interferometers -the Large Binocular Telescope Interferometer (LBTI) built by the University of Tucson and described in [4], and the LBT INterferometric Camera for Near-InfraRed and Visible Adaptive INterferometry for Astronomy (LINC-NIRVANA), which is a stellar interferometer built by a German consortium led by the Max-Planck-Institute for Astronomy in Heidelberg, Germany and described in [5]. For interferometry, the spatial resolution is determined by the largest baseline, which means the maximal distance of any two points on the primary mirrors.…”

Section: Introductionmentioning

confidence: 99%

“…The internal controller was developed at an earlier stage of the project [9]. On the contrary, LBTI uses a kind of tweeterwoofer approach, with one slower piezo drive having a larger travel range to compensate for slow but large differences and one smaller, faster one with a small travel range for disturbances of higher frequencies [4]. We will focus on LBTI, for which measurement results will be presented.…”

Section: Introductionmentioning

confidence: 99%

“…However, a good delay compensation is even more important for LINC-NIRVANA, due to its larger input delay to the compensation device, the cause of which will be explained in more detail at the end of Section IV. [4]), including the tweeter-woofer setup composed of a fast ( 1 ) and a slow ( 2 ) piston corrector. The mirror motion of M1, M2 and M3 ( 1 -3 ) on both sides due to windloads is measured using 3 accelerometers along the optical axis of each mirror.…”

Section: Introductionmentioning

confidence: 99%

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Delay Compensation for Real Time Disturbance Estimation at Extremely Large Telescopes

Böhm

Pott

Kürster

et al. 2017

IEEE Trans. Contr. Syst. Technol.

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Abstract-In ground-based astronomy, aberrations due to structural vibrations, such as piston, limit the achievable resolution and cannot be corrected using adaptive optics for large telescopes. We present a model-free strategy to estimate and compensate piston aberrations due to vibrations of optical components using accelerometer disturbance feedforward, eventually allowing the use of fainter guide stars both for the fringe detector and in the adaptive optics loop (AO-loop). Because the correction performance is very sensitive to signal delays, we present a strategy to add a delay compensation to the developed disturbance estimator, which can in principle be applied to many other applications outside of astronomy that lack observer performance due to a measurement delay or need a prediction to compensate for input delays. The ability to estimate vibration disturbances in the critical frequency range of 8 Hz to 60 Hz is demonstrated with on sky data from the Large Binocular Telescope Interferometer (LBTI), an interferometer at the Large Bincoular Telescope (LBT). The experimental results are promising, indicating the ability to suppress differential piston induced by telescope vibrations by a factor of about 3 (RMS), which is significantly better than any currently commissioned system.

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“…22 After passing through a large beam combiner (UBC; Universal Beam Combiner 23 ), the light enters a science instrument dewar (NIC; Nulling Infrared Camera 24 ), and then is directed to a 1-5 µm camera (LMIRcam; L/M-band Infrared Camera 25 ) and/or a 10µm camera (NOMIC; Nulling Optimized Mid-Infrared Camera 26 ) with the option of sending H or K-band light to a phase sensor. 27 A block diagram of the system is shown in Figure 1. LBTI is designed to be a versatile instrument that can image the two telescope beams separately, overlap the two beams incoherently, overlap the beams coherently for wide-field (Fizeau) interferometry, 28 or overlap the beams and pupils for nulling interferometry.…”

Section: Large Binocular Telescope Interferometer (Lbti)mentioning

confidence: 99%

High contrast imaging at the LBT: the LEECH exoplanet imaging survey

et al. 2014

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In Spring 2013, the LEECH (LBTI Exozodi Exoplanet Common Hunt) survey began its ∼130-night campaign from the Large Binocular Telescope (LBT) atop Mt Graham, Arizona. This survey benefits from the many technological achievements of the LBT, including two 8.4-meter mirrors on a single fixed mount, dual adaptive secondary mirrors for high Strehl performance, and a cold beam combiner to dramatically reduce the telescope's overall background emissivity. LEECH neatly complements other high-contrast planet imaging efforts by observing stars at L' (3.8 µm), as opposed to the shorter wavelength near-infrared bands (1-2.4 µm) of other surveys. This portion of the spectrum offers deep mass sensitivity, especially around nearby adolescent (∼0.1-1 Gyr) stars. LEECH's contrast is competitive with other extreme adaptive optics systems, while providing an alternative survey strategy. Additionally, LEECH is characterizing known exoplanetary systems with observations from 3-5µm in preparation for JWST.

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Co-phasing the Large Binocular Telescope: status and performance of LBTI/PHASECam

Cited by 20 publications

References 9 publications

An overview and the current status of instrumentation at the Large Binocular Telescope Observatory

An overview and the current status of instrumentation at the Large Binocular Telescope Observatory

Delay Compensation for Real Time Disturbance Estimation at Extremely Large Telescopes

High contrast imaging at the LBT: the LEECH exoplanet imaging survey

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