Abstracts of LBT-related
contributions at the Meeting
Conference 4837: Large Ground-Based Telescopes
[4837-15] The Large Binocular Telescope Project
J. M. Hill, The University of Arizona
Piero Salinari, Osservatorio Astrofisico di Arcetri
Abstract:
The Large Binocular Telescope (LBT) Project is a collaboration between
institutions in Arizona, Germany, Italy, and Ohio. The first of two 8.4-meter
borosilicate honeycomb primary mirrors for LBT is being polished at the Steward
Observatory Mirror Lab this year. The second of the two 8.4-meter mirror blanks
waits its turn in the polishing queue. The baseline optical configuration of LBT
includes adaptive infrared secondaries of a Gregorian design. The F/15
secondaries are undersized to provide a low thermal background focal plane which
is unvignetted over a 4-arcminute diameter field-of-view. These adaptive
secondary mirrors with 672 voice-coil actuators are now in the early stages of
fabrication. The interferometric focus combining the light from the two
8.4-meter primaries will reimage the two folded Gregorian focal planes to three
central locations for phased array imaging. The telescope elevation structure
accommodates swing arm spiders which allow rapid interchange of the various
secondary and tertiary mirrors as well as prime focus cameras. The telescope
structure accommodates installation of a vacuum bell jar for aluminizing the
primary mirrors in-situ on the telescope. The telescope structure was fabricated
and pre-assembled in Italy by Ansaldo-Camozzi in Milan. The structure was
disassembled, packed and shipped to Arizona. The enclosure was built on Mt.
Graham and is ready for telescope installation.
pp. 140-153
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[4837-24] Completion of the Large Binocular Telescope
Enclosure
Jose Teran U., James H. Slagle, John M. Hill and Daniel H.
Neff,
M3 Engineering & Technology Corp and the University of Arizona
Abstract:
The Large Binocular Telescope (LBT) under construction on Mount Graham, Arizona
is a unique instrument, which supports two 8.4-meter primary mirrors on the same
mount. The telescope mirrors will provide a collecting area equivalent to an
11.8 circular aperture plus a diffraction baseline of 22.8 meters. This unique
instrument presented new enclosure challenges and configurations in order to
accommodate the Owner's design, telescope operating criteria and budget.
The LBT enclosure completed in the summer of 2002 provides
useful information on the planning, designing and construction of a telescope
enclosure. The use of a team approach by the contractors, engineers, and the
project office has been successful in maintaining quality construction at a
reasonable price. This paper discusses the various systems implemented on the
LBT enclosure and the lessons learned during the course of the design and
construction.
pp. 217-224
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[4837-69] Fabrication of Mirrors for the Magellan
telescopes and the Large Binocular Telescope
H. M. Martin, et al., The University of Arizona
Abstract:
We describe the fabrication and testing of the 6.5m f/1.25 primary mirrors for
the Magellan telescopes and the 8.4m f/1.14 primary mirrors for the Large
Binocular Telescope (LBT). These mirrors, along with the 6.5m MMT primary, are
the fastest and most aspheric large mirrors ever made. .......
pp. 609-618
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Conference 4838: Interferometry for Optical Astronomy II
[4838-13] The Large Binocular Telescope Interferometer
P. M. Hinz, J. R. P. Angel, D. W. McCarthy, W. F.
Hoffmann, C. Y. Peng, The University of Arizona
Abstract:
The Large Binocular Telescope (LBT),with dual 8.4 m optics on a common mount,is
unique among the large-aperture interferometers.Deformable secondaries on the
telescope capable of adaptive atmospheric correction allow beam combination
after only three warm reflections.The design allows the implementation of two
powerful uses of interferometry: suppression of starlight (or nulling
interferometry) and wide-field imaging (or Fizeau interferometry). Nulling will
allow detection of extrasolar planetary systems (from either zodiacal emission
or giant planets)down to solar system-equivalent levels for nearby stars.This
will dramatically increase our knowledge of the prevalence and make-up of
extrasolar planetary systems.Fizeau interferometry will allow imaging of even
complex structure at the resolution of a 22.8 m telescope.To implement these two
powerful techniques the University of Arizona and NASA are collaborating to
build the Large Binocular Telescope Interferometer (LBTI) a cryogenic instrument
capable of sensitive interferometric observations in the infrared.
pp. 108-112
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[4838-109] Performance of the restoration of
interferometric images from the Large Binocular Telescope -- the effects of
angular coverage and partial adaptive optics correction
M. Carbillet, Osservatorio Astrofisico di Arcetri
with S. Correia, P. Boccacci and M. Bertero
Abstract:
This presentation reports the status of our study concerning the imaging
properties of the Large Binocular Telescope (LBT) interferometer, and namely the
effects of limited angular coverage and partial adaptive optics (AO) correction.
The limitation in angular coverage, together with the correlated problem of
angular smearing due to time-averaging of the interferometric images, is
investigated for relevant cases depending on the declination of the observed
object. Results are encouraging even in case of incomplete coverage. Partial
AO-correction can result in a wide range of image quality, but can also create
significant differences within a same field-of-view, especially between a
suitable reference star to be used for post-observation multiple deconvolution
and the observed object. Our study deals with both the problem of space-variance
of the AO-corrected point-spread function, and that of global quality oftheAO-correction.
Uniformity, rather than global quality, is found to be the key-problem. After
considering the single-conjugate AO case, we reach to some conclusions for the
more interesting, and actually wide-field, case implying multi-conjugate AO. The
whole study is performed on different types of object, from binary stars to
diffuse objects, and a combined one with a high-dynamic range.
pp. 444-455
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[4838-110] LINC-NIRVANA a Fizeau beam combiner for the
Large Binocular Telescope
T. M. Herbst, MPIA Heidelberg
R. Ragazzoni, Osservatorio Astrofisico di Arcetri
and many others
Abstract:
Fizeau interferometry at the Large Binocular Telescope (LBT) offers significant
advantages over other facilities in terms of spatial resolution, field of view,
and sensitivity. We provide an update of the LINC-NIRVANA project, which aims to
bring a near-infrared and visible wavelength Fizeau beam combiner to the LBT by
late 2005. As with any complex instrument, a number of detailed requirements
drive the final design adopted.
pp. 456-465
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Conference 4839: Adaptive Optical System Technologies II
[4839-20] First Light Adaptive Optics System for Large
Binocular Telescope
Simone Esposito, Osservatorio Astrofisico di Arcetri
and a cast of thousands
Abstract:
The paper describes the design of the single conjugate Adaptive Optics system to
be installed on the LBT telescope. This system will be located in the
Acquisition, Guiding and Wavefront sensor unit (AGW) mounted at the front bent
Gregorian focus of LBT. Two innovative key features of this system are the
Adaptive Secondary Mirror and the Pyramid Wavefront Sensor. The secondary
provides 672 actuators wavefront correction available at the various foci of
LBT. Due to the adaptive secondary mirror there is no need to optically
conjugate the pupil on the deformable mirror. This allows having a very short
sensor optical path made up using small dimension refractive optics. The overall
AO system has a transmission of 70 % and fits in a rectangle of about 400x320mm.
The pyramid sensor allows having different pupil sampling using on-chip binning
of the detector. Main pupil samplings for the LBT system are 30x30, 15x15 and
10x10. Reference star acquisition is obtained moving the wavefront sensor unit
in a field of view of 3x2 arcmin. Computer simulations of the overall system
performance show the good correction achievable in J, H, and K. In particular,
in our configuration, the limiting magnitude of pyramid sensor results more than
one magnitude fainter with respect to Shack- Hartmann sensor. This feature
directly translates in an increased sky coverage that is, in K band, about
doubled with respect to the same AO system using a Shack-Hartmann sensor.
pp. 164-173
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[4839-85] Adaptive Secondary Mirrors for the Large
Binocular Telescope
A. Riccardi, Osservatorio Astrofisico di Arcetri
et al.
Abstract:
The two adaptive secondary (AS) mirrors for LBT (LBT672) represent the new
generation of the AS technology. Their design is based on the experience earned
during the extensive tests of the previous generation unit (the MMT AS mirror).
Both the mechanics and the electronics have been revised, improving the
stability, reliability, maintenance and computational power of the system. The
deformable mirror of each unit consists of a 1.6mm-thick Zerodur shell having a
diameter of 911mm. The front surface is concave to match the Gregorian design of
the telescope. Its figure is controlled by 672 electro-magnetic force actuators
that are supported and cooled by an aluminum plate. The actuator forces are
controlled using a combination of feed-forward and de-centralized closed loop
compensation, thanks to the feedback signals from the 672 co-located capacitive
position sensors. The surface reference for the capacitive sensors is a
50mm-thick Zerodur shell faced to the back surface of the thin mirror and
rigidly connected to the support plate of the actuators. Digital real-time
control and unit monitoring is obtained using new custom-made on-board
electronics based on new generation 32bit oating-point DSPs. The total
computational power (121 G op/s) of the LBT672 units allows using the control
electronics as wave-front computer without any reduction of the actuator control
capability. We report the details of the new features introduced in the LBT672
design and the preliminary laboratory results obtained on a prototype used to
test them. Finally the facility in Arcetri to test the final LBT672 units is
presented
pp. 721-732
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[4839-90] LBT adaptive secondary units final design and
construction
D. Gallieni, ADS International
E.Anaclerio, P.G.Lazzarini, A.Ripamonti, R.Spairani, C.DelVecchio, P.Salinari,
A.Riccardi, P.Stefanini, R.Biasi
Abstract:
The Large Binocular Telescope will perform its first level AO correction at
visual wavelengths by the two Gregorian secondary mirrors. Each unit is made by
a 911 mm diameter and 1.6 mm thick Zerodur shell which shape is controlled by
672 electromagnetic actuators at 1 kHz rate. The shape of each mirror is
referred to a Zerodur 50 mm thick backplate through a set of capacitive sensors
co-located with the actuators. Each adaptive secondary unit embeds its real time
computer for actuator control and communication. Each unit is aligned into the
secondary hub by a 6 d.o.f. hexapod system. The construction of the AO units
started this year, while the hexapods have been completed in 2001. We present in
this paper the final design of the adaptive secondary systems with particular
emphasis on the modifications that we made based on the MMT adaptive secondary
experience. We will also report the first results of the subsystems development
tests.
pp. 765-771
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(1948 kB) Powerpoint poster for 4839-90 and 4839-91 (3752 kB)
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[4839-91] LBT adaptive secondary electronics
Roberto Biasi, Microgate S.r.l.
Mario Andrighettoni, Daniele Veronese, Valdemaro Biliotti, Luca Fini, Armando
Riccardi, P.Mantegazza, D.Gallieni
Abstract:
The adaptive secondary mirror is a fundamental part in the LBT adaptive optics
architecture. The thin, continuous mirror is controlled by 672 electromagnetic
actuators (voice coil motors) with local position feedback (capacitive sensor)
and allows to perform from tip-tilt to high order wavefront correction, but also
chopping. The adaptive secondary is controlled by a DSP-based dedicated
electronics. The control electronics does not only implement the mirror position
control tasks, but does also realize the Real Time Reconstructor (RTR). The
control system, while maintaining a similar architecture to the MMT adaptive
secondary one, shows a substantial enhancement in terms of computational power,
rising in the range of hundreds of Gigaflops. This allows to minimize the
computational time required to apply the wavefront correction pattern from the
wavefront sensor acquisition, even in case of high order reconstructor dynamics.
The electronics is housed in compact cooled crates placed in the adaptive
secondary hub. Apart from the power supply lines, it is connected to the other
components of the adaptive control system just through a very high speed fiber
optic link, capable of 2.9 Gigabit/s of actual data throughput. The control
system has been designed according to modular concept, so that the number of
channels can be easily increased or reduced for adapting the electronics to
different correctors. A substantial effort has been dedicated to the flexibility
and on-field configurability of system. In this frame, the same electronics (or
part of it) can be easily adapted to become the building block for the data
processing unit required for Multi-Conjugated Adaptive Optics.
pp. 772-782
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[4839-101] Large Binocular Telescope Facility SCIDAR:
First Results
D. L. McKenna, Steward Observatory
R. Avila, UNAM
J. M. Hill, The University of Arizona
S. Hippler, MPIA
Piero Salinari, Osservatorio Astrofisico di Arcetri
P. C. Stanton, Alacron Inc.
R. Weiss, MPIA
Abstract:
We present the design and recent results from the Large Binocular Telescope
(LBT) facility SCIDAR. To our knowledge, this work is the first SCIDAR designed
as a user instrument for routine seeing measurements in support of telescope
operations. Using a commercial off-the-shelf approach, we have minimized the
resources required for system construction.
pp. 825-836
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[4839-149] Performance of the First-Light Adaptive
Optics System of LBT by Means of CAOS Simulations
Marcel Carbillet, Osservatorio Astrofisico di Arcetri
and others
Abstract:
This presentation reports the numerical simulations we have done in order to
evaluate the performance of the rst-light AO system of LBT. The simulation tool
used for this purpose is the Software Package CAOS, applicable for a wide range
of AO systems and for which a brief recall of the main features is made. The
whole process of atmospheric propagation of light, wavefront sensing (using a
complete model of the pyramid wavefront sensor), wavefront reconstruction (using
the LBT672 adaptive secondary mirror modes), and closing of the loop, is
simulated. The results are given in terms of obtained Strehl ratios in J-, H-,
and K-band. Estimation of the resulting sky-coverage in K-band for di erent
regions of the sky are also expressed. A comparison with the performance that
would be obtained by using a Shack-Hartmann sensor is presented, con rming the
gain achievable with the pyramid sensor. Keywords: Large Binocular Telescope,
rst-light adaptive optics system, pyramid wavefront sensor, numerical
simulations 1.
pp. 131-139
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Conference 4841: Instrument Design and Performance for
Optical/Infrared Ground-Based Telescopes
[4841-05] Overview of Instrumentation for the Large
Binocular Telescope
R. M. Wagner, LBTO, The University of Arizona
Abstract:
An overview of the 3 facility instruments and 2 strategic interferometric
instruments under construction for the Large Binocular Telescope is
presented.Planned optical instrumentation includes the Large Binocular Camera (LBC),a
pair of wide-field (25 x 25 arcmin) UB/VRI optimized mosaic CCD imagers at the
prime focus, and the MultiObject Double Spectrograph (MODS), a pair of dual-beam
blue-red optimized longslit spectro- graphs mounted at the straight-through F/15
Gregorian focus incorporating multiple slit masks for multi-object spectroscopy
over a 5 arcmin field and spectral resolutions of 2000-8000. Infrared
instrumentation includes the LBT Near-IR Spectroscopic Utility with Camera and
Integral Field Unit for Extragalactic Research (LUCIFER), a modular
near-infrared (0.9-2.5 micron) imager and spectrograph pair mounted at a bent
interior focal station and designed for seeing limited (FOV: 4 x 4 arcmin) and
diffraction limited (FOV: 0.5 x 0.5 arcmin) imaging and longslit spectroscopy,
seeing limited multiobject spectroscopy utilizing cooled slit masks, and
optional diffraction limited integral field spectroscopy. Strategic instruments
under development include an interferometric cryogenic beam combiner with NIR
and thermal IR instruments for Fizeau imaging and nulling interferometry, and an
optical bench beam combiner with visible and NIR imagers utilizing in the future
multi-conjugate adaptive optics for angular resolutions as high as 5 mas at a
wavelength of 0.5 micron. The availability of all these instruments mounted
simultaneously on the LBT permits flexible scheduling and improved operational
support.
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[4841-44]
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[4841-60]
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[4841-87]
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Conference 4848: Advanced Telescope and Instrumentation
Control Software II
[4848-43] LUCIFER control software: an OO approach
using CORBA technology
Jütte, Marcus; Polsterer, Kai; Lehmitz, Michael; Dettmar,
Ralf-Jürgen, Astronomisches Institut der Ruhr-Universität Bochum
Abstract:
In this paper we present the design of the control software for the LBT NIR
spectroscopic Utility with Camera and Integral-Field unit for Extragalactic
Research (LUCIFER) which is one of the first-light instruments for the Large
Binocular Telescope (LBT) on Mt. Graham, Arizona. The LBT will be equipped with
two identical LUCIFER instruments for both mirrors. Furthermore we give an
overview of the intended hardware structure of the instrument. Since the project
requires a detailed and exact modeling of the software we present UML diagrams
starting with an overall model down to use case, activity and class diagrams
including an example for one special instrument unit.
pp. 387-393
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To see how hard the LBT astronomers and engineers were
working at the conference in Waikoloa, click here:
G. Brusa, S. Esposito, R. Biasi
G. Brusa, J. Hill
B. Marano, R. Ragazzoni
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