Conference 4004: Telescope Structures, Enclosures,
Controls, Assembly/Integration/Validation, and Commissioning
[4004-07] 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. Arizona includes astronomers
at The University of Arizona, Arizona State University and Northern Arizona
University. Germany is represented by the LBT Beteiligungsgesellschaft which is
composed of Max-Planck-Institut für Astronomie in Heidelberg, Landessterwarte
Heidelberg, Max-Planck-Institut für Radioastronomie in Bonn, Max-Planck-Institut
für extraterrestrische Physik in Munich and Astrophysikalisches Institut
Potsdam. The Italian astronomical community is represented by the Osservatorio
Astrofisico di Arcetri in Florence. Partners at individual institutions include
The Ohio State University in Columbus, The University of Notre Dame and Research
Corporation in Tucson. The second of two 8.4m borosilicate honeycomb primary
mirrors for LBT is being cast at the Steward Observatory Mirror Lab this year.
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. 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. 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. Maximum stiffness and minimal thermal
disturbance were important drivers for the design of the telescope in order to
provide the best possible images for interferometric observations. The telescope
structure accommodates installation of a vacuum bell jar for aluminizing the
primary mirrors in-situ on the telescope. The telescope structure is being
fabricated in Italy by Ansaldo Energia S.p.A. in Milan. After pre-erection in
the factory, it will be shipped to Arizona toward the end of the year. The
enclosure is being built on Mt. Graham under the auspices of Hart Construction
Management Services of Safford, Arizona. The enclosure will be completed later
this year and ready for telescope installation.
pp. 36-46
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[4004-16] Nearly completed
Large Binocular Telescope facility yields many lessons learned
J. H. Slagle, J. M. Hill, W. B. Davison, Steward
Observatory/Univ. of Arizona
W. Hart, Hart Construction Management Services, Inc.
J. U. Teran, M3 Engineering & Technology Corp.
Abstract:
The use of a team approach by contractors, engineers and
management to build the Large Binocular Telescope (LBT) has been successful in
maintaining quality construction at a reasonable price. No matter how efficient
the team, the building of a 16 story building, with a totally unique design, and
on just 1.2 acres of land does present formidable problems. This paper will
present the current status of the LBT construction on Mt. Graham and how the
team approach has continued to be successful in providing quality solutions on a
timely basis while keeping the costs of construction to a minimum. The paper
will discuss many issues that project managers must plan for when undertaking
new and unique designs and what steps managers can take to avoid costly delays.
pp. 446-456
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[4004-19] Large Binocular
Telescope M3 units design
D. Gallieni, ADS International s.r.l. (Italy)
J. M. Hill, Steward Observatory/Univ. of Arizona
P. Salinari, Osservatorio Astrofisico di Arcetri (Italy)
W. B. Davison, Steward Observatory/Univ. of Arizona
Abstract:
We report on the design of the two tertiary mirrors of the
Large Binocular Telescope. The tertiary mirrors are flat octagonal shaped
540x640 mm Hextek honeycombs made of Schott borosilicate. Each mirror cell is
mounted on three linear actuators for the active control of the mirror pointing
and for the adjustment of the telescope optical path length. Each tertiary
mirror unit embeds a rotator stage to point at four different instrument
stations on the telescope. Particular effort is devoted to the optimization of
the honeycomb mirror support system to minimize the optical surface RMS
deformation at the different mirror attitudes.
pp.482-489
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[4004-23] Large Binocular
Telescope erection
L. Miglietta, Astrophysical Observatory of Arcetri (Italy)
D. Gallieni, E. Anaclerio, ADS International s.r.l. (Italy)
G. Castelli, G. Tassa Din, P. Villa, Ansaldo Energia S.p.A. (Italy)
G. Marchiori, A. Zanon, European Industrial Engineering s.r.l. (Italy)
R. Tomelleri, P. Rossettini, Tomelleri s.r.l. (Italy)
Abstract:
The Large Binocular Telescope is currently in pre-erection
at the Ansaldo Energia workshop in Milan. Since late 1998 the manufacturing of
the Azimuth and Elevation structures has been taken place in North Italy along
with the main auxiliary equipment, and since September 1999, the Azimuth Ring
have been assembled and aligned on the new concrete foundation poured months
before in the Ansaldo area. The pre-erection activity in Italy will take some
months more from now and the final acceptance tests are scheduled for July 2000;
after that the whole telescope will be disassembled and shipped to Mt. Graham.
In this paper, the Authors, part of some industrial companies and public
institutes main character in this scientific and technical challenge, briefly
describe the manufacturing and the machining processes of the telescope
components, the results and the procedures adopted of the pre-assembling process
as test bench for the final erection in Arizona.
pp. 115-126
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[4004-25] The Structural
Design of the Co-Rotating Enclosure for the Large Binocular Telescope
D. H. Neff, J. U. Teran, E. A. Hileman, H. J. Lewsley, M3
Engineering & Technology Corp.
Abstract:
The Large Binocular Telescope (LBT) under construction on
Mt. Graham.
pp. 135-142
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[4004-32] Design and
realization of ancillary control loops for the MMT adaptive optics system
G. Z. Angeli, B. C. Fitz-Patrick, M. Lloyd-Hart, Steward
Observatory/Univ. of Arizona
Abstract:
The adaptive optics system of the Multiple Mirror
Telescope is going to realize a high speed (1 kHz bandwidth) and high order (336
actuators) wavefront correction. However, to achieve the required 0.08 arcsec
pointing stability the focal point of the Shack-Hartman wavefront sensor must be
kept aligned to the Cassegrain focus better than 10
mm in spite of the
non-common path tip/tilt error due to mechanical and thermal deformation of the
telescope structure. The wave-front sensor must also be rotated with high
precision to keep it aligned with the deformable secondary mirror in spite of
the parallactic angle correction of the telescope. Our approach is to use a
feed-forward loop to eliminate the adverse effect of deformation. A fast,
deterministic field bus is applied to interconnect the actuators, sensors and
computers. The bandwidth (500kbs) and latency (less than 1 ms) of the DeviceNet
serial bus is adequate to support our distributed control system. The field bus
architecture simplifies and standardizes the control software as well as
improves the reliability of the electronics by reducing the wiring.
pp. 202-211
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Conference 4006: Interferometry in Optical Astronomy
[4006-37] Nulling
interferometric beam combiner utilizing dielectric plates: experimental results
in the visible broadband
R. M. Morgan, J. H. Burge, N. J. Woolf, Univ. of Arizona
Abstract:
The heart of TPF is the nulling beam combiner: a set of
optics that combines the light from various collecting telescopes to produce a
central destructive fringe rather than the natural constructive fringe.
pp. 340-348
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[4006-38] BLINC: a testbed
for nulling interferometry in the thermal infrared
P. M. Hinz, J. R. P. Angel, N. J. Woolf, W. F. Hoffmann,
D. W. McCarthy, Jr., Steward Observatory/Univ. of Arizona
Abstract:
A key technology in NASA's plans for a Terrestrial Planet
Finder (TPF) is nulling interferometry in the thermal infrared.
pp. 349-353
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[4006-61] Tomographic methods
for the restoration of LBT images
M. Bertero and P. Boccacci, Univ. di Genova (Italy)
>S. Correia, A. Richichi, Osservatorio Astrofisico di Arcetri (Italy)
Abstract:
The Large Binocular Telescope (LBT) has been designed for
providing images with high sensitivity and resolution by means of
optical/infrared interferometry. It will require specific methods for data
reduction since the image of an astronomical object will be obtained from a set
of interferometric images corresponding to different orientations of the
baseline. In this paper we first stress an interesting analogy between the
images of LBT and the projections in Computed tomography (CT). Next we use this
analogy for extending to LBT some iterative restoration methods developed for
CT, such as ML-EM (Maximum Likelihood -Expectation Maximization), its
accelerated version OS-EM (Ordered Subset - Expectation Maximization) and the
improved version RAMLA (Row-Action Maximum Likelihood Algorithm). These
iterative methods approximate solutions of the Maximum Likelihood problem in the
case of Poisson noise. We also consider iterative methods which have been
proposed for solving the same problem in the case of Gaussian noise, in
particular the Iterative Space Recostruction Algortithm (ISRA) and the Projected
Landweber (PL) method. All these methods are implemented and tested by means of
same simulated LBT images.
pp. 514-522
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[4006-79] Large Binocular
Telescope image restoration using simulated adaptively corrected point-spread
functions
S. Correia, M. Carbillet, A. Richichi, Osservatorio
Astrofisico di Arcetri (Italy)
M. Bertero and P. Boccacci, Univ. di Genova (Italy)
Abstract:
In this paper we present simulations of Large Binocular
Telescope (LBT) image reconstruction carried out on different types of
scientific object. The set of Adaptive Optics-corrected point-spread functions
(AO-corrected PSFs) used was generated by means of the Code for Adaptive Optics
System (CAOS 2.0). For clarity only one restoration method was applied to the
simulated data, namely the extension of the Lucy-Richardson (LR) algorithm, also
called ML-EM (Maximum Likelihood - Expectation Maximization). When possible we
evaluated the quality of the restorations obtained both by astrometric and
photometric analysis. By comparison with results obtained using analytical PSFs,
we point out the effect induced by the AO correction on the precision of the
retrieved astrometric and photometric parameters or on the morphology of the
reconstructed object.
pp. 650-658
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[4006-80] Cryogenic
Beamcombiner for Very Low Background, 2-20 Micron Interferometry on the 22.8m
Large Binocular Telescope
D. W. McCarthy, E. M. Sabatke, R. J. Sarlot, P. M. Hinz,
and J. H. Burge, The University of Arizona
Abstract:
Interferometry with the 22.8m Large Binocular Telescope
(LBT) will be a uniquely powerful tool in the thermal infrared (2-20 microns)
because of the unusual combination of low thermal emissivity, high spatial
resolution, broad (u,v)-plane coverage, and high photometric sensitivity.
Equipped with a central cooled beamcombiner, the LBT is capable of both spatial
interferometry and nulling interferometry. Adaptive secondaries, as well as a
common mount for the two 8.4m primary mirrors, permit beam combination after
only three warm reflections. We present an all-reflective optical design for the
beamcombiner which satisfies the requirement of large interferometric fields for
Fizeau- style imaging as well as the low thermal background and achromaticity
required for nulling. The beamcombiner operates over a wavelength range of 2-20
microns to feed a variety of interchangeable cameras and spectrographs.
Integrated tip-tilt and pathlength (phase) sensors permit accurate control of
these errors caused both by atmospheric turbulence and telescope flexure. With
nulling interferometry the LBT will be unsurpassed in its sensitivity to circumstellar
environments. At 11 microns the instrument will be sensitive to zodiacal dust
down to solar level around nearby stars. At 4 microns planets as small as
Jupiter and younger than one billion years will be detectable.
pp. 659-672
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[4006-82] LINC: a
near-infrared beam combiner for the Large Binocular Telescope
T. M. Herbst, H. W. Rix, P. Bizenberger, and M. Ollivier,
Max-Planck-Institut für Astronomie (Germany)
Abstract:
The Large Binocular Telescope (LBT), currently under
construction on Mount Graham in Arizona, will be the world's largest single
telescope when it is completed in 2003. With its dual, 8.4 meter diameter
primary mirrors and a maximum baseline of 23 meters, LBT will provide
interferometrists an unprecedented combination of large collecting area, wide
field of view, and high spatial resolution.
To take advantage of this, several concepts for
beam-combiners and associated instrumentation are under development. We review
the current concepts for a beam-combiner to operate in the near-infrared,
specifically those proposed by the MPIA in Heidelberg and the Arcetri
Observatory in Florence, and emphasize the need for a wide collaboration in the
design and realization of this project.
Because the two mirrors of the telescope have a common
mount, the entrance pupil geometry of the interferometer does not vary for
different pointing directions. This makes it relatively easy to construct an
instrument that preserves this geometry, allowing image-plane or "Fizeau"
interferometry. Our simulations suggest that we will be able to achieve true
imagery with ~10 mas resolution over a field of several tens of arcseconds in
diameter with excellent sensitivity (for example, S/N of 10 on a 20 nJy point
source in 3 hours at K').
Such performance enables a variety of fundamental, new
science programs. For example, we anticipate pushing the supernova cosmology
studies to beyond redshift 3, studying the time evolution of stellar jets, and
detecting Jupiter-mass planets around stars within 100 pc due to their reflex,
astrometric wobble. Building this instrument represents a significant challenge,
however. The prototype instrument will likely be uncooled, but we are examining
options for eventually having a fully cryogenic beam combiner. Ultimately, an
additional, internal adaptive corrector may increase the Strehl ratio over a
larger field of view and allow operation at wavelengths shorter than 1 micron.
pp. 673-680
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[4006-128] Second-order phase
theory in multiple aperture systems
E. M. Sabatke and J. M. Sasian, University of Arizona
Abstract:
We establish the groundwork for a phase theory applicable
to multiple-aperture systems. We examine the phase behaviour of a reference
system
pp. 1083-1089
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[4006-132] Considerations
about the differential piston for adaptive optics interferometry
B. Femenia, M. Carbillet, S. Esposito, A. Riccardi,
Osservatorio Astrofisico di Arcetri (Italy)
Abstract:
The contribution extends a previous work where the concept
of piston angular anisoplanatism was introduced and the issue of sky coverage
for large ground-based optical interferometers was raised. We obtain expressions
......
pp. 1116-1127
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Conference 4007: Adaptive Optical Systems Technology
[4007-01] The adaptive
secondary mirror for the 6.5m conversion of the Multiple Mirror Telescope:
latest laboratory results from the P36 prototype
A. Riccardi, G. Brusa, V. Biliotti, C. Del Vecchio, P.
Salinari, P. Stefanini, Osservatorio Astrofisico di Arcetri (Italy)
P. Mantegazza, Politecnico di Milano (Italy)
R. Biasi, M. Andrighettoni, MicroGate S.r.L. (Italy)
C. Franchini, Media Lario S.r.L. (Italy)
D. Gallieni, ADS International S.r.L. (Italy)
M. Lloyd-Hart, P. C. McGuire, S. M. Miller, H. M. Martin, Steward
Observatory/Univ. of Arizona
Abstract:
The 336-actuator adaptive secondary unit (MMT336) for the
new MMT is being assembled in Italy and will be delivered in June 2000 for the
acceptance test at Steward Observatory (Tucson, AZ). The latest results obtained
on a reduced-size (36 actuators) prototype called P36 are reported, confirming a
settling time less than 1 ms measured in previous tests. .....
pp.524-531
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[4007-06] Optical fabrication
of the MMT adaptive secondary mirror
H. M. Martin, J. H. Burge, Steward Observatory/Univ. of
Arizona
C. Del Vecchio, Astrophysical Observatory of Arcetri (Italy);
L. R. Dettmann, S. M. Miller, B. K. Smith, F. P. Wildi, Steward
Observatory/Univ. of Arizona
Abstract:
We describe the optical fabrication of the adaptive
secondary mirror for the MMT. The 640 mm f/15 secondary consists of a flexible
glass shell, 1.8 mm thick, whose shape is controlled by 336 electromagnetic
actuators. It is designed to give diffraction-limited images at a wavelength of
1 micron. For generating and polishing, the shell was supported by attaching it
to a rigid glass blocking body with a thin layer of pitch. It could then be
figured and measured using techniques developed for rigid secondaries. The
highly aspheric surface was polished with a 30 cm stressed lap and small passive
tools, and measured using a swing-arm profilometer and a holographic test plate.
The goal for fabrication was to produce diffraction-limited images in the
visible, after simulated adaptive correction using only a small fraction of the
typical actuator forces. This translates into a surface accuracy of less than 19
nm rms with correction forces of less than 0.05 N rms. We achieved a surface
accuracy of 8 nm rms after simulated correction The adaptive optics system for
the 6.5 m MMT is based on an adaptive secondary mirror designed to give
diffraction-limited images in the near-infrared, between 1 and 5 microns.
pp.502-507
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[4007-08] LBT adaptive
secondary preliminary design
D. Gallieni, ADS International s.r.l. (Italy)
C. Del Vecchio, Astrophysical Observatory of Arcetri (Italy)
E. Anaclerio, ADS International s.r.l. (Italy)
P. G. Lazzarini, ADS International s.r.l. (Italy)
Abstract:
We report on the design of the two Gregorian adaptive
secondary mirrors of the Large Binocular Telescope. Each adaptive secondary is a
911 m wide and 1.5 mm thick Zerodur shell controlled by a pattern of 918
electromagnetic actuators. The shape of the mirror is referred to a stable ULE
backplate by means of capacitive sensors co-located to the actuators pattern.
The preliminary design of the system is addressed with particular attention to
the reference plate optimization.
pp.508-515
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[4007-09] Numerical
simulations of the LBT adaptive secondary mirror
C. Del Vecchio, Astrophysical Observatory of Arcetri
(Italy)
D. Gallieni, ADS International s.r.l. (Italy)
Abstract:
In this paper we describe the design of the deformable
mirror of the Large Binocular Telescope adaptive secondary unit. Starting from
the optical design, a numerical model of the ultra-thin, aspherical glass shell,
accommodating the 918 magnets on the selected actuator geometry, has been run.
Using this model, we can evaluate the response of this crucial component of the
telescope optics with great accuracy. The DM is analyzed from the mechanical
standpoint -- gravity deformations, wavefront residue, corrections of magnetic
interactions, dynamics -- in order to compute the optical performances in the
most demanding operational circumstances.
pp.516-523
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[4007-27] Atmospheric
tomography with Rayleigh laser beacons for correction of wide fields and 30 m
class telescopes
J. R. P. Angel and M. Lloyd-Hart, Steward Observatory, The
University of Arizona
Abstract:
Single sodium beacons will likely be the most convenient
for adaptive systems to correct 6-10 m class telescopes over a small field of
view (the isoplanatic angle), provided reliable, powerful 589 nm lasers become
available and affordable. However, when adaptive optics are applied to extended
fields of view and correction of telescopes as large as 32 m diameter, it seems
likely that laser beacons produced by Rayleigh scattering will be preferred. For
these more demanding applications which require atmospheric tomography, Rayleigh
beacons come into their own for two reasons. First, the cone effect, which
causes the high turbulence to be sampled at a different scale, is no longer
problematic when multiple lasers are used and height dependence is solved for
explicitly. Second, the tomographic solution can make use of the beacon created
by a laser pulse during all of its journey through the upper atmosphere, not
just scattering from a thin layer selected by range gating. In this way a laser
that costs an order of magnitude less to buy and maintain than a sodium laser of
the same power can yield a brighter beacon and more information about the
atmospheric turbulence. This is important because both the number and brightness
of beacons or stars must increase with the number of layers included in the
tomographic solution. For the same reason, tomography with natural stars is
unlikely to be valuable for very large telescopes because in general the number
and required brightness of each star increase with corrected field angle, while
current narrow-field adaptive optics systems relying on natural stars are
already very limited in sky coverage. Our method for tomography to take
advantage of Rayleigh scattering over a wide range of heights uses short pulses
from near diffraction-limited, ultraviolet lasers, projected from a small
aperture above the telescope s secondary mirror. Each pulse subtends less than 1
arcsec at any instant as it travels up through many kilometers. An imaging
detector at the main telescope focus conjugate to mid-height is used to record
fast movies of the rising pulses as they come into and out of focus. Phase
diversity analysis of the movies taken together then yields the
three-dimensional turbulence of the atmosphere.
pp.270-276
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[4007-30] New Approach to
Rayleigh Guide Beacons
M. Lloyd-Hart, S. M. Jeffries, E. K. Hege and J. R. P.
Angel, Steward Observatory/Univ. of Arizona
Abstract:
We present analysis and numerical simulations of a new
method to sense atmospheric wavefront distortion in real time with Rayleigh
beacons. Multiple range-gated images of a single pulse from the laser are used
to determine each phase map, provid-ing an advantage over other methods in that
photon noise is substantially reduced for a given brightness of the beacon. A
laser at about 350 nm projects collimated pulses of light adjacent to the
telescope. Rayleigh-scattered light from each pulse is recorded through the full
telescope aperture in a sequence of video frames, each a few ms long. Images are
captured as the pulse approaches and passes through the height at which the
camera is focused. Phase diversity is thus naturally introduced between the
frames. An iterative algorithm is used to extract the pupil-plane phases from
the recorded intensity distributions. We anticipate that such beacons are likely
to be valuable in future advanced systems for adaptive optics on very large tele-scopes
with multiple laser beacons and deformable mirrors that aim to provide a large
corrected field of view by tomography of the atmospheric turbulence.
pp.277-283
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[4007-51] Wavefront sensing
and guiding units for the Large Binocular Telescope
Jesper Storm, Astrophysikalishes Institut Potsdam (AIP),
Germany
Walter Seifert, Landessternwarte Heidelberg, Germany
Svend Marian Bauer, AIP, Germany
Frank Dionies, AIP, Germany
Ulfert Hanschur, AIP, Germany
John Hill, Steward Observatory, Tucson, USA
Guenther Moestl, AIP, Germany
Piero Salinari, Arcetri Observatory, Firenze, Italy
Waldemar Varava, AIP, Germany
Hans Zinnecker, AIP, Germany
Abstract:
The Large Binocular Telescope (LBT) will be equipped with
fully adaptive secondary mirrors from first light which is currently planned for
mid-2002. To allow the science instruments to benefit from this feature, we ar
ecurrently designing a set of wavefront sensing systems for the base-line
telescope. One of the design goals is to take full advantage of the fact that
the adaptive correction is performed with the secondary mirror which means that
we do not have to introduce an additional warm surface in the IR beam.
Consequently we will follow the upgraded-MMT concept of using the light
reflected off a tilted instrument entrance window for the tip-tilt guiding as
well as for the wavefront sensing. Another design goal is to have an upgrade
path ready for the first few years of operation which will allow us to migrate
from the use of natural stars to the use of either sodium laser stars or
Rayleigh beacons as the light source for the adaptive optics sensing. The three
techniques operate in quite different ways which introduces significantly
different constraints on the design. In particular the Rayleigh beacons are
complicated as a minimum of four simultaneous beams has to be observed and it is
necessary to be able to focus down to altitudes of the order 20km. We will
present the current status of our design including the proposed upgrade path.
The expected performance will also be outlined.
pp.461-469
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[4007-56] Adaptive optics
simulation tests for imaging with the Large Binocular Telescope
M. Carbillet, S. Correia, B. Femenia, A. Riccardi,
Osservatorio Astrofisico di Arcetri
Abstract:
In this contribution we present a first application of the
ongoing numerical simulations that are carried out in order to study the
adaptive optics (AO) correction and the subsequent imaging post-processing when
observing with the Large Binocular Telescope (LBT) interferometer. The
simulation tool used as a starting point for this study is the software package
CAOS 2.0 (Code for Adaptive Optics Systems, version 2.0), for its AO-simulation
capabilities and its modular structure. It is used here in order to generate the
turbulence-corrupted and subsequently adaptive-optics- corrected interferometric
point-spread functions corresponding to the simultaneous observation of both a
scientific object and a reference star, for three parallactic angles
corresponding to three observation runs during the night. The obtained data are
therefore used as the inputs of a multiple deconvolution method planned for
imaging with the LBT interferometer. As an example, we have simulated the
observation, in the R-band, of a Betelgeuse-like stellar object of 15th
magnitude, 30 mas diameter, and with a 3 mas bright spot, under two different
conditions of turbulence and AO-correction (leading to Strehl ratios of ~0.15
and ~0.45, respectively). Final results are found to be very encouraging.
pp.155-166
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[4007-121] Adaptive optics
for the 6.5m MMT
M. Lloyd-Hart, F. P. Wildi, G. Z. Angeli, W. B. Davison,
B. C. Fitz-Patrick, R. L. Johnson, M. A. Kenworthy, P. C. McGuire, B. Martin, S.
M. Miller, and J. R. P. Angel, Steward Observatory/Univ. of Arizona
Abstract:
The adaptive optics system for the 6.5m MMT conversion
telescope will be the first to compensate the aberrated wavefront at the
telescope's secondary mirror. This approach has unique advantages in terms of
optical simplicity, high throughput and low emissivity. We report here the
present state of construction, and the results of static and dynamic performance
tests of the Cassegrain optical package.
pp.167-174
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Conference 4008: Optical and IR Telescope Instrumentation
and Detectors
[4008-49] A Double Prime
Focus Camera for the F/1.14 Large Binocular Telescope.
R. Ragazzoni[1], E. Giallongo[2], F. Pasian[3], F.
Pedichini[2], M. Turatto[1], and D. Gallieni[4]
1: Astronomical Observatory of Padova (Italy)
2: Astronomical Observatory of Roma (Italy)
3: Astronomical Observatory of Trieste (Italy)
4: ADS International srl (Italy)
Abstract:
The Large Binocular Telescope is currently in the
pre-erection phase. The prime focus instrument will be used at the first light
and its final design have been carried out during last months. Given the
peculiarity of the telescope optics (a double 8.4m mirrors on the same mounting)
we designed two prime focus camera with a five-lens refractive correctors,
optimized in the blue-side (namely U and B Johnson bands) and red-side (V, R and
I Johnson bands) of the visible spectrum. This independent optimization is
effective both in the optical design, whose achromaticity requirements are
relaxed, and both from the coating side. Detectors also reflects this choice,
being optimized separately We present the most relevant features of the
instrument and the optical design as well as the structural and mechanical
layout. Each of the two Prime Focus camera gather light from a very fast, F/1.14
parabolic primary mirror. The field is corrected over roughly half a degree in
size, allowing optical performances in terms of 80% of Encircled Enedrgy in
better than ~0.3arcsec. Focal length is slightly augmented in order to provide a
better pixel sampling using 13.5um EEV chips. The CCD array is made up with 4
EEV 42-90 chips, on both channels, to obtain an equivalent 6000 x 6000 pixels
optimzing the AR coating to the U-B-V and V-R-I bands respectively. The array
will be readed out in 10 seconds using a 1 Megapixel/second controller with four
video channels. The cryostat will use a state of the art dewar to reach an
holding time of several days using a limited amount of liquid nitrogen to avoid
misbalancing of the telescope during evaporation. The whole mechanical design
has been modelled using Finite Elements analysis in order to check for
mechanical flexures of the mount tube and of the optical components by
themseleves. A brief overview of the informatic facilities to be provided with
the instrument and of a few science case studies that can be attacked from this
instrument are also givne. Current the instruemtn has been partially funded for
its realization whose first-light is expected shortly after the one of the LBT.
pp. 439-446
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[4008-05] Multiobject double
spectrograph for the Large Binocular Telescope
P. S. Osmer, B. Atwood, P. L. Byard, D. L. DePoy, T. P.
O'Brien, R. W. Pogge, D. Weinberg, Department of Astronomy, The Ohio State
University.
Abstract:
We are designing and will build a Multi-Object Double
Spectrograph (MODS) for the Large Binocular Telescope (LBT). The main themes of
our planned research for the LBT with MODS will be the formation of and
evolution of galaxies and their nuclei, and the evolution of large-scale
structures in the universe (although MODS will be used for many areas of modern
astrophysics). The combination of the light gathering power of the LBT with the
multi-object capability of MODS will allow study of the chemical, dynamical, and
assembly history of galaxies, the history of cosmic star formation, and the
evolution of three-dimensional structure in the distributions of high-redshift
galaxies, Lyman-limit systems, and Ly-a forest absorbers, all in unprecedented
detail. The high efficiency of MODS over the full optical band will enable
observations of key spectral features in galaxies and quasars from z=0 to z=7.
The MODS instrument will have a range of intermediate spectral resolutions
(1000-10000 for a 0.6 arcsec wide slit) and will deliver high throughput from
320 to 1000 nm through the use of two separate optical channels optimized
individually for blue and red wavelengths. It will have multi-object capability
over a 4’ field as well as a cross-dispersed mode. The design will allow for
future upgrades of additional cameras, integral field capability (to take
advantage of projected adaptive optics for LBT), and other gratings. MODS will
use an open architecture, modular design approach, and a minimum number of
optical elements. This will result in a flexible and powerful instrument while
keeping the project costs down.
The construction of MODS will be the main instrumentation
project for the OSU Astronomy Department for the next several years.
gzip'd
Postscript file (490 kB)
Acrobat PDF
file (495 kB)
pp. 40-49
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[4008-16] Design study for an
Adaptive Optics Visual Echelle Spectrograph (AVES) for the VLT
R. Pallavicini, P. Caldara, Osservatorio Astronomico di
Palermo, Italy
L. Pasquini, B. Delabre, N. Hubin, European Southern Observatory, Garching bei
Muenchen, Germany
P. Molaro, P. Bonifacio, P. Santin, P. Dimarcantonio, M. Comari, Osservatorio
Astronomico di Trieste, Italy
L. Mantegazza, R. Mazzoleni, E. Molinari, F. Zerbi, Osservatorio Astronomico di
Brera, Milano
G. Bonanno, S. Catalano, M. Rodono, Osservatorio Astrofisico di Catania. Italy
Abstract:
A design study is currently underway by a consortium of
Italian Institutes and collaborating scientists at ESO for the development of an
Adaptive Optics Visual Echelle Spectrograph (AVES) for the VLT. A preliminary
concept for the instrument was presented at the SPIE conference in Kona in 1998.
The instrument is intended for medium-resolution (R ~ 20,000) spectroscopy of
faint sky-limited or detector limited observations of galactic and extragalactic
objects, down to a magnitude limit of R=22. In its current design, it is
conceived for a possible use as parallel instrument of the Nasmyth Adaptics
Optics System (NAOS) at the ESO VLT, but it could also be used, with some
modifications, at other large telescopes with adaptive optics capabilities (e.g.
the LBT). The opto-mechanical design will be presented, together with the
specifications for Instrument Control Software, electronics and detector system.
The possibility of adding an imaging mode will also be discussed. The advantages
of adaptive optics for medium and high-resolution spectroscopy will be
highlightened.
pp. 167-174
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[4008-83] LUCIFER - a NIR
spectrograph and imager for the LBT
Holger Mandel, Immo Appenzeller, Ralf Mohr, Walter
Seifert, Wenli Xu, Landessternwarte Konigstuhl 12 D-69117 Heidelberg, Germany
Tom Herbst and Rainer Lenzen, Max Planck Institut fur Astronomie, Konigstuhl 17,
D-69117 Heidelberg, Germany
Niranjan Thatte and Frank Eisenhauer, Max Planck Institut fur Extraterrestrische
Physik, P.O. Box 1603, D-85740 Garching, Germany
Roland Lemke, Dominik Bomans, Thomas Luks, Astronomisches Institut der Ruhr-Universitat
Bochum, Universitatsstr. 150, D-44780 Bochum, Germany
Peter Weiser, Fachhochschule fur Technik und Gestaltung, Windeckstr. 110,
D-68163 Mannheim
Abstract:
LUCIFER (LBT NIR-Spectroscopic Utility with Camera and
Integral-Field Unit for Extragalactic Research) is a full cryogenic NIR
spectrograph and imager to be build by a consortium of five institutes (Landessternwarte
Heidelberg, Max Planck Institut fur Astronomie in Heidelberg, Max Planck
Institut fur Extraterrestrische Physik in Garching, Astronomisches Institut der
Ruhr-Universitat Bochum and of the Fachhochschule fur Technik und Gestaltung in
Mannheim). The instrument has been chosen as one of three first-light
instruments for the Large Binocular Telescope (LBT) on Mt. Graham, Arizona which
becomes available to the community in autumn 2002. A second instrument follows
18 month later.
Both LUCIFER-instruments will be mounted at the bent
Gregorian focii of the two individual LBT-mirrors and includes six
observing-modes:
- Seeing limited imaging over a 4 arcmin FOV
- Seeing limited longslit spectroscopy
- Seeing limited multi-object spectroscopy (MOS)
- Diffraction limited imaging over a 0.7 arcmin FOV
- Diffraction limited longslit spectroscopy
- Integral field spectroscopy (IFU)
According to the present schedule the Preliminary Design
Review (PDR) for the project will be hold in February 2000, the Critical Design
Review (CDR) follows in June/July 2000. At this meeting first results of our
optical and cryo-mechanical design studies are presented.
pp. 767-777
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[4008-111] MODS: Optical
Design for a Multi-Object Dual Spectrograph
P. L. Byard, T. P. O'Brien, Department of Astronomy, The
Ohio State University
Abstract:
The paper describes the optical design for the Multi
Object Dual Spectrograph (MODS) for the Large Binocular Telescope (LBT). MODS is
designed to cover the entire spectrum accessible to silicon CCDs from a
ground-based telescopes with the highest possible throughput. Multi-object
capability is available using 0.6 arc-second slit masks covering a high quality
field of 4 arc-minutes in diameter with an extended field of up to 6 arc-minutes
in diameter with reduced image quality. Under the very best seeing conditions
and with the LBT adaptive optics in operation, slit widths of 0.3 arc seconds
can be used to enhance the resolving power and/or reduce the background.
The optical path is divided into blue and red channels by
a dichroic beam splitter following the slit or slit masks. The blue channel
covers a wavelength range from the atmospheric cut-off at ~300 nm to ~ 650 nm
while the red channel covers the range from ~650 nm to the limit of useful
sensitivity of silicon CCDs (~1000 nm). This approach allows the optimization of
transmissive and reflective coatings to provide the very highest throughput for
each channel.
The design is conventional in the use of reflective
parabolic collimators. However, the cameras are designed as decentered Schmidt/Maksutovs
with large aspheric coefficients for the inner surface of the corrector and
mirror. This approach enables the field flattener and detector to be positioned
outside the beam entering the camera where it will not add to the loss of light
within the system. Figures are presented showing image quality for imaging and
spectrographic modes.
pp. 934-941
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[4008-126] LUCIFER-MOS: A
cryogenic multi-object infrared spectrograph for the LBT
R. Hofmann, N. Thatte, M. Tecza, F. Eisenhauer, M. Lehnert,
Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrasse, 85740
Garching, Germany
Abstract:
We present the MOS unit for LUCIFER, the cryogenic
near-infrared spectrograph for the Large Binocular Telescope (LBT). The MOS unit
consists of 15 deployable integral field units (d-IFUs), each sampling 30 object
points covering a small field of view of 2 arc seconds. The individual IFUs
consist of a bundle of monolithic lenslet-fiber units made from silica-silica
fibers, so as to achieve high fill factors in the focal plane. A cryogenic
robotic fiber positioner will reposition the d-IFUs within a field of 4 x 4 arc
minutes. The output of the fibers will be fed to the LUCIFER spectrograph, which
will provide high resolution spectroscopy (R ~ 5000) covering one of the J, H or
K atmospheric windows. The entire MOS unit operates at 77 K, ensuring low
thermal background and high sensitivity. The large apertures of the LBT, and the
use of OH avoidance techniques will enable infrared multi-object spectroscopy of
faint high redshift galaxies with the LUCIFER MOS unit.
pp. 1094-1102
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[4008-58] PMAS Fiber
Spectrograph: Design, Manufacture and Performance
M. M. Roth, Astrophysical Institute Potsdam
U. Laux, Weimar, Germany
W. Heilemann, Carl Zeiss Jena, Germany
Abstract:
PMAS, the Potsdam Multi-Aperture Spectrophotometer is
currently being developed as a travelling instrument of AIP. It is prototyped
for first light at the Calar Alto 3.5m telescope with an option to go to other
telescopes with little modification. PMAS is a high efficiency integral field
spectrograph with low/medium spectral resolution, covering the whole optical
wavelength range from 350 to 900nm without refocus. With the requirements of
spectral and photometric stability it is therefore an ideal instrument for
spectrophotometry with full 2-dimensional spatial resolution. The layout
consists of a lens array, coupled to a fiber bundle, which is fed to the fiber
spectrograph. The spectrograph is a fully dioptric 150/450mm collimator and
180/270mm camera system for reflective gratings. It is corrected over the whole
nominal wavelength range with average/maximum 80% design spot concentrations of
12/20um for the camera, and 14/24um for the whole system, respectively. The
lenses which are made from Schott glasses and CaF2 blanks have been fabricated
and integrated into complete systems by Carl Zeiss Jena, Germany. We will
describe the optical design and report on the measured performance.
pp. 485-496
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[4008-28] PMAS Design and
Integration
M. M. Roth, S-M. Bauer, F. Dionies, T. Fechner, T. Hahn,
A. Kelz, J. Paschke, E. Popow, J. Schmoll, D. Wolter, Astrophysical Institute
Potsdam
W. Altmann, Tiefenbach
U. Laux, Weimar, Germany
Abstract:
PMAS, the Potsdam Multi-Aperture Spectrophotometer has
been designed and is currently being integrated as a traveling instrument of
the Astrophysical Institute Potsdam. It is a UV-Visual integral field
spectrograph, with optimized efficiency and stability for use as a 3D
spectrophotometer. PMAS is prototyped for first light at the Calar Alto 3.5m
telescope with an option to go to other telescopes (e.g. LBT). We present the
final design layout, details of the mechanics including results from FE studies,
the optics, detector systems, and instrument control. We will report on the
current status of the integration.
pp. 277-288
Top
Conference 4015: Radio Telescopes
[4015-30] Submillimeter-wave
receiver system for the Large Binocular Telescope
C. Y. Drouet d'Aubigny, C. K. Walker, C. E. Groppi, J. M.
Hill and J. H. Bieging, Steward Observatory/Univ. of Arizona
S. M. Pompea, Pompea & Associates
Abstract:
The Large Binocular Telescope (LBT) now under construction
by the LBT Corporation partners on Mt. Graham, Arizona will offer unique
opportunities for observing at submillimeter wavelengths. The LBT will be
composed of two 8.4m optical quality mirrors mounted on a common support
structure. When used as an interferometer, the telescope will be able to achieve
the diffraction limited resolution of a 22.8m aperture. At 350 microns, the LBT
primaries will be essentially perfect (20 nm rms) and have a total light
gathering power equivalent to a state-of-the-art (main beam efficiency ~0.35),
~19 meter diameter submillimeter telescope. In our presentation we will describe
a coherent beam combiner and focal plane receiver system which will permit
phase-switched, interferometric observations to be performed with LBT at 350
microns. First light observations with a single LBT mirror are expected in 2002,
with interferometric observations beginning after the installation of the second
mirror about 1.5 years later.
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