Guido Brusa - Academia.edu (original) (raw)

Papers by Guido Brusa

Research paper thumbnail of Statistical Properties of a Class of Deterministic Cellular Automata

Europhysics Letters (EPL), 1989

Research paper thumbnail of Observations of Herbig Ae Disks with Nulling Interferometry

The Astrophysical Journal, Apr 1, 2007

We present the results of 10 µm nulling interferometric observations of 13 Herbig Ae stars using ... more We present the results of 10 µm nulling interferometric observations of 13 Herbig Ae stars using the Magellan I (Baade) and the MMT 6.5 m telescopes. A portion of the observations was completed with the adaptive secondary at the MMT. We have conclusively spatially resolved 3 of the 13 stars, HD 100546, AB Aur, and HD 179218, the latter two recently resolved using adaptive optics in combination with nulling interferometry. For the resolved objects we find that the 10 µm emitting regions have a spatial extent of 15-30 AU in diameter. We also have some evidence for resolved emission surrounding an additional 2 stars (V892 Tau and R CrA). For those objects in our study with mid-IR SEDs classifications from Meeus et al. (2001), we find that the Group I objects (those with constant to increasing mid-IR flux) are more likely to be resolved, within our limited sample. This trend is evident in correlations in the inferred disk sizes vs. the sub-millimeter SED slope and disk size vs. fractional infrared luminosity of the systems. We explore the spatial distribution and orientation of the warm dust in the resolved systems and constrain physical models which are consistent with their observational signatures.

Research paper thumbnail of First light of the 6.5-m MMT adaptive optics system

Proceedings of SPIE, Dec 31, 2003

The adaptive optics system of the 6.5m MMT with its deformable secondary has seen first light on ... more The adaptive optics system of the 6.5m MMT with its deformable secondary has seen first light on the sky in November 2002. Since then, it has logged over 30 nights at the telescope and has been used with several scientific cameras and a dedicated IR infrared camera. Results so far are extremely encouraging with Strehls of up to 20% in H-band and 98% in M limited in part by the control algorithm that is being improved. Reliability of the deformable secondary mirror (DM) has been remarkable with only one occurrence of a malfunction that required removing the secondary from its hub. In this paper, we review the milestones achieved and the performances obtained in the first year of operation. We will also address the operational constraints associated with the deformable secondary and the steps taken to relax these constraints. We show that despite its apparent complexity, an adaptive secondary AO system can be operated with modest effort from the telescope and AO staff

Research paper thumbnail of Adaptive Optics Science with the MMT Adaptive Secondary: Mid-IR AO Imaging of the Post-AGB Star AC Her

Springer eBooks, Nov 17, 2005

The world's first adaptive secondary has been commissioned at the 6.5 m MMT. Early science r... more The world's first adaptive secondary has been commissioned at the 6.5 m MMT. Early science results suggests that it is unique and highly productive. Nearly diffraction-limited 0.07” H band images have been obtained of the Trapezium core [Close et al. 2003b]. ...

Research paper thumbnail of Off-line and on-line modal optimization of the MMT-AO system

Proceedings of SPIE, Aug 18, 2005

The MMT adaptive optics system has been in operation for over 2 years. 1, 2 Besides being a techn... more The MMT adaptive optics system has been in operation for over 2 years. 1, 2 Besides being a technological demonstration, it has achieved remarkable success. 3, 4 However, the system is presently limited by a few factors, one of which is the lack of an optimised controller. In this paper, we review the optimised modal integrator as introduced in Ref 5 and evaluate its potential for MMT-AO. We nd that it can indeed increase the system sensitivity by one magnitude but that a careful analysis of wave front sensor data must be performed to remove artefacts that can severely bias the outcome of the optimization.

Research paper thumbnail of Final review of adaptive optics results from the preconversion MMT

Proceedings of SPIE, Oct 17, 1997

The FASTTRAC II adaptive optics instrument has been used at the Multiple Mirror Telescope (MMT) f... more The FASTTRAC II adaptive optics instrument has been used at the Multiple Mirror Telescope (MMT) for the past 2 years to provide improved image resolution in the near infrared. Results have been obtained using both natural guide stars and an artificial sodium laser beacon. With the imminent closure of the MMT prior to its conversion to a single-mirror 6.5 m telescope, FASTTRAC II has come to the end of its life. The instrument has been to the telescope for a total of 8 runs, and during that time it has been of enormous value both as a learning aid, demonstrating the requirements of its successor on the 6.5 m, and as a scientific tool. At this meeting, we present a selection of astrophysical data derived from FASTTRAC II, including the first closed-loop demonstration of an adaptive optics system using a sodium laser beacon. The sodium laser has been used to obtain near diffraction-limited near-infrared images of the core of M13, allowing the construction of a color-magnitude diagram to below the main sequence turnoff. Results have also been obtained from several gravitationally lensed quasars, and the cores of nearby galaxies in the local group. We also summarize work characterizing atmospheric conditions at the site. These studies have proceeded in two areasunderstanding the behavior of the phase perturbation with field angle and time, and characterizing the return from the sodium resonance beacon.

Research paper thumbnail of Toward visible wavelength coherent imaging with the LBT

Proceedings of SPIE, Jul 24, 2014

ABSTRACT The Large Binocular Telescope with its integrated adaptive optics systems and the LBTI b... more ABSTRACT The Large Binocular Telescope with its integrated adaptive optics systems and the LBTI beamcombiner provides a good platform for carrying out coherent imagin across its 22.7 m baseline. The first cameras used with LBTI have focused on infrared wavelengths. We describe a concept, called the LBT Interferometer Visible Extension (LIVE) to carry out coherent imaging with the LBT at visible wavelengths. LIVE will be able to create images of some of the stars with the largest angular diameters, map the surface of solar system moons, and provide detailed imaging of the inner scattered light regions of protoplanetary and transition disks. An initial approach can use the beamcombiner with its existing infrared phase sensor to carry out coherent imaging using frame selection to improve the image quality. Refined and more versatile phase sensing and correction can be implemented in a second stage to enable observations of a wider range of targets. LIVE will work both as a coherent imager, as well as a flexible dual aperture AO imager where simultaneous differential measurements can be made through independent use of each arm. We describe the science case and technical description below. We plan to develop the system with a flexible approach that allows increasingly complex modes of observation to be added once the basic performance is demonstrated.

Research paper thumbnail of PCR: a PC-based wave front reconstructor for MMT-AO

Proceedings of SPIE, Jul 12, 2008

... We thank Manny Montoya, Matthew Kenworthy, Richard Sosa and the MMT operators for their valua... more ... We thank Manny Montoya, Matthew Kenworthy, Richard Sosa and the MMT operators for their valuable contributions. 12. ... 2. Christoph Baranac, Michael Llyod-Hart, N. Mark Milton, ThomasStalcup, Miguel Snyder, Vidhya Vaitheeswaran, Don McCarthy, and Roger Anger ...

Research paper thumbnail of Adaptive optics capabilities at the Large Binocular Telescope Observatory

Proceedings of SPIE, Jul 26, 2016

We present an overview of the current and future adaptive optics systems at the LBTO along with t... more We present an overview of the current and future adaptive optics systems at the LBTO along with the current and planned science instruments they feed. All the AO systems make use of the two 672 actuator adaptive secondary mirrors. They are (1) FLAO (NGS/SCAO) feeding the LUCI NIR imagers/spectrographs; (2) LBTI/AO (NGS/SCAO) feeding the NIR/MIR imagers and LBTI beam combiner; (3) the ARGOS LGS GLAO system feeding LUCIs; and (4) LINC-NIRVANA-an NGS/MCAO imager and interferometer system. AO performance of the current systems is presented along with proposed performances for the newer systems taking into account the future instrumentation.

Research paper thumbnail of Determining the interaction matrix using starlight

Proceedings of SPIE, Oct 25, 2004

ABSTRACT

Research paper thumbnail of Status of the NGS adaptive optic system at the MMT Telescope

Proceedings of SPIE, Oct 25, 2004

The Natural Guide Star (NGS) Adaptive Optics System at the MMT Telescope (MMTAO) on Mt. Hopkins i... more The Natural Guide Star (NGS) Adaptive Optics System at the MMT Telescope (MMTAO) on Mt. Hopkins in Southern Arizona is the first in the world the use the secondary mirror as the correcting deformable mirror. Its 2.0 mm thin shell mirror, whose shape is controlled by 336 voice coil actuators, allows for nearly maximum throughput of light into the science camera. With several more deformable secondary mirrors coming online in the next few years, the lessons learned building, characterizing and operating the MMT Adaptive Optic System has proven to be quite valuable. These lessons will be discussed as well as future plans for the MMTAO System.

Research paper thumbnail of High‐Resolution Mid‐Infrared Imaging of the Asymptotic Giant Branch Star RV Bootis with the Steward Observatory Adaptive Optics System

The Astrophysical Journal, Feb 10, 2005

We present high-resolution ($0B1), very high Strehl ratio (0:97 AE 0:03) mid-IR adaptive optics (... more We present high-resolution ($0B1), very high Strehl ratio (0:97 AE 0:03) mid-IR adaptive optics (AO) images of the asymptotic giant branch (AGB) star RV Boo utilizing the MMT adaptive secondary AO system. RV Boo was observed at a number of wavelengths over two epochs (9.8 m in 2003 May and 8.8, 9.8, and 11.7 m in 2004 February) and appeared slightly extended at all wavelengths. While the extension is very slight at 8.8 and 11.7 m, the extension is somewhat more pronounced at 9.8 m. With such high Strehl ratios, we can achieve superresolutions of 0B1 by deconvolving RV Boo with a point-spread function (PSF) derived from an unresolved star. We tentatively resolve RV Boo into a 0B16 FWHM extension at a position angle of 120. At a distance of 390 þ250 À100 pc, this corresponds to a FWHM of 60 þ40 À15 AU. We measure a total flux at 9.8 m of 145 AE 24 Jy for the disk and star. Based on a dust thermal emission model for the observed IR spectral energy distribution and the 9.8 m AO image, we derive a disk dust mass of 1:6 ; 10 À6 M and an inclination of 30-45 from edge-on. We discuss whether the dust disk observed around RV Boo is an example of the early stages in the formation of asymmetric structure in planetary nebulae.

Research paper thumbnail of Adaptive Optics Nulling Interferometric Observations of AB Aur and V892 Tau: Resolved Disks in the Mid-IR

AAS, Dec 1, 2004

We present the results of adaptive optics nulling interferometric observations of two Herbig Ae s... more We present the results of adaptive optics nulling interferometric observations of two Herbig Ae stars, AB Aur and V892 Tau, at 10.3 microns. Our observations show resolved circumstellar emission from both sources. The emission from AB Aur suggests that there is an inclined disk surrounding the star. The diameter of the disk is derived to be 24 to 30 AU with an inclination of 45 to 65 degrees from face-on, and a major-axis PA of 30 +/- 15 degrees (E of N). Differences in the physical characteristics between the mid-IR emission and emission at other wavelengths found in previous studies suggest a complex structure for AB Aur's circumstellar environment, which may not be explained by a disk alone. The similarity in the observed size of AB Aur's resolved emission and that of another Herbig Ae star, HD 100546, is likely coincidental, as their respective evolutionary states and spectral energy distributions suggest significantly different circumstellar environments. The PI was supported under a Michelson Graduate Fellowship

Research paper thumbnail of Liquid Crystal Wavefront Correctors: Computer Simulation Results

Research paper thumbnail of Adaptive Secondary Development

Research paper thumbnail of Closed-loop performances of a modal MCAO system using real star configurations: the young open cluster NGC2362 as seen by MAD

European Southern Observatory Conference and Workshop Proceedings, 2002

We present in this contribution expected performances of a classical multi-conjugate adaptive opt... more We present in this contribution expected performances of a classical multi-conjugate adaptive optics (MCAO) modal system operating in closed-loop. The presented results were obtained by means of realistic numerical simulations considering natural asterisms of a few guide stars, measured Cn2 profiles, 8x8 Shack-Hartmann sensors, and two correcting mirrors, approaching so the actual situation of the ESO MAD (Multi-conjugate Adaptive optics

Research paper thumbnail of Measuring aspheric surfaces with reflection deflectometry

Spie Newsroom, Sep 18, 2013

Research paper thumbnail of Adaptive secondary mirrors performance and reliability improvements at the Large Binocular Telescope

The adaptive secondary mirrors (ASMs), being an integral part of the telescope optical train, hav... more The adaptive secondary mirrors (ASMs), being an integral part of the telescope optical train, have huge advantages over other wave-front correctors. At the same time, because of this specific characteristic, high performance and high reliability is required from an ASM. In this paper, we report on algorithm/software developments at the Large Binocular Telescope designed to improve performance and reliability of the two 672-voice-coil-actuators ASMs. By making use of the ASMs telemetry, we are able to intervene when critical condition occurs, monitor the daily operation of the ASMs and review the long-term trends to plan future maintenance activities.

Research paper thumbnail of Engineering aspects of the Large Binocular Telescope Observatory adaptive optics systems

Proceedings of SPIE, Jul 26, 2016

Vertical profiles of the atmospheric optical turbulence strength and velocity is of critical impo... more Vertical profiles of the atmospheric optical turbulence strength and velocity is of critical importance for simulating, designing, and operating the next generation of instruments for the European Extremely Large Telescope. Many of these instruments are already well into the design phase meaning these profies are required immediately to ensure they are optimised for the unique conditions likely to be observed. Stereo-SCIDAR is a generalised SCIDAR instrument which is used to characterise the profile of the atmospheric optical turbulence strength and wind velocity using triangulation between two optical binary stars. Stereo-SCIDAR has demonstrated the capability to resolve turbulent layers with the required vertical resolution to support wide-field ELT instrument designs. These high resolution atmospheric parameters are critical for design studies and statistical evaluation of on-sky performance under real conditions. Here we report on the new Stereo-SCIDAR instrument installed on one of the Auxillary Telescope ports of the Very Large Telescope array at Cerro Paranal. Paranal is located approximately 20 km from Cerro Armazones, the site of the E-ELT. Although the surface layer of the turbulence will be different for the two sites due to local geography, the high-altitude resolution profiles of the free atmosphere from this instrument will be the most accurate available for the E-ELT site. In addition, these unbiased and independent profiles are also used to further characterise the site of the VLT. This enables instrument performance calibration, optimisation and data analysis of, for example, the ESO Adaptive Optics facility and the Next Generation Transit Survey. It will also be used to validate atmospheric models for turbulence forecasting. We show early results from the commissioning and address future implications of the results.

Research paper thumbnail of HIGH-RESOLUTION MID-INFRARED IMAGING OF THE ASYMPTOTIC GIANT BRANCH STAR RV BOOTIS WITH THE STEWARD OBSERVATORY ADAPTIVE OPTICS SYSTEM B. A. Biller, L. M. Close, A. Li, 1 J. H. Bieging, W. F. Hoffmann, P. M. Hinz, D. Miller

We present high-resolution ($0B1), very high Strehl ratio (0:97 AE 0:03) mid-IR adaptive optics (... more We present high-resolution ($0B1), very high Strehl ratio (0:97 AE 0:03) mid-IR adaptive optics (AO) images of the asymptotic giant branch (AGB) star RV Boo utilizing the MMT adaptive secondary AO system. RV Boo was observed at a number of wavelengths over two epochs (9.8 m in 2003 May and 8.8, 9.8, and 11.7 m in 2004 February) and appeared slightly extended at all wavelengths. While the extension is very slight at 8.8 and 11.7 m, the extension is somewhat more pronounced at 9.8 m. With such high Strehl ratios, we can achieve superresolutions of 0B1 by deconvolving RV Boo with a point-spread function (PSF) derived from an unresolved star. We tentatively resolve RV Boo into a 0B16 FWHM extension at a position angle of 120. At a distance of 390 þ250 À100 pc, this corresponds to a FWHM of 60 þ40 À15 AU. We measure a total flux at 9.8 m of 145 AE 24 Jy for the disk and star. Based on a dust thermal emission model for the observed IR spectral energy distribution and the 9.8 m AO image, we derive a disk dust mass of 1:6 ; 10 À6 M and an inclination of 30-45 from edge-on. We discuss whether the dust disk observed around RV Boo is an example of the early stages in the formation of asymmetric structure in planetary nebulae.

Research paper thumbnail of Statistical Properties of a Class of Deterministic Cellular Automata

Europhysics Letters (EPL), 1989

Research paper thumbnail of Observations of Herbig Ae Disks with Nulling Interferometry

The Astrophysical Journal, Apr 1, 2007

We present the results of 10 µm nulling interferometric observations of 13 Herbig Ae stars using ... more We present the results of 10 µm nulling interferometric observations of 13 Herbig Ae stars using the Magellan I (Baade) and the MMT 6.5 m telescopes. A portion of the observations was completed with the adaptive secondary at the MMT. We have conclusively spatially resolved 3 of the 13 stars, HD 100546, AB Aur, and HD 179218, the latter two recently resolved using adaptive optics in combination with nulling interferometry. For the resolved objects we find that the 10 µm emitting regions have a spatial extent of 15-30 AU in diameter. We also have some evidence for resolved emission surrounding an additional 2 stars (V892 Tau and R CrA). For those objects in our study with mid-IR SEDs classifications from Meeus et al. (2001), we find that the Group I objects (those with constant to increasing mid-IR flux) are more likely to be resolved, within our limited sample. This trend is evident in correlations in the inferred disk sizes vs. the sub-millimeter SED slope and disk size vs. fractional infrared luminosity of the systems. We explore the spatial distribution and orientation of the warm dust in the resolved systems and constrain physical models which are consistent with their observational signatures.

Research paper thumbnail of First light of the 6.5-m MMT adaptive optics system

Proceedings of SPIE, Dec 31, 2003

The adaptive optics system of the 6.5m MMT with its deformable secondary has seen first light on ... more The adaptive optics system of the 6.5m MMT with its deformable secondary has seen first light on the sky in November 2002. Since then, it has logged over 30 nights at the telescope and has been used with several scientific cameras and a dedicated IR infrared camera. Results so far are extremely encouraging with Strehls of up to 20% in H-band and 98% in M limited in part by the control algorithm that is being improved. Reliability of the deformable secondary mirror (DM) has been remarkable with only one occurrence of a malfunction that required removing the secondary from its hub. In this paper, we review the milestones achieved and the performances obtained in the first year of operation. We will also address the operational constraints associated with the deformable secondary and the steps taken to relax these constraints. We show that despite its apparent complexity, an adaptive secondary AO system can be operated with modest effort from the telescope and AO staff

Research paper thumbnail of Adaptive Optics Science with the MMT Adaptive Secondary: Mid-IR AO Imaging of the Post-AGB Star AC Her

Springer eBooks, Nov 17, 2005

The world's first adaptive secondary has been commissioned at the 6.5 m MMT. Early science r... more The world's first adaptive secondary has been commissioned at the 6.5 m MMT. Early science results suggests that it is unique and highly productive. Nearly diffraction-limited 0.07” H band images have been obtained of the Trapezium core [Close et al. 2003b]. ...

Research paper thumbnail of Off-line and on-line modal optimization of the MMT-AO system

Proceedings of SPIE, Aug 18, 2005

The MMT adaptive optics system has been in operation for over 2 years. 1, 2 Besides being a techn... more The MMT adaptive optics system has been in operation for over 2 years. 1, 2 Besides being a technological demonstration, it has achieved remarkable success. 3, 4 However, the system is presently limited by a few factors, one of which is the lack of an optimised controller. In this paper, we review the optimised modal integrator as introduced in Ref 5 and evaluate its potential for MMT-AO. We nd that it can indeed increase the system sensitivity by one magnitude but that a careful analysis of wave front sensor data must be performed to remove artefacts that can severely bias the outcome of the optimization.

Research paper thumbnail of Final review of adaptive optics results from the preconversion MMT

Proceedings of SPIE, Oct 17, 1997

The FASTTRAC II adaptive optics instrument has been used at the Multiple Mirror Telescope (MMT) f... more The FASTTRAC II adaptive optics instrument has been used at the Multiple Mirror Telescope (MMT) for the past 2 years to provide improved image resolution in the near infrared. Results have been obtained using both natural guide stars and an artificial sodium laser beacon. With the imminent closure of the MMT prior to its conversion to a single-mirror 6.5 m telescope, FASTTRAC II has come to the end of its life. The instrument has been to the telescope for a total of 8 runs, and during that time it has been of enormous value both as a learning aid, demonstrating the requirements of its successor on the 6.5 m, and as a scientific tool. At this meeting, we present a selection of astrophysical data derived from FASTTRAC II, including the first closed-loop demonstration of an adaptive optics system using a sodium laser beacon. The sodium laser has been used to obtain near diffraction-limited near-infrared images of the core of M13, allowing the construction of a color-magnitude diagram to below the main sequence turnoff. Results have also been obtained from several gravitationally lensed quasars, and the cores of nearby galaxies in the local group. We also summarize work characterizing atmospheric conditions at the site. These studies have proceeded in two areasunderstanding the behavior of the phase perturbation with field angle and time, and characterizing the return from the sodium resonance beacon.

Research paper thumbnail of Toward visible wavelength coherent imaging with the LBT

Proceedings of SPIE, Jul 24, 2014

ABSTRACT The Large Binocular Telescope with its integrated adaptive optics systems and the LBTI b... more ABSTRACT The Large Binocular Telescope with its integrated adaptive optics systems and the LBTI beamcombiner provides a good platform for carrying out coherent imagin across its 22.7 m baseline. The first cameras used with LBTI have focused on infrared wavelengths. We describe a concept, called the LBT Interferometer Visible Extension (LIVE) to carry out coherent imaging with the LBT at visible wavelengths. LIVE will be able to create images of some of the stars with the largest angular diameters, map the surface of solar system moons, and provide detailed imaging of the inner scattered light regions of protoplanetary and transition disks. An initial approach can use the beamcombiner with its existing infrared phase sensor to carry out coherent imaging using frame selection to improve the image quality. Refined and more versatile phase sensing and correction can be implemented in a second stage to enable observations of a wider range of targets. LIVE will work both as a coherent imager, as well as a flexible dual aperture AO imager where simultaneous differential measurements can be made through independent use of each arm. We describe the science case and technical description below. We plan to develop the system with a flexible approach that allows increasingly complex modes of observation to be added once the basic performance is demonstrated.

Research paper thumbnail of PCR: a PC-based wave front reconstructor for MMT-AO

Proceedings of SPIE, Jul 12, 2008

... We thank Manny Montoya, Matthew Kenworthy, Richard Sosa and the MMT operators for their valua... more ... We thank Manny Montoya, Matthew Kenworthy, Richard Sosa and the MMT operators for their valuable contributions. 12. ... 2. Christoph Baranac, Michael Llyod-Hart, N. Mark Milton, ThomasStalcup, Miguel Snyder, Vidhya Vaitheeswaran, Don McCarthy, and Roger Anger ...

Research paper thumbnail of Adaptive optics capabilities at the Large Binocular Telescope Observatory

Proceedings of SPIE, Jul 26, 2016

We present an overview of the current and future adaptive optics systems at the LBTO along with t... more We present an overview of the current and future adaptive optics systems at the LBTO along with the current and planned science instruments they feed. All the AO systems make use of the two 672 actuator adaptive secondary mirrors. They are (1) FLAO (NGS/SCAO) feeding the LUCI NIR imagers/spectrographs; (2) LBTI/AO (NGS/SCAO) feeding the NIR/MIR imagers and LBTI beam combiner; (3) the ARGOS LGS GLAO system feeding LUCIs; and (4) LINC-NIRVANA-an NGS/MCAO imager and interferometer system. AO performance of the current systems is presented along with proposed performances for the newer systems taking into account the future instrumentation.

Research paper thumbnail of Determining the interaction matrix using starlight

Proceedings of SPIE, Oct 25, 2004

ABSTRACT

Research paper thumbnail of Status of the NGS adaptive optic system at the MMT Telescope

Proceedings of SPIE, Oct 25, 2004

The Natural Guide Star (NGS) Adaptive Optics System at the MMT Telescope (MMTAO) on Mt. Hopkins i... more The Natural Guide Star (NGS) Adaptive Optics System at the MMT Telescope (MMTAO) on Mt. Hopkins in Southern Arizona is the first in the world the use the secondary mirror as the correcting deformable mirror. Its 2.0 mm thin shell mirror, whose shape is controlled by 336 voice coil actuators, allows for nearly maximum throughput of light into the science camera. With several more deformable secondary mirrors coming online in the next few years, the lessons learned building, characterizing and operating the MMT Adaptive Optic System has proven to be quite valuable. These lessons will be discussed as well as future plans for the MMTAO System.

Research paper thumbnail of High‐Resolution Mid‐Infrared Imaging of the Asymptotic Giant Branch Star RV Bootis with the Steward Observatory Adaptive Optics System

The Astrophysical Journal, Feb 10, 2005

We present high-resolution ($0B1), very high Strehl ratio (0:97 AE 0:03) mid-IR adaptive optics (... more We present high-resolution ($0B1), very high Strehl ratio (0:97 AE 0:03) mid-IR adaptive optics (AO) images of the asymptotic giant branch (AGB) star RV Boo utilizing the MMT adaptive secondary AO system. RV Boo was observed at a number of wavelengths over two epochs (9.8 m in 2003 May and 8.8, 9.8, and 11.7 m in 2004 February) and appeared slightly extended at all wavelengths. While the extension is very slight at 8.8 and 11.7 m, the extension is somewhat more pronounced at 9.8 m. With such high Strehl ratios, we can achieve superresolutions of 0B1 by deconvolving RV Boo with a point-spread function (PSF) derived from an unresolved star. We tentatively resolve RV Boo into a 0B16 FWHM extension at a position angle of 120. At a distance of 390 þ250 À100 pc, this corresponds to a FWHM of 60 þ40 À15 AU. We measure a total flux at 9.8 m of 145 AE 24 Jy for the disk and star. Based on a dust thermal emission model for the observed IR spectral energy distribution and the 9.8 m AO image, we derive a disk dust mass of 1:6 ; 10 À6 M and an inclination of 30-45 from edge-on. We discuss whether the dust disk observed around RV Boo is an example of the early stages in the formation of asymmetric structure in planetary nebulae.

Research paper thumbnail of Adaptive Optics Nulling Interferometric Observations of AB Aur and V892 Tau: Resolved Disks in the Mid-IR

AAS, Dec 1, 2004

We present the results of adaptive optics nulling interferometric observations of two Herbig Ae s... more We present the results of adaptive optics nulling interferometric observations of two Herbig Ae stars, AB Aur and V892 Tau, at 10.3 microns. Our observations show resolved circumstellar emission from both sources. The emission from AB Aur suggests that there is an inclined disk surrounding the star. The diameter of the disk is derived to be 24 to 30 AU with an inclination of 45 to 65 degrees from face-on, and a major-axis PA of 30 +/- 15 degrees (E of N). Differences in the physical characteristics between the mid-IR emission and emission at other wavelengths found in previous studies suggest a complex structure for AB Aur's circumstellar environment, which may not be explained by a disk alone. The similarity in the observed size of AB Aur's resolved emission and that of another Herbig Ae star, HD 100546, is likely coincidental, as their respective evolutionary states and spectral energy distributions suggest significantly different circumstellar environments. The PI was supported under a Michelson Graduate Fellowship

Research paper thumbnail of Liquid Crystal Wavefront Correctors: Computer Simulation Results

Research paper thumbnail of Adaptive Secondary Development

Research paper thumbnail of Closed-loop performances of a modal MCAO system using real star configurations: the young open cluster NGC2362 as seen by MAD

European Southern Observatory Conference and Workshop Proceedings, 2002

We present in this contribution expected performances of a classical multi-conjugate adaptive opt... more We present in this contribution expected performances of a classical multi-conjugate adaptive optics (MCAO) modal system operating in closed-loop. The presented results were obtained by means of realistic numerical simulations considering natural asterisms of a few guide stars, measured Cn2 profiles, 8x8 Shack-Hartmann sensors, and two correcting mirrors, approaching so the actual situation of the ESO MAD (Multi-conjugate Adaptive optics

Research paper thumbnail of Measuring aspheric surfaces with reflection deflectometry

Spie Newsroom, Sep 18, 2013

Research paper thumbnail of Adaptive secondary mirrors performance and reliability improvements at the Large Binocular Telescope

The adaptive secondary mirrors (ASMs), being an integral part of the telescope optical train, hav... more The adaptive secondary mirrors (ASMs), being an integral part of the telescope optical train, have huge advantages over other wave-front correctors. At the same time, because of this specific characteristic, high performance and high reliability is required from an ASM. In this paper, we report on algorithm/software developments at the Large Binocular Telescope designed to improve performance and reliability of the two 672-voice-coil-actuators ASMs. By making use of the ASMs telemetry, we are able to intervene when critical condition occurs, monitor the daily operation of the ASMs and review the long-term trends to plan future maintenance activities.

Research paper thumbnail of Engineering aspects of the Large Binocular Telescope Observatory adaptive optics systems

Proceedings of SPIE, Jul 26, 2016

Vertical profiles of the atmospheric optical turbulence strength and velocity is of critical impo... more Vertical profiles of the atmospheric optical turbulence strength and velocity is of critical importance for simulating, designing, and operating the next generation of instruments for the European Extremely Large Telescope. Many of these instruments are already well into the design phase meaning these profies are required immediately to ensure they are optimised for the unique conditions likely to be observed. Stereo-SCIDAR is a generalised SCIDAR instrument which is used to characterise the profile of the atmospheric optical turbulence strength and wind velocity using triangulation between two optical binary stars. Stereo-SCIDAR has demonstrated the capability to resolve turbulent layers with the required vertical resolution to support wide-field ELT instrument designs. These high resolution atmospheric parameters are critical for design studies and statistical evaluation of on-sky performance under real conditions. Here we report on the new Stereo-SCIDAR instrument installed on one of the Auxillary Telescope ports of the Very Large Telescope array at Cerro Paranal. Paranal is located approximately 20 km from Cerro Armazones, the site of the E-ELT. Although the surface layer of the turbulence will be different for the two sites due to local geography, the high-altitude resolution profiles of the free atmosphere from this instrument will be the most accurate available for the E-ELT site. In addition, these unbiased and independent profiles are also used to further characterise the site of the VLT. This enables instrument performance calibration, optimisation and data analysis of, for example, the ESO Adaptive Optics facility and the Next Generation Transit Survey. It will also be used to validate atmospheric models for turbulence forecasting. We show early results from the commissioning and address future implications of the results.

Research paper thumbnail of HIGH-RESOLUTION MID-INFRARED IMAGING OF THE ASYMPTOTIC GIANT BRANCH STAR RV BOOTIS WITH THE STEWARD OBSERVATORY ADAPTIVE OPTICS SYSTEM B. A. Biller, L. M. Close, A. Li, 1 J. H. Bieging, W. F. Hoffmann, P. M. Hinz, D. Miller

We present high-resolution ($0B1), very high Strehl ratio (0:97 AE 0:03) mid-IR adaptive optics (... more We present high-resolution ($0B1), very high Strehl ratio (0:97 AE 0:03) mid-IR adaptive optics (AO) images of the asymptotic giant branch (AGB) star RV Boo utilizing the MMT adaptive secondary AO system. RV Boo was observed at a number of wavelengths over two epochs (9.8 m in 2003 May and 8.8, 9.8, and 11.7 m in 2004 February) and appeared slightly extended at all wavelengths. While the extension is very slight at 8.8 and 11.7 m, the extension is somewhat more pronounced at 9.8 m. With such high Strehl ratios, we can achieve superresolutions of 0B1 by deconvolving RV Boo with a point-spread function (PSF) derived from an unresolved star. We tentatively resolve RV Boo into a 0B16 FWHM extension at a position angle of 120. At a distance of 390 þ250 À100 pc, this corresponds to a FWHM of 60 þ40 À15 AU. We measure a total flux at 9.8 m of 145 AE 24 Jy for the disk and star. Based on a dust thermal emission model for the observed IR spectral energy distribution and the 9.8 m AO image, we derive a disk dust mass of 1:6 ; 10 À6 M and an inclination of 30-45 from edge-on. We discuss whether the dust disk observed around RV Boo is an example of the early stages in the formation of asymmetric structure in planetary nebulae.