Dr. Julian C. Christou Profile

Dr. Julian C. Christou

Adaptive Optics Scientist at Gemini Observatory

SPIE Involvement:

Author

Publications (66)

Proceedings Article | 28 August 2024 Poster

Poster

Gemini 2.0: Gemini North wide-field ground layer adaptive optics

Christophe Clergeon, Natalia McCarthy, Christy Cunningham, Ruben Diaz, Paul Hirst, Thomas Hayward, Julia Scharwächter, Julian Christou, Gabriel Perez, Claudio Gaspar, Pedro Gigoux, Thomas Schneider, Kimberly Tomasino-Reed, Rolando Rogers, Martin Tschimmel, Jesse Ball

Proceedings Volume 13097, 130976V (2024) https://doi.org/10.1117/12.3020693

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Proceedings Article | 28 August 2024 Presentation

Presentation

US adaptive optics roadmap to achieve Astro2020

Julian Christou, Peter Wizinowich

Proceedings Volume 13097, 130971F (2024) https://doi.org/10.1117/12.3025881

KEYWORDS: Adaptive optics, Telescopes, Imaging systems, Wavefront sensors, Spatial resolution, Space operations, Optical coherence, Equipment, Diffraction limit, Astrophysics

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Proceedings Article | 27 August 2024 Presentation + Paper

Presentation + Paper

Adaptive optics at Gemini observatories: past, present, and future

Célia Blain, Julian Christou, Christophe Clergeon, Ruben Diaz, Aurea Garcia-Rissmann, Vincent Garrel, Stephen Goodsell, Masen Lamb, Garima Singh, Gaetano Sivo

Proceedings Volume 13097, 130970M (2024) https://doi.org/10.1117/12.3019127

KEYWORDS: Adaptive optics, Gemini Observatory, Equipment, Telescopes, Design, Gemini Planet Imager, Imaging systems, Real-time computing, Wavefront sensors

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Proceedings Article | 21 August 2024 Poster + Paper

Poster + Paper

ALTAIR, Gemini North SCAO: challenges and performance review

Christophe Clergeon, John White, Eduardo Tapia, Andrew Stephens, Thomas Schneider, Emma Kurz, Jesse Ball, Hawi Stecher, Atsuko Nitta, Vincent Garrel, Garima Singh, Julian Christou, Andy Adamson

Proceedings Volume 13096, 130969I (2024) https://doi.org/10.1117/12.3020913

KEYWORDS: Gemini Observatory, Adaptive optics, Deformable mirrors, Near infrared

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Proceedings Article | 25 August 2022 Presentation + Paper

Presentation + Paper

SHARK-NIR: from design to installation, ready to dive into first light

M. Bergomi, L. Marafatto, E. Carolo, D. Greggio, D. Ricci, D. Vassallo, L. Lessio, K. K. Radhakrishnan Santhakumari, G. Umbriaco, M. Dima, S. Di Filippo, V. D'Orazi, D. Mesa, M. Montoya, L. Mohr, V. Viotto, A. Baruffolo, F. Biondi, S. Chavan, Si. Chinellato, M. De Pascale, K. Don, P. Grenz, F. Laudisio, J. Leisenrin, R. Ragazzoni, F. Pedichini, R. Piazzesi, E. Pinna, A. Puglisi, A. Bianco, A. Carlotti, C. Knapic, M. Vicinanza, A. Zanutta, J. Christou, A. Conrad, L. Funk, C. Veillet, J. Farinato

Proceedings Volume 12187, 1218709 (2022) https://doi.org/10.1117/12.2629388

KEYWORDS: Telescopes, Cameras, Coronagraphy, Observatories, Optical benches, Sensors, Electronics, Adaptive optics, Spectroscopes

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Proceedings Article | 14 December 2020 Presentation

Presentation

Adaptive optics all the time at the LBTO

Julian Christou, Christian Veillet, Douglas Miller, Guido Brusa, Alessandaro Cavallaro, Gregory Taylor, Laura Funk, Al Conrad, Gustavo Rahmer, Xianyu Zhang, Shane Walsh, Steve Ertel, Enrico Pinna, Simone Esposito

Proceedings Volume 11448, 1144824 (2020) https://doi.org/10.1117/12.2562443

KEYWORDS: Adaptive optics, Calibration, Mirrors, Wavefront sensors, Image quality, Reliability, Actuators, Wavefronts, Matrices

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Proceedings Article | 13 December 2020 Poster + Paper

Poster + Paper

Neural network wavefront sensor for the Large Binocular Telescope Observatory

Pedro Escárate, Gustavo Rahmer, Julian Christou

Proceedings Volume 11448, 114484F (2020) https://doi.org/10.1117/12.2562406

KEYWORDS: Observatories, Wavefront sensors, Telescopes, Adaptive optics, Stars, Laser applications, Image quality, Atmospheric optics, Laser systems engineering, Sodium

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Proceedings Article | 13 December 2020 Poster + Paper

Poster + Paper

Adaptive secondary mirrors performance and reliability improvements at the Large Binocular Telescope

Xianyu Zhang, Guido Brusa, Douglas Miller, Matthieu Bec, Julian Christou, Armando Riccardi, Marco Xompero

Proceedings Volume 11448, 114485O (2020) https://doi.org/10.1117/12.2560850

KEYWORDS: Telescopes, Reliability, Mirrors, Failure analysis, Adaptive optics, Algorithm development, Complex systems, Actuators, Databases, Interfaces

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Proceedings Article | 13 December 2020 Poster + Paper

Poster + Paper

Adaptive secondary mirrors upgrades at the Large Binocular Telescope

Guido Brusa, Xianyu Zhang, Michael Lefebvre, Julian Christou, Albert Conrad, Roberto Biasi, Mario Andrighettoni, Martin Glück, Moritz Straub, Jörg-Uwe Pott

Proceedings Volume 11448, 114485T (2020) https://doi.org/10.1117/12.2563092

KEYWORDS: Telescopes, Mirrors, Interferometers, Control systems, Electronics, Adaptive optics, Cameras, New and emerging technologies, Reliability, Signal attenuation

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Proceedings Article | 13 December 2020 Poster + Paper

Poster + Paper

Enhanced seeing mode: a technique for improving wide-field angular resolution in the near-infrared using adaptive optics

Barry Rothberg, Julian Christou, Douglas Miller, Dave Thompson, Gregory Taylor, Christian Veillet, R. Gatto

Proceedings Volume 11448, 114485I (2020) https://doi.org/10.1117/12.2563359

KEYWORDS: Adaptive optics, Spatial resolution, Electronic support measures, Cameras, Stars, Imaging spectroscopy, Image quality, Infrared telescopes, Infrared cameras, Image quality standards

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Proceedings Article | 3 January 2020 Paper

Paper

GNAO: an MCAO facility for Gemini North

Gaetano Sivo, David Palmer, Julia Scahrwächter, Morten Andersen, Natalie Provost, Eduardo Marin, Marcos van Dam, Brian Chinn, Emmanuel Chirre, Charles Cavedoni, Thomas Schneider, Stacy Kang, Paul Hirst, William Rambold, Angelic Ebbers, Pedro Gigoux, Laure Catala, Thomas Hayward, John Blakeslee, Henry Roe, Jennifer Lotz, Scot Kleinman, Suresh Sivanandam, Anja Krause, Mark Ammons, Chadwick Trujillo, Chris Packham, Franck Marchis, Julian Christou, James Jee, John Bally, Mike Pierce, Thomas Puzia, Paolo Turri, Hwihyun Kim, Meg Schwamb, Trent Dupuy, Ruben Diaz, Rodrigo Carrasco, Benoit Neichel, Carlos Correia, Eric Steinbring, François Rigaut, Jean-Pierre Véran, Mark Chun, Masen Lamb, Scott Chapman, Simone Esposito, Thierry Fusco

Proceedings Volume 11203, 112030N (2020) https://doi.org/10.1117/12.2539706

KEYWORDS: Gemini Observatory, Adaptive optics, Telescopes, Astronomy, Laser guide stars, Stars, Observatories, Imaging systems, Diffraction, Spatial resolution

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Proceedings Article | 18 July 2018 Paper

Paper

Vibration environment of the LBTO/AO system

Pedro Escárate, Julian Christou, Gustavo Rahmer, John Hill, Doug Miller, Greg Taylor

Proceedings Volume 10703, 107034F (2018) https://doi.org/10.1117/12.2313882

KEYWORDS: Adaptive optics, Telescopes, Wavefront sensors, Atmospheric propagation, Deformable mirrors, Astronomy, Image quality

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Proceedings Article | 13 July 2018 Presentation + Paper

Presentation + Paper

Adaptive optics systems at the Large Binocular Telescope: status, upgrades, and improvements

Julian Christou, Guido Brusa, Al Conrad, John Hill, Douglas Miller, Gustavo Rahmer, Gregory Taylor, Christian Veillet, Xianyu Zhang

Proceedings Volume 10703, 107030A (2018) https://doi.org/10.1117/12.2312782

KEYWORDS: Adaptive optics, Telescopes, Stars, Interferometry, Cameras, Mirrors, Sensors, Electronic support measures, Actuators, Spectroscopy

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Proceedings Article | 10 July 2018 Paper

Paper

Recurrence quantification analysis as a post-processing technique in adaptive optics high contrast imaging

M. Stangalini, G. Li Causi, F. Pedichini, S. Antoniucci, M. Mattioli, J. Christou, G. Consolini, D. Hope, S. Jefferies, R. Piazzesi, V. Testa

Proceedings Volume 10703, 107032V (2018) https://doi.org/10.1117/12.2313355

KEYWORDS: Signal detection, Adaptive optics, Point spread functions, Astronomy, Photons, Astronomical imaging, Dynamical systems, Analytical research, Interference (communication), Data acquisition

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Proceedings Article | 10 July 2018 Paper

Paper

Airplanes and satellites: how to keep LGS operations efficient and safe at the Large Binocular Telescope Observatory

Gustavo Rahmer, Michael Lefebvre, Julian Christou

Proceedings Volume 10704, 107042P (2018) https://doi.org/10.1117/12.2314105

KEYWORDS: Telescopes, Satellites, Observatories, Antennas, Space telescopes, Signal detection, Mirrors, Laser safety, Laser beam propagation, Adaptive optics

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SPIE Journal Paper | 25 April 2017

Speckle statistics in adaptive optics images at visible wavelengths

Marco Stangalini, Fernando Pedichini, Enrico Pinna, Julian Christou, John Hill, Alfio Puglisi, Vanessa Bailey, Mauro Centrone, Dario Del Moro, Simone Esposito, Fabrizio Fiore, Emanuele Giallongo, Phil Hinz, Amali Vaz

JATIS, Vol. 3, Issue 02, 025001, (April 2017) https://doi.org/10.1117/12.10.1117/1.JATIS.3.2.025001

KEYWORDS: Adaptive optics, Speckle, Speckle pattern, Point spread functions, Statistical analysis, Imaging systems, Data acquisition, Coronagraphy, Atmospheric optics, Telescopes

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Proceedings Article | 1 August 2016 Paper

Paper

LBTO's long march to full operation: step 2

Christian Veillet, David Ashby, Julian Christou, John Hill, John Little, Douglas Summers, R. Mark Wagner, Elena Masciadri, Alessio Turchi

Proceedings Volume 9910, 99100S (2016) https://doi.org/10.1117/12.2234570

KEYWORDS: Telescopes, Interferometry, Adaptive optics, Observatories, Control systems, Mirrors, Cameras, Spectroscopy, Virtual colonoscopy, Gemini Observatory

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Proceedings Article | 27 July 2016 Paper

Paper

Adaptive optics operations at the Large Binocular Telescope Observatory

Douglas Miller, Gregory Taylor, Julian Christou, Xianyu Zhang, Guido Brusa Zappellini, Gustavo Rahmer, Michael Lefebvre, Alfio Puglisi, Enrico Pinna, Simone Esposito

Proceedings Volume 9909, 99092G (2016) https://doi.org/10.1117/12.2234324

KEYWORDS: Adaptive optics, Telescopes, Observatories, Stars, Mirrors, Actuators, Monochromatic aberrations, Calibration, Sensors, Active optics

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Proceedings Article | 27 July 2016 Paper

Paper

Telescope performance at the Large Binocular Telescope

John Hill, Barry Rothberg, Julian Christou, Kellee Summers, Douglas Summers

Proceedings Volume 9906, 99064L (2016) https://doi.org/10.1117/12.2234466

KEYWORDS: Telescopes, Mirrors, Image quality, Adaptive optics, Observatories, Stars, Active optics, Cameras, Monochromatic aberrations, Control systems

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Proceedings Article | 27 July 2016 Paper

Paper

Adaptive optics capabilities at the Large Binocular Telescope Observatory

J. Christou, G. Brusa, A. Conrad, S. Esposito, T. Herbst, P. Hinz, J. Hill, D. Miller, S. Rabien, G. Rahmer, G. Taylor, C. Veillet, X. Zhang

Proceedings Volume 9909, 99092E (2016) https://doi.org/10.1117/12.2231783

KEYWORDS: Adaptive optics, Telescopes, Imaging systems, Mirrors, Stars, Optical benches, Sensors, Interferometry, Cameras, Point spread functions

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Proceedings Article | 26 July 2016 Paper

Paper

Engineering aspects of the Large Binocular Telescope Observatory adaptive optics systems

Guido Brusa, Dave Ashby, Julian Christou, Jonathan Kern, Michael Lefebvre, Tom McMahon, Douglas Miller, Gustavo Rahmer, Richard Sosa, Gregory Taylor, Conrad Vogel, Xianyu Zhang

Proceedings Volume 9909, 990903 (2016) https://doi.org/10.1117/12.2234733

KEYWORDS: Adaptive optics, Telescopes, Sensors, Mirrors, Calibration, Control systems, Actuators, Coating, Observatories, Interferometers

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Proceedings Article | 15 July 2016 Paper

Paper

Aircraft avoidance for laser propagation at the Large Binocular Telescope Observatory: life under a busy airspace

Gustavo Rahmer, Michael Lefebvre, Julian Christou

Proceedings Volume 9910, 99102G (2016) https://doi.org/10.1117/12.2231909

KEYWORDS: Transmission electron microscopy, Spherical lenses, Visibility, Wave propagation, Interferometry, Antennas, Physics, Sensors, Beam propagation method, Polarization

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Proceedings Article | 6 August 2014 Paper

Paper

LBTO's long march to full operation - step 1

C. Veillet, J. Brynnel, J. Hill, R. Wagner, D. Ashby, J. Christou, J. Little, D. Summers

Proceedings Volume 9149, 914916 (2014) https://doi.org/10.1117/12.2055744

KEYWORDS: Telescopes, Adaptive optics, Observatories, Mirrors, Interferometry, Space telescopes, Interferometers, Cameras, Sensors, Sun

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Proceedings Article | 6 August 2014 Paper

Paper

Early laser operations at the Large Binocular Telescope Observatory

Gustavo Rahmer, Michael Lefebvre, Julian Christou, Walfried Raab, Sebastian Rabien, Julian Ziegleder, José Borelli, Wolfgang Gässler

Proceedings Volume 9149, 91492A (2014) https://doi.org/10.1117/12.2056774

KEYWORDS: Telescopes, Laser safety, Space telescopes, Observatories, Laser systems engineering, Safety, Space operations, Satellites, Mirrors, Visualization

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Proceedings Article | 4 August 2014 Paper

Paper

Living with adaptive secondary mirrors 365/7/24

Julian Christou, Guido Brusa , Juan Carlos Guerra , Michael Lefebvre, Douglas Miller, Gustavo Rahmer, Richard Sosa, Michael Wagner

Proceedings Volume 9148, 91480F (2014) https://doi.org/10.1117/12.2056361

KEYWORDS: Actuators, Telescopes, Adaptive optics, Mirrors, Contamination, Digital signal processing, Wavefront sensors, Electronics, Wavefronts, Sensors

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Proceedings Article | 24 July 2014 Paper

Paper

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

D. Defrère, P. Hinz, E. Downey, D. Ashby, V. Bailey, G. Brusa , J. Christou, W. Danchi, P. Grenz, J. Hill, W. Hoffmann, J. Leisenring, J. Lozi, T. McMahon, B. Mennesson, R. Millan-Gabet, M. Montoya, K. Powell, A. Skemer, V. Vaitheeswaran, A. Vaz, C. Veillet

Proceedings Volume 9146, 914609 (2014) https://doi.org/10.1117/12.2057178

KEYWORDS: Telescopes, Mirrors, Phase measurement, Interferometry, Nulling interferometry, Sensors, Space telescopes, Interferometers, Infrared imaging, Exoplanets

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Proceedings Article | 21 July 2014 Paper

Paper

Status of the ARGOS project

Sebastian Rabien, Lothar Barl, Udo Beckmann, Marco Bonaglia, José Luis Borelli, Joar Brynnel, Peter Buschkamp, Lorenzo Busoni, Julian Christou, Claus Connot, Richard Davies, Matthias Deysenroth, Simone Esposito, Wolfgang Gässler, Hans Gemperlein, Michael Hart, Martin Kulas, Michael Lefebvre, Michael Lehmitz, Tommaso Mazzoni, Edmund Nussbaum, Gilles Orban de Xivry, Diethard Peter, Andreas Quirrenbach, Walfried Raab, Gustavo Rahmer, Jesper Storm, Julian Ziegleder

Proceedings Volume 9148, 91481B (2014) https://doi.org/10.1117/12.2055932

KEYWORDS: Wavefront sensors, Sensors, Telescopes, Laser guide stars, Mirrors, Adaptive optics, Calibration, Stars, Laser systems engineering, Imaging spectroscopy

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Proceedings Article | 10 July 2014 Paper

Paper

The Large Binocular Telescope: binocular all the time

J. Hill, D. Ashby, J. Brynnel, J. Christou, John Little, D. Summers, C. Veillet, R. Wagner

Proceedings Volume 9145, 914502 (2014) https://doi.org/10.1117/12.2055218

KEYWORDS: Telescopes, Adaptive optics, Mirrors, Stars, Cameras, Spectroscopy, Wavefront sensors, Collimation, Observatories, Active optics

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Proceedings Article | 26 September 2013 Paper

Paper

The LBT experience of adaptive secondary mirror operations for routine seeing- and diffraction-limited science operations

J. Guerra, G. Brusa, J. Christou, D. Miller, A. Ricardi, M. Xompero, R. Briguglio, M. Wagner, M. Lefebvre, R. Sosa

Proceedings Volume 8860, 886014 (2013) https://doi.org/10.1117/12.2034002

KEYWORDS: Telescopes, Contamination, Mirrors, Adaptive optics, Actuators, Space telescopes, Failure analysis, Point spread functions, Active optics, Observatories

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Proceedings Article | 24 September 2012 Paper

Paper

Gemini's instrumentation program: latest results and long-range plan

Maxime Boccas, S. Kleinman, Stephen Goodsell, Eric Tollestrup, Andrew Adamson, Gustavo Arriagada, Julian Christou, Patricio Gonzalez, Kevin Hanna, Markus Hartung, Manuel Lazo, Rachel Mason, Benoît Neichel, Gabriel Perez, Doug Simons, Brian Walls, John White

Proceedings Volume 8446, 844606 (2012) https://doi.org/10.1117/12.925516

KEYWORDS: Gemini Observatory, Spectrographs, Observatories, Adaptive optics, Telescopes, Sensors, Gemini Planet Imager, Mid-IR, Charge-coupled devices, Stars

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Proceedings Article | 13 September 2012 Paper

Paper

Adaptive optics point spread function reconstruction project at W. M. Keck Observatory: first results with faint natural guide stars

Laurent Jolissaint, Chris Neyman, Julian Christou, Peter Wizinowich

Proceedings Volume 8447, 844728 (2012) https://doi.org/10.1117/12.926607

KEYWORDS: Adaptive optics, Point spread functions, Stars, Actuators, Keck Observatory, Telescopes, Optical transfer functions, Interference (communication), Wavefronts, Data modeling

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Proceedings Article | 13 September 2012 Paper

Paper

Vibrations in AO control: a short analysis of on-sky data around the world

Caroline Kulcsár, Gaetano Sivo, Henri-François Raynaud, Benoît Neichel, Franҫois Rigaut, Julian Christou, Andres Guesalaga, Carlos Correia, Jean-Pierre Véran, Eric Gendron, Fabrice Vidal, Gérard Rousset, Tim Morris, Simone Esposito, Fernando Quiros-Pacheco, Guido Agapito, Enrico Fedrigo, Lorenzo Pettazzi, Richard Clare, Riccardo Muradore, Olivier Guyon, Frantz Martinache, Serge Meimon, Jean-Marc Conan

Proceedings Volume 8447, 84471C (2012) https://doi.org/10.1117/12.925984

KEYWORDS: Adaptive optics, Telescopes, Gemini Observatory, Gemini Planet Imager, Data acquisition, Turbulence, Autoregressive models, Coronagraphy, Visible radiation, Performance modeling

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Proceedings Article | 13 September 2012 Paper

Paper

Retrieving the telescope and instrument static wavefront aberration with a phase diversity procedure using on-sky adaptive optics corrected images

Laurent Jolissaint, Laurent Mugnier, Chris Neyman, Julian Christou, Peter Wizinowich

Proceedings Volume 8447, 844716 (2012) https://doi.org/10.1117/12.926637

KEYWORDS: Wavefronts, Point spread functions, Adaptive optics, Telescopes, Sensors, Error analysis, Calibration, Wavefront reconstruction, Vignetting, Space telescopes

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Proceedings Article | 13 September 2012 Paper

Paper

Increasing sky coverage with the Gemini North ALTAIR/LGS AO system

Julian Christou, Maxime Boccas, Angelic Ebbers, Richard McDermid, Richard Oram, Chadwick Trujillo, Brian Walls

Proceedings Volume 8447, 84473E (2012) https://doi.org/10.1117/12.925507

KEYWORDS: Stars, Sodium, Adaptive optics, Gemini Observatory, National Ignition Facility, Laser guide stars, Point spread functions, Rayleigh scattering, Linear filtering, Wavefront sensors

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Proceedings Article | 30 July 2010 Paper

Paper

Laser operations at the 8-10m class telescopes Gemini, Keck, and the VLT: lessons learned, old and new challenges

Paola Amico, Randall Campbell, Julian Christou

Proceedings Volume 7737, 77370A (2010) https://doi.org/10.1117/12.858615

KEYWORDS: Telescopes, Adaptive optics, Gemini Observatory, Observatories, Clouds, Laser scattering, Laser beam propagation, Stars, Astronomy, Sodium

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Proceedings Article | 29 July 2010 Paper

Paper

Weighing black holes using open-loop focus corrections for LGS-AO observations of galaxy nuclei at Gemini Observatory

Richard McDermid, Davor Krajnovic, Michele Cappellari, Chadwick Trujillo, Julian Christou, Roger Davies

Proceedings Volume 7736, 77365W (2010) https://doi.org/10.1117/12.856572

KEYWORDS: Galactic astronomy, National Ignition Facility, Point spread functions, Adaptive optics, Telescopes, Gemini Observatory, Sodium, Stars, Kinematics, Spatial resolution

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Proceedings Article | 29 July 2010 Paper

Paper

Application of wavelength diversity for astronomical adaptive optics imaging

Daniel Burke, Nicholas Devaney, Julian Christou, Markus Hartung

Proceedings Volume 7736, 77365U (2010) https://doi.org/10.1117/12.856953

KEYWORDS: Point spread functions, Adaptive optics, Data analysis, Telescopes, Data modeling, Stars, Photometry, Error analysis, Binary data, Wavefronts

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Proceedings Article | 28 July 2010 Paper

Paper

Novel multi-frame approach to photometry of exoplanets

Szymon Gladysz, Natalia Yaitskova, Julian Christou

Proceedings Volume 7736, 77361H (2010) https://doi.org/10.1117/12.856458

KEYWORDS: Adaptive optics, Photometry, Speckle, Planets, Stars, Deconvolution, Point spread functions, Exoplanets, Coronagraphy, Wavefronts

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Proceedings Article | 28 July 2010 Paper

Paper

Adaptive optics point spread function reconstruction: lessons learned from on-sky experiment on Altair/Gemini and pathway for future systems

Laurent Jolissaint, Julian Christou, Peter Wizinowich, Eline Tolstoy

Proceedings Volume 7736, 77361F (2010) https://doi.org/10.1117/12.857670

KEYWORDS: Point spread functions, Adaptive optics, Telescopes, Wavefronts, Optical transfer functions, Systems modeling, Space telescopes, Stars, Gemini Observatory, Calibration

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Proceedings Article | 13 July 2010 Paper

Paper

ALTAIR performance and updates at Gemini North

Julian Christou, Benoit Neichel, Francois Rigaut, Michael Sheehan, Richard McDermid, Gelys Trancho, Chadwick Trujillo, Brian Walls

Proceedings Volume 7736, 77361R (2010) https://doi.org/10.1117/12.856776

KEYWORDS: Point spread functions, Adaptive optics, Stars, K band, Gemini Observatory, Calibration, Wavefront sensors, Telescopes, Data modeling, Laser guide stars

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Proceedings Article | 10 July 2008 Paper

Paper

Lucky imaging and speckle discrimination for the detection of faint companions with adaptive optics

Szymon Gladysz, Julian Christou, Nicholas Law, Richard Dekany, Michael Redfern, Craig Mackay

Proceedings Volume 7015, 70152H (2008) https://doi.org/10.1117/12.788442

KEYWORDS: Speckle, Adaptive optics, Stars, Point spread functions, Observatories, Image quality, Stochastic processes, Image stacking, Signal detection, Telescopes

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Proceedings Article | 28 June 2006 Paper

Paper

Strehl ratio and image sharpness for adaptive optics

Julian Christou, Kenneth Mighell, Russell Makidon

Proceedings Volume 6272, 62721Y (2006) https://doi.org/10.1117/12.670430

KEYWORDS: Signal to noise ratio, Adaptive optics, Point spread functions, Wavefronts, Image quality, Electrons, Interference (communication), Space telescopes, Error analysis, Telescopes

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Proceedings Article | 27 June 2006 Paper

Paper

Long exposure point spread function estimation from adaptive optics loop data: validation and results

Jose Marino, Thomas Rimmele, Julian Christou

Proceedings Volume 6272, 62723W (2006) https://doi.org/10.1117/12.672297

KEYWORDS: Point spread functions, Adaptive optics, Stars, Wavefronts, Image quality, Diffraction, Calibration, Optical transfer functions, Mirrors, Acousto-optics

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Proceedings Article | 27 June 2006 Paper

Paper

Characterization of the Lick adaptive optics point spread function

Szymon Gladysz, Julian Christou, Michael Redfern

Proceedings Volume 6272, 62720J (2006) https://doi.org/10.1117/12.671605

KEYWORDS: Point spread functions, Adaptive optics, Speckle, Observatories, Stars, Image stacking, Calibration, Imaging systems, Image quality, Bromine

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Proceedings Article | 27 June 2006 Paper

Paper

Analysis of K-band imaging of the wide binary system σ CrB with the Lick Observatory NGS AO system

Kenneth Mighell, Julian Christou, Jack Drummond

Proceedings Volume 6272, 62720I (2006) https://doi.org/10.1117/12.670574

KEYWORDS: Adaptive optics, Point spread functions, Stars, Photometry, Imaging systems, K band, Error analysis, Observatories, Deconvolution, Calibration

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Proceedings Article | 25 October 2004 Paper

Paper

Sky tests of a laser-pumped sodium guidestar with and without beam compensation

Jack Drummond, John Telle, Craig Denman, Paul Hillman, James Spinhirne, Julian Christou

Proceedings Volume 5490, (2004) https://doi.org/10.1117/12.556869

KEYWORDS: Telescopes, Adaptive optics, Polarization, Stars, Laser guide stars, Sodium guide stars, Sodium, Charge-coupled devices, Photon polarization, Optical filters

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Proceedings Article | 25 October 2004 Paper

Paper

Is that really your Strehl ratio?

Lewis Roberts, Marshall Perrin, Franck Marchis, Anand Sivaramakrishnan, Russell Makidon, Julian Christou, Bruce Macintosh, Lisa Poyneer, Marcos van Dam, Mitchell Troy

Proceedings Volume 5490, (2004) https://doi.org/10.1117/12.549115

KEYWORDS: Point spread functions, Diffraction, Adaptive optics, Photometry, Telescopes, Monte Carlo methods, Wavefronts, Computer simulations, Optical transfer functions, Modulation transfer functions

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Proceedings Article | 25 October 2004 Paper

Paper

Long-exposure point spread function estimation from adaptive optics loop data

Jose Marino, Thomas Rimmele, Julian Christou

Proceedings Volume 5490, (2004) https://doi.org/10.1117/12.551954

KEYWORDS: Point spread functions, Adaptive optics, Acousto-optics, Optical transfer functions, Image quality, Mirrors, Wavefronts, Diffraction, Doppler effect, Telescopes

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Proceedings Article | 7 February 2003 Paper

Paper

Anisoplanatism within the isoplanatic patch

Julian Christou, E. Steinbring, Sandra Faber, Donald Gavel, Jennifer Patience, Elinor Gates

Proceedings Volume 4839, (2003) https://doi.org/10.1117/12.467863

KEYWORDS: Point spread functions, Stars, Adaptive optics, Binary data, Spatial frequencies, Motion measurement, Observatories, Cameras, K band, Deconvolution

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Proceedings Article | 4 February 2002 Paper

Paper

Preliminary measurements of residual tip-tilt motion and Strehl ratios for laser guide star compensation at Lick Observatory

Julian Christou, Donald Gavel, Jennifer Patience, Elinor Gates

Proceedings Volume 4494, (2002) https://doi.org/10.1117/12.454805

KEYWORDS: Adaptive optics, Stars, Observatories, Telescopes, Laser guide stars, Motion measurement, Spatial frequencies, Image stacking, Modulation transfer functions, K band

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Proceedings Article | 27 September 1999 Paper

Paper

Object-independent point spread function and wavefront phase estimation

Julian Christou, Stuart Jefferies, E. Keith Hege

Proceedings Volume 3762, (1999) https://doi.org/10.1117/12.363575

KEYWORDS: Point spread functions, Signal to noise ratio, Satellites, Wavefronts, Deconvolution, Adaptive optics, Stars, Observatories, Reconstruction algorithms, Scintillation

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Proceedings Article | 7 December 1998 Paper

Paper

Physically constrained iterative deconvolution of adaptive optics images

Julian Christou, E. Keith Hege, Stuart Jefferies, Matthew Cheselka

Proceedings Volume 3494, (1998) https://doi.org/10.1117/12.332416

KEYWORDS: Signal to noise ratio, Point spread functions, Adaptive optics, Stars, Deconvolution, Photometry, Spatial frequencies, Satellites, Computer simulations, Detection and tracking algorithms

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Proceedings Article | 11 September 1998 Paper

Paper

Starfire Optical Range 3.5-m telescope adaptive optical system

James Spinhirne, Jeff Allen, George Ameer, James Brown, Julian Christou, Terry Duncan, R. Eager, Mark Ealey, Brent Ellerbroek, Robert Fugate, Gary Jones, R. Kuhns, David Lee, William Lowrey, Michael Oliker, Raymond Ruane, David Swindle, Joshua Voas, Walter Wild, Keith Wilson, John Wynia

Proceedings Volume 3353, (1998) https://doi.org/10.1117/12.321689

KEYWORDS: Sensors, Adaptive optics, Telescopes, Mirrors, Actuators, Deformable mirrors, Cameras, Digital signal processing, CCD image sensors, CCD cameras

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Proceedings Article | 11 September 1998 Paper

Paper

Deconvolution of ADONIS images

Julian Christou, Franck Marchis, Nancy Ageorges, Domenico Bonaccini, Francois Rigaut

Proceedings Volume 3353, (1998) https://doi.org/10.1117/12.321719

KEYWORDS: Point spread functions, Deconvolution, Stars, Observatories, Adaptive optics, Imaging systems, Diffraction, Thermography, Image processing, Satellites

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Proceedings Article | 11 September 1998 Paper

Paper

Increasing the useful field of view of an adaptive optics system

Mark Chun, Walter Wild, Fang Shi, Michael Smutko, Edward Kibblewhite, Robert Fugate, Julian Christou

Proceedings Volume 3353, (1998) https://doi.org/10.1117/12.321631

KEYWORDS: Wavefronts, Adaptive optics, Stars, Telescopes, Rayleigh guide stars, Turbulence, Wavefront reconstruction, Calibration, Atmospheric optics, Atmospheric corrections

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Proceedings Article | 11 September 1998 Paper

Paper

First results of the Starfire Optical Range 3.5-m telescope adaptive optics system: point spread functions and tracking performance

David Lee, Brent Ellerbroek, Julian Christou

Proceedings Volume 3353, (1998) https://doi.org/10.1117/12.321730

KEYWORDS: Adaptive optics, Point spread functions, Stars, Cameras, Space telescopes, Telescopes, Sensors, Mirrors, Actuators, Imaging systems

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Proceedings Article | 11 September 1998 Paper

Paper

Blind Bayesian restoration of adaptive optics telescope images using generalized Gaussian Markov random field models

Brian Jeffs, Julian Christou

Proceedings Volume 3353, (1998) https://doi.org/10.1117/12.321721

KEYWORDS: Adaptive optics, Point spread functions, Satellites, Image resolution, Space telescopes, Ions, Telescopes, Image restoration, Algorithm development, Resolution enhancement technologies

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Proceedings Article | 17 October 1997 Paper

Paper

Deconvolution of adaptive optics near-infrared system (ADONIS) images

Julian Christou, Domenico Bonaccini, Nancy Ageorges

Proceedings Volume 3126, (1997) https://doi.org/10.1117/12.279065

KEYWORDS: Point spread functions, Deconvolution, Adaptive optics, Signal to noise ratio, Stars, Speckle, Observatories, Error analysis, K band, Calibration

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Proceedings Article | 17 October 1997 Paper

Paper

Performance of the ESO AO system, ADONIS, at the La Silla 3.6-m telescope

Domenico Bonaccini, E. Prieto, Patrice Corporon, Julian Christou, D. Le Mignan, Pablo Prado, Roland Gredel, Norbert Hubin

Proceedings Volume 3126, (1997) https://doi.org/10.1117/12.290172

KEYWORDS: Adaptive optics, K band, Telescopes, Lanthanum, Mirrors, Point spread functions, Stars, Cameras, Signal to noise ratio, Deconvolution

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Proceedings Article | 25 August 1995 Paper

Paper

Blind deconvolution post-processing of images corrected by adaptive optics

Julian Christou

Proceedings Volume 2534, (1995) https://doi.org/10.1117/12.217741

KEYWORDS: Point spread functions, Adaptive optics, Deconvolution, Stars, Advanced distributed simulations, Convolution, Electronic filtering, Calcium, Detection and tracking algorithms, Signal to noise ratio

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Proceedings Article | 23 August 1995 Paper

Paper

Speckle deconvolution imaging using an iterative algorithm

Julian Christou, E. Keith Hege, Stuart Jefferies

Proceedings Volume 2566, (1995) https://doi.org/10.1117/12.217368

KEYWORDS: Point spread functions, Speckle, Detection and tracking algorithms, Deconvolution, Reconstruction algorithms, Signal to noise ratio, Speckle imaging, Convolution, Stars, Image stacking

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Proceedings Article | 9 June 1994 Paper

Paper

Application of multiframe iterative blind deconvolution for diverse astronomical imaging

Julian Christou, E. Keith Hege, Stuart Jefferies, Christoph Keller

Proceedings Volume 2200, (1994) https://doi.org/10.1117/12.177275

KEYWORDS: Point spread functions, Speckle, Signal to noise ratio, Deconvolution, Convolution, Asteroids, Adaptive optics, Image restoration, Speckle imaging, Spatial frequencies

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Proceedings Article | 31 May 1994 Paper

Paper

Images of asteroids 1 Ceres, 2 Pallas, and 4 Vesta with adaptive optics at the Starfire Optical Range

Jack Drummond, Julian Christou

Proceedings Volume 2201, (1994) https://doi.org/10.1117/12.176080

KEYWORDS: Asteroids, Adaptive optics, Image filtering, Telescopes, Speckle, Deconvolution, Stars, Image resolution, Point spread functions, Geometrical optics

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Proceedings Article | 1 August 1990 Paper

Paper

Application of a deconvolution technique to enforce a-priori object constraints to 2-D IR speckle data

Julian Christou

Proceedings Volume 1237, (1990) https://doi.org/10.1117/12.19315

KEYWORDS: Deconvolution, Speckle, Interferometry, Stars, Spatial frequencies, Reconstruction algorithms, Astronomy, Infrared radiation, Computer simulations, Infrared imaging

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Proceedings Article | 1 August 1990 Paper

Paper

Experience and further developments with the NOAO infrared speckle camera

Stephen Ridgway, Julian Christou, Ronald Probst

Proceedings Volume 1237, (1990) https://doi.org/10.1117/12.19321

KEYWORDS: Speckle, Infrared imaging, Infrared radiation, Infrared cameras, Imaging systems, Sensors, Cameras, Spatial resolution, Stars, Telescopes

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Proceedings Article | 1 August 1990 Paper

Paper

Diffraction-limited imaging at IR wavelengths using aperture masks and fully filled apertures

Christopher Haniff, David Buscher, Julian Christou, Stephen Ridgway

Proceedings Volume 1237, (1990) https://doi.org/10.1117/12.19299

KEYWORDS: Calibration, Image restoration, Speckle, Ultraviolet radiation, Astronomy, Signal to noise ratio, Interferometry, Phase measurement, Telescopes, Stars

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Showing 5 of 66 publications

Conference Committee Involvement (7)

Image Reconstruction from Incomplete Data VIII

11 August 2015 | San Diego, California, United States

Image Reconstruction from Incomplete Data VII

14 August 2012 | San Diego, California, United States

Image Reconstruction from Incomplete Data VI

2 August 2010 | San Diego, California, United States

Image Reconstruction from Incomplete Data V

11 August 2008 | San Diego, California, United States

Image Reconstruction from Incomplete Data IV

14 August 2006 | San Diego, California, United States

Showing 5 of 7 Conference Committees

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