Mr. Erik M. Johansson Profile

Erik M. Johansson

SPIE Involvement:

Author

Area of Expertise:

Adaptive Optics , Atmospheric Speckle Imaging , Phase Retrieval , Signal and Image Processing , Numerical Methods and Algorithm Development , Real-Time Software Development

Profile Summary

I am currently the project manager for the Wavefront Correction System on the Daniel K Inouye Solar Telescope. Prior to that I worked on the Keck Observatory Adaptive Optics system.

Publications (37)

Proceedings Article | 11 September 2024 Presentation + Paper

Presentation + Paper

The US National Science Foundation Daniel K. Inouye Solar Telescope operations commissioning: results and lessons learned

Thomas Rimmele, Alexandra Tritschler, Andres Parraguez, Friedrich Wöger, Bret Goodrich, Luke Johnson, Heather Marshall, Paul Jeffers, Alisdair Davey, Robert Tawa, Gary Candido, David Boboltz, Tetsu Anan, Christian Beck, Gianna Cauzzi, Serena Criscuoli, André Fehlmann, Catherine Fischer, David Harrington, Sarah Jaeggli, Maxim Kramar, David Kuridze, Thomas Schad, Dirk Schmidt, Joao Manuel da Silva Santos, Lucas Tarr, Han Uitenbroek, James Arnow, Joel Davidow, Dale Deibert, Alysa Derks, Arthur Eigenbrot, Tony Hays, Erik Johansson, Daniel Spiess, Frazer Watson, Scott Wiant, Hillary Hope Head, David Morris, Manuel Díaz Alfaro, Nuria Wright-Garba, Anthony Santini, Andrew Beard, David Berst, Bryan Cummings, Andrew Ferayorni, Stephen Guzzo, John Hubbard, Jon Munoz, Isabell Scholl, Eric Cross, Colleen Donnelly, Steve O'Brien, Rodell Agdinaoay, Wade Bortz, Christopher Foster, Gary Foster, Chriselle Ann Galapon, Brian Gregory, Stephanie Guzman, Marco Guzman, James Hoag, Mary Liang, Karl Newman, Brialyn Onodera, Sebastien Poupar, Myles Puentes, Lukas Rimmele, Erik Starman, Stacey Sueoka, Richard Summers, Aimee Szabo, Louis Szabo, Timothy Williams, Charles White, Chad Bader, James Barry, Eric Bio, Terran Carter, Linda Evans, Bruce Keahi, Kealli Koki, Michael Lay, Aidan Lay, Justin Lay, Barry Poe, Norman Tong, Roberto Casini, Alfred deWijn, Jeffrey Kuhn, Haosheng Lin, Thomas Kentischer, Clemens Halbgewachs

Proceedings Volume 13094, 130940Y (2024) https://doi.org/10.1117/12.3022760

KEYWORDS: Equipment, Magnetism, Calibration, Adaptive optics, Tunable filters, Polarization, Solar telescopes, Solar processes, Optical filters, Sun

Read Abstract +

Proceedings Article | 29 August 2022 Presentation + Paper

Presentation + Paper

The National Science Foundation’s Daniel K. Inouye Solar Telescope: status and first results

Thomas Rimmele, Mark Warner, Roberto Casini, Jeffery Kuhn, Haosheng Lin, Friedrich Wöger, Alexandra Tritschler, Alisdair Davey, Alfred de Wijn, Andre Fehlmann, David Harrington, Sarah Jaeggli, Thomas Schad, Tetsu Anan, Christian Beck, Heather Marshall, Paul Jeffers, Andrew Beard, David Berst, Eric Cross, Bryan Cummings, Colleen Donneley, Arthur Eigenbrot, Andrew Ferayorni, Christopher Foster, Chriselle Ann Galapon, Bret Goodrich, Brian Gregory, Stephanie Guzman, Stephen Guzzo, John Hubbard, Erik Johansson, Luke Johnson, Mary Liang, Brialyn Onodera, Myles Puentes, Lukas Rimmele, Erik Starman, Stacey Sueoka, Richard Summers, Aimee Szabo, Louis Szabo, Timothy Williams, Charles White

Proceedings Volume 12182, 121820Z (2022) https://doi.org/10.1117/12.2644469

KEYWORDS: Adaptive optics, Solar telescopes, Telescopes, Mirrors, Visible radiation, Solar processes, Magnetism, Sun, Polarization, Polarimetry

Read Abstract +

Proceedings Article | 15 December 2020 Presentation + Paper

Presentation + Paper

First light with adaptive optics: the performance of the DKIST high-order adaptive optics

Luke Johnson, Erik Johansson, Jose Marino, Kit Richards, Thomas Rimmele, Iris Wang, Friedrich Wöger

Proceedings Volume 11448, 114480T (2020) https://doi.org/10.1117/12.2563427

KEYWORDS: Adaptive optics, Wavefront sensors, Wavefronts, Telescopes, Active optics, Solar telescopes, Deformable mirrors, Field programmable gate arrays, Active remote sensing, Sensing systems

Read Abstract +

Proceedings Article | 11 July 2018 Paper

Paper

The DKIST low order wavefront sensor

Erik Johansson, Keith Cummings, Mark Drobilek, Luke Johnson, Kit Richards, Rachel Rampy, Friedrich Wöger

Proceedings Volume 10703, 107035P (2018) https://doi.org/10.1117/12.2313745

KEYWORDS: Wavefronts, Cameras, Wavefront sensors, Monochromatic aberrations, Image sensors, Adaptive optics, Sensors, Microlens array, Mirrors, Relays

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Proceedings Article | 10 July 2018 Presentation + Paper

Presentation + Paper

Laboratory integration of the DKIST wavefront correction system

Luke Johnson, Keith Cummings, Mark Drobilek, Erik Johansson, Jose Marino, Rachel Rampy, Kit Richards, Thomas Rimmele, Predrag Sekulic, Friedrich Wöger

Proceedings Volume 10703, 107030F (2018) https://doi.org/10.1117/12.2314012

KEYWORDS: Wavefronts, Wavefront sensors, Telescopes, Adaptive optics, Calibration, Mirrors, Cameras, Control systems, Active optics

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Proceedings Article | 6 July 2018 Paper

Paper

Construction update of the Daniel K. Inouye Solar Telescope project

Mark Warner, Thomas Rimmele, Valentin Pillet, Roberto Casini, Steve Berukoff, Simon Craig, Andrew Ferayorni, Bret Goodrich, Robert Hubbard, David Harrington, Paul Jeffers, Erik Johansson, Ruth Kneale, Jeff Kuhn, Chen Liang, Haosheng Lin, Heather Marshall, Mihalis Mathioudakis, William McBride, Joseph McMullin, William McVeigh, Predrag Sekulic, Wolfgang Schmidt, Steve Shimko, Stacey Sueoka, Rich Summers, Alexandra Tritschler, Timothy Williams, Friedrich Wöger

Proceedings Volume 10700, 107000V (2018) https://doi.org/10.1117/12.2314212

KEYWORDS: Telescopes, Optical fabrication, Cameras, Mirrors, Control systems, Solar processes, Observatories, Polarimetry, Imaging systems, Polarization

Read Abstract +

Construction of the Daniel K. Inouye Solar Telescope (DKIST) is well underway on the Haleakalā summit on the Hawaiian island of Maui. Featuring a 4-m aperture and an off-axis Gregorian configuration, the DKIST will be the world’s largest solar telescope. It is designed to make high-precision measurements of fundamental astrophysical processes and produce large amounts of spectropolarimetric and imaging data. These data will support research on solar magnetism and its influence on solar wind, flares, coronal mass ejections, and solar irradiance variability. Because of its large aperture, the DKIST will be able to sense the corona’s magnetic field—a goal that has previously eluded scientists—enabling observations that will provide answers about the heating of stellar coronae and the origins of space weather and exo-weather. The telescope will cover a broad wavelength range (0.35 to 28 microns) and operate as a coronagraph at infrared (IR) wavelengths. Achieving the diffraction limit of the 4-m aperture, even at visible wavelengths, is paramount to these science goals. The DKIST’s state-of-the-art adaptive optics systems will provide diffraction-limited imaging, resolving features that are approximately 20 km in size on the Sun.

At the start of operations, five instruments will be deployed: a visible broadband imager (VTF), a visible spectropolarimeter (ViSP), a visible tunable filter (VTF), a diffraction-limited near-IR spectropolarimeter (DLNIRSP), and a cryogenic near-IR spectropolarimeter (cryo-NIRSP). At the end of 2017, the project finished its fifth year of construction and eighth year overall. Major milestones included delivery of the commissioning blank, the completed primary mirror (M1), and its cell. Commissioning and testing of the coudé rotator is complete and the installation of the coudé cleanroom is underway; likewise, commissioning of the telescope mount assembly (TMA) has also begun. Various other systems and equipment are also being installed and tested. Finally, the observatory integration, testing, and commissioning (IT&C) activities have begun, including the first coating of the M1 commissioning blank and its integration within its cell assembly. Science mirror coating and initial on-sky activities are both anticipated in 2018.

Proceedings Article | 18 August 2016 Paper

Paper

Construction status of the Daniel K. Inouye solar telescope

Joseph McMullin, Thomas Rimmele, Mark Warner, Valentin Pillet, Roberto Casini, Steve Berukoff, Simon Craig, David Elmore, Andrew Ferayorni, Bret Goodrich, Robert Hubbard, David Harrington, Steve Hegwer, Paul Jeffers, Erik Johansson, Jeff Kuhn, Haosheng Lin, Heather Marshall, Mihalis Mathioudakis, William McBride, William McVeigh, LeEllen Phelps, Wolfgang Schmidt, Steve Shimko, Stacey Sueoka, Alexandra Tritschler, Timothy Williams, Friedrich Wöger

Proceedings Volume 9906, 99061B (2016) https://doi.org/10.1117/12.2235227

KEYWORDS: Imaging systems, Observatories, Solar processes, Telescopes, Mirrors, Optical fabrication, Buildings, Space telescopes, Control systems, Deformable mirrors

Read Abstract +

We provide an update on the construction status of the Daniel K. Inouye Solar Telescope. This 4-m diameter facility is designed to enable detection and spatial/temporal resolution of the predicted, fundamental astrophysical processes driving solar magnetism at their intrinsic scales throughout the solar atmosphere. These data will drive key research on solar magnetism and its influence on solar winds, flares, coronal mass ejections and solar irradiance variability. The facility is developed to support a broad wavelength range (0.35 to 28 microns) and will employ state-of-the-art adaptive optics systems to provide diffraction limited imaging, resolving features approximately 20 km on the Sun. At the start of operations, there will be five instruments initially deployed: Visible Broadband Imager (VBI; National Solar Observatory), Visible SpectroPolarimeter (ViSP; NCAR High Altitude Observatory), Visible Tunable Filter (VTF (a Fabry-Perot tunable spectropolarimeter); Kiepenheuer Institute for Solarphysics), Diffraction Limited NIR Spectropolarimeter (DL-NIRSP; University of Hawaii, Institute for Astronomy) and the Cryogenic NIR Spectropolarimeter (Cryo-NIRSP; University of Hawaii, Institute for Astronomy).

As of mid-2016, the project construction is in its 4th year of site construction and 7th year overall. Major milestones in the off-site development include the conclusion of the polishing of the M1 mirror by University of Arizona, College of Optical Sciences, the delivery of the Top End Optical Assembly (L3), the acceptance of the Deformable Mirror System (Xinetics); all optical systems have been contracted and are either accepted or in fabrication. The Enclosure and Telescope Mount Assembly passed through their factory acceptance in 2014 and 2015, respectively. The enclosure site construction is currently concluding while the Telescope Mount Assembly site erection is underway. The facility buildings (Utility and Support and Operations) have been completed with ongoing work on the thermal systems to support the challenging imaging requirements needed for the solar research.

Finally, we present the construction phase performance (schedule, budget) with projections for the start of early operations.

Proceedings Article | 8 August 2016 Paper

Paper

Project management and control of the Daniel K. Inouye Solar Telescope

Joseph McMullin, William McVeigh, Mark Warner, Thomas Rimmele, Simon Craig, Andrew Ferayorni, Bret Goodrich, Robert Hubbard, Rex Hunter, Paul Jeffers, Erik Johansson, Heather Marshall, William McBride, LeEllen Phelps, Steve Shimko, Alexandra Tritschler, Timothy Williams, Friedrich Wöger

Proceedings Volume 9911, 99110K (2016) https://doi.org/10.1117/12.2235225

KEYWORDS: Solar telescopes, Systems engineering, Observatories, Content addressable memory, Chromium, Control systems, Neodymium, Databases, Phase modulation, Process control

Read Abstract +

Proceedings Article | 26 July 2016 Paper

Paper

Status of the DKIST system for solar adaptive optics

Luke Johnson, Keith Cummings, Mark Drobilek, Erik Johansson, Jose Marino, Kit Richards, Thomas Rimmele, Predrag Sekulic, Friedrich Wöger

Proceedings Volume 9909, 99090Y (2016) https://doi.org/10.1117/12.2233528

KEYWORDS: Adaptive optics, Wavefronts, Wavefront sensors, Optical fabrication, Actuators, Real-time computing, Signal to noise ratio, Image processing, Cameras, Control systems

Read Abstract +

When the Daniel K. Inouye Solar Telescope (DKIST) achieves first light in 2019, it will deliver the highest spatial resolution images of the solar atmosphere ever recorded. Additionally, the DKIST will observe the Sun with unprecedented polarimetric sensitivity and spectral resolution, spurring a leap forward in our understanding of the physical processes occurring on the Sun.

The DKIST wavefront correction system will provide active alignment control and jitter compensation for all six of the DKIST science instruments. Five of the instruments will also be fed by a conventional adaptive optics (AO) system, which corrects for high frequency jitter and atmospheric wavefront disturbances. The AO system is built around an extended-source correlating Shack-Hartmann wavefront sensor, a Physik Instrumente fast tip-tilt mirror (FTTM) and a Xinetics 1600-actuator deformable mirror (DM), which are controlled by an FPGA-based real-time system running at 1975 Hz. It is designed to achieve on-axis Strehl of 0.3 at 500 nm in median seeing (r₀ = 7 cm) and Strehl of 0.6 at 630 nm in excellent seeing (r₀ = 20 cm).

The DKIST wavefront correction team has completed the design phase and is well into the fabrication phase. The FTTM and DM have both been delivered to the DKIST laboratory in Boulder, CO. The real-time controller has been completed and is able to read out the camera and deliver commands to the DM with a total latency of approximately 750 μs. All optics and optomechanics, including many high-precision custom optics, mounts, and stages, are completed or nearing the end of the fabrication process and will soon undergo rigorous acceptance testing.

Before installing the wavefront correction system at the telescope, it will be assembled as a testbed in the laboratory. In the lab, performance tests beginning with component-level testing and continuing to full system testing will ensure that the wavefront correction system meets all performance requirements. Further work in the lab will focus on fine-tuning our alignment and calibration procedures so that installation and alignment on the summit will proceed as efficiently as possible.

Proceedings Article | 7 August 2014 Paper

Paper

Solar adaptive optics with the DKIST: status report

Luke Johnson, Keith Cummings, Mark Drobilek, Scott Gregory, Steve Hegwer, Erik Johansson, Jose Marino, Kit Richards, Thomas Rimmele, Predrag Sekulic, Friedrich Wöger

Proceedings Volume 9148, 91481S (2014) https://doi.org/10.1117/12.2056990

KEYWORDS: Wavefronts, Wavefront sensors, Mirrors, Adaptive optics, Actuators, Telescopes, Control systems, Field programmable gate arrays, Active optics, Real-time computing

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Proceedings Article | 4 August 2014 Paper

Paper

Daniel K. Inouye Solar Telescope: integration testing and commissioning planning

Simon Craig, Scott Bulau, Kerry Gonzales, Eric Hansen, Bret Goodrich, Robert Hubbard, Eric Johansson, Chen Liang, Ruth Kneale, William McBride, Predrag Sekulic, Timothy Williams

Proceedings Volume 9150, 91500C (2014) https://doi.org/10.1117/12.2056793

KEYWORDS: Mirrors, Optical alignment, Optical fabrication, Safety, Telescopes, Control systems, Coating, Wavefronts, Solar telescopes, Wavefront sensors

Read Abstract +

Proceedings Article | 22 July 2014 Paper

Paper

Construction status of the Daniel K. Inouye Solar Telescope

Joseph McMullin, Thomas Rimmele, Valentin Martínez Pillet, Thomas Berger, Roberto Casini, Simon Craig, David Elmore, Bret Goodrich, Steve Hegwer, Robert Hubbard, Erik Johansson, Jeffrey Kuhn, Haosheng Lin, William McVeigh, Wolfgang Schmidt, Steve Shimko, Alexandra Tritschler, Mark Warner, Friedrich Wöger

Proceedings Volume 9145, 914525 (2014) https://doi.org/10.1117/12.2055483

KEYWORDS: Observatories, Solar telescopes, Optical fabrication, Telescopes, Astronomy, Adaptive optics, Visible radiation, Control systems, Sun, Solar processes

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Proceedings Article | 24 September 2012 Paper

Paper

A standard framework for developing instrument controllers for the ATST

John Hubbard, Erik Johansson

Proceedings Volume 8451, 84510O (2012) https://doi.org/10.1117/12.926283

KEYWORDS: Control systems, Standards development, Cameras, Visible radiation, Telescopes, Observatories, Imaging systems, Software development, Sensors, Java

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Proceedings Article | 24 September 2012 Paper

Paper

Simultaneous control of multiple instruments at the Advanced Technology Solar Telescope

Erik Johansson, Bret Goodrich

Proceedings Volume 8451, 84510J (2012) https://doi.org/10.1117/12.926441

KEYWORDS: Control systems, Observatories, Telescopes, Calibration, Human-machine interfaces, Solar telescopes, Modulators, Cameras, Polarization, Standards development

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Proceedings Article | 28 July 2010 Paper

Paper

W. M. Keck Observatory's next-generation adaptive optics facility

P. Wizinowich, S. Adkins, R. Dekany, D. Gavel, C. Max, R. Bartos, J. Bell, A. Bouchez, J. Chin, A. Conrad, A. Delacroix, E. Johansson, R. Kupke, C. Lockwood, J. Lyke, F. Marchis, E. McGrath, D. Medeiros, M. Morris, D. Morrison, C. Neyman, S. Panteleev, M. Pollard, M. Reinig, T. Stalcup, S. Thomas, M. Troy, K. Tsubota, V. Velur, K. Wallace, E. Wetherell

Proceedings Volume 7736, 77360K (2010) https://doi.org/10.1117/12.857628

KEYWORDS: Adaptive optics, Telescopes, Wavefront sensors, Stars, Tomography, Control systems, Keck Observatory, Galactic astronomy, Wavefronts, Sensors

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Proceedings Article | 8 August 2008 Paper

Paper

W. M. Keck Observatory's next-generation adaptive optics facility

P. Wizinowich, R. Dekany, D. Gavel, C. Max, S. Adkins, B. Bauman, J. Bell, A. Bouchez, M. Britton, J. Chin, R. Flicker, E. Johansson, R. Kupke, D. Le Mignant, C. Lockwood, D. Medeiros, E. McGrath, A. Moore, C. Neyman, M. Reinig, V. Velur

Proceedings Volume 7015, 701511 (2008) https://doi.org/10.1117/12.790154

KEYWORDS: Adaptive optics, Wavefront sensors, Telescopes, Wavefronts, Stars, Control systems, Sensors, Relays, Point spread functions, Tomography

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Proceedings Article | 15 July 2008 Paper

Paper

Concept for the Keck Next Generation Adaptive Optics system

Donald Gavel, Richard Dekany, Claire Max, Peter Wizinowich, Sean Adkins, Brian Bauman, Jim Bell, Erik Johansson, Renate Kupke, Chris Lockwood, Anna Moore, Chris Neyman, Marc Reinig, Viswa Velur

Proceedings Volume 7015, 701567 (2008) https://doi.org/10.1117/12.790250

KEYWORDS: Adaptive optics, Relays, Stars, Sensors, Wavefront sensors, Mirrors, Laser guide stars, Wavefronts, Microelectromechanical systems, Control systems

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Proceedings Article | 12 July 2008 Paper

Paper

AO operations at the W. M. Keck Observatory

Randall Campbell, David Le Mignant, Marcos van Dam, Al Conrad, Kenny Grace, Marc Kassis, James Lyke, Hien Tran, Jason Chin, Elizabeth Chock, Steven Doyle, Robert Goodrich, Erik Johansson, Tomas Krasuski, Christine Melcher, Douglas Summers, Roger Sumner, Peter Wizinowich

Proceedings Volume 7016, 701604 (2008) https://doi.org/10.1117/12.790118

KEYWORDS: Adaptive optics, Telescopes, Observatories, Stars, Keck Observatory, Satellites, Laser safety, Safety, Calibration, Space telescopes

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Proceedings Article | 11 July 2008 Paper

Paper

Upgrading the Keck AO wavefront controllers

Erik Johansson, Marcos van Dam, Paul Stomski, James Bell, Jason Chin, Roger Sumner, Peter Wizinowich, Roberto Biasi, Mario Andrighettoni, Dietrich Pescoller

Proceedings Volume 7015, 70153E (2008) https://doi.org/10.1117/12.790198

KEYWORDS: Adaptive optics, Stars, Digital signal processing, Wavefronts, Wavefront sensors, Mirrors, Cameras, K band, Sensors, Keck Observatory

Read Abstract +

Proceedings Article | 29 June 2006 Paper

Paper

LGS AO operations at the W.M. Keck Observatory

David Le Mignant, Randall Campbell, Antonin Bouchez, Jason Chin, Elizabeth Chock, Al Conrad, Marcos van Dam, Steve Doyle, Robert Goodrich, Erik Johansson, Robert Lafon, James Lyke, Christine Melcher, Ronald Mouser, Douglas Summers, Cynthia Wilburn, Peter Wizinowich

Proceedings Volume 6270, 62700C (2006) https://doi.org/10.1117/12.671837

KEYWORDS: Adaptive optics, Telescopes, Stars, Laser safety, Keck Observatory, Observatories, Space telescopes, Laser guide stars, Sodium, Cameras

Read Abstract +

Proceedings Article | 28 June 2006 Paper

Paper

Angular anisoplanatism in laser guide star adaptive optics

Marcos van Dam, Richard Sasiela, Antonin Bouchez, David Le Mignant, Randy Campbell, Jason Chin, Scott Hartman, Erik Johansson, Robert Lafon, Paul Stomski, Douglas Summers, Peter Wizinowich

Proceedings Volume 6272, 627231 (2006) https://doi.org/10.1117/12.669737

KEYWORDS: Adaptive optics, Stars, Turbulence, Wavefronts, Laser guide stars, K band, Telescopes, Image quality, Keck Observatory, Error analysis

Read Abstract +

Proceedings Article | 27 June 2006 Paper

Paper

Adaptive optics developments at Keck Observatory

Peter Wizinowich, Jason Chin, Erik Johansson, Stephan Kellner, Robert Lafon, David Le Mignant, Chris Neyman, Paul Stomski, Doug Summers, Roger Sumner, Marcos van Dam

Proceedings Volume 6272, 627209 (2006) https://doi.org/10.1117/12.672104

KEYWORDS: Adaptive optics, Wavefronts, Cameras, Telescopes, Wavefront sensors, Keck Observatory, Stars, Imaging systems, Mirrors, Control systems

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Proceedings Article | 27 June 2006 Paper

Paper

LGS AO at W.M. Keck Observatory: routine operations and remaining challenges

David Le Mignant, Marcos van Dam, Antonin Bouchez, Jason Chin, Elizabeth Chock, Randall Campbell, Al Conrad, Steve Doyle, Robert Goodrich, Erik Johansson, Shui Kwok, Robert Lafon, James Lyke, Christine Melcher, Ronald Mouser, Douglas Summers, Paul Stomski, Cynthia Wilburn, Peter Wizinowich

Proceedings Volume 6272, 627201 (2006) https://doi.org/10.1117/12.671939

KEYWORDS: Adaptive optics, Stars, Telescopes, Laser guide stars, Sodium, Keck Observatory, Sensors, Laser safety, Calibration, Target acquisition

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Proceedings Article | 27 June 2006 Paper

Paper

Comparison of tip-tilt controllers using the STRAP wavefront sensor in the W.M. Keck Observatory laser guide star adaptive optics system

Douglas Looze, Marcos van Dam, Erik Johansson

Proceedings Volume 6272, 62724L (2006) https://doi.org/10.1117/12.672427

KEYWORDS: Mirrors, Adaptive optics, Wavefront sensors, Avalanche photodetectors, Wavefronts, Lead, Keck Observatory, Laser guide stars, Signal to noise ratio, Systems modeling

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Proceedings Article | 25 October 2004 Paper

Paper

Focus and pointing adjustments necessary for laser guide star adaptive optics at the W.M. Keck Observatory

Douglas Summers, Antonin Bouchez, Jason Chin, Adam Contos, Scott Hartman, Erik Johansson, Robert Lafon, David Le Mignant, Paul Stomski, Marcos van Dam, Peter Wizinowich

Proceedings Volume 5490, (2004) https://doi.org/10.1117/12.553060

KEYWORDS: Sodium, Adaptive optics, Telescopes, Mirrors, Fluorescence correlation spectroscopy, Control systems, Keck Observatory, Cameras, Wavefronts, Projection systems

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Proceedings Article | 25 October 2004 Paper

Paper

Keck laser guide star adaptive optics: science verification results

Antonin Bouchez, David Le Mignant, Marcos van Dam, Jason Chin, Scott Hartman, Erik Johansson, Robert Lafon, Paul Stomski, Douglas Summers, Peter Wizinowich

Proceedings Volume 5490, (2004) https://doi.org/10.1117/12.552503

KEYWORDS: Adaptive optics, Stars, Laser guide stars, Telescopes, Sodium, Cameras, Image processing, Wavefronts, Imaging systems, Sensors

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Proceedings Article | 25 October 2004 Paper

Paper

Adaptive optics developments at Keck Observatory

Peter Wizinowich, David Le Mignant, Antonin Bouchez, Jason Chin, Adam Contos, Scott Hartman, Erik Johansson, Robert Lafon, Chris Neyman, Paul Stomski, Doug Summers, Marcos van Dam

Proceedings Volume 5490, (2004) https://doi.org/10.1117/12.552489

KEYWORDS: Adaptive optics, Wavefronts, Telescopes, Keck Observatory, Cameras, Image segmentation, Stars, Sodium, Mirrors, Projection systems

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Proceedings Article | 1 June 2004 Paper

Paper

Intracavity adaptive correction of a 10-kW solid state heat-capacity laser

Kai LaFortune, Randall Hurd, Erik Johansson, Clifford Dane, Scott Fochs, James Brase

Proceedings Volume 5333, (2004) https://doi.org/10.1117/12.531034

KEYWORDS: Wavefront sensors, Wavefronts, Control systems, Resonators, Adaptive optics, Actuators, Laser beam diagnostics, Diagnostics, Solid state lasers, Deformable mirrors

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Proceedings Article | 7 July 2000 Paper

Paper

Initial performance of the Keck AO wavefront controller system

Erik Johansson, D. Scott Acton, Jong An, Kenneth Avicola, Barton Beeman, James Brase, Carmen Carrano, John Gathright, Donald Gavel, Randall Hurd, Olivier Lai, William Lupton, Bruce Macintosh, Claire Max, Scot Olivier, J. Shelton, Paul Stomski, Kevin Tsubota, Kenneth Waltjen, James Watson, Peter Wizinowich

Proceedings Volume 4007, (2000) https://doi.org/10.1117/12.390320

KEYWORDS: Wavefronts, Adaptive optics, Deformable mirrors, Control systems, Data modeling, Diagnostics, Mathematical modeling, Mirrors, Keck Observatory, Telescopes

Read Abstract +

Proceedings Article | 14 September 1994 Paper

Paper

Advanced ground-penetrating radar

John Warhus, Jeffrey Mast, Erik Johansson, Scott Nelson

Proceedings Volume 2275, (1994) https://doi.org/10.1117/12.186714

KEYWORDS: Bridges, Antennas, Inspection, Imaging systems, Radar, General packet radio service, Transmitters, Ground penetrating radar, Image resolution, Dielectrics

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Proceedings Article | 14 September 1994 Paper

Paper

Three-dimensional ground-penetrating radar imaging using synthetic aperture time-domain focusing

Erik Johansson, Jeffrey Mast

Proceedings Volume 2275, (1994) https://doi.org/10.1117/12.186717

KEYWORDS: Antennas, Transmitters, Data acquisition, Receivers, Radar, Image processing, 3D image processing, Radar imaging, Ground penetrating radar, Signal attenuation

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Proceedings Article | 14 September 1994 Paper

Paper

Three-dimensional ground-penetrating radar imaging using multifrequency diffraction tomography

Jeffrey Mast, Erik Johansson

Proceedings Volume 2275, (1994) https://doi.org/10.1117/12.186716

KEYWORDS: Antennas, Wave propagation, 3D image processing, Visualization, Tomography, Radar, Ground penetrating radar, Diffraction, Scattering, Interfaces

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Proceedings Article | 9 June 1994 Paper

Paper

Simulation of stellar speckle imaging

Erik Johansson, Donald Gavel

Proceedings Volume 2200, (1994) https://doi.org/10.1117/12.177254

KEYWORDS: Turbulence, Atmospheric propagation, Spatial frequencies, Speckle imaging, Optical filters, Computer simulations, Atmospheric turbulence, Atmospheric modeling, Fourier transforms, Large screens

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Proceedings Article | 31 May 1994 Paper

Paper

Performance of adaptive optics at Lick Observatory

Scot Olivier, Jong An, Kenneth Avicola, Horst Bissinger, James Brase, Herbert Friedman, Donald Gavel, Erik Johansson, Claire Max, Kenneth Waltjen, William Fisher, William Bradford

Proceedings Volume 2201, (1994) https://doi.org/10.1117/12.176022

KEYWORDS: Adaptive optics, Stars, Wavefronts, Telescopes, Mirrors, Observatories, Deformable mirrors, Astronomy, Servomechanisms, Atmospheric optics

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SPIE Journal Paper | 1 March 1992

Extended-image reconstruction through horizontal path turbulence using bispectral speckle interferometry

Taylor Lawrence, J. Patrick Fitch, Dennis Goodman, Norbert Massie, Robert Sherwood, Erik Johansson

OE, Vol. 31, Issue 03, (March 1992) https://doi.org/10.1117/12.10.1117/12.56083

KEYWORDS: Charge-coupled devices, Satellites, Speckle, Satellite imaging, Telescopes, Speckle imaging, Image processing, CCD image sensors, Imaging systems, Turbulence

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Proceedings Article | 1 November 1990 Paper

Paper

Bispectral-based optimization algorithms for speckle imaging

Dennis Goodman, Taylor Lawrence, J. Patrick Fitch, Erik Johansson

Proceedings Volume 1351, (1990) https://doi.org/10.1117/12.23664

KEYWORDS: Optimization (mathematics), Speckle imaging

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Proceedings Article | 1 August 1990 Paper

Paper

Simulating speckle interferometry

Erik Johansson, Taylor Lawrence, J. Patrick Fitch, Robert Sherwood

Proceedings Volume 1237, (1990) https://doi.org/10.1117/12.19317

KEYWORDS: Speckle, Imaging systems, Charge-coupled devices, Device simulation, Image processing, Fourier transforms, Photons, Optical transfer functions, Telescopes, Interferometry

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Showing 5 of 37 publications

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