Mr. Predrag Sekulic Profile

Predrag Sekulic

Area of Expertise:

Optical Alignment , Optical Metrology , Integration Test & Commissioning , Optical Design , Space , Astronomy

Websites:

Company Website

Publications (16)

Proceedings Article | 17 March 2023 Presentation

Initial test results for NASA Goddard’s low-cost optical terminal adaptive optics system

Daniel Paulson, Predrag Sekulic, Robert Lafon, Patrick Thompson, Stephen Hall, Kristoffer Olsen, Nikki Desch, Haleh Safavi

Proceedings Volume 12413, 124130Y (2023) https://doi.org/10.1117/12.2654236

KEYWORDS: Adaptive optics, Telescopes, Telecommunications, Optical communications, Atmospheric turbulence, Wavefront distortions, Turbulence, Speckle pattern, Space operations, Single mode fibers

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Proceedings Article | 15 March 2023 Presentation + Paper

NASA’s LCOT (low-cost optical terminal) FSOS (free-space optical subsystem): concept, design, build, and test

Patrick Thompson, Armen Caroglanian, Jeffrey Guzek, Stephen Hall, Robert Lafon, Kristoffer Olsen, Daniel Paulson, Haleh Safavi, Predrag Sekulic, Oscar Ta, Mark Wilson

Proceedings Volume 12413, 124130X (2023) https://doi.org/10.1117/12.2653355

KEYWORDS: Adaptive optics, Design and modelling, Telescopes, Free space optics, Commercial off the shelf technology, Cameras, Interfaces, Mirrors, Tunable filters, Telecommunications

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Proceedings Article | 15 March 2023 Presentation + Paper

Current status of NASA’s Low-Cost Optical Terminal (LCOT) at Goddard Space Flight Center

Robert Lafon, Yingxin Bai, Armen Caroglanian, James Dailey, Nikki Desch, Howard Garon, Steve Hall, Ron Miller, Dan Paulson, Haleh Safavi, Predrag Sekulic, John Speer, Patrick Thompson, Victoria Wu

Proceedings Volume 12413, 124130V (2023) https://doi.org/10.1117/12.2652103

KEYWORDS: Telescopes, Laser communication terminals, Adaptive optics, Quantum optical communication, Laser communications, Cameras

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Proceedings Article | 13 December 2020 Poster

The DKIST Visible Broadband Imager

Andrew Ferayorni, Andrew Beard, Friedrich Wöger, Scott Gregory, Christopher Runyan, Predrag Sekulic

Proceedings Volume 11447, 11447AI (2020) https://doi.org/10.1117/12.2563224

KEYWORDS: Imaging systems, Solar telescopes, Observatories, Temporal resolution, Telescopes, Sun

Proceedings Article | 10 July 2018 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 Presentation + Paper

Development of DKIST IT&C Shack-Hartmann wavefront measurement system

Chen Liang, Predrag Sekulic, Kerry Gonzales, Pierre Aka, Simon Craig

Proceedings Volume 10700, 107001R (2018) https://doi.org/10.1117/12.2312832

KEYWORDS: Wavefronts, Calibration, Wavefront sensors, Optical design, Mirrors, Optical alignment, Solar telescopes, Telescopes

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Proceedings Article | 6 July 2018 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

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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 | 21 November 2017 Open Access

Nulling interferometry for the darwin mission: laboratory demonstration experiment

Marc Ollivier, Alain Léger, Predrag Sekulic, Alain Labèque, Guy Michel

Proceedings Volume 10569, 1056911 (2017) https://doi.org/10.1117/12.2307875

KEYWORDS: Optical filters, Interferometers, Wavefronts, Nulling interferometry, Spatial filters, Infrared radiation, Polarization, Gas lasers, Thermography, Optical fibers

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Proceedings Article | 16 August 2016 Paper

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

Simon Craig, Kerry Gonzales, Robert Hubbard, Chen Liang, Ruth Kneale, William McBride, Predrag Sekulic, Timothy Williams

Proceedings Volume 9911, 991102 (2016) https://doi.org/10.1117/12.2233654

KEYWORDS: Solar telescopes, Systems engineering, Telescopes, Visualization, Astronomy, Geographic information systems, Coating, Optical alignment, Wavefronts, Systems modeling

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Proceedings Article | 9 August 2016 Paper

DKIST visible broadband imager alignment in laboratory: first results

Predrag Sekulic, Scott Gregory, Steve Hegwer, Andrew Ferayorni, Friedrich Woeger

Proceedings Volume 9908, 99085A (2016) https://doi.org/10.1117/12.2233660

KEYWORDS: Optical alignment, Interferometry, Tolerancing, Lenses, Data modeling, Mirrors, Objectives, Interferometers, Monochromatic aberrations, Monte Carlo methods

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Proceedings Article | 27 July 2016 Paper

Daniel K. Inouye Solar Telescope optical alignment plan

Predrag Sekulic, Chen Liang, Kerry Gonzales, Robert Hubbard, Simon Craig

Proceedings Volume 9906, 990653 (2016) https://doi.org/10.1117/12.2233604

KEYWORDS: Optical alignment, Telescopes, Solar telescopes, Mirrors, Wavefronts, Off axis mirrors, Wavefront sensors, Optical alignment, Off axis mirrors, Metrology, Tolerancing, Device simulation

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Proceedings Article | 26 July 2016 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

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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

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

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

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Proceedings Article | 26 February 2003 Paper

New polychromatic test bench for Darwin/TPF nulling interferometer laboratory demonstration

Alain Labeque, Alain Leger, Predrag Sekulic, Frank Brachet, Marc Ollivier, Thierry Lepine, Claude Valette, Claude Lizambert, Veronique Hervier

Proceedings Volume 4852, (2003) https://doi.org/10.1117/12.460698

KEYWORDS: Beam splitters, Planets, Interferometers, Nulling interferometry, Space telescopes, Telescopes, Infrared radiation, Phase shifts, Mirrors, Metrology

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Proceedings Article | 5 July 2000 Paper

Nulling interferometry for the DARWIN mission: experimental demonstration of the concept in the thermal infrared with high levels of rejection

Marc Ollivier, Jean-Marie Mariotti, Predrag Sekulic, Guy Michel, Alain Leger, Patrick Bouchareine, Jacqueline Brunaud, Vincent Coude du Foresto, Bertrand Mennesson, Pascal Borde, Anne Amy-Klein, A. Vanlerberghe, Pierre-Olivier Lagage, Guy Artzner, Fabien Malbet

Proceedings Volume 4006, (2000) https://doi.org/10.1117/12.390226

KEYWORDS: Interferometers, Optical filters, Nulling interferometry, Infrared radiation, Wavefronts, Thermography, Spatial filters, Optical fibers, Information operations, Infrared sensors

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Showing 5 of 16 publications

Conference Committee Involvement (5)

Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation V

17 July 2022 | Montréal, Québec, Canada

Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation IV

14 December 2020 | Online Only, California, United States

Ground-based and Airborne Telescopes VIII

14 December 2020 | Online Only, California, United States

Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation IV

13 December 2020 | San Diego, California, United States

Ground-based and Airborne Telescopes VII

10 June 2018 | Austin, Texas, United States

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