Dr. David J. Schlegel Profile

Dr. David J. Schlegel

at Lawrence Berkeley National Lab

SPIE Involvement:

Author

Publications (19)

Proceedings Article | 18 July 2024 Poster + Paper

Investigations on assembly and coverage for modular focal planes of multiplexed telescopes

Maxime Rombach, Xiangyu Xu, Ricardo Araujo, Markus Thurneysen, Stefane Caseiro, Corentin Magnenat, Joseph Silber, Malak Galal, David Schlegel, Jean-Paul Kneib

Proceedings Volume 13096, 130969V (2024) https://doi.org/10.1117/12.3018315

KEYWORDS: Robots, Tolerancing, Deformation, Telescopes, Equipment, Vignetting, Manufacturing, Finite element methods, Design, Multiplexing

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Proceedings Article | 29 August 2022 Poster + Paper

MegaMapper: concept and optical design for a 6.5m aperture massively multiplexed spectroscopic facility

Guillermo Blanc, Joseph Harry Silber, Stephen Smee, Robert Barkhouser, Robert Besuner, Jeffrey Crane, Juna Kollmeier, Povilas Palunas, David Schlegel, Stephen Shectman, Ricardo Araujo, Charlie Baltay, Mohamed Bouri, Emily Farr, Julien Guy, Leopoldo Infante, Jean-Paul Kneib, Travis Mandeville, Claire Poppett, David Rabinowitz, Solange Ramirez, Michael Schubnell, Joshua Simon, Markus Thurneysen, Sarah Tuttle, William Van Shourt, Stefanie Wachter

Proceedings Volume 12182, 1218230 (2022) https://doi.org/10.1117/12.2625992

KEYWORDS: Telescopes, Spectrographs, Mirrors, Optical design, Spectroscopy, Robots, Optical instrument design, Multiplexing, Robotics, Image quality

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Proceedings Article | 13 December 2020 Poster + Paper

The DESI sky continuum monitor system

Suk Sien Tie, David Kirkby, Paul Martini, Claire Poppett, Daniel Pappalardo, David Schlegel, Jonathan Shover, Julien Guy, Kevin Fanning, Klaus Honscheid, Michael Lampton, Patrick Jelinsky, Robert Besuner, Kai Zhang, David Brooks, Peter Doel, Yutong Duan, Enrique Gastañaga, Robert Kehoe, Martin Landriau, Michael Levi, Francisco Prada, Gregory Tarle

Proceedings Volume 11447, 1144785 (2020) https://doi.org/10.1117/12.2561436

KEYWORDS: Cameras, Optical filters, Spectroscopes, Baryon acoustic oscillations, Galactic astronomy, Telescopes, Fiber optics, Spectrographs, Imaging systems, Spectroscopy

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Proceedings Article | 10 July 2018 Presentation + Paper

Fabrication of the DESI corrector lenses

Timothy Miller, Robert Besuner, Michael Levi, Michael Lampton, Patrick Jelinsky, Henry Heetderks, David Schlegel, Jerry Edelstein, Peter Doel, David Brooks, Stephen Kent, Gary Poczulp, Michael Sholl

Proceedings Volume 10706, 107060X (2018) https://doi.org/10.1117/12.2312949

KEYWORDS: Lenses, Telescopes, Polishing, Glasses, Tolerancing, Astronomy, Silica, Optical design, Data modeling, Surface finishing

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Proceedings Article | 10 July 2018 Presentation + Paper

Broadband anti-reflection coating for the meter class Dark Energy Spectroscopic Instrument lenses

Charles Kennemore, Debi Archer, Russ Barbaria, Joe Bertolina, Rick Dix, Katy Dodson, Sharon Doi-Okray, Aaron Gallon, Bill Sweet, Timothy Miller, Robert Besuner, Michael Levi, Michael Lampton, Pat Jelinsky, Jerry Edelstein, David Schlegel, Jeremy McCauley, Henry Heetderks, Michael Sholl, Peter Doel, David Brooks, Stephen Kent

Proceedings Volume 10706, 107061S (2018) https://doi.org/10.1117/12.2313006

KEYWORDS: Coating, Lenses, Antireflective coatings, Spectroscopes, Astronomy, Computer aided design

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The Dark Energy Spectroscopic Instrument (DESI), currently under construction, will be used to measure the expansion history of the Universe using the Baryon Acoustic Oscillation technique. The spectra of 35 million galaxies and quasars over 14000 sq deg will be measured during the life of the experiment. A new prime focus corrector for the KPNO Mayall telescope will deliver light to 5000 fiber optic positioners. The fibers, in turn, feed ten broad-band spectrographs. We will describe the broadband AR coating (360 nm to 980nm) that was applied to the lenses of the camera system for DESI using ion assisted deposition techniques in a 3 m coating chamber. The camera has 6 lenses ranging in diameter from 0.8 m to 1.14 m, weighing from 84 kg to 237 kg and made from fused silica or BK7. The size and shape of the surfaces provided challenges in design, uniformity control, handling, tooling and process control. Single surface average transmission and minimum transmission met requirements. The varied optical surfaces and angle of incidence considerations meant the uniformity of the coating was of prime concern. The surface radius of curvature (ROC) for the 12 surfaces ranged from nearly flat to a ROC of 611 mm and a sag of 140 mm. One lens surface has an angle of incidence variation from normal incidence to 40°. Creating a design with a larger than required bandwidth to compensate for the non-uniformity and angle variation created the ability to reduce the required coating uniformity across the lens and a single design to be used for all common substrate surfaces. While a perfectly uniform coating is often the goal it is usually not practicable or cost effective for highly curved surfaces. The coating chamber geometry allowed multiple radial positions of the deposition sources as well as substrate height variability. Using these two variables we were able to avoid using any masking to achieve the uniformity required to meet radial and angle performance goals. Very broadband AR coatings usually have several very thin and optically important layers. The DESI coating design has layers approaching 3 nm in thickness. Having sensitive thin layers in the design meant controlling layer thickness and azimuthal variation were critical to manufacturing repeatability. Through use of strategically placed quartz crystal monitors combined with stable deposition plumes, the manufacturing variability was reduced to acceptable levels. Low deposition rates and higher rotation rates also provided some stability to azimuthal variation.

Proceedings Article | 9 July 2018 Paper

A predictive optical sky background model for DESI

Parker Fagrelius, David Schlegel

Proceedings Volume 10702, 107027D (2018) https://doi.org/10.1117/12.2311714

KEYWORDS: Spectrographs, Galactic astronomy, Data modeling, Calibration, Sun, Telescopes, Signal to noise ratio, Cameras, Airglow, Observatories

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Proceedings Article | 9 July 2018 Paper

Design and production of the DESI fibre cables

Jürgen Schmoll, Robert Besuner, David Bramall, David Brooks, Jerry Edelstein, Patrick Jelinsky, Michael Levi, Graham Murray, Claire Poppett, Ray Sharples, Luke Tyas, David Schlegel

Proceedings Volume 10702, 107027N (2018) https://doi.org/10.1117/12.2312140

KEYWORDS: Spectrographs, Telescopes, Product engineering, Optical fibers, Manufacturing, Astronomy, Metrology

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Proceedings Article | 6 July 2018 Presentation + Paper

Overview of the Dark Energy Spectroscopic Instrument

Paul Martini, Stephen Bailey, Robert Besuner, David Brooks, Peter Doel, Jerry Edelstein, Daniel Eisenstein, Brenna Flaugher, Gaston Gutierrez, Stewart Harris, Klaus Honscheid, Patrick Jelinsky, Richard Joyce, Stephen Kent, Michael Levi, Francisco Prada, Claire Poppett, David Rabinowitz, Constance Rockosi, Laia Cardiel Sas, David Schlegel, Michael Schubnell, Ray Sharples, Joseph Silber, David Sprayberry, Risa Wechsler

Proceedings Volume 10702, 107021F (2018) https://doi.org/10.1117/12.2313063

KEYWORDS: Spectrographs, Cameras, Telescopes, Imaging systems, Spectroscopes, Control systems, Camera shutters, Near infrared, Astronomy, Physics

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Proceedings Article | 9 August 2016 Paper

Mosaic3: a red-sensitive upgrade for the prime focus camera at the Mayall 4m telescope

Arjun Dey, David Rabinowitz, Armin Karcher, Chris Bebek, Charles Baltay, David Sprayberry, Frank Valdes, Bob Stupak, John Donaldson, Will Emmet, Tom Hurteau, Behzad Abareshi, Bob Marshall, Dustin Lang, Mike Fitzpatrick, Phil Daly, Dick Joyce, David Schlegel, Heidi Schweiker, Lori Allen, Bob Blum, Michael Levi

Proceedings Volume 9908, 99082C (2016) https://doi.org/10.1117/12.2231488

KEYWORDS: Charge-coupled devices, Galactic astronomy, Telescopes, Cameras, Charge-coupled devices, Spectroscopes, Observatories, CCD cameras, Astronomy, Imaging systems, Image quality

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Proceedings Article | 9 August 2016 Paper

ProtoDESI: risk reduction experiment for the Dark Energy Spectroscopic Instrument

Parker Fagrelius, Charles Baltay, Christopher Bebek, Robert Besuner, Francisco Castander, Arjun Dey, Elizabeth Buckley-Geer, Ann Elliott, William Emmet, Brenna Flaugher, Irena Gershkovich, Klaus Honscheid, Dick Joyce, Stephen Kent, Robert Marshall, Ronald Probst, David Rabinowitz, Kevin Reil, David Schlegel, Michael Schubnell, Santiago Serrano, Joseph Silber, David Sprayberry, Greg Tarle

Proceedings Volume 9908, 99087X (2016) https://doi.org/10.1117/12.2231760

KEYWORDS: Galactic astronomy, Telescopes, Control systems, Spectroscopes, Cameras, Stars, Robotics, Light emitting diodes, Photometry, Astronomy

Read Abstract +

The Dark Energy Spectroscopic Instrument (DESI) is under construction to measure the expansion history of the Universe using the Baryon Acoustic Oscillation technique. The spectra of 40 million galaxies over 14,000 sq. deg. will be measured during the life of the experiment. A new prime focus corrector for the KPNO Mayall telescope will deliver light to 5000 fiber optic positioners. The fibers in turn feed ten broad-band spectrographs. We describe the ProtoDESI experiment, planned for installation and commissioning at the Mayall telescope in the fall of 2016, which will test the fiber positioning system for DESI. The ProtoDESI focal plate, consisting of 10 fiber positioners, illuminated fiducials, and a guide, focus and alignment (GFA) sensor module, will be installed behind the existing Mosaic prime focus corrector. A Fiber View Camera (FVC) will be mounted to the lower surface of the primary mirror cell and a subset of the Instrument Control System (ICS) will control the ProtoDESI subsystems, communicate with the Telescope Control System (TCS), and collect instrument monitoring data. Short optical fibers from the positioners will be routed to the back of the focal plane where they will be imaged by the Fiber Photometry Camera (FPC) or back-illuminated by a LED system. Target objects will be identified relative to guide stars, and using the GFA in a control loop with the ICS/TCS system, the guide stars will remain stable on pre-identified GFA pixels. The fiber positioners will then be commanded to the target locations and placed on the targets iteratively, using the FVC to centroid on back-illuminated fibers and fiducials to make corrective delta motions. When the positioners are aligned with the targets on-sky, the FPC will measure the intensities from the positioners’ fibers which can then be dithered to look for intensity changes, indicating how well the fibers were initially positioned on target centers. The final goal is to operate ProtoDESI on the Mayall telescope for a 6-hour period during one night, successfully placing targets on the intended fibers for the duration of a typical DESI science exposure.

Proceedings Article | 5 October 2012 Paper

Mapping the universe with BigBOSS

Nick Mostek, Kyle Barbary, Christopher Bebek, Arjun Dey, Jerry Edelstein, Patrick Jelinsky, Alex Kim, Michael Lampton, Michael Levi, Patrick McDonald, Claire Poppett, Natalie Roe, David Schlegel, Michael Sholl

Proceedings Volume 8446, 84460Q (2012) https://doi.org/10.1117/12.924915

KEYWORDS: Galactic astronomy, Baryon acoustic oscillations, Spectrographs, Monte Carlo methods, Distance measurement, Spectroscopy, Device simulation, Error analysis, Photons, Data modeling

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Proceedings Article | 24 September 2012 Paper

Performance of the Apache Point Observatory Galactic Evolution Experiment (APOGEE) high-resolution near-infrared multi-object fiber spectrograph

John Wilson, F. Hearty, M. Skrutskie, S. Majewski, R. Schiavon, D. Eisenstein, J. Gunn, J. Holtzman, D. Nidever, B. Gillespie, D. Weinberg, B. Blank, C. Henderson, S. Smee, R. Barkhouser, A. Harding, S. Hope, G. Fitzgerald, T. Stolberg, J. Arns, M. Nelson, S. Brunner, A. Burton, E. Walker, C. Lam, P. Maseman, J. Barr, F. Leger, L. Carey, N. MacDonald, G. Ebelke, S. Beland, T. Horne, E. Young, G. Rieke, M. Rieke, T. O'Brien, J. Crane, M. Carr, C. Harrison, R. Stoll, M. Vernieri, M. Shetrone, C. Allende-Prieto, J. Johnson, P. Frinchaboy, G. Zasowski, A. Garcia Perez, D. Bizyaev, K. Cunha, V. Smith, Sz. Meszaros, B. Zhao, M. Hayden, S. D. Chojnowski, B. Andrews, C. Loomis, R. Owen, M. Klaene, J. Brinkmann, F. Stauffer, D. Long, W. Jordan, D. Holder, F. Cope, T. Naugle, B. Pfaffenberger, D. Schlegel, M. Blanton, D. Muna, B. Weaver, S. Snedden, K. Pan, H. Brewington, E. Malanushenko, V. Malanushenko, A. Simmons, D. Oravetz, S. Mahadevan, S. Halverson

Proceedings Volume 8446, 84460H (2012) https://doi.org/10.1117/12.927140

KEYWORDS: Sensors, Cameras, Telescopes, Observatories, Stars, Mirrors, Calibration, Spectrographs, Collimators, Astronomical imaging

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Proceedings Article | 24 September 2012 Paper

BigBOSS: a stage IV dark energy redshift survey

Michael Sholl, Mark Ackerman, Chris Bebek, Robert Besuner, Arjun Dey, Jerry Edelstein, Patrick Jelinsky, Michael Lampton, Michael Levi, Ming Liang, Paul Perry, Natalie Roe, Joseph Silber, David Schlegel

Proceedings Volume 8446, 844667 (2012) https://doi.org/10.1117/12.926179

KEYWORDS: Actuators, Spectroscopy, Cameras, Galactic astronomy, Telescopes, Sensors, Astronomical imaging, Mirrors, Collimators, Astronomy

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Proceedings Article | 24 September 2012 Paper

The BigBOSS spectrograph

Patrick Jelinsky, Chris Bebek, Robert Besuner, Pierre-Henri Carton, Jerry Edelstein, Michael Lampton, Michael Levi, Claire Poppett, Eric Prieto, David Schlegel, Michael Sholl

Proceedings Volume 8446, 844668 (2012) https://doi.org/10.1117/12.925451

KEYWORDS: Spectrographs, Sensors, Cameras, Spectral resolution, Collimators, Reflectivity, Near infrared, Galactic astronomy, Glasses, Optical design

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Proceedings Article | 24 September 2012 Paper

Integrating BigBOSS with the Mayall Telescope

Robert Besuner, Chris Bebek, Arjun Dey, Will Goble, Dick Joyce, Michael Levi, Kevin Reil, David Schlegel, Michael Sholl

Proceedings Volume 8446, 844652 (2012) https://doi.org/10.1117/12.925497

KEYWORDS: Telescopes, Mirrors, Spectrographs, Space telescopes, Cameras, Fourier transforms, Optical fibers, Baryon acoustic oscillations, Sensors, Astronomical imaging

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Proceedings Article | 13 September 2012 Paper

Tunable laser techniques for improving the precision of observational astronomy

Claire Cramer, Steven Brown, Keith Lykke, John Woodward, Stephen Bailey, David Schlegel, Adam Bolton, Joel Brownstein, Peter Doherty, Christopher Stubbs, Amali Vaz, Andrew Szentgyorgyi

Proceedings Volume 8450, 84500S (2012) https://doi.org/10.1117/12.925198

KEYWORDS: Calibration, Tunable lasers, Sensors, Spectrographs, Point spread functions, Telescopes, Astronomy, Spectral calibration, Laser applications, Space telescopes

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Proceedings Article | 22 September 2011 Paper

BigBOSS: enabling widefield cosmology on the Mayall Telescope

Michael Sholl, Chris Bebek, Robert Besuner, Arjun Dey, Jerry Edelstein, Patrick Jelinsky, Michael Lampton, Michael Levi, Ming Liang, Paul Perry, Natalie Roe, David Schlegel

Proceedings Volume 8127, 81270D (2011) https://doi.org/10.1117/12.894381

KEYWORDS: Telescopes, Galactic astronomy, Prisms, Spectrometers, Silica, Actuators, Astronomical imaging, Lenses, Interfaces, Baryon acoustic oscillations

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Proceedings Article | 25 July 2008 Paper

LBNL fiber positioners for wide-field spectroscopy

David Schlegel, Bill Ghiorso

Proceedings Volume 7018, 701850 (2008) https://doi.org/10.1117/12.801673

KEYWORDS: Actuators, Galactic astronomy, Computer programming, Switches, Calibration, Cameras, Optical fibers, Telescopes, Spectroscopy, Magnetism

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Proceedings Article | 30 September 2004 Paper

Mass-producing spectra: the SDSS spectrographic system

Peter Newman, Dan Long, Stephanie Snedden, S. Kleinman, Atsuko Nitta, Michael Harvanek, Jurek Krzesinski, Howard Brewington, J. Barentine, Eric Neilsen, David Schlegel

Proceedings Volume 5492, (2004) https://doi.org/10.1117/12.541394

KEYWORDS: Telescopes, Spectrographs, Imaging spectroscopy, Stars, Calibration, Imaging systems, Mirrors, Spectroscopy, Databases, Observatories

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Showing 5 of 19 publications

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