Dr. Phillip A. Willems Profile

Dr. Phillip A. Willems

at Jet Propulsion Lab

SPIE Involvement:

Author

Publications (19)

Proceedings Article | 27 August 2022 Presentation + Paper

NASA’s starshade technology development activity

Phil Willems, Stuart Shaklan, Renyu Hu, Stefan Martin, Doug Lisman, Serena Ferraro, Matt Stegman, Anthony Harness, Gregg Freebury, Manan Arya

Proceedings Volume 12180, 121802N (2022) https://doi.org/10.1117/12.2635326

KEYWORDS: Exoplanets, Telescopes, Astrophysics, Diffraction, Astronomical imaging, Coronagraphy

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Proceedings Article | 27 August 2022 Presentation + Paper

Completion of model validation experiments at the Princeton starshade testbed

Stuart Shaklan, Anthony Harness, N. Jeremy Kasdin, Michael Galvin, K. Balasubramanian, Victor White, Karl Yee, Richard Muller, Phillip Willems, Philip Dumont, Simon Vuong, Doug Lisman

Proceedings Volume 12180, 121802O (2022) https://doi.org/10.1117/12.2629445

KEYWORDS: Diffraction, Data modeling, Polarization, Photomasks, Telescopes, Manufacturing, Etching, Optical instrument design, Finite-difference time-domain method, Error analysis

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Proceedings Article | 27 August 2022 Poster + Paper

Final optomechanical upgrades to the Princeton starshade testbed

Michael Galvin, Anthony Harness, N. Jeremy Kasdin, Phil Willems, Stuart Shaklan

Proceedings Volume 12180, 1218063 (2022) https://doi.org/10.1117/12.2628995

KEYWORDS: Switches, Laser safety, Cameras, Electron multiplying charge coupled devices, Safety, Fiber lasers, Planets, Laser systems engineering, Telescopes, Sun

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Proceedings Article | 1 September 2021 Presentation + Paper

Optical experiments and model validation of perturbed starshade designs

Anthony Harness, Stuart Shaklan, Phil Willems, N. Jeremy Kasdin, K. Balasubramanian, Victor White, Karl Yee, Philip Dumont, Rich Muller, Simon Vuong, Michael Galvin

Proceedings Volume 11823, 1182312 (2021) https://doi.org/10.1117/12.2595409

KEYWORDS: Data modeling, Diffraction, Manufacturing, Polarization, Exoplanets, Performance modeling, Optics manufacturing, Near field diffraction

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Proceedings Article | 24 August 2021 Presentation + Paper

The Gamow Explorer: a Gamma-Ray Burst Observatory to study the high redshift universe and enable multi-messenger astrophysics

N. White, F. Bauer, W. Baumgartner, M. Bautz, E. Berger, B. Cenko, T.-C. Chang, A. Falcone, H. Fausey, C. Feldman, D. Fox, O. Fox, A. Fruchter, C. Fryer, G. Ghirlanda, K. Gorski, C. Grant, S. Guiriec, M. Hart, D. Hartmann, J. Hennawi, D. Kann, D. Kaplan, J. Kennea, D. Kocevski, C. Kouveliotou, C. Lawrence, A. Levan, A. Lidz, A. Lien, T. Littenberg, L. Mas-Ribas, M. Moss, P. O'Brien, J. O'Meara, D. Palmer, D. Pasham, J. Racusin, R. Remillard, O. Roberts, P. Roming, M. Rud, R. Salvaterra, R. Sambruna, M. Seiffert, G. Sun, N. R. Tanvir, R. Terrile, N. Thomas, A. van der Horst, W. T. Verstrand, P. Willems, C. Wilson-Hodge, E. Young, L. Amati, E. Bozzo, O. Karczewski, C. Hernandez-Monteagudo, R. Rebolo Lopez, R. Genova-Santos, A. Martin, J. Granot, P. Bemiamini, R. Gil, E. Burns

Proceedings Volume 11821, 1182109 (2021) https://doi.org/10.1117/12.2599293

KEYWORDS: Galactic astronomy, X-rays, Stars, Observatories, James Webb Space Telescope, Astrophysics, Sensors, Metals, Absorption, Telescopes

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Proceedings Article | 20 August 2021 Presentation + Paper

The Photo-z Infrared Telescope (PIRT) – a space instrument for rapid follow up of high-redshift gamma-ray bursts and electromagnetic counterparts to gravitational wave events

M. Seiffert, A. Balady, T.-C. Chang, R. Dyer, H. Fausey, S. Guiriec, M. Hart, R. O. Morris, J. I. Rodriguez, P. Roming, M. Rud, D. Russel, R. Sambruna, R. Terrile, V. Torossian, A. van der Horst, N. White, P. Willems, A. Woodmansee, E.T. Young

Proceedings Volume 11819, 1181906 (2021) https://doi.org/10.1117/12.2599088

KEYWORDS: Sensors, Telescopes, Electronics, James Webb Space Telescope, Gamma radiation, Infrared telescopes, Monte Carlo methods, Electromagnetism, Control systems, Aerospace engineering

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SPIE Journal Paper | 25 January 2021 Open Access

Mapping the observable sky for a Remote Occulter working with ground-based telescopes

Eliad Peretz, John Mather, Lucas Pabarcius, Sara Seager, Stuart Shaklan, Sergi Hildebrandt, Phil Willems, Kevin Hall

JATIS, Vol. 7, Issue 02, 021212, (January 2021) https://doi.org/10.1117/12.10.1117/1.JATIS.7.2.021212

KEYWORDS: Telescopes, Stars, Sun, Exoplanets, Planets, Signal to noise ratio, Device simulation, Point spread functions, Observatories, Optical instrument design

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SPIE Journal Paper | 9 January 2021 Open Access

Starshade rendezvous: exoplanet sensitivity and observing strategy

Andrew Romero-Wolf, Geoffrey Bryden, Sara Seager, N. Jeremy Kasdin, Jeff Booth, Matt Greenhouse, Doug Lisman, Bruce Macintosh, Stuart Shaklan, Melissa Vess, Steve Warwick, David Webb, John Ziemer, Andrew Gray, Michael Hughes, Greg Agnes, Jonathan Arenberg, S. Case Bradford, Michael Fong, Jennifer Gregory, Steve Matousek, Jason Rhodes, Phil Willems, Simone D'Amico, John Debes, Shawn Domagal-Goldman, Sergi Hildebrandt, Renyu Hu, Alina Kiessling, Nikole Lewis, Maxime Rizzo, Aki Roberge, Tyler Robinson, Leslie Rogers, Dmitry Savransky, Chris Stark

JATIS, Vol. 7, Issue 02, 021210, (January 2021) https://doi.org/10.1117/12.10.1117/1.JATIS.7.2.021210

KEYWORDS: Planets, Exoplanets, Stars, Telescopes, Signal to noise ratio, Spectroscopy, Target detection, Observatories, Sensors, Point spread functions

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SPIE Journal Paper | 8 January 2021 Open Access

Overview and reassessment of noise budget of starshade exoplanet imaging

Renyu Hu, Doug Lisman, Stuart Shaklan, Stefan Martin, Phil Willems, Kendra Short

JATIS, Vol. 7, Issue 02, 021205, (January 2021) https://doi.org/10.1117/12.10.1117/1.JATIS.7.2.021205

KEYWORDS: Planets, Stars, Exoplanets, Telescopes, Calibration, Stray light, Particles, Reflector telescopes, Coating, Sensors

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High-contrast imaging enabled by a starshade in formation flight with a space telescope can provide a near-term pathway to search for and characterize temperate and small planets of nearby stars. NASA’s Starshade Technology Development Activity to TRL5 (S5) is rapidly maturing the required technologies to the point at which starshades could be integrated into potential future missions. We reappraise the noise budget of starshade-enabled exoplanet imaging to incorporate the experimentally demonstrated optical performance of the starshade and its optical edge. Our analyses of stray light sources—including the leakage through micrometeoroid damage and the reflection of bright celestial bodies—indicate that sunlight scattered by the optical edge (i.e., the solar glint) is by far the dominant stray light. With telescope and observation parameters that approximately correspond to Starshade Rendezvous with Roman and Habitable Exoplanet Observatory (HabEx), we find that the dominating noise source is exozodiacal light for characterizing a temperate and Earth-sized planet around Sun-like and earlier stars and the solar glint for later-type stars. Further, reducing the brightness of solar glint by a factor of 10 with a coating would prevent it from becoming the dominant noise for both Roman and HabEx. With an instrument contrast of 10 − 10, the residual starlight is not a dominant noise, and increasing the contrast level by a factor 10 does not lead to any appreciable change in the expected science performance. If unbiased calibration of the background to the photon-noise limit can be achieved, Starshade Rendezvous with Roman could provide nearly photon-limited spectroscopy of temperate and Earth-sized planets of F, G, and K stars <4 parsecs away, and HabEx could extend this capability to many more stars <8 parsecs. Larger rocky planets around stars <8 parsecs would be within the reach of Roman. To achieve these capabilities, the exozodiacal light may need to be calibrated to a precision better than 2% and the solar glint to better than 5%. Our analysis shows that the expected temporal variability of the solar glint is unlikely to hinder the calibration, and the main challenge for background calibration likely comes from the unsmooth spatial distribution of exozodiacal dust in some stars. Taken together, these results validate the optical noise budget and technology milestones adopted by S5 against key science objectives and inform the priorities of future technology developments and science and industry community partnerships.

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SPIE Journal Paper | 8 January 2021 Open Access

NASA’s starshade technology development activity

Phil Willems, Doug Lisman

JATIS, Vol. 7, Issue 02, 021203, (January 2021) https://doi.org/10.1117/12.10.1117/1.JATIS.7.2.021203

KEYWORDS: Exoplanets, Telescopes, Stars, Prototyping, Sun, Space operations, Opacity, Imaging spectroscopy, Diffraction, Coronagraphy

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SPIE Journal Paper | 8 January 2021 Open Access

Optical verification experiments of sub-scale starshades

Anthony Harness, Stuart Shaklan, Phillip Willems, N. Jeremy Kasdin, Bala Balasubramanian, Philip Dumont, Victor White, Karl Yee, Rich Muller, Michael Galvin

JATIS, Vol. 7, Issue 02, 021207, (January 2021) https://doi.org/10.1117/12.10.1117/1.JATIS.7.2.021207

KEYWORDS: Diffraction, Photomasks, Data modeling, Apodization, Polarization, Geometrical optics, Manufacturing, Cameras, Optics manufacturing, Calibration

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Proceedings Article | 13 December 2020 Presentation + Paper

Validation of diffraction models with experimental results from the Princeton starshade testbed

Anthony Harness, Stuart Shaklan, N. Jeremy Kasdin, Phillip Willems, K. Balasubramanian, Philip Dumont, Victor White, Karl Yee, Rich Muller, Simon Vuong, Michael Galvin

Proceedings Volume 11443, 114431R (2020) https://doi.org/10.1117/12.2561048

KEYWORDS: Diffraction, Data modeling, Spectroscopy, Exoplanets, Space operations

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Proceedings Article | 17 September 2019 Presentation + Paper

Mapping the observable sky for a remote occulter working with ground-based telescopes

Eliad Peretz, John Mather, Sara Seager, Richard Slonaker, Stuart Shaklan, Phil Willems, Sergei Hildebrant

Proceedings Volume 11117, 111170S (2019) https://doi.org/10.1117/12.2528756

KEYWORDS: Large telescopes, Telescopes, Target detection, Observatories, Exoplanetary science, Adaptive optics, Spectroscopes, Time metrology, Imaging spectroscopy, Spectroscopy

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Proceedings Article | 9 September 2019 Presentation + Paper

Demonstration of 1e-10 contrast at the inner working angle of a starshade in broadband light and at a flight-like Fresnel number

Anthony Harness, Stuart Shaklan, N. Jeremy Kasdin, Michael Galvin, Phillip Willems, Kunjithapatham Balasubramanian, Victor White, Karl Yee, Richard Muller, Philip Dumont, Simon Vuong

Proceedings Volume 11117, 111170L (2019) https://doi.org/10.1117/12.2528445

KEYWORDS: Diffraction, Data modeling, Cameras, Polarization, Geometrical optics, Exoplanets, Apodization, Rayleigh scattering, Atmospheric propagation, Laser beam propagation

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Proceedings Article | 9 September 2019 Presentation + Paper

Rayleigh scattering in the Princeton starshade testbed

Phil Willems, Anthony Harness

Proceedings Volume 11117, 111170M (2019) https://doi.org/10.1117/12.2528077

KEYWORDS: Rayleigh scattering, Light scattering

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Proceedings Article | 27 July 2018 Paper

The NEID precision radial velocity spectrometer: port adapter overview, requirements, and test plan

Sarah Logsdon, Michael McElwain, Qian Gong, Ming Liang, Fernando Santoro, Christian Schwab, Chad Bender, Cullen Blake, Samuel Halverson, Fred Hearty, Emily Hunting, Kurt Jaehnig, Suvrath Mahadevan, Andrew Monson, Jeffrey Percival, Jayadev Rajagopal, Lawrence Ramsey, Arpita Roy, Michael Smith, Ryan Terrien, Erik Timmermann, Phil Willems, Marsha Wolf, Jason Wright

Proceedings Volume 10702, 1070267 (2018) https://doi.org/10.1117/12.2312209

KEYWORDS: Optical fibers, Telescopes, Cameras, Spectroscopy, Stars, Astronomy, Exoplanets, Observatories, Atmospheric corrections, Systems engineering

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Proceedings Article | 24 July 2018 Presentation + Paper

The HOSTS survey for exo-zodiacal dust: preliminary results and future prospects

S. Ertel, G. Kennedy, D. Defrère, P. Hinz, A. Shannon, B. Mennesson, W. C. Danchi, C. Gelino, J. M. Hill, W. Hoffman, G. Rieke, E. Spalding, J. Stone, A. Vaz, A. Weinberger, P. Willems, O. Absil, P. Arbo, V. Bailey, C. Beichman, G. Bryden, E. Downey, O. Durney, S. Esposito, A. Gaspar, P. Grenz, C. Haniff, J. Leisenring, L. Marion, T. McMahon, R. Millan-Gabet, M. Montoya, K. Morzinski, E. Pinna, J. Power, A. Puglisi, A. Roberge, E. Serabyn, A. Skemer, K. Stapelfeldt, K. Y. L. Su, V. Vaitheeswaran, M. Wyatt

Proceedings Volume 10698, 106981V (2018) https://doi.org/10.1117/12.2313685

KEYWORDS: Stars, Planets, Calibration, Statistical analysis, Exoplanets, Space telescopes, Nulling interferometry, Astronomy, Telescopes, Interferometry

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The presence of large amounts of dust in the habitable zones of nearby stars is a significant obstacle for future exo-Earth imaging missions. We executed the HOSTS (Hunt for Observable Signatures of Terrestrial Systems) survey to determine the typical amount of such exozodiacal dust around a sample of nearby main sequence stars. The majority of the data have been analyzed and we present here an update of our ongoing work. Nulling interferometry in N band was used to suppress the bright stellar light and to detect faint, extended circumstellar dust emission. We present an overview of the latest results from our ongoing work. We find seven new N band excesses in addition to the high confidence confirmation of three that were previously known. We find the first detections around Sun-like stars and around stars without previously known circumstellar dust. Our overall detection rate is 23%. The inferred occurrence rate is comparable for early type and Sun-like stars, but decreases from 71^{+11 -20}% for stars with previously detected mid- to far-infrared excess to 11^{+9 -4}% for stars without such excess, confirming earlier results at high confidence. For completed observations on individual stars, our sensitivity is five to ten times better than previous results. Assuming a lognormal luminosity function of the dust, we find upper limits on the median dust level around all stars without previously known mid to far infrared excess of 11.5 zodis at 95% confidence level. The corresponding upper limit for Sun-like stars is 16 zodis. An LBTI vetted target list of Sun-like stars for exo-Earth imaging would have a corresponding limit of 7.5 zodis. We provide important new insights into the occurrence rate and typical levels of habitable zone dust around main sequence stars. Exploiting the full range of capabilities of the LBTI provides a critical opportunity for the detailed characterization of a sample of exozodiacal dust disks to understand the origin, distribution, and properties of the dust.

Proceedings Article | 9 July 2018 Paper

The NEID precision radial velocity spectrometer: optical design of the port adapter and ADC

Christian Schwab, Ming Liang, Qian Gong, Chad Bender, Cullen Blake, Samuel Halverson, Daniel Harbeck, Fred Hearty, Emily Hunting, Kurt Jaehnig, Sarah Logsdon, Suvrath Mahadevan, Michael McElwain, Andrew Monson, Jeffrey Percival, Jayadev Rajagopal, Lawrence Ramsey, Paul Robertson, Arpita Roy, Fernando Santoro, Michael Smith, Ryan Terrien, Erik Timmermann, Phil Willems, Marsha Wolf, Jason Wright

Proceedings Volume 10702, 1070271 (2018) https://doi.org/10.1117/12.2314420

KEYWORDS: Target acquisition, Atmospheric corrections, Telescopes, Mirrors, Collimators, Cameras, Beam splitters, Coating, Spectrographs, Reflectivity

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Proceedings Article | 3 February 2006 Paper

Nonlinear optical effects in the LIGO gravitational-wave interferometer

Phil Willems

Proceedings Volume 5975, 59750H (2006) https://doi.org/10.1117/12.675551

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Showing 5 of 19 publications

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