Dr. W. Thomas Roberts Profile

Dr. W. Thomas Roberts

Member of Technical Staff at Jet Propulsion Lab

SPIE Involvement:

Author

Publications (25)

Proceedings Article | 13 March 2024 Presentation

Optical links with electronically steerable apertures

Jared Sisler, Prachi Thureja, Joseph Kovalik, William T. Roberts, Ruzan Sokhoyan, Harry Atwater, Abhijit Biswas

Proceedings Volume 12877, 128770N (2024) https://doi.org/10.1117/12.3003475

KEYWORDS: Free space optics, Beam steering, Transceivers, Free space optical communications, Wavefront sensors, Solar system, Robotics, Reflection, Plasmonics, Oxides

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Proceedings Article | 13 March 2024 Presentation + Paper

Enhancing the optical communication telescope laboratory (OCTL) to support quantum communications between Earth and space

Alexander Lohrmann, Ioana Craiciu, Kittrin Matthews, Gerardo Ortiz, Lewis Roberts, W. Thomas Roberts, Ryan Rogalin, Dmitrios Antsos, Matthew Shaw, Makan Mohageg

Proceedings Volume 12911, 1291104 (2024) https://doi.org/10.1117/12.2691440

KEYWORDS: Polarization, Satellites, Dielectric polarization, Telescopes, Design, Quantum detection, Quantum key distribution, Quantum systems, Polarization control, Quantum receivers

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Proceedings Article | 15 March 2023 Presentation + Paper

Ground station for terabyte infrared delivery (TBIRD)

Sabino Piazzolla, William Roberts, Joseph Kovalik, Michael Peng, Vachik Garkanian, Christine Chen, William Buehlman, Mark Brewer, Gerardo Ortiz, Kittrin Matthews, Angel Velasco, Abhijit Biswas

Proceedings Volume 12413, 1241311 (2023) https://doi.org/10.1117/12.2655123

KEYWORDS: Telescopes, Adaptive optics, Cameras, Satellites, Wavefront sensors, Clouds, Beam splitters, Optical turbulence

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Proceedings Article | 15 March 2023 Presentation + Paper

On-orbit demonstration of 200-Gbps laser communication downlink from the TBIRD CubeSat

Curt Schieler, Kathleen Riesing, Bryan Bilyeu, Jesse Chang, Ajay Garg, Noah Gilbert, Andrew Horvath, Robert Reeve, Bryan Robinson, Jade Wang, Sabino Piazzolla, W. Tom Roberts, Joseph Kovalik, Beth Keer

Proceedings Volume 12413, 1241302 (2023) https://doi.org/10.1117/12.2651297

KEYWORDS: Satellite communications, Free space optical communications, Automatic repeat request, Space operations, Adaptive optics, Telescopes, Telecommunications, Receivers, Laser communication terminals, Laser communications, Transceivers, Data communications

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Proceedings Article | 2 March 2020 Paper

Deep space optical communications (DSOC) beam expander design and engineering

D. Driscoll, B. Zellers, J. Schomacker, J. Carro, W. Roberts, D. MacDonald, J. Guregian, W. Klipstein

Proceedings Volume 11272, 112720H (2020) https://doi.org/10.1117/12.2546678

KEYWORDS: Telescopes, Silicon carbide, Beam expanders, Wavefronts, Mirrors, Space operations, Optical communications, Laser communications

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Proceedings Article | 20 November 2017 Open Access

Development and qualification of a fiber optic cable for Martian environments

C. Lindensmith, W. T. Roberts, M. Meacham, M. Ott, F. LaRocca, W. J. Thomes

Proceedings Volume 10565, 1056519 (2017) https://doi.org/10.1117/12.2309109

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Proceedings Article | 20 November 2017 Open Access

Multi-mode optical fibers for connecting space-based spectrometers

W. T. Roberts, C. Lindenmisth, S. Bender, E. Miller, E. Motts, M. Ott, F. LaRocca, J. Thomes

Proceedings Volume 10565, 105651A (2017) https://doi.org/10.1117/12.2309137

KEYWORDS: Spectrometers, Optical fibers, Cladding, Astronomical imaging, Laser induced breakdown spectroscopy, Raman spectroscopy, Head, Light scattering, Silica, Plasma

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Laser spectral analysis systems are increasingly being considered for in situ analysis of the atomic and molecular composition of selected rock and soil samples on other planets [1][2][3]. Both Laser Induced Breakdown Spectroscopy (LIBS) and Raman spectroscopy are used to identify the constituents of soil and rock samples in situ. LIBS instruments use a high peak-power laser to ablate a minute area of the surface of a sample. The resulting plasma is observed with an optical head, which collects the emitted light for analysis by one or more spectrometers. By identifying the ion emission lines observed in the plasma, the constituent elements and their abundance can be deduced. In Raman spectroscopy, laser photons incident on the sample surface are scattered and experience a Raman shift, exchanging small amounts of energy with the molecules scattering the light. By observing the spectrum of the scattered light, it is possible to determine the molecular composition of the sample.

For both types of instruments, there are advantages to physically separating the light collecting optics from the spectroscopy optics. The light collection system will often have articulating or rotating elements to facilitate the interrogation of multiple samples with minimum expenditure of energy and motion. As such, the optical head is often placed on a boom or an appendage allowing it to be pointed in different directions or easily positioned in different locations. By contrast, the spectrometry portion of the instrument is often well-served by placing it in a more static location. The detectors often operate more consistently in a thermally-controlled environment. Placing them deep within the spacecraft structure also provides some shielding from ionizing radiation, extending the instrument’s useful life. Finally, the spectrometry portion of the instrument often contains significant mass, such that keeping it off of the moving portion of the platform, allowing that portion to be significantly smaller, less massive and less robust.

Large core multi-mode optical fibers are often used to accommodate the optical connection of the two separated portions of such instrumentation. In some cases, significant throughput efficiency improvement can be realized by judiciously orienting the strands of multi-fiber cable, close-bunching them to accommodate a tight focus of the optical system on the optical side of the connection, and splaying them out linearly along a spectrometer slit on the other end.

For such instrumentation to work effectively in identifying elements and molecules, and especially to produce accurate quantitative results, the spectral throughput of the optical fiber connection must be consistent over varying temperatures, over the range of motion of the optical head (and it’s implied optical cable stresses), and over angle-aperture invariant of the total system. While the first two of these conditions have been demonstrated[4], spectral observations of the latter present a cause for concern, and may have an impact on future design of fiber-connected LIBS and Raman spectroscopy instruments. In short, we have observed that the shape of the spectral efficiency curve of a large multi-mode core optical fiber changes as a function of input angle.

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Proceedings Article | 20 November 2017 Open Access

Transceiver optics for interplanetary communications

W. T. Roberts, W. Farr, B. Rider, D. Sampath

Proceedings Volume 10565, 105651G (2017) https://doi.org/10.1117/12.2309136

KEYWORDS: Mirrors, Transceivers, Telecommunications, Optical communications, Space telescopes, Telescopes, Sun, Astronomical imaging, Light scattering, Scattering

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Proceedings Article | 24 February 2017 Presentation + Paper

Discovery deep space optical communications (DSOC) transceiver

W. Thomas Roberts

Proceedings Volume 10096, 100960V (2017) https://doi.org/10.1117/12.2256001

KEYWORDS: Laser communications, Optical communications, Transceivers, Stray light, Optical design, Mirrors, Telescopes, Cameras, Beam splitters, Space telescopes

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Proceedings Article | 15 March 2016 Paper

Overview of Ground Station 1 of the NASA space communications and navigation program

W. Roberts, D. Antsos, A. Croonquist, S. Piazzolla, L. Roberts, V. Garkanian, T. Trinh, M. Wright, R. Rogalin, J. Wu, L. Clare

Proceedings Volume 9739, 97390B (2016) https://doi.org/10.1117/12.2217465

KEYWORDS: Laser communications, Optical communications, Telecommunications, Telescopes, Laser safety, Laser systems engineering, Laser optics, Adaptive optics, Space operations, Atmospheric optics, Data communications, Clouds

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Proceedings Article | 15 March 2016 Paper

Overview and status of the laser communication relay demonstration

E. Luzhanskiy, B. Edwards, D. Israel, D. Cornwell, J. Staren, N. Cummings, T. Roberts, R. Patschke

Proceedings Volume 9739, 97390C (2016) https://doi.org/10.1117/12.2218182

KEYWORDS: Relays, Telecommunications, Laser communications, Satellites, Free space optical communications, Free space optics, Satellite communications, Modulation, Space operations, Laser systems engineering, Optical communications, Integrated optics, Space telescopes, Data communications, Electronics, Telescopes, Adaptive optics

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Proceedings Article | 6 March 2014 Paper

Monolithic telescopes for free-space optical communications

W. Thomas Roberts

Proceedings Volume 8971, 89710N (2014) https://doi.org/10.1117/12.2045109

KEYWORDS: Telescopes, Space telescopes, Optical instrument design, Mirrors, Free space optical communications, Tolerancing, Optical components, Reflectors, Telecommunications, Optical alignment

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Proceedings Article | 6 March 2014 Paper

LLCD operations using the Optical Communications Telescope Laboratory (OCTL)

Abhijit Biswas, Joseph Kovalik, Malcolm Wright, William Roberts, Michael Cheng, Kevin Quirk, Meera Srinivasan, Matthew Shaw, Kevin Birnbaum

Proceedings Volume 8971, 89710X (2014) https://doi.org/10.1117/12.2044087

KEYWORDS: Telescopes, Space telescopes, Cameras, Receivers, Laser safety, Space operations, Laser applications, Clouds, Sensors, Stars

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Proceedings Article | 22 March 2013 Paper

The Lunar Laser OCTL Terminal (LLOT) optical systems

W. Thomas Roberts, Malcolm Wright

Proceedings Volume 8610, 86100P (2013) https://doi.org/10.1117/12.2004415

KEYWORDS: Telescopes, Space telescopes, Zoom lenses, Beam splitters, Mirrors, Control systems, Sensors, Transmitters, Optical alignment, Modulation

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Proceedings Article | 2 March 2011 Paper

Deep-space optical terminals (DOT)

H. Hemmati, W. Farr, A. Biswas, K. Birnbaum, W. Roberts, K. Quirk, S. Townes

Proceedings Volume 7923, 79230C (2011) https://doi.org/10.1117/12.878930

KEYWORDS: Telescopes, Space telescopes, Sensors, Space operations, Mars, Photons, Control systems, Signal detection, Receivers, Modulation

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Proceedings Article | 26 February 2010 Paper

OCTL to OICETS optical link experiment (OTOOLE) electrooptical systems

W. Thomas Roberts, Malcolm Wright, Joseph Kovalik, Vachik Garkanian, Keith Wilson

Proceedings Volume 7587, 75870Y (2010) https://doi.org/10.1117/12.855137

KEYWORDS: Telescopes, Space telescopes, Sensors, Mirrors, Optical communications, Space operations, Modulation, Telecommunications, Laser communications, Satellites

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Proceedings Article | 26 February 2010 Paper

Data products for the OCTL to OICETS optical link experiment

J. Kovalik, A. Biswas, K. Wilson, M. Wright, W. Roberts

Proceedings Volume 7587, 75870C (2010) https://doi.org/10.1117/12.845623

KEYWORDS: Data acquisition, Sensors, Satellites, Telescopes, Binary data, Receivers, Atmospheric modeling, Optical communications, Signal detection, Video

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Proceedings Article | 26 February 2010 Paper

Preliminary results of the OCTL to OICETS optical link experiment (OTOOLE)

Keith Wilson, Joseph Kovalik, Abhijit Biswas, Malcolm Wright, William Roberts, Yoshihisa Takayama, Shiro Yamakawa

Proceedings Volume 7587, 758703 (2010) https://doi.org/10.1117/12.845063

KEYWORDS: Satellites, Telescopes, Receivers, Optical communications, Satellite communications, Laser communications, Sensors, Space telescopes, Modulation, Mirrors

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Proceedings Article | 26 February 2010 Paper

Stray light modeling and performance of the 15cm deep space optical communications transceiver (DSOCT)

W. Thomas Roberts

Proceedings Volume 7587, 75870V (2010) https://doi.org/10.1117/12.840784

KEYWORDS: Sun, Telescopes, Mirrors, Sensors, Light scattering, Stray light, Transceivers, Scattering, Optical communications, Space telescopes

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Proceedings Article | 24 February 2009 Paper

Compact deep-space optical communications transceiver

W. Thomas Roberts, Jeffrey Charles

Proceedings Volume 7199, 71990L (2009) https://doi.org/10.1117/12.806290

KEYWORDS: Mirrors, Telescopes, Transceivers, Optical communications, Optical instrument design, Space telescopes, Optical design, Collimation, Telecommunications, Optics manufacturing

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Proceedings Article | 24 February 2009 Paper

Canonical deep space optical communications transceiver

Gerardo Ortiz, William Farr, Jeffrey Charles, W. Thomas Roberts, Virginio Sannibale, Jonathan Gin, Adit Saharaspude, Vachik Garkanian

Proceedings Volume 7199, 71990K (2009) https://doi.org/10.1117/12.812410

KEYWORDS: Transceivers, Space operations, Electronics, Control systems, Astronomical imaging, Optical communications, Sensors, Vibration isolation, Computer aided design, Space telescopes

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Proceedings Article | 4 May 2007 Paper

Development of laser beam transmission strategies for future ground-to-space optical communications

Keith Wilson, Joseph Kovalik, Abhijit Biswas, William Roberts

Proceedings Volume 6551, 65510B (2007) https://doi.org/10.1117/12.720803

KEYWORDS: Space telescopes, Telescopes, Satellites, Mirrors, Optical communications, Signal attenuation, Space operations, Laser beam propagation, Laser safety, Sensors

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