Prof. James P. Lloyd Profile

Prof. James P. Lloyd

Associate Professor at Cornell Univ

SPIE Involvement:

Author

Publications (38)

Proceedings Article | 26 August 2022 Presentation + Paper

Origins and design of the Aperture Masking Interferometer on JWST

Peter Tuthill, Anand Sivaramakrishnan, James Lloyd

Proceedings Volume 12183, 121830Q (2022) https://doi.org/10.1117/12.2635818

KEYWORDS: Planets, Exoplanets, James Webb Space Telescope, Stars, Interferometers, Data modeling, Interferometry, Atmospheric modeling, Atmospheric physics, Telescopes

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Proceedings Article | 1 September 2017 Paper

Optimization of high-inclination orbits using planetary flybys for a zodiacal light-imaging mission

Gabriel Soto, James Lloyd, Dmitry Savransky, Keith Grogan, Amlan Sinha

Proceedings Volume 10400, 104001X (2017) https://doi.org/10.1117/12.2274069

KEYWORDS: Exoplanets, Solar system, Algorithm development, Mechanics, Light, Light scattering, Pollution control, Space operations, Cameras, Detection and tracking algorithms

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SPIE Journal Paper | 2 December 2016 Open Access

High-resolution broadband spectroscopy using externally dispersed interferometry at the Hale telescope: part 2, photon noise theory

David Erskine, Jerry Edelstein, Edward Wishnow, Martin Sirk, Philip Muirhead, Matthew Muterspaugh, James Lloyd

JATIS, Vol. 2, Issue 04, 045001, (December 2016) https://doi.org/10.1117/12.10.1117/1.JATIS.2.4.045001

KEYWORDS: Signal to noise ratio, Spectrographs, Interference (communication), Interferometry, Point spread functions, Interferometers, Spectroscopes, Sensors, Image resolution, Fourier transforms

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High-resolution broadband spectroscopy at near-infrared (NIR) wavelengths (950 to 2450 nm) has been performed using externally dispersed interferometry (EDI) at the Hale telescope at Mt. Palomar, with the TEDI interferometer mounted within the central hole of the 200-in. primary mirror in series with the comounted TripleSpec NIR echelle spectrograph. These are the first multidelay EDI demonstrations on starlight. We demonstrated very high (10×) resolution boost and dramatic (20× or more) robustness to point spread function wavelength drifts in the native spectrograph. Data analysis, results, and instrument noise are described in a companion paper (part 1). This part 2 describes theoretical photon limited and readout noise limited behaviors, using simulated spectra and instrument model with noise added at the detector. We show that a single interferometer delay can be used to reduce the high frequency noise at the original resolution (1× boost case), and that except for delays much smaller than the native response peak half width, the fringing and nonfringing noises act uncorrelated and add in quadrature. This is due to the frequency shifting of the noise due to the heterodyning effect. We find a sum rule for the noise variance for multiple delays. The multiple delay EDI using a Gaussian distribution of exposure times has noise-to-signal ratio for photon-limited noise similar to a classical spectrograph with reduced slitwidth and reduced flux, proportional to the square root of resolution boost achieved, but without the focal spot limitation and pixel spacing Nyquist limitations. At low boost (∼1×) EDI has ∼1.4× smaller noise than conventional, and at >10× boost, EDI has ∼1.4× larger noise than conventional. Readout noise is minimized by the use of three or four steps instead of 10 of TEDI. Net noise grows as step phases change from symmetrical arrangement with wavenumber across the band. For three (or four) steps, we calculate a multiplicative bandwidth of 1.8:1 (2.3:1), sufficient to handle the visible band (400 to 700 nm, 1.8:1) and most of TripleSpec (2.6:1).

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Proceedings Article | 9 August 2016 Paper

Dramatic robustness of a multiple delay dispersed interferometer to spectrograph errors: how mixing delays reduces or cancels wavelength drift

David Erskine, E. Linder, E. Wishnow, J. Edelstein, M. Sirk, P. Muirhead, J. Lloyd, A. Kim

Proceedings Volume 9908, 99085Y (2016) https://doi.org/10.1117/12.2230182

KEYWORDS: Spectrographs, Interferometers, Doppler effect, Point spread functions, Moire patterns, Fabry–Perot interferometers, Lamps, Sensors, Wavelets, Data modeling

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SPIE Journal Paper | 27 May 2016 Open Access

High-resolution broadband spectroscopy using externally dispersed interferometry at the Hale telescope: Part 1, data analysis and results

David Erskine, Jerry Edelstein, Edward Wishnow, Martin Sirk, Philip Muirhead, Matthew Muterspaugh, James Lloyd, Yuzo Ishikawa, Eliza McDonald, William Shourt, Andrew Vanderburg

JATIS, Vol. 2, Issue 02, 025004, (May 2016) https://doi.org/10.1117/12.10.1117/1.JATIS.2.2.025004

KEYWORDS: Spectrographs, Point spread functions, Stars, Fabry–Perot interferometers, Interferometry, Spectroscopes, Interferometers, Lamps, Modulation transfer functions, Wavelets

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Proceedings Article | 2 August 2014 Paper

Advances in stellar imaging with occultations from the CASSINI spacecraft

Paul Stewart, Peter Tuthill, Phillip Nicholson, Matthew Hedman, James Lloyd

Proceedings Volume 9143, 91431G (2014) https://doi.org/10.1117/12.2055631

KEYWORDS: Stars, Space operations, Data modeling, Tomography, Reconstruction algorithms, Saturn, Signal to noise ratio, Image resolution, Atmospheric modeling, Spectrographs

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Proceedings Article | 21 September 2012 Paper

Non-redundant Aperture Masking Interferometry (AMI) and segment phasing with JWST-NIRISS

Anand Sivaramakrishnan, David Lafrenière, K. E. Saavik Ford, Barry McKernan, Anthony Cheetham, Alexandra Greenbaum, Peter Tuthill, James Lloyd, Michael Ireland, René Doyon, Mathilde Beaulieu, André Martel, Anton Koekemoer, Frantz Martinache, Peter Teuben

Proceedings Volume 8442, 84422S (2012) https://doi.org/10.1117/12.925565

KEYWORDS: James Webb Space Telescope, Visibility, Interferometry, Space telescopes, Sensors, Calibration, Telescopes, Mirrors, Wavefronts, Image segmentation

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The Aperture Masked Interferometry (AMI) mode on JWST-NIRISS is implemented as a 7-hole, 15% throughput, non-redundant mask (NRM) that operates with 5-8% bandwidth filters at 3.8, 4.3, and 4.8 microns. We present refined estimates of AMI's expected point-source contrast, using realizations of noise matched to JWST pointing requirements, NIRISS detector noise, and Rev-V JWST wavefront error models for the telescope and instrument. We describe our point-source binary data reduction algorithm, which we use as a standardized method to compare different observational strategies. For a 7.5 magnitude star we report a 10-a detection at between 8.7 and 9.2 magnitudes of contrast between 100 mas to 400 mas respectively, using closure phases and squared visibilities in the absence of bad pixels, but with various other noise sources. With 3% of the pixels unusable, the expected contrast drops by about 0.5 magnitudes. AMI should be able to reach targets as bright as M=5. There will be significant overlap between Gemini-GPI and ESO-SPHERE targets and AMI's search space, and a complementarity with NIRCam's coronagraph. We also illustrate synthesis imaging with AMI, demonstrating an imaging dynamic range of 25 at 100 mas scales. We tailor existing radio interferometric methods to retrieve a faint bar across a bright nucleus, and explain the similarities to synthesis imaging at radio wavelengths. Modest contrast observations of dusty accretion flows around AGNs will be feasible for NIRISS AMI. We show our early results of image-plane deconvolution as well. Finally, we report progress on an NRM-inspired approach to mitigate mission-level risk associated with JWST's specialized wavefront sensing hardware. By combining narrow band and medium band Nyquist-sampled images taken with a science camera we can sense JWST primary mirror segment tip-tilt to lOmas, and piston to a few nm. We can sense inter-segment piston errors of up to 5 coherence lengths of the broadest bandpass filter used ( 250-500 0m depending on the filters). Our approach scales well with an increasing number of segments, which makes it relevant for future segmented-primary space missions.

Proceedings Article | 12 September 2012 Paper

Aperture mask interferometry with an integral field spectrograph

Neil Zimmerman, Anand Sivaramakrishnan, David Bernat, Ben Oppenheimer, Sasha Hinkley, James Lloyd, Peter Tuthill, Douglas Brenner, Ian Parry, Michal Simon, John Krist, Laurent Pueyo

Proceedings Volume 8445, 84452G (2012) https://doi.org/10.1117/12.926204

KEYWORDS: Stars, Adaptive optics, Calibration, Iterated function systems, Telescopes, Spectrographs, Interferometry, Space telescopes, Coronagraphy, Spectroscopy

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Proceedings Article | 15 September 2011 Paper

Ten-fold spectral resolution boosting using TEDI at the Mt. Palomar NIR Triplespec spectrograph

David Erskine, J. Edelstein, P. Muirhead, M. Muterspaugh, K. Covey, D. Mondo, A. Vanderburg, P. Andelson, D. Kimber, M. Sirk, J. Lloyd

Proceedings Volume 8146, 81460M (2011) https://doi.org/10.1117/12.892664

KEYWORDS: Spectrographs, Interferometers, Modulation transfer functions, Intelligence systems, Fourier transforms, Spectral resolution, Data modeling, Interferometry, Doppler effect, Spectroscopy

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Proceedings Article | 11 August 2010 Paper

Planetary system and star formation science with non-redundant masking on JWST

Anand Sivaramakrishnan, David Lafrenière, Peter Tuthill, Michael Ireland, James Lloyd, Frantz Martinache, Russell Makidon, Rémi Soummer, René Doyon, Mathilde Beaulieu, Sébastien Parmentier, Charles Beichman

Proceedings Volume 7731, 77313W (2010) https://doi.org/10.1117/12.858161

KEYWORDS: James Webb Space Telescope, Stars, Space telescopes, Visibility, Sensors, Planets, Telescopes, Calibration, Point spread functions, Wavefronts

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Proceedings Article | 21 July 2010 Paper

Infrared radial velocimetry with TEDI: performance development

Jerry Edelstein, Philip Muirhead, Jason Wright, Kevin Covey, David Erskine, Matthew Muterspaugh, James Lloyd, Samuel Halverson, Mario Marckwordt, Daniel Mondo

Proceedings Volume 7735, 773583 (2010) https://doi.org/10.1117/12.858312

KEYWORDS: Interferometers, Telescopes, Optical fibers, Spectrographs, Dispersion, Stars, Mirrors, Infrared radiation, Target acquisition, Interferometry

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Proceedings Article | 21 July 2010 Paper

Precise infrared radial velocimetry with the Triplespec Exoplanet Discovery Instrument: current performance and results

Philip Muirhead, Jerry Edelstein, Jason Wright, David Erskine, Matthew Muterspaugh, Kevin Covey, Mario Marckwordt, Samuel Halverson, Daniel Mondo, James Lloyd

Proceedings Volume 7735, 77357X (2010) https://doi.org/10.1117/12.857196

KEYWORDS: Interferometers, Stars, Doppler effect, Exoplanets, Spectrographs, Telescopes, Modulation, Krypton, Velocity measurements, Device simulation

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Proceedings Article | 20 August 2009 Paper

Planetary system and star formation science with non-redundant masking on JWST

Anand Sivaramakrishnan, Peter Tuthill, Michael Ireland, James Lloyd, Frantz Martinache, Rémi Soummer, Russell Makidon, René Doyon, Mathilde Beaulieu, Charles Beichman

Proceedings Volume 7440, 74400Y (2009) https://doi.org/10.1117/12.826633

KEYWORDS: James Webb Space Telescope, Space telescopes, Stars, Wavefronts, Point spread functions, Coronagraphy, Telescopes, Sensors, Calibration, Mirrors

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Proceedings Article | 9 July 2008 Paper

The performance of TripleSpec at Palomar

Terry Herter, Charles Henderson, John Wilson, Keith Matthews, Gustavo Rahmer, Marco Bonati, Philip Muirhead, Joseph Adams, James Lloyd, Michael Skrutskie, Dae-Sik Moon, Stephen Parshley, Matthew Nelson, Frantz Martinache, George Gull

Proceedings Volume 7014, 70140X (2008) https://doi.org/10.1117/12.789660

KEYWORDS: Telescopes, Spectrographs, Mirrors, Prisms, Space telescopes, Stars, Sensors, Cameras, Spectral resolution, Observatories

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Proceedings Article | 9 July 2008 Paper

Dispersed interferometry for infrared exoplanet velocimetry

Jerry Edelstein, Matthew Muterspaugh, David Erskine, Mario Marckwordt, W. Michael Feuerstein, Tony Mercer, Agnieszka Czeszumska, Jaclyn Schwer, Sam Halverson, James Lloyd, Philip Muirhead, Jason Wright, Terry Herter

Proceedings Volume 7014, 70147F (2008) https://doi.org/10.1117/12.790315

KEYWORDS: Stars, Planets, Spectrographs, Interferometry, Exoplanets, Doppler effect, Velocity measurements, Velocimetry, Infrared radiation, Interferometers

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Proceedings Article | 4 October 2007 Paper

TEDI: the TripleSpec Exoplanet Discovery Instrument

Jerry Edelstein, Matthew Ward Muterspaugh, David Erskine, W. Michael Feuerstein, Mario Marckwordt, Ed Wishnow, James Lloyd, Terry Herter, Phillip Muirhead, George Gull, Charles Henderson, Stephen Parshley

Proceedings Volume 6693, 66930W (2007) https://doi.org/10.1117/12.735474

KEYWORDS: Spectrographs, Stars, Interferometers, Absorption, Telescopes, Doppler effect, Exoplanets, Planets, Calibration, Mirrors

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Proceedings Article | 6 July 2006 Paper

Instrumentation for the CCAT Telescope

G. Stacey, S. Golwala, C. Bradford, C. Dowell, G. Cortes-Medellin, T. Nikola, J. Zmuidzinas, T. Herter, S. Radford, J. Lloyd, A. Blain, R. Brown, D. Campbell, R. Giovanelli, P. Goldsmith, P. Harvey, C. Henderson, W. Langer, T. Phillips, A. C. S. Readhead, D. Woody

Proceedings Volume 6275, 62751G (2006) https://doi.org/10.1117/12.672176

KEYWORDS: Cameras, Sensors, Telescopes, Spectrometers, Multiplexing, Receivers, Bolometers, Antennas, Mirrors, Polarization

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Proceedings Article | 30 June 2006 Paper

Noise studies of externally dispersed interferometry for Doppler velocimetry

David Erskine, Jerry Edelstein, James Lloyd, Philip Muirhead

Proceedings Volume 6269, 62692P (2006) https://doi.org/10.1117/12.670683

KEYWORDS: Doppler effect, Spectrographs, Interferometers, Signal to noise ratio, Velocimetry, Signal detection, Fourier transforms, Solids, Sensors, Heterodyning

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Proceedings Article | 28 June 2006 Paper

Sparse-aperture adaptive optics

Peter Tuthill, James Lloyd, Michael Ireland, Frantz Martinache, John Monnier, Henry Woodruff, Theo ten Brummelaar, Nils Turner, Charles Townes

Proceedings Volume 6272, 62723A (2006) https://doi.org/10.1117/12.672342

KEYWORDS: Adaptive optics, Calibration, Point spread functions, Modulation transfer functions, Visibility, Telescopes, Interferometry, Signal to noise ratio, Deconvolution, Binary data

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Proceedings Article | 28 June 2006 Paper

The TEDI instrument for near-IR radial velocity surveys

Jerry Edelstein, David Erskine, James Lloyd, Terry Herter, Mario Marckwordt, Michael Feuerstein

Proceedings Volume 6269, 62691E (2006) https://doi.org/10.1117/12.672014

KEYWORDS: Spectrographs, Interferometers, Doppler effect, Stars, Absorption, Planets, Interferometry, Telescopes, Velocimetry, Mirrors

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Proceedings Article | 15 September 2005 Paper

Externally dispersed interferometry for planetary studies

David Erskine, Jerry Edelstein, Daniel Harbeck, James Lloyd

Proceedings Volume 5905, 59050R (2005) https://doi.org/10.1117/12.617879

KEYWORDS: Spectrographs, Doppler effect, Interferometers, Stars, Planets, Absorption, Spectroscopy, Spatial frequencies, Interferometry, Signal detection

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