Roman coronagraph instrument: engineering overview and status

Poberezhskiy, Ilya; Heydorff, Kathryn; Luchik, T. S.; Zhang, Feng; Cady, Eric; Bedrosian, Gasia; Colavita, M. M.; Creager, Brandon; Goullioud, Renaud; Groff, Tyler D.; Grue, Amanda; Monacelli, Brian; Morrissey, Patrick; Kempenaar, Joshua; Kern, Brian; King, Matthew E.; Koch, Timothy R.; Krist, John; Kuan, Gary M.; Lam, Jonathan C.; Lewis, Dorothy E.; Mok, Fai; Muliere, David; Nemati, B.; Noecker, Charley; Oseas, Jeffrey M.; Riggs, A. J. Eldorado; Shreckengost, Belinda

doi:10.1117/12.2630540

Cited by 7 publications

(10 citation statements)

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“…The coronagraph is a NASA technology demonstration, which means that it is funded chiefly to demonstrate new technologies that could reduce risk for future missions by providing a platform not only to advance the state of the art but also to provide a real-world test of the elements together as a system. The CGI is advancing the technical state of the art in several areas, including deformable mirror technology, masks, detectors, and algorithms 6 . Some requirements (and goals), such as lifetime are based on the anticipated future needs of NASA exoplanetary missions 7…”

Section: Requirementsmentioning

confidence: 99%

“…The CGI is advancing the technical state of the art in several areas, including deformable mirror technology, masks, detectors, and algorithms. 6 Some requirements (and goals), such as lifetime are based on the anticipated future needs of NASA exoplanetary missions. [7][8][9] Models of coronagraph performance 10 place challenging detection goals on the EMCCD.…”

Section: Requirementsmentioning

confidence: 99%

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Flight photon counting electron multiplying charge coupled device development for the Roman Space Telescope coronagraph instrument

Morrissey

Harding

Bush

et al. 2023

J. Astron. Telesc. Instrum. Syst.

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We describe the development of flight electron multiplying charge coupled devices (EMCCDs) for the photon-counting camera system of a coronagraph instrument (CGI) to be flown on the 2.4-m Nancy Grace Roman Space Telescope. Roman is a NASA flagship mission that will study dark energy and dark matter, and search for exoplanets with a planned launch in the mid-2020s. The CGI is intended to demonstrate technologies required for high-contrast imaging and spectroscopy of exoplanets, such as high-speed wavefront sensing and pointing control, adaptive optics with deformable mirrors, and ultralow noise signal detection with photon counting, visible-sensitive (350 to 950 nm) detectors. The camera system is at the heart of these demonstrations and is required to sense both faint and bright targets (10 −4 − 10 7 counts-s −1 ) adaptively at up to 1000 frames-s −1 to provide the necessary feedback to the instrument control loops. The system includes two identical cameras, one to demonstrate faint light scientific capability, and the other to provide high-speed real-time sensing of instrument pointing disturbances. Our program at the Jet Propulsion Laboratory (Pasadena, California, United States) has evaluated the low-signal performance of radiation-damaged commercial EMCCD sensors and used those measurements as a basis for targeted radiation hardening modifications developed in partnership with the Open University (Milton Keynes, United Kingdom) and Teledyne-e2v (Chelmsford, United Kingdom). A pair of EMCCDs with test features was then developed and their low signal performance is reported here. The program has resulted in the development of a flight version of the EMCCD with low signal performance improved by more than a factor of three over the commercial one after exposure to 2.6 × 10 9 protons-cm −2 (10 MeV equivalent). The flight EMCCD sensors are contributed by ESA through a contract with Teledyne-e2v (Chelmsford, United Kingdom). We will describe the program requirements, sensor design, test results and metrics used to evaluate photon counting performance.

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Section: Requirementsmentioning

confidence: 99%

Section: Requirementsmentioning

confidence: 99%

Flight photon counting electron multiplying charge coupled device development for the Roman Space Telescope coronagraph instrument

Morrissey

Harding

Bush

et al. 2023

J. Astron. Telesc. Instrum. Syst.

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“…This way the transient creep of each DM's lead magnesium niobate (PMN) material will have settled. 3 The finer modifications of the shapes during wavefront control will be sufficiently small in amplitude to minimize creep during operation. The attitude control system (ACS) is commanded to point the telescope to a predefined sky position, centered on a particular star.…”

Section: Cgi Concept Of Operationmentioning

confidence: 99%

“…CGI will do this by improving starlight suppression overall and particularly close to the star. [3][4][5][6] For a coronagraph to effectively reshape and control unwanted starlight diffraction, the ideal pupil would be an unobscured circular aperture because of its symmetry and mathematical simplicity. Thus the integration of a coronagraph to a wide field telescope like Roman, with its large secondary mirror and struts, posed a number of challenges to the optical design.…”

Section: Introductionmentioning

confidence: 99%

“…The second Roman instrument, the CGI, is a visible-band coronagraph technology demonstrator that will narrow the gap of over four orders of magnitude between the sensitivity needed to detect an exo-Earth and the current state of the art. CGI will do this by improving starlight suppression overall and particularly close to the star 3 – 6 …”

Section: Introductionmentioning

confidence: 99%

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Analytical performance model and error budget for the Roman coronagraph instrument

Nemati,

Krist,

Poberezhskiy

et al. 2023

J. Astron. Telesc. Instrum. Syst.

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Simulation of High-contrast Polarimetric Observations of Debris Disks with the Roman Coronagraph Instrument

Anche,

Douglas,

Milani

et al. 2023

PASP

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The Nancy Grace Roman Space Telescope Coronagraph Instrument will enable the polarimetric imaging of debris disks and inner dust belts in the optical and near-infrared wavelengths, in addition to the high-contrast polarimetric imaging and spectroscopy of exoplanets. The Coronagraph uses two Wollaston prisms to produce four orthogonally polarized images and is expected to measure the polarization fraction with measurement errors <3% per spatial resolution element. To simulate the polarization observations through the Hybrid Lyot Coronagraph (HLC) and Shaped Pupil Coronagraph (SPC), we model disk scattering, the coronagraphic point-response function, detector noise, speckles, jitter, and instrumental polarization and calculate the Stokes parameters. To illustrate the potential for discovery and a better understanding of known systems with both the HLC and SPC modes, we model the debris disks around Epsilon Eridani and HR 4796A, respectively. For Epsilon Eridani, using astrosilicates with 0.37 ± 0.01 as the peak input polarization fraction in one resolution element, we recover the peak disk polarization fraction of 0.33 ± 0.01. Similarly, for HR 4796A, for a peak input polarization fraction of 0.92 ± 0.01, we obtain the peak output polarization fraction as 0.80 ± 0.03. The Coronagraph design meets the required precision, and forward modeling is needed to accurately estimate the polarization fraction.

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Roman coronagraph instrument: engineering overview and status

Cited by 7 publications

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Flight photon counting electron multiplying charge coupled device development for the Roman Space Telescope coronagraph instrument

Flight photon counting electron multiplying charge coupled device development for the Roman Space Telescope coronagraph instrument

Analytical performance model and error budget for the Roman coronagraph instrument

Simulation of High-contrast Polarimetric Observations of Debris Disks with the Roman Coronagraph Instrument

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