WFIRST-AFTA coronagraph shaped pupil masks: design, fabrication, and characterization

Balasubramanian, Kunjithapatham; White, Victor; Yee, Karl; Echternach, P. M.; Muller, Richard E.; Dickie, Matthew R.; Cady, Eric; Prada, Camilo Mejia; Ryan, Daniel; Poberezhskiy, Ilya; Kern, Brian; Zhou, Hanying; Krist, John; Nemati, Bijan; Riggs, A. J. Eldorado; Zimmerman, Neil; Kasdin, N. Jeremy

doi:10.1117/1.jatis.2.1.011005

Cited by 36 publications

(18 citation statements)

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“…20 and 21) and the shaped pupil coronagraph (SPC). 22,23 The HLC and SPC are combined into a single package, the occulting mask coronagraph (OMC), in which operation in HLC or SPC mode is determined by the selection of a flip mirror. The backup instrument is the phase-induced amplitude apodization complex mask coronagraph (PIAACMC).…”

Section: Coronagraph Modelmentioning

confidence: 99%

Science yield estimate with the Wide-Field Infrared Survey Telescope coronagraph

Traub

Breckinridge

Greene

et al. 2016

J. Astron. Telesc. Instrum. Syst

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Abstract. The coronagraph instrument (CGI) on the Wide-Field Infrared Survey Telescope will directly image and spectrally characterize planets and circumstellar disks around nearby stars. Here we estimate the expected science yield of the CGI for known radial-velocity (RV) planets and potential circumstellar disks. The science return is estimated for three types of coronagraphs: the hybrid Lyot and shaped pupil are the currently planned designs, and the phase-induced amplitude apodizing complex mask coronagraph is the backup design. We compare the potential performance of each type for imaging as well as spectroscopy. We find that the RV targets can be imaged in sufficient numbers to produce substantial advances in the science of nearby exoplanets. To illustrate the potential for circumstellar disk detections, we estimate the brightness of zodiacal-type disks, which could be detected simultaneously during RV planet observations.

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Section: Coronagraph Modelmentioning

confidence: 99%

Science yield estimate with the Wide-Field Infrared Survey Telescope coronagraph

Traub

Breckinridge

Greene

et al. 2016

J. Astron. Telesc. Instrum. Syst

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“…An optimized SPLC reaches the contrast and inner working angle of the well-established APLC design family, while benefitting from a precise, achromatic transmission characteristic that is most feasible with a binary apodizer. 59 Our numerical optimization experiments have revealed a rich parameter space in the Lyot stop transmission profile. The apodizer and Lyot stop can be optimized simultaneously, leading to solutions with higher throughput and a sharper PSF for a given contrast and bandwidth.…”

Section: Resultsmentioning

confidence: 98%

“…We identify this design category as the shaped pupil Lyot coronagraph (SPLC). The SPLC offers a persuasive union of the virtues of the SPC and the APLC: a binary apodizer with achromatic transmission properties and promising fabrication avenues, 59,71,72 and the relatively small inner working angle and robustness to aberrations of an APLC. 73 2 Lyot coronagraphy with an unobscured circular aperture Although coronagraph designs for obscured apertures are the ones of the highest practical interest and relevance to WFIRST-AFTA and the general community, a clear circular telescope aperture offers a natural starting point to understand how the SPLC relates functionally to the conventional APLC.…”

Section: Introductionmentioning

confidence: 99%

Shaped pupil Lyot coronagraphs: high-contrast solutions for restricted focal planes

Zimmerman

Riggs

Kasdin

et al. 2016

J. Astron. Telesc. Instrum. Syst

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Coronagraphs of the apodized pupil and shaped pupil varieties use the Fraunhofer diffraction properties of amplitude masks to create regions of high contrast in the vicinity of a target star. Here we present a hybrid coronagraph architecture in which a binary, hard-edged shaped pupil mask replaces the gray, smooth apodizer of the apodized pupil Lyot coronagraph (APLC). For any contrast and bandwidth goal in this configuration, as long as the prescribed region of contrast is restricted to a finite area in the image, a shaped pupil is the apodizer with the highest transmission. We relate the starlight cancellation mechanism to that of the conventional APLC. We introduce a new class of solutions in which the amplitude profile of the Lyot stop, instead of being fixed as a padded replica of the telescope aperture, is jointly optimized with the apodizer. Finally, we describe shaped pupil Lyot coronagraph (SPLC) designs for the baseline architecture of the WFIRST-AFTA coronagraph. These SPLCs help to enable two scientific objectives of the WFIRST-AFTA mission: (i) broadband spectroscopy to characterize exoplanet atmospheres in reflected starlight and (ii) debris disk imaging. and second a "Lyot stop" to block the outer edge of the re-collimated on-axis beam before it is reimaged. 12 To take advantage of the diffraction-limited imaging capabilities of high-order adaptive optics (AO) systems, beginning in the 1990s classical Lyot designs were revised for high-contrast stellar coronagraphy. [13][14][15][16][17][18] Through Fourier optical analysis and modeling, researchers soon discovered the remarkable performance benefits of apodizing the entrance pupil of a coronagraph. [19][20][21] Since then, the transmission profile of this apodizer mask has been a topic of vigorous study. [22][23][24][25][26][27] One resulting family of designs, the apodized pupil Lyot coronagraph (APLC), has been successfully integrated with several AO-fed cameras to facilitate deep observations of young exoplanetary systems at near-infrared wavelengths.As an alternative to a coronagraph with two or more mask planes, pupil apodization by itself is perhaps the simplest and oldest way to reject unwanted starlight from a telescope image. 28,29 Fraunhofer diffraction theory dictates the way any change in the shape or transmission profile of the entrance pupil redistributes a star's energy in the image plane. This relationship can be used to design an apodizer whose point spread function (PSF) has a zone of high contrast near the star, without additional coronagraph masks. This is the shaped pupil approach developed by N. J. Kasdin and collaborators, who pioneered the optimization of apodizers with binary-valued transmission. [30][31][32][33] In recent years, shaped pupil solutions have evolved to work around arbitrary two-dimensional telescope apertures, in parallel with similar breakthroughs in APLC design. [34][35][36][37][38][39] The relative simplicity of a single mask, however, comes with a sacrifice in how close the dark search region can be push...

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“…To accomplish all of these tasks, WFIRST-CGI will be equipped with two coronagraphs: a hybrid lyot coronagraph (HLC, Trauger et al 2016), and a shaped-pupil coronagraph (SPC, Balasubramanian et al 2016). The HLC will be paired with imaging capabilities and will have an annular field of view extending to small inner working angles.…”

Section: Wfirst-cgi Mission and Noise Modelmentioning

confidence: 99%

Characterization of Exoplanet Atmospheres with the Optical Coronagraph on WFIRST

Lacy

Shlivko

Burrows

2019

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Wide-Field Infrared Survey Telescope (WFIRST)-CGI is a NASA technology demonstration mission that is charged with demonstrating key technologies for future exo-Earth imaging missions in space. In the process, it will obtain images and low-resolution spectra of a handful to a dozen extrasolar planets and possibly protoplanetary disks. Its unprecedented contrast levels in the optical will provide astronomers' with their first direct look at mature, Jupiter-sized planets at moderate separations. This paper addresses the question: what science can be done with such data? An analytic noise model, which is informed by the ongoing engineering developments, is used to compute maximum achievable signal-to-noise ratios and scientifically viable integration times for hypothetical star-planet systems, as well as to investigate the constraining power of various combinations of WFIRST-CGI photometric and spectral observations. This work introduces two simple models for planetary geometric albedos, which are inspired largely by the solar system's gas giants. The first planet model is a hybrid Jupiter-Neptune model, which separately treats the short and long wavelengths where chromophores and methane dominate absorption, respectively. The second planet model fixes cloud and haze properties in CoolTLusty to match Jupiter's albedo spectrum, it then perturbs only the metallicity. MCMC retrievals performed on simulated observations are used to assess the precision with which planet model parameters can be measured subject to different exposure times and observing cases. Planet radius is recovered within±15% for all observing cases with both the hybrid model and the CoolTLusty metallicity grid. Fit results for both models' parameterizations of geometric albedo spectra demonstrate that a rough indication of the metallicity or methane content should be possible for some WFIRST-CGI targets. We conclude that real observations will likely be able to differentiate between extreme cases using these models, but will lack the precision necessary to uncover subtle trends.

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WFIRST-AFTA coronagraph shaped pupil masks: design, fabrication, and characterization

Cited by 36 publications

References 0 publications

Science yield estimate with the Wide-Field Infrared Survey Telescope coronagraph

Science yield estimate with the Wide-Field Infrared Survey Telescope coronagraph

Shaped pupil Lyot coronagraphs: high-contrast solutions for restricted focal planes

Characterization of Exoplanet Atmospheres with the Optical Coronagraph on WFIRST

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