Design and demonstration of hybrid Lyot coronagraph masks for improved spectral bandwidth and throughput

Moody, Dwight; Gordon, Brian; Trauger, John T.

doi:10.1117/12.790133

Cited by 23 publications

(21 citation statements)

References 10 publications

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“…Furthermore, the occulting spot in the Lyot coronagraph can be replaced by more complicated focal plane masks that involve a combination of phase shifting and apodization, such as the hybrid Lyot coronagraph (Kuchner & Traub 2002;Moody & Trauger 2007;Moody et al 2008;Trauger et al 2012;Trauger et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Polynomial Apodizers for Centrally Obscured Vortex Coronagraphs

Fogarty

Pueyo

Mazoyer

et al. 2017

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Several coronagraph designs have been proposed over the last two decades to directly image exoplanets. Among these designs, vector vortex coronagraphs provide theoretically perfect starlight cancellation along with small inner working angles when deployed on telescopes with unobstructed pupils. However, current and planned space missions and ground-based extremely large telescopes present complex pupil geometries, including large central obscurations caused by secondary mirrors, that prevent vortex coronagraphs from rejecting on-axis sources entirely. Recent solutions combining the vortex phase mask with a ring-apodized pupil have been proposed to circumvent this issue, but provide a limited throughput for vortex charges > 2. We present pupil plane apodizations for charge 2, 4, and 6 vector vortex coronagraphs that compensate for pupil geometries with circularly symmetric central obstructions caused by on-axis secondary mirrors. These apodizations are derived analytically and allow vortex coronagraphs to retain theoretically perfect nulling in the presence of obstructed pupils. For a charge 4 vortex, we design polynomial apodization functions assuming a greyscale apodizing filter that represent a substantial gain in throughput over the ring-apodized vortex coronagraph design, while for a charge 6 vortex, we design polynomial apodized vortex coronagraphs that have 70% total energy throughput for the entire range of central obscuration sizes studied. We propose methods for optimizing apodizations produced with either greyscale apodizing filters or shaped mirrors. We conclude by demonstrating how this design may be combined with apodizations numerically optimized for struts and primary mirror segment gaps to design terrestrial exoplanet imagers for complex pupils.

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Section: Introductionmentioning

confidence: 99%

Polynomial Apodizers for Centrally Obscured Vortex Coronagraphs

Fogarty

Pueyo

Mazoyer

et al. 2017

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“…In general, these parasitic phase shifts violate the criteria for band-limited coronagraph masks, and further, real materials exhibit significant dispersion in optical properties over spectral bandwidths up to 20% that are of interest for exoplanet astronomy. The complex apodization approach 8,9 provides a measure of control over phase by adding a non-absorbing thickness-profiled dielectric layer. These new Lyot masks are composed of one metal layer and one dielectric layer superimposed on a glass substrate.…”

Section: Mask Designmentioning

confidence: 99%

Complex apodization Lyot coronagraphy for the direct imaging of exoplanet systems: design, fabrication, and laboratory demonstration

Trauger

Moody

Gordon

et al. 2012

Space Telescopes and Instrumentation 2012: Optical, Infrared, and Millimeter Wave

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We review the design, fabrication, performance, and future prospects for a complex apodized Lyot coronagraph for highcontrast exoplanet imaging and spectroscopy. We present a newly designed circular focal plane mask with an inner working angle of 2.5 λ/D. Thickness-profiled metallic and dielectric films superimposed on a glass substrate provide control over both the real and imaginary parts of the coronagraph wavefront. Together with a deformable mirror for control of wavefront phase, the complex Lyot coronagraph potentially exceeds billion-to-one contrast over dark fields extending to within angular separations of 2.5 λ/D from the central star, over spectral bandwidths of 20% or more, and with throughput efficiencies better than 50%.Our approach is demonstrated with a linear occulting mask, for which we report our best laboratory imaging contrast achieved to date. Raw image contrasts of 3×10 -10 over 2% bandwidths, 6×10 -10 over 10% bandwidths, and 2×10 -9 over 20% bandwidths are consistently achieved across high contrast fields extending from an inner working angle of 3 λ/D to a radius of 15 λ/D. Occulter performance is analyzed in light of experiments and optical models, and prospects for further progress are summarized.The science capability of the hybrid Lyot coronagraph is compared with requirements for ACCESS, a representative space coronagraph concept for the direct imaging and spectroscopy of exoplanet systems. This work has been supported by NASA's Strategic Astrophysics Technology / Technology Demonstrations for Exoplanet Missions (SAT/TDEM) program.

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“…The concept was introduced by Kuchner and Traub 15 and extended to higher-order configurations by Kuchner et al 16 . These coronagraph masks have been manufactured in HEBS glass 17 and more recently as vacuum-deposited metal films 11 . The best high-contrast results to date have been obtained with a band-limited coronagraph in JPL's High Contrast Imaging Testbed (HCIT) 18 .…”

Section: The Four Coronagraph Typesmentioning

confidence: 99%

“…The best high-contrast results to date have been obtained with a band-limited coronagraph in JPL's High Contrast Imaging Testbed (HCIT) 18 . Over the last five years, the testbed has steadily set new records in high-contrast imaging, reaching 6.4 × 10 -10 contrast in a spectral bandwidth of 10% over a field of view spanning 4-10 λ/D 11,19 . The testbed has also been used to demonstrate long-term contrast stability of 10 -11 over periods of five hours or more 20 .…”

Section: The Four Coronagraph Typesmentioning

confidence: 99%

ACCESS: a NASA mission concept study of an Actively Corrected Coronagraph for Exoplanet System Studies

Trauger

Stapelfeldt

Traub

et al. 2008

Space Telescopes and Instrumentation 2008: Optical, Infrared, and Millimeter

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ACCESS (Actively-Corrected Coronagraph for Exoplanet System Studies) develops the science and engineering case for an investigation of exosolar giant planets, super-earths, exo-earths, and dust/debris fields that would be accessible to a medium-scale NASA mission. The study begins with the observation that coronagraph architectures of all types (other than the external occulter) call for an exceptionally stable telescope and spacecraft, as well as active wavefront correction with one or more deformable mirrors (DMs). During the study, the Lyot, shaped pupil, PIAA, and a number of other coronagraph architectures will all be evaluated on a level playing field that considers science capability (including contrast at the inner working angle (IWA), throughput efficiency, and spectral bandwidth), engineering readiness (including maturity of technology, instrument complexity, and sensitivity to wavefront errors), and mission cost so that a preferred coronagraph architecture can be selected and developed for a medium-class mission.

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Design and demonstration of hybrid Lyot coronagraph masks for improved spectral bandwidth and throughput

Cited by 23 publications

References 10 publications

Polynomial Apodizers for Centrally Obscured Vortex Coronagraphs

Polynomial Apodizers for Centrally Obscured Vortex Coronagraphs

Complex apodization Lyot coronagraphy for the direct imaging of exoplanet systems: design, fabrication, and laboratory demonstration

ACCESS: a NASA mission concept study of an Actively Corrected Coronagraph for Exoplanet System Studies

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