A hybrid Lyot coronagraph for the direct imaging and spectroscopy of exoplanet systems: recent results and prospects

Trauger, John T.; Moody, Dwight; Gordon, Brian; Krist, John; Mawet, Dimitri

doi:10.1117/12.895032

Cited by 27 publications

(23 citation statements)

References 8 publications

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“…This location has the benefit of being common-path and common-band with the coronagraph. The reflective Lyot stop is appropriate for transmissive phase mask coronagraphs like the VVC, whereas a reflective coronagraph mask is more suitable for systems where the occulting mask rejects the starlight -such as the band-limited mask 9 or PIAA-based coronagraphs.…”

Section: Lowfs Optionsmentioning

confidence: 99%

The low-order wavefront sensor for the PICTURE-C mission

et al. 2015

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The PICTURE-C mission will fly a 60 cm off-axis unobscured telescope and two high-contrast coronagraphs in successive high-altitude balloon flights with the goal of directly imaging and spectrally characterizing visible scattered light from exozodiacal dust in the interior 1-10 AU of nearby exoplanetary systems. The first flight in 2017 will use a 10´4 visible nulling coronagraph (previously flown on the PICTURE sounding rocket) and the second flight in 2019 will use a 10´7 vector vortex coronagraph. A low-order wavefront corrector (LOWC) will be used in both flights to remove time-varying aberrations from the coronagraph wavefront. The LOWC actuator is a 76-channel high-stroke deformable mirror packaged on top of a tip-tilt stage. This paper will detail the selection of a complementary high-speed, low-order wavefront sensor (LOWFS) for the mission. The relative performance and feasibility of several LOWFS designs will be compared including the Shack-Hartmann, Lyot LOWFS, and the curvature sensor. To test the different sensors, a model of the time-varying wavefront is constructed using measured pointing data and inertial dynamics models to simulate optical alignment perturbations and surface deformation in the balloon environment.

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Section: Lowfs Optionsmentioning

confidence: 99%

The low-order wavefront sensor for the PICTURE-C mission

et al. 2015

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“…Trauger et al 2010; 9 for an example prototype see Trauger & Traub 2007 10 and Trauger et al 2011 11 ). In particular, instruments using a vector vortex mask can theoretically provide perfect on-axis light rejection for an unobstructed aperture.…”

Section: 4mentioning

confidence: 99%

Optimal apodizations for on-axis vector vortex coronagraphs

Fogarty

Pueyo

Mawet³

2014

SPIE Proceedings

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Imaging planets requires instruments capable of dealing with extreme contrast ratios and that have a high resolution. Coronagraphs that can reach a contrast ratio in a neighborhood of 10 9 will be capable of observing Jupiter-like planets, while those with a contrast greater than a benchmark number of 10 10 to within a few λ/D of an on-axis star will render possible imaging of Earth-like planets. Plans for achieving this feat have been developed for use on telescopes with unobscured, circularly symmetric apertures. However; given that the next generation of large telescopes are on-axis designs with support structures in the telescope aperture and a central obstruction due to the secondary mirror, it has proven necessary to develop coronagraphic techniques that compensate for obstructions. Pueyo & Norman (2012) present a possible solution to the problem of the support structures using ACAD. In this paper, we present a coronagraphic design that uses a vector vortex and pupil apodization to compensate for the secondary mirror that could possibly be used in conjunction with a wavefront control system and/or ACAD. This coronagraph is capable of achieving a contrast ratio of at least 10 10 in a working angle of (1.5 − 30) λ/D in conjunction with an on-axis telescope. We can construct our pupil using a classical transmissive apodizer or pupil remapping. We find that the mirror shapes required are relatively simple (requiring ≤ 40 degrees of freedom to describe) and we expect they will be feasible to manufacture, and potentially even to implement with deformable mirrors. By combining existing high-contrast imaging techniques, we demonstrate that a relatively simple design may be used to image exo-Earths.

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“…For instance, let us emphasize the successful implementation of the apodizing phase plates (APP) at the MMT 41 and NACO. 42 Finally, note that the hybrid band-limited (HBL) coronagraph makes use of both amplitude and phase modulation, 43 which allows it to also access smaller angles (1λ/d is in theory feasible with a second-order HBL, but at the expense of significant throughput losses). The HBL coronagraph currently holds the world record of the deepest and broadest (in terms of bandwidth) demonstrated contrast level in the lab, down to an IWA of 3λ/d (Sect.…”

Section: Small-angle Coronagraphsmentioning

confidence: 99%

Review of small-angle coronagraphic techniques in the wake of ground-based second-generation adaptive optics systems

Mawet

Pueyo

Lawson

et al. 2012

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

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Small-angle coronagraphy is technically and scientifically appealing because it enables the use of smaller telescopes, allows covering wider wavelength ranges, and potentially increases the yield and completeness of circumstellar environment -exoplanets and disks -detection and characterization campaigns. However, opening up this new parameter space is challenging. Here we will review the four posts of high contrast imaging and their intricate interactions at very small angles (within the first 4 resolution elements from the star). The four posts are: choice of coronagraph, optimized wavefront control, observing strategy, and post-processing methods. After detailing each of the four foundations, we will present the lessons learned from the 10+ years of operations of zeroth and first-generation adaptive optics systems. We will then tentatively show how informative the current integration of second-generation adaptive optics system is, and which lessons can already be drawn from this fresh experience. Then, we will review the current state of the art, by presenting world record contrasts obtained in the framework of technological demonstrations for space-based exoplanet imaging and characterization mission concepts. Finally, we will conclude by emphasizing the importance of the cross-breeding between techniques developed for both ground-based and space-based projects, which is relevant for future high contrast imaging instruments and facilities in space or on the ground. . The left axis shows both the Planet/Star contrast ratio together with the corresponding rms wavefront quality necessary to reach it (assuming a high order deformable mirror, e.g. 64 by 64 actuators). The right axis shows the corresponding ∆ magnitude relative to the central star. The x axis shows the angular separation in arcsec. All detectivity curves are 5σ and scaled for a 1-hour observing time. An asterisk denotes predicted contrast for future instruments. Keck-NIRC2, VLT-NACO, Palomar-WCS, and HST-ACS curves show current representative capabilities of these high contrast imaging workhorse instruments. Improving upon these first generation instrument, we present here as well the expected progress of the second generation (e.g. GPI and SPHERE) both in terms of contrast and inner working angle, which is the very focus of the current review. Note that the Palomar-P3K-P1640 second generation instrument is already on sky, and the curve presented here is based on real data. Longer term projections include JWST-NIRCam, TMT PFI, and E-ELT EPICS. Over-plotted are the K-band fluxes for 9 of the 15 or so extra-solar planets that have been imaged so far. In the lower part of the figure are plotted our solar system planets as they would appear in reflected light around a Sun-like star at a distance of 10 pc. One caveat to this comparison plot is the diversity in wavelength ranges covered, and the obvious but inevitable overlap between the reflected light and thermal emission regimes.

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A hybrid Lyot coronagraph for the direct imaging and spectroscopy of exoplanet systems: recent results and prospects

Cited by 27 publications

References 8 publications

The low-order wavefront sensor for the PICTURE-C mission

The low-order wavefront sensor for the PICTURE-C mission

Optimal apodizations for on-axis vector vortex coronagraphs

Review of small-angle coronagraphic techniques in the wake of ground-based second-generation adaptive optics systems

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