Frontiers of Engineering Reports on Leading-Edge Engineering from the 2015 Symposium (2016) / Chapter Skim
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Starlight Suppression: Technologies for Direct Imaging of Exoplanets--Dmitry Savransky
Starlight Suppression: Technologies for Direct Imaging of Exoplanets--Dmitry Savransky
Pages 45-54
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From page 45... ...
This short paper reviews the challenges of exoplanet imaging, techniques used to overcome them, and the status of technology development for exoplanet imagers in space. IMAGING OF EXOPLANETS A telescope operates by collecting light from an astronomical source using a finite-sized aperture -- either the entrance pupil of a refractive system or the primary mirror of a reflective one -- and bringing the light to a focus on an imag 45
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From page 46... ...
The pupil is conjugate with the entrance pupil of the whole system, so that the first image, where no coronagraph elements are in place, is equivalent to the intensity distribution seen by the entrance aperture of the whole system. The central dark spot in the first image is due to the secondary mirror that partially obscures the primary aperture in this system.
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From page 47... ...
λ = wavelength; D = aperture diameter. To deal with residual diffracted light in the classical Lyot coronagraph, an additional pupil plane can be introduced before the FPM with a partially transmissive mask to apodize the beam and minimize diffraction effects downstream (Soummer 2005)
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From page 48... ...
Many coronagraph designs are also highly sensitive to misalignment, vibration, and optical surface errors. Coronagraphs being evaluated for use in space all rely on active wavefront control via deformable mirrors, which have only recently begun to be demonstrated for use in space (Cahoy et al.
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From page 49... ...
This method requires a space telescope to fly in formation, over a baseline of tens of thousands of kilometers, with an occulting spacecraft, or starshade. The starshade must be tens of meters in diameter and specifically shaped, as diffraction effects would cause light to be scattered back into the shadow cast by a simple flat plate.
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From page 50... ...
. Starshade contrasts are also highly sensitive to shape, positioning, and alignment errors, leading to μm order manufacturing tolerances, mm deployment tolerances, and meter-scale alignment tolerances throughout the course of an observation (Shaklan et al.
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From page 51... ...
FIGURE 4 Colored points represent a simulated population of exoplanets based on prior surveys; asterisks represent contrast estimates for known, indirectly detected exoplanets at their most favorable viewing geometries; and the black lines are the predicted contrasts for one design of the Wide Field Infrared Space Telescope (WFIRST) coronagraph at various levels of telescope stability.
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From page 52... ...
Sirbu D, Kasdin NJ, Vanderbei RJ.
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From page 53... ...
Boca Raton, FL: CRC Press. Vanderbei RJ, Cady E, Kasdin NJ.
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