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31 August 2005 Coronagraph mask tolerances for exo-Earth detection
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Abstract
The direct detection at visible wavelengths of Earth-like planets around nearby stars requires starlight suppression by a factor of 1010 - 1011 at offsets of order 100 mas. It has been shown that perfect suppression is possible in principle, using a combination of a band-limited focal plane coronagraphic mask and a pupil plane Lyot stop. Errors in the transmission amplitude and phase of the mask degrade the performance. These errors can be corrected completely at a given wavelength and polarization using deformable mirrors (DMs) operating in the pupil plane of the system. Both the errors and correction have different chromatic dependences, however, and the DM correction becomes ineffective as the optical bandwidth is increased. The mask errors can be divided into 2 classes: (1) errors that are uncorrelated with the mask pattern, arising, for example, from the surface roughness of the mask substrate, and (2) errors that are correlated with the mask pattern. We present the results of analysis of random errors and simulate the effects of systematic errors using a specific example mask design. In both cases we find that the contrast required by TPF-C imposes very challenging demands on the design and fabrication of the masks. Several potential mitigation approaches are discussed.
© (2005) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Oliver P. Lay, Joseph J. Green, Daniel J. Hoppe, and Stuart B. Shaklan "Coronagraph mask tolerances for exo-Earth detection", Proc. SPIE 5905, Techniques and Instrumentation for Detection of Exoplanets II, 59050I (31 August 2005); https://doi.org/10.1117/12.618063
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