Impact of near-angle scatter on exo-Earth coronagraphy

H. Philip Stahl; David D. Smith; Bijan Nemati

doi:10.1117/12.3021201

23 August 2024 Impact of near-angle scatter on exo-Earth coronagraphy

H. Philip Stahl, David D. Smith, Bijan Nemati

Proceedings Volume 13092, Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave; 1309265 (2024) https://doi.org/10.1117/12.3021201
Event: SPIE Astronomical Telescopes + Instrumentation, 2024, Yokohama, Japan

Conference Poster

Abstract

Near-Angle Scatter (NAS) of the host star’s light may limit the ability of a potential Habitable Worlds Observatory (HWO) to detect and characterize an Earth-like planet around a Sun-like star via coronagraphy. NAS from each optical surface produces an E-field across the dark hole that is coherent. These E-fields sum and could be as large or larger than the coronagraph mask leakage E-field. NAS E-fields contribute to the dark hole noise floor via both shot noise and heterodyne amplification of the wavefront instability. The amount of NAS is determined entirely by the statistical properties of the optical surface microroughness and the operating wavelength. Surface properties include not only the rms roughness, but also correlation length and the functional form of the distribution itself. This paper derives an expression that specifies the surface statistics required to achieve a given coronagraph error budget NAS throughput allocation. Analysis does not include scatter from coating columnar structure, edges, contamination, micrometeoroid impacts, or polarization.

Citation Download Citation

H. Philip Stahl, David D. Smith, and Bijan Nemati "Impact of near-angle scatter on exo-Earth coronagraphy", Proc. SPIE 13092, Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave, 1309265 (23 August 2024); https://doi.org/10.1117/12.3021201

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