Modeling the scatter of sunlight from starshade edges

Dylan McKeithen; Stuart Shaklan; Stefan Martin; Christine Bradley; Raju Manthena

doi:10.1117/12.2530026

9 September 2019 Modeling the scatter of sunlight from starshade edges

Dylan McKeithen, Stuart Shaklan, Stefan Martin, Christine Bradley, Raju Manthena

Proceedings Volume 11117, Techniques and Instrumentation for Detection of Exoplanets IX; 111171L (2019) https://doi.org/10.1117/12.2530026
Event: SPIE Optical Engineering + Applications, 2019, San Diego, California, United States

Abstract

A sunflower-like starshade positioned between an exoplanet host star and a telescope forms a deep shadow at the telescope enabling the faint exoplanet to be viewed without being overwhelmed by veiling glare from the star. The starshade perimeter has hundreds of meters of sharp edge that are directly exposed to sunlight. The sunlight diffracts and reflects from the edge resulting in a glint pattern that can be brighter than the exoplanet. We have developed models of the edge glint to explain laboratory measurements, to guide the development of edges with minimum glint, and to determine the fundamental glint floor which is set by diffraction. The models include finite difference time domain calculations, Sommerfeld's half-plane diffraction expressions, and a micro-facet scattering model. Models successfully reproduce the features and magnitude of the measured polarization-dependent scatter and show that measured edges are performing near the theoretical limit.

Citation Download Citation

Dylan McKeithen, Stuart Shaklan, Stefan Martin, Christine Bradley, and Raju Manthena "Modeling the scatter of sunlight from starshade edges", Proc. SPIE 11117, Techniques and Instrumentation for Detection of Exoplanets IX, 111171L (9 September 2019); https://doi.org/10.1117/12.2530026

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