Starshades are designed to enable the direct observation of an exoplanet by blocking the light of the planet's star from reaching the telescope. As discussed in our companion paper [S. Shaklan et al., "Solar glint from uncoated starshade optical edges," J. Astron. Telesc. Instrum. Syst. 7(2), 021204 (2021)], diffraction and reflection of sunlight incident on the starshade's razor-sharp uncoated edges will appear as glint that may be brighter than the feeble light of the exoplanet. We report on the measurement and modeling of thin, conformal, multilayer antireflection coatings that reduce solar glint by more than an order of magnitude when applied to uncoated edges. We used the Lumerical finite-difference time-domain simulation software suite to determine the performance of coatings designed to work on a flat surface when applied to a sharp, curved edge. Laboratory measurements of coated edges, including a 50-cm long segment, confirm the glint reduction predicted by these models. We consider two coating approaches and compare their performance: a line-of-sight coating and a coating that uniformly covers the entire terminal edge. Starting with a wide range of coating designs emphasizing different angles of incidence and bandpass characteristics, we use Lumerical to account for edge diffraction and reflection, and we optimize the designs for the Starshade Rendezvous Mission and the HabEx mission concept.

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