Dark coatings with tailorable BRDF and thermal-emissivity for light-blocking starshade membranes

ZeCoat Corporation will develop a roll-to-roll coating process to manufacture low reflectance coatings with high optical density for a star shadersquo;s light blocking membrane.nbsp; The coatings will be applied to polyimide membrane surfaces such as KaptonTM or NovastratTM and will be designed to produce low reflectance surfaces with tailorable scatter properties. The coatings may also be applied in a batch coating process to substrates such as light baffles.Low-reflectance surfaces are needed for starshade light-blocking membranes to reduce stray light resulting from out-of-plane petals, and from light sources nearly behind the telescope.nbsp;nbsp; Existing darkening materials such as carbon nanotubes and columnar structures such as etched silicon, typically have poor durability, are damaged by abrasion, create particulate contamination, and the processes do not scale easily for large size optics.nbsp; In this SBIR, we will demonstrate the feasibility of creating new materials and processes that alleviate these deficiencies.nbsp;In Phase I, we demonstrated the feasibility of manufacturing low reflectance coatings using our existing batch coating processes.nbsp;nbsp; Coating designs were characterized for optical and thermal properties, as well as, environmental durability.nbsp;In Phase II, we will develop a novel, roll-to-roll coating process to manufacture multi-layer optical coatings in the large quantities needed for future starshades, and to create competitively-priced light-absorbing materials for commercial sensor systems.