ZeCoat Corporation will develop a specular, low reflectance coating with high optical density for a star shade’s light blocking membrane. The coatings will be applied to polyimide membrane surfaces such as KaptonTM or CP1TM and will be designed to produce very dark and specular surfaces. The coatings may also be applied directly to rigid substrates such as light baffles.
Low reflectance surfaces are needed for starshades to reduce stray light from entering the telescope from earthshine, moonshine, near-planets, and background stars and galaxies. A specular membrane will ensure only a small solid angle of light coming from directly behind the telescope can produce stray light. A specular coating will also prevent the reflectance phenomenon known as the "opposition effect", which causes an observed brightening in the retro-direction from coherent backscater off a rough surface.
Existing blackening processes such as carbon nanotubes, copper oxides, carbon-filled KaptonTM, and others, result in rough surfaces that reflect and scatter significant energy. Many of these three-dimensional surfaces are easily damaged by abrasion (creating particulate contamination), degrade in humidity during ground storage, degrade in the high radiation environments of space, or in the case of black-KaptonTM, are significantly reflective and relatively heavy. In this SBIR, we will demonstrate the feasibility of creating new materials and processes that alleviate these deficiencies.
In Phase I polyimide membrane materials will be coated with our batch coating process to demonstrate feasibility. The batch process utilizes a moving evaporation source and rotating substrate to achieve coating uniformity over a broad area.
In Phase II, we will develop a novel, roll-to-roll process to manufacture precision optical coatings in the quantities needed for future starshades and commercial applications.
Starshade membranes, WFIRST, HabEx, LUVOIR, LISA, light suppression for light baffles and optical sensors
This technology will help reduce the optical signature of future commercial satellite constellations such as Starlink, which threaten to create excessive light pollution interfering with ground-based telescope observations.
Commercial stray light reduction applications include cell phone cameras, telescope light baffles, and many optical sensor applications.