Ultra-high, Omnidirectional, and Space Service Capability Light-Absorption Surface for Space Optical Systems.

There is a growing demand for ultra-black surfaces for stray light suppression in space optical systems due to their extremely high absorptance. However, developing omnidirectional, high-absorption ultra-black surfaces that meet the harsh requirements of the space service environment remains challenging. This work proposes a design strategy combining light-trapping microstructures with carbon nanotube (CNT) films, in which the Bidirectional Reflectance Distribution Function (BRDF) of the films is treated as the surface scattering property of the microstructures, enabling microstructure unit feature design via ray tracing. Simulation results indicate that, under the scattering characteristics of the coating, the pyramid configuration significantly enhances light-trapping capability significantly while maintaining good angular tolerance. Furthermore, the pyramid light-trapping microstructure ultra-black (PLMU) surfaces are fabricated using ultra-precision fly-cutting (UPFC) and plasma-enhanced chemical vapor deposition (PECVD), achieving a maximum single-panel area of 200 mm × 150 mm. This surface exhibits an extremely low average hemispherical reflectance (R < 0.48%) in the visible range, with reflectance remaining below 2% even at a 60° incidence angle. Finally, outgassing tests, thermal cycling, and other space qualification tests confirm excellent in-orbit performance. The proposed method shows great potential for realizing large-area fabrication of highly absorptive ultra-black surfaces for aerospace applications, offering substantial promise for improving stray light suppression in space optical systems.