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

Area of Science:

• Materials Science and Engineering
• Optical Engineering
• Aerospace Engineering

Background:

• Increasing demand for ultra-black surfaces in space optical systems for stray light suppression.
• Challenges in developing omnidirectional, high-absorption ultra-black surfaces for the space environment.

Purpose of the Study:

• To propose a novel design strategy for ultra-black surfaces combining light-trapping microstructures and carbon nanotube (CNT) films.
• To enable microstructure unit feature design via ray tracing by treating the Bidirectional Reflectance Distribution Function (BRDF) of CNT films as surface scattering properties.
• To achieve large-area fabrication of highly absorptive ultra-black surfaces for aerospace applications.

Main Methods:

• Design strategy combining light-trapping microstructures with carbon nanotube (CNT) films.
• Ray tracing for microstructure unit feature design based on BRDF of CNT films.
• Fabrication using ultra-precision fly-cutting (UPFC) and plasma-enhanced chemical vapor deposition (PECVD).

Main Results:

• Pyramid configuration significantly enhances light-trapping capability with good angular tolerance.
• Fabricated pyramid light-trapping microstructure ultra-black (PLMU) surfaces with a maximum area of 200 mm × 150 mm.
• Achieved average hemispherical reflectance (R < 0.48%) in the visible range, with reflectance below 2% at 60° incidence.
• Confirmed excellent in-orbit performance through outgassing tests and thermal cycling.

Conclusions:

• The proposed method effectively creates large-area, highly absorptive ultra-black surfaces.
• Demonstrated potential for improving stray light suppression in space optical systems.
• The developed surfaces meet the harsh requirements of the space service environment.