Optimization design of an ultralight large-aperture space mirror

Area of Science:

• Optics and Space Technology
• Materials Science and Engineering

Background:

• Ultralight space mirrors are crucial for enhancing the capabilities of space telescopes.
• Traditional lightweighting methods often compromise mirror performance.

Purpose of the Study:

• To design and optimize a 2-meter aperture ultralight space mirror with superior structural and dynamic properties.
• To validate the design through finite-element analysis and experimental comparison.

Main Methods:

• Employed experimental design and multiobjective integrated optimization to determine mirror structure and parameters.
• Incorporated elliptical holes near the neutral surface and utilized a three-point back support system.
• Conducted finite-element analysis to assess surface figure error and eigenfrequencies.
• Fabricated the mirror using reaction-bonded silicon carbide.

Main Results:

• Achieved a surface figure error of 10.4 nm under 1g in the x-direction, suitable for visible light optics.
• Determined eigenfrequencies of 70 Hz (x-direction), 70 Hz (y-direction), and 90 Hz (z-direction), indicating excellent dynamic performance.
• The fabricated mirror has a mass of 105 kg and a surface density of 34 kg/m², representing a 50% mass reduction compared to traditional methods.
• Experimental validation showed a relative error within 4% for eigenfrequencies.

Conclusions:

• The developed ultralight mirror design offers reliable optimization results for large-aperture space applications.
• The design demonstrates excellent performance in terms of optical accuracy and dynamic stability.
• This advancement facilitates the development of next-generation, lighter, and more efficient space telescopes.