Adjustable bipod flexures for mounting mirrors in a space telescope.

Area of Science:

• Optical engineering
• Mechanical engineering
• Astrophysics instrumentation

Background:

• Space telescopes require precise optical components, like primary mirrors, susceptible to gravitational distortion during ground testing.
• Conventional mounting methods, such as bipod flexures, may not adequately address these distortions, impacting optical performance.

Purpose of the Study:

• To introduce and evaluate a new mirror mounting technique for space telescope primary mirrors.
• To mitigate astigmatic aberration caused by gravitational distortion during horizontal testing.
• To enhance the mechanical safety and optical stability of mirror mounts for space applications.

Main Methods:

• Developed a novel flexure mount incorporating mechanical shims to replace conventional bipod flexures.
• Investigated the relationship between shim thickness and astigmatism reduction.
• Conducted interferometric testing in a horizontal setup, including 180° mirror rotation, to assess system error.
• Performed finite element method (FEM) analysis and vibration tests.

Main Results:

• The proposed shimmed flexure mount effectively reduced astigmatic aberration caused by gravitational distortion.
• Gravitational stress at the adhesive coupling was reduced by approximately 50% compared to conventional bipod flexures.
• FEM analysis results correlated well with experimental optical interferometer data.
• Vibration tests confirmed the mechanical safety and optical stability of the mount.

Conclusions:

• The new mirror mounting technique offers a viable solution for minimizing gravitational effects on primary mirrors during testing.
• The shimmed flexure mount provides improved mechanical safety under launch loads and ensures optical stability.
• This technique is suitable for space applications, enhancing the reliability of space telescope optical systems.