Hybrid ball-hinged secondary mirror assembly for high-precision surface shape maintenance.

Area of Science:

• Optical Engineering
• Telescope Design
• Thermal Management

Background:

• Secondary mirrors in optical telescopes are susceptible to ambient temperature fluctuations.
• Temperature variations cause surface shape distortions, impacting optical performance.

Purpose of the Study:

• To propose and evaluate a hybrid ball-hinged secondary mirror assembly (HSMA) for enhanced thermal adaptation.
• To investigate the HSMA's ability to mitigate temperature-induced surface distortions.

Main Methods:

• Finite element modeling (FEM) was employed to simulate temperature-induced surface shape distortions.
• Analysis included evaluating performance across a wide temperature range (-30°C to 70°C).
• The influence of gravity-induced distortions at different attitudes (0-90°) was also assessed.

Main Results:

• Simulations demonstrated minimal and negligible changes in secondary mirror surface distortions.
• Maximum residual distortions (PV and RMS) were as low as 16.31 nm and 3.005 nm, respectively.
• Both simulation and experimental results confirmed the HSMA's ability to maintain high-precision surface shape.

Conclusions:

• The hybrid ball-hinged secondary mirror assembly effectively achieves thermal adaptation in optical telescopes.
• The HSMA maintains high-precision surface shape under wide temperature variations and different gravitational orientations.