Analysis and verification on multi-DOF optical path sensitivity of an off-axis four-mirror telescope

Area of Science:

• Optical Engineering
• Astrophysical Instrumentation
• Structural Mechanics

Background:

• Structural stability is crucial for off-axis four-mirror space telescopes to maintain optical performance.
• Structural deformations can alter the optical path, impacting telescope functionality.
• Understanding the influence of various degrees of freedom (DOFs) in mirror displacement is essential.

Purpose of the Study:

• To develop a model analyzing the impact of multi-DOF rigid body displacements of mirrors on the optical path.
• To predict the sensitivity of each DOF to structural deformation.
• To identify critical DOFs for structural stability in space telescopes.

Main Methods:

• Development of a computational model to simulate mirror displacements and their effect on the optical path.
• Sensitivity analysis of different DOFs for mirror movement.
• Validation of model predictions through Zemax simulations and experimental testing.

Main Results:

• Identified specific DOFs with significant impact on the optical path, varying by mirror.
• Primary mirror's Z-axis translation, Y-axis translation, and X-axis rotation were found to be highly sensitive DOFs.
• X-axis rotation of the primary mirror caused greater optical path variation than the secondary mirror.

Conclusions:

• Specific mirror displacements (e.g., primary mirror's Z-translation, Y-translation, X-rotation) critically affect optical path stability.
• These sensitive DOFs require focused attention during telescope design and testing.
• The study provides valuable references for ultra-high-precision structural stability measurements and ultra-stable structure design, particularly for gravitational wave telescopes.