Design of a Dynamic Secondary Mirror Truss Adjustment Mechanism for Large Aperture Telescopes

This study focuses on the dynamic secondary mirror truss adjustment mechanism for large aperture telescopes. The relative positions between the primary and secondary mirrors have stringent requirements for large aperture optical telescopes, with an aperture of more than 2 m. Due to the large mass of the primary mirror, the secondary mirror system is designed as an adjustable mechanism with multiple degrees of freedom, dramatically impacting telescope imaging. The kinematic modeling is followed by a detailed description of the designed adjustment mechanism, and then a static and modal analysis of the designed mechanism is performed. Subsequently, a kinematic performance test of the experimental prototype is conducted. The developed mechanism can travel up to +/- 5 mm in the z-direction with an accuracy of 16 mu m and deflection of +/- 0.574 degrees in the xy-direction. It provides accuracy better than 6.4 arcseconds.