A large size ion beam figuring system for 1.2m astronomical telescopes fabrication

Abstract

An ion beam figuring system (KDIBF2000) for final figuring of large size optics has been designed and built by National University of Defense Technology in China. It can figure optics up to the maximum dimensions of 2.0m×2.0m×0.4m with five axes of servo-motion used to control ion source movement. For operational facility, there are two vacuum chambers with main work chamber and a small supplementary chamber isolated by a flapper valve. The main chamber has two work zones, which can meantime hold a large optics with Φ1.5m and a small optics with 0.4m. The small optics can be transferred through supplementary chamber with a moving vehicle. By this way, it is very convenient and economical to gain the material removal function and check the system’s process performance. Now, this system has been gone into running to figure large SiC off-axis aspheric optics. Next step, a 1.2m SiC aspheric primary mirror will be figure by this system.