Design of a large five-axis ultra-precision ion beam figuring machine: structure optimization and dynamic performance analysis

Large aperture optical components are widely used in deep space exploration and high-precision earth observation system. Ion beam figuring (IBF) is usually used as the last polishing process, and its polishing accuracy determines the optical primary mirror precision, so an IBF machine plays a very important role in the production process of large-size optics. In this paper, the state-of-the-art large-aperture IBF equipment is introduced firstly. Next, the structures, equipment parameters, and design considerations of our IBF equipment are presented. Motion accuracy and dynamic performance are the two prioritized design issues; all researches are carried out around these two issues. Then, the key design points and characteristic analyses of IBF machine are presented, including structure analysis and optimization of the vacuum chamber, the relationship analysis between the dynamic performance of the moving system and the polishing accuracy, and multi-objective optimization design and modal analysis of motion components. Finally, the dynamic characteristics and motion errors of the IBF machine are tested, and the test results show that the machine performance indexes meet the design requirements.