Design and performance analysis of an ultraprecision ion beam polishing tool.

First, we introduce requirements for the ion beam polishing tool used in the subnanometer precision process. Based on the ion beam figuring (IBF) principle, the definitive factor of the IBF capability is analyzed, and the deficiencies of the ion beam polishing tool are identified. The effect of focused ion optics on the ion beam removal function is based on theoretic calculation and computer simulation; and focused three-grid ion optics are developed and tested. Finally, a 150 mm flat optics element is figured and results show that the contour error decreases from 15.58 nm RMS to 0.796 nm RMS, demonstrating that the ion beam polishing tool is very efficient for optical IBF.