One-dimensional ion-beam figuring solution from Brookhaven National Laboratory

We demonstrate a novel One-Dimensional Ion-Beam Figuring (1D-IBF) solution from Brookhaven National Laboratory. Three improvements are introduced to the new 1D-IBF system. First, the misalignment of the coordinate systems between the metrology and the 1D-IBF hardware is minimized by integrating both the sample mirror and the Beam Removal Function (BRF) mirror into a single mirror holder. The measured BRF center is then used as a reference to calibrate the coordinate correspondence. Second, a Constrained Linear Least-Squares (CLLS) algorithm with a coarse-to-fine scheme is proposed to keep the non-negativity of the dwell time as well as ensure it smoothly duplicate the required removal amount. Third, a dwell time slicing strategy is used to smooth the implementation of the dwell time in the real 1D-IBF fabrication process. Experimental results demonstrate that the proposed 1D-IBF solution reduces the residual profile errors to sub-nanometer Root Mean Square (RMS) for both flat and spherical mirrors.