Bayesian Principle Based Dwell Time Algorithm for Ion Beam Figuring of Low Gradient Mirrors

Abstract

Ion beam figuring is a technology of figuring mirrors errors of high efficiency. Dwell time algorithm is one of the key problems. Based on the Bayesian principle, an iterative dwell time algorithm for planar mirrors is deduced from the computer controlled optics shaping principle. With the Gaussian extension for the data edge, the edge effect is weakened. The rapid approximate calculation of the velocity for the realization of dwell time is presented, and then the model relation between the realization error and the process parameters is deduced. By the additional smoothing factors from the error model, the realization precision for the dwell time is improved. Based on the properties of the removal function, the shaping process of low gradient mirrors can be approximated to the linear model of planar mirrors. With these discussions, the error surface controlling technology for low gradient mirrors is set up. At last, the figuring experiments on planar and spherical samples are made; the convergence rates of both can reach 9. It is concluded that the linear model is reasonable and the approximate velocity is effective. The ion beam figuring technology based on these algorithms is a deterministic process of high efficiency and can be used to correct the surface error precisely and rapidly.