Model and Method to Determine Dwell Time in Ion Beam Figuring

To determine the dwell time is an important problem in ion beam figuring. Usually, the ion beam figuring process can be described by a two-dimensional convolution equation including dwell time and thus it can be solved theoretically by deconvolution. However, deconvolution is an ill-posed problem. Therefore the dwell time is difficult to be well solved. In order to solve the problem, a discrete linear model named CEH model was introduced and its advantages were discussed. And the truncated singular value decomposition (TSVD) method was proposed to solve the dwell time in CEH model. Furthermore, L-curve was introduced to analyze the relationship between the residual rms error and the material removal amount, and to evaluate the different picking methods of removal and dwell grid points in CEH model. Simulation results show that CEH model and TSVD method are suitable to determine the dwell time in optics fabrication using ion beam figuring.