The process of Ion Beam Figuring (IBF) can be described by a two-dimensional convolution equation which including
dwell time. Solving the dwell time is a key problem in IBF. Theoretically, the dwell time can be solved from a
two-dimensional deconvolution. However, it is often ill-posed]; the suitable solution of that is hard to get. In this article, a
dwell time algorithm is proposed, depending on the characters of IBF. Usually, the Beam Removal Function (BRF) in
IBF is Gaussian, which can be regarded as a headstand Gaussian filter. In its stop-band, the filter has various filtering
abilities for various frequencies. The dwell time algorithm proposed in this article is just based on this concept. The
Curved Surface Smooth Extension (CSSE) method and Fast Fourier Transform (FFT) algorithm are also used. The
simulation results show that this algorithm is high precision, effective, and suitable for actual application.