Ion beam figuring high gradient optical aspherical surface

Ion beam figuring(IBF) is commonly used during the process of fine optical fabrication. According to sputtering theory, material removal rate varies with the ion inject angle and the surface curvature. During the process of figuring high gradient aspherical surface, the removal function of ion beam figuring should be calibrated strictly to guarantee the accuracy of the figuring results. In this paper, we describe the influence of ion density distribution and surface curvature on material removal rate. Since the removal function varies from point to point within the ion bombed region for high gradient surface, rectification matrix was proposed to fix the disparity between the practical removal function and flat removal function. Experiments were implemented with high gradient aspherical surface to prove the rectification matrix can fit the variety of the material removal rate effectively.