Finite Element Analysis for PZT Actuated Deformable Polishing Lap

In aspheric mirror polishing progress, the deformable polishing lap can change the lap surface to fit the surface of aspheric optical mirror. A novel method of designing deformable polishing lap is brought forward by using PZT actuator. It consists of an aluminum disk which can change surface profile continuously under the control of PZT actuators. When the deformable aspherical polishing lap moves on the surface of aspherical mirror, the needed deformation of each PZT actuator is calculated at any location. After each PZT actuator deforming, the surface profile of deformable aspherical polishing lap is changed to an off-axis surface of aspheric optical mirror at that location. In this paper, the rational of novel deformable polishing lap is introduced, and the calculation formula of PZT actuator deformation is explored also. By using finite element method (FEM), the deforming capability of the novel deformable polishing lap is simulated to reform a hyperboloid mirror with diameter 350mm,k(-)-1.112155, R(-)840.0 mm. The results of two type of PZT actuator arrangement are compared and analyzed. The results show that the novel deformable polishing lap can reshape to fit the surface of aspheric mirror and the RMS is less than 2um.