A novel method for measuring and correcting the surface shape error of the pitch lap in the full-aperture continuous polishing

Continuous polishing is a significant process to fabricate optical workpiece with nano figure precision. The figure of the optical workpiece is to a large extent dependent on the surface shape of the pitch lap. In this study, a novel method is proposed to determine the lap shape error by moving the measurement point in a generally radial direction while the lap rotates and correct the lap shape error by employing a small heat tool considering its viscoelastic property. It is validated that the surface shape error of the pitch lap can be corrected dramatically by the method, and the workpiece figure attempts to target the lap shape so as to reach a uniform material removal.