Numerical design tools for thermal replication of optical-quality surfaces

Abstract

The slumping of molten glass under gravity into a mould, so as to replicate the mould surface on the upper free surface of the glass, is used in the manufacture of some optical components for which the curvature of the upper free surface is critical. A finite-element simulation of the process based on the creeping-flow equations is described. In addition a method is given for computing surface curvature from the non-exact discrete data produced by the finite-element computations. These methods are illustrated for a particular case of a circular glass disc slumping into a spherical mould. (C) 2000 Elsevier Science Ltd. All rights reserved.