Abstract

In the manufacture of rotationally symmetric optics, it is often cost effective to grind in the asphericity prior to polishing. The larger and faster the asphere, the more this is so. In almost all cases, the aspheric departure from a vertex sphere is a small fraction of the sagitta (sag) of the surface. Since virtually all measuring instruments have an accuracy that is proportional to their total range, a nearly ideal device for measuring aspheric sag would measure just the departure from the vertex sphere.

© 1990 Optical Society of America