Surface characteristics of diamond turned laser optics

The high energy laser program requires large diameter metal mirrors capable of superior optical performance. One of the methods of obtaining these mirrors is by diamond turning, which can be described as superfinishing a metal surface by single-point tooling. Flat and curved surfaces from one-cm to 40-cm diameter with a surface finish better than 25 angstroms RMS were produced in Y-12. The surface finish, light scattering, reflectivity, and absorptivity of many of these surfaces were measured by several laboratories. Instrumental methods and a summary of the results are presented.