An increasingly important tool in the characterization and measurement of optical materials and components in the Wyko TOPO Noncontact Surface Profiler. Optically, it consists of a low- to medium-power microscope in which the objective, depending upon the power, is a visible light interferometer of either Michelson, Mireau, or Linnik design. By integrating a detector array into the viewing system and attaching the reference arm of the interferometer to a piezoelectric transducer, the technique of surface profiling by phase shifting is accomplished by computer.

The potential utility of this system to the investigator interested in the fundamental mechanisms of laser-induced damage is enormous, provided that the user is aware of its proper use and limitations. This paper is intended to act as a user's guide to the TOPO system in such cases and to document its precision and accuracy limitations given a variety of surface types and measurement configurations.