INTERFEROMETRIC PROFILER FOR ROUGH SURFACES

Conventional interferometric methods of surface profiling are limited in the magnitude of surface height that can be accurately measured because of phase ambiguity errors on steep local slopes. Other optical methods that have been developed for surface profiling frequency suffer from poor height resolution and slow measurement speed for three-dimensional profiles. Contact profilometers such as stylus-based instruments suffer from slow measurement speed, especially when three-dimensional profiles of the surface are required. Stylus tips can also scratch delicate surfaces during the course of the measurement. A new method of optical, noncontact profiling of rough surfaces is described that utilizes interferometric techniques as well as digital signal-processing algorithms to produce fast, accurate, and repeatable three-dimensional surface profile measurements.