Stylus profiling instrument for measuring statistical properties of smooth optical surfaces

A surface profiling instrument is described which produces digitized surface profiles and other statistical data. Sharp styli are available that can give height resolution of the order of 1-2 A and lateral resolution of a few tenths of a micrometer on smooth surfaces. The stylus loading can be adjusted so that no permanent marks are left on the surface. Representative surface profiles and autocovariance functions are shown for various materials, and roughnesses measured with the instrument are compared with values obtained using other techniques.