Because of the session at this Microscopy and Microanalysis 2000 meeting concerned with the microanalysis of irregular surfaces, it seems appropriate to briefly review the methods used for the characterization of rough surfaces. This includes both mathematical tools for the concise description of surface roughness, and instruments used to acquire the necessary data. These methods are widely used in industry to characterize and specify the roughness of surfaces prepared by various machining, grinding, polishing, chemical etching, and physical and chemical deposition techniques, and to correlate the surface roughness with performance.

Historically, surface roughness has been measured by performing a linear traverse with a mechanical stylus that is sensitive to vertical displacements of nm but with a lateral resolution on the order of pm, which is quite similar to the dimensions of the region analyzed by X-ray microanalysis. Recently, more comprehensive characterizations have been obtained using a raster scan over surface areas.