Conclusion
Surface metrology

The role of surfaces in modern technology justifies the large number of new instruments that have been developed to study them. Characterizing surfaces from a purely geometric point of view is a complex task. One-dimensional signal processing tools (filters, spectrum analyzers) have found their equivalents for two-dimensional quantities, and for isotropic surfaces, the one-dimensional analysis of a profile is sufficient to provide a good understanding of the surface. In addition to calibrating the probes and sensors used to map a surface, we need to know the bandwidths of the transfer functions of the instrumentation used. This last condition is often the most difficult to meet when comparing results obtained by different methods.

We've seen a wide variety of devices, some of which measure a vertical dimension, some a difference in dimensions between neighboring...