A profilometer determines the surface profile of a sample on the nanometre scale. There are two kinds of profilometers: stylus and optical. Stylus profilometers move a probe along the surface of a sample to determine its nanoscale topography. Stylus profilometry is extremely sensitive and supplies high-quality resolution. However, it is not highly responsive to soft surfaces, the probe can become tainted by the sample and it can also be destructive to some very sensitive samples.
Optical profilometry uses a beam of light rather than a physical probe to achieve the same results without touching a sample. The technique is highly-dependent on the ability to accurately point the light in a manner that allows the profilometer to determine the sample surface in three dimensions.