is an instrument that measures a surface’s roughness or profile. ... A profilometer

A profilometer is an instrument that measures a surface’s roughness or profile. There are
basically two types of profilometers: contact and no-contact (or optical). In a contact profilometer,
the instrument physically contacts the surface with a probe, called a stylus, to accurately map the
surface of a sample. A user can set parameters such as contact force appropriate to the samples
hardness and perform post processing of data through a GUI interface. The stylus itself is made
from diamond with a very small radius; as tight as 25 nm. A contact profilometer offers several
advantages: they typically offer higher resolution capability than optical versions, they are not
susceptible to sample color or dirtiness, but the stylus can be damaged if the operator is not
careful. To mitigate potential damage and ensure accuracy, many contact profilometers are
placed in an enclosure because external forces such as airflow can cause the stylus to move.
Optical profilometers scan the surface without making physical contact, a desirable trait if
maintenance is a concern or if the instrument is to be operated by less experienced individuals.
However either type of profilometer can be damaged if an operator attempts to hand adjust the
sample table or drives the stylus/lens into the table and vice-versa with the proper adjustment
controls. Optical profilometers offer good resolution, but can be affected by sample cleanliness
and color unlike contact versions.