Part measurement methods include physically touching the part with a probe or a micrometer, or using a noncontact approach, such as an optical comparator or vision system. With macroscale parts, touching a part is often acceptable since the part is not affected by the measurement. But with microparts, touch is sometimes not an option, since the measurement process moves or otherwise affects the part.

Error budgeting, also called uncertainty budgeting or uncertainty analysis, is a simple tool used for processes having tolerances that are difficult to achieve. It originally was developed for diamond turning—operations in which parts are turned with single-point-diamond tools—but is widely used in metrology, optics and other high-precision applications.

Fabrication of micro components and devices often requires specialized metrology to confirm that critical dimensions meet design specifications. The fit and finish of microparts can affect the quality and performance of higher level assemblies and, ultimately, customer satisfaction with the supplier and its products.