Dial gauge is a measuring instrument employed to measure linear displacement. Depending on the reading system, dial gauge can be classified into dial gauge, where reading is performed thanks to a clock, and digital, where reading is performed directly on an electronic digital indicator.
Dial gauge bases its operation principle on the displacement reading of a mobile cylindrical rod that slides inside a tubular guide. The end of the rod, called probe, is in contact with the surface of the measured object.
Digital dial gauge adopts this operation principle: minimum displacements of the rod are converted into electrical pulses countable by an electronic indicator. Electronics evolution has allowed the realization of miniaturized and very low-consumable indicators, so a common button battery can easily feed them. The display of dial gauges are normally made with a resolution of 0.01 mm or 0.001 mm.