The endface of a connector refers to the circular cross-section of the filament where light is emitted and received, and the surrounding ferrule. The endface is often polished to improve upon the endface geometrical properties, which in turn provide better optical coupling. The fiber endface undergoes a visual inspection for defects, as well as testing on an interferometer, for endface geometry that will encourage good mating between connectors. Three main properties are examined on the interferometer