The interferometric surfaces are used as a reference for controlling the planarity of other surfaces. By placing the surface to be checked in contact with that of the interferometric surfaces, airy zones are created where the contact between the two surfaces is imperfect. After introducing a specific light source the passing light creates interference fringes that make it possible to quantify the flatness error of the measured surface. If the two surfaces are perfectly flat, fully parallel lines (fringes) can be seen.
Lobre s.r.l. realizes various models of interferometric surfaces.