Radius of curvature measurement by spectrum controlled interferometry

摘要

The value of the radius of curvature of the inspection surface 14 is measured by a single spectrum-controlled interferometry using a reference surface 18 of known radius of curvature. The inspection surface is located at the confocal position 24 of the reference surface 18, and the light source 16 is modulated to produce localized interference fringes 30-34, 36-40, 42-46 at the inspection surface. The interference fringes are then processed with a conventional interference analysis tool to identify the exact position of the inspection surface with respect to the reference surface and to determine the distance between the inspection surface and the reference surface. The radius of curvature of the inspection surface is conveniently obtained by subtracting its distance from the known radius of curvature of the reference surface. [Selection diagram]