Exact measurements of surface profiles of a glass plate by a superluminescent diode interferometer

Abstract

A superluminescent diode interferometer that uses sinusoidal phase-modulating interferometry and the shifting method is applied to measure the front and rear surface profiles of a glass plate with an accuracy of a few nanometers. Since the roughness of the reference surface is large, a glass plate is put behind the object as another reference surface, which is estimated by the shifting method with an accuracy of a few nanometers.