Phase shifting in an oblique incidence interferometer

Abstract

The evaluation of the interference pattern of a prism interferometer by a phase-stepping technique is described. The required phase shift is achieved by moving the surface under test perpendicular to the hypotenuse of the prism. Limits of this phase-shifting technique are discussed. A calibration method of the phase shift between the interferograms for the adjustable sensitivity of the interferometer is shown. Finally measurements of technical surfaces are presented.