Diffraction Efficiency of Phase Type Zone-plate and Zone-plate Interferometer

Abstract

In a zone-plate interferometry using diffraction lights of the same order, the interference fringes have high visibility, because intensity of reference light is equal to that of measurement one. When diffraction lights combined with the other order are used as the reference light and the measurement one, the fringe visibility obtained by the interferometry is low, because the intensity of the reference light is not equal to that of the measurement one. The diffraction efficiency of the zone-plate should be adjusted to obtain clear fringes in the interferometer. The diffraction efficiency of phase type zone-plate was theoretically investigated and examined. The theoretical results were agreed well with the experimental results. Fringes with a high visibility were obtained by the use of the zone-plate producing the proper diffraction efficiency.