Applications of Classical Theory of Interferometry to Holography

Abstract

The elaborate theory and practice of interferometry have been established principally to meet the situation that the available light sources have finite size (finite spatial coherence) and finite coherence length (finite temporal coherence). The theory of localization of fringes provides means to reduce the effect of the source size in a. plane to be considered and give rise to a system of bright and well-defined fringes exclusively in this plane. The symmetric arrangement of two arms of the interferometer is convenient to match the path lengths to a desired accuracy. The advent of lasers seriously changed the situation. If a single mode emission from a He-Ne laser is used in the laboratory experiment, an arrangement of two arms is sufficient to produce clear fringes and no considerations are necessary to compensate both the source size and the coherence length. Once two waves originating from a laser intersect together, there appears a system of non-localized fringes, however complex in shape the waves may be. This ensures the astonishingly well-defined reconstruction of a three-dimensional and diffuse object from a hologram which is nothing but a record of interference fringes between a simple plane or spherical wave (reference wave) and a rather complex wave issuing from the object.