Holographic Phase Recording by Interference between Reconstructed Wavefronts from Separate Holograms

Abstract

DISTRIBUTIONS of phase variation in light wavefronts can only be made visible by converting them into corresponding distributions of amplitude. This is achieved directly by interference with a “reference” wavefront, which is, of course, the basic principle of all two beam interferometers, and is also the means by which changes in a phase distribution recorded holographically may be made visible^1–3. The papers referred to give accounts of (a) the “live” interference fringes, which are seen when a hologram is replaced exactly in its original position in the same apparatus after processing, and changes occur in the object which result in phase variation at the hologram, and (b) the “frozen” fringes, seen when two reconstructed wavefronts from a single hologram plate, corresponding to two successive exposures the plate has received, interfere to reveal the change in the phase distribution in the object field between the exposures.