Theory of holographic interferometry

A simple theory of three forms of holographic interferometry “time‐average,” multiple‐exposure, and “real‐time” (live) interferometry is presented, based on a new development in holographic “image synthesis” (complex amplitude addition and subtraction), introduced in 1965 by D. Gabor and G. W. Stroke et al. They demonstrated the remarkable property of holography: Interference can occur between two or more light beams that are not superimposed either in time or in space, if the holographic intensities corresponding to the beams are obtained with the aid of a coherent reference‐background beam of the same spatial shape and if these intensities are successively added in the same hologram. Following the independent discovery of holographic interferometry, in 1965, by J. M. Burch; by R. L. Powell and K. A. Stetson; and by L. O. Heflinger, R. F. Wuerker, and R. E. Brooks, among others, it was found that two or more successive photographic additions of the hologram intensities (corresponding to two or more seque...