Phase-Difference Amplification by Nonlinear Holograms

Bryngdahl pointed out that a photographic plate, exposed to fine interference fringes and processed with high gamma, can record an amplification of the original phase difference. Interferograms obtained with this technique are shown. With a Mach-Zehnder two-beam interferometer, 14-fold phase-difference amplification was observed. Sources of experimental errors encountered in practice are discussed.