A modification of hologram interferometry applicable to the study of transparent objects of moderate optical quality has been devised which combines hologram and moiré techniques and allows the observation of high contrast, relatively unlocalized, interferometric fringes under conditions less critical than those of the conventional hologram interferometer. By spatially modulating one beam of the interferometer during exposure, moiré fringes may be obtained in the reconstruction which distort and move with optical phase changes in either beam of the interferometer. An analysis of the origin and nature of these distortions is given and experimental verification of the analysis is presented.
G. B. Brandt, "Hologram-Moiré Interferometry for Transparent Objects," Appl. Opt. 6, 1535-1540 (1967)