Threefold seismic or acoustical holographic interferograms may be used to enhance a particular phase contour characterizing very subtle changes in the shape, position, or acoustical properties of objects of geophysical interest. The hologram may be either a reflection or transmission hologram, and objects may be reflectors, phase objects or combinations of these. In every case, by choosing the proper weights for the three holograms and the proper reference phase angles, any particular phase contour characterizing subtle changes in the objects or their positions can be made to exhibit relative reconstructed image-background contrasts of unity. The technique is particularly applicable to the problem of delineating objects of geophysical interest. It is shown that the technique may be used even when objects do not change. Theoretical ideas are supported by appeal to computer models, laboratory model data, and seismic field data. Other applications, such as imaging body tissue, are suggested.
Acoust. Imaging and Hologr., V. 1, No. 1, PP. 71-110