Apodization in numerical holography

Apodization, a process in which the energy in a diffraction pattern is redistributed among the main lobes and the side lobes, has proved its usefulness in optical imaging systems and in linear sonar arrays. It can also make the numerical reconstruction of holograms more adaptable to varying requirements. To demonstrate, the hologram of a rectangular slot is first reconstructed numerically in the conventional manner. It is then reconstructed after apodizing the diffraction pattern contained in the hologram. One type of apodization led to a reconstructed image that accentuated the discontinuity at the edge of the slot. Another type gave an image with a concentration of energy at the center of the object, thus minimizing interference from nearby objects. It is expected that the method can be extended to other objects by expressing them as summations of rectangular slots.