Twin-image elimination in Gabor holography

Abstract

It is shown that the “twin-image” may be eliminated from images of real (e.g., thin and purely absorptive) objects generated by Gabor holography using straightforward linear filtering. The technique tends to emphasize otherwise small contributions from the “intermodulation term” and an algorithm is demonstrated that can estimate the intermodulation term and, therefore, largely eliminate its effects from the processed image. Holograms of complex objects are analyzed and it is shown that they may be reconstructed without twin image effects provided the objects obey a size constraint that is similar to, but less stringent and more precise than, the conventional Fraunhofer condition.