Digital decoding of in-line holograms

In-line holography is a useful tool in the study of dynamic objects in three-dimensional space. A hologram is a specific non-linear coding which is recorded in the presence of coherent illumination. The physical reconstruction is done by reilluminating the hologram, and the resulting image is contaminated by the interfering twin-image. Here in this dissertation, a system of digital filters is presented, which is applied directly to the in-line hologram and maps the hologram into an image of the boundaries (edges) of the objects encoded in it, provided that the object distribution function is real. This technique bypasses physical reconstruction completely and gives a clear decoding of the objects. In the first stage of the system, the hologram is approximated as the dc shifted output of a linear system. An approximation inverse filter is used to obtain the desired object distribution from the hologram since the exact inverse is not realizable. The linear approximate inverse filter is a truncated series expansion of the inverse filter in the Fourier transform domain.