New experimental results to demonstrate that the annoying DC in the reconstructed wavefronts from in-line holograms could be successfully eliminated are presented in this paper. The complete elimination of DC has been achieved by making proper use of a Mach-Zehnder interferometer. The results for an in-line hololens and an in-line Fourier transform hologram are discussed.

New methods involving the manipulation of fundamental wavefronts (e.g., plane and spherical) with simple optical components such as pinholes and spherical lenses have been developed for the fabrication of elliptic, hyperbolic and conical holographic zone plates. Also parabolic zone plates by holographic techniques have been obtained for the first time. The performance behaviour of these zone plates has been studied. Further a phenomenological explanation is offered for the observed improved fringe contrast obtained with a spherical reference wave.

Self-images of a number of spatially periodic (e.g., gratings) and quasiperiodic (e.g., halftone picture) objects have been systematically studied. These studies indicate that self-imaging techniques could be useful in optical computing type operations. It is also established that the Rayleigh relation in the context of self-imaging is quantitatively in error.