Application of the Moiré-effect in digital holography

Digital holography enables the opportunity to get amplitude as well as phase information of an optical wave field at the position of the detector. This wave field can be numerical reconstructed in any distance to the detector. The pixel pitch of the detector determines in free space holography the resolvable angle, under which an object can be recorded. By applying the Moiré-effect it is possible to increase the resolvable angle by a factor of 2. Therefore CCD-structure and hologram can act as lattices which are creating Moiré-structures when the resolution of the CCD-chip is not sufficient to completely resolve the holographic pattern. By taking 3 images with a phase-shifted reference beam a digital hologram with an increased number of measuring points can be created, containing more information about the optical wave field and allowing the reconstruction of objects under a larger angle.