Electroholography enables the projection of three-dimensional (3-D) images using a spatial-light modulator. The extreme computational complexity and load involved in generating a hologram make realtime production of holograms difficult. Many methods have been proposed to overcome this challenge and realize real-time reconstruction of 3-D motion pictures. We review two real-time reconstruction techniques for aerial-projection holographic displays. The first reduces the computational load required for a hologram by using an image-type computer-generated hologram (CGH) because an image-type CGH is generated from a 3-D object that is located on or close to the hologram plane. The other technique parallelizes CGH calculation via a graphics processing unit by exploiting the independence of each pixel in the holographic plane. © The Authors.Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

We propose a phase retrieval method using axial diffraction patterns under planar and spherical wave illuminations. The proposed method uses a ptychographic iterative engine (PIE) for the phase retrieval algorithm. The proposed approach uses multiple diffraction patterns. Thus, adjusting the alignment of each diffraction pattern is mandatory, and we propose a method to adjust the alignment. In addition, a random selection of the measured diffraction patterns is used to further accelerate the convergence of the PIE-based optimization. To confirm the effectiveness of the proposed method, we compare the conventional and proposed methods using a simulation and optical experiments.