Speckle-free, shaded 3D images produced by computer-generated holography.

A hologram display technique that provides speckle-free, shaded reconstructed images is proposed. A three-dimensional object consists of object points; these object points are divided into plural object point groups that are generated in a time-sequential manner. Each object point group consists of a two-dimensional (2D) array of object points that are separated so as to prevent interference among them. Each object point group is generated by displaying a 2D array of zone plates on a high-speed spatial light modulator (SLM). The amplitude distribution of the zone plates is modulated two-dimensionally based on Phong shading to shade the reconstructed images. The 2D amplitude distribution of the zone plates is decomposed into multiple binary patterns that are displayed by the SLM in a time-sequential manner. The proposed method is experimentally verified.