Hyperboloidal reflection for full-parallax multiview 3D display observable from all directions

Abstract

To realize three-dimensional (3D) displays observable from all directions, we propose utilizing a hyperboloidal mirror to reflect light in all directions. The hyperboloidal mirror has two focal points in imaging relation. Thus, an image displayed near one focal point is reconstructed as a virtual image near the other focal point after the hyperboloidal mirror reflection. Owing to the geometrical property of the hyperboloidal mirror, the diverging angle of the reflected light can be much larger than that of conventional planar displays. However, there is a problem that the imaging magnification ratio depends on the propagation direction. This is one reason for distortion in hyperboloidal mirror imaging, and must be solved appropriately. This paper proposes a technical method to overcome the above distortion depending on the propagation direction by multi-view-based integral imaging. In integral imaging, the propagation direction of each elemental image is optically limited; therefore, the magnification ratio can be regarded as approximately constant within each propagation. Thus, the combination of integral imaging and hyperboloidal mirror reflection enables display of arbitrary multiple images with a very wide viewing zone without specially caring about the distortion. By displaying multiple images with proper parallax corresponding to the propagation directions, a full-parallax multi-view-based 3D display can be realized. In this study, a large hyperboloidal mirror with a diameter of 15 cm was used, and a 3D display with the horizontal and vertical viewing zones of 135 • and 60 • , respectively, has been successfully demonstrated.