Expanding energy envelope in holographic display via mutually coherent multi-directional illumination

Abstract

Holographic display is considered as the most promising three-dimensional (3D) display due to its unique feature of reconstructing arbitrary wavefronts. However, the limited étendue, which hinders the immersive experience of observers, remains a major unresolved issue in holographic display technique. In this paper, we propose a novel approach to tweak the constraints of étendue by expanding the energy envelope in holographic display via mutually coherent multi-illumination. The proposed concept contains both a light source design for generating a mutually coherent multi-directional wave and a computer-generated hologram optimization framework for providing high-resolution 3D holograms. To verify the proposed approach, a benchtop prototype of a holographic near-eye display providing an intrinsic large exit-pupil is implemented. The experimental results clearly show that the exit-pupil is effectively expanded by four times and an appropriate viewpoint image is reconstructed according to the view position.

Non-convex optimization for inverse problem solving in computer-generated holography

“…Through the combination of a well-performed physical model, a well-chosen initial object phase, and a well-defined loss function, SGD itself has been verified to achieve good reconstructions of POHs, which leads to impressive accomplishments in 3D display with less or without speckles 67 , 139 . And, because the early adoption of SGD in CGH was linked with camera-in-the-loop optimization 133 , hardware involution was developed in tandem with the promotion of SGD-based hologram synthesis, in which the pattern captured by the camera replaced the reconstructed intensity in optimizations.…”

“…Reference 138 is reprinted with permission from © ACM. References 67 , 84 , 139 are reprinted under a Creative Commons Attribution 4.0 International License …”

“…These computationally generated focal stacks at multiple depths are jointly involved in optimization together with the target object, which enables the diffractive reconstruction to better imitate the natural defocus blur, especially in holographic display 194 . The light field method originates from holographic stereograms which reconstruct an array of directional views of the object with a single hologram 139 , 195 – 197 , as is shown in Fig. 8c .…”