The limited space-bandwidth product of digital holography results in a trade-off between the field of view (FOV) and eye motion box (EMB) size. One potential approach to overcome this trade-off is to use a waveguide as a pupil expander. However, this approach has the constraint of generating only infinite depth images or 2D images, which can cause visual discomfort. To address this issue, a novel method that enhances the space-bandwidth product while providing a 3D image with full depth range is necessary. In this paper, we introduce a projection-type holographic display that combines a waveguide, a spatial light modulator, and a laser light source to display true 3D holographic images with an extended FOV. Experimental results demonstrate that this method effectively generates holographic 3D images with an FOV expanded 4 times in the horizontal direction compared to conventional methods.
Holographic Optical Elements (HOEs) have emerged as a pivotal technology in enhancing holographic Augmented Reality (AR) display systems. This paper presents an innovative approach that utilizes an off-axis arrangement with an HOE to secure a wide field of view up to 55°, making significant strides in volumetric reduction compared to conventional 4f filtering systems. However, a challenge arises from Bragg mismatch in the HOE, which creates aberrations. Our work proposes a method for compensating these aberrations on a voxel-by-voxel basis, substantially improving the quality of the holographic display. Limitations such as the 2mm maximum size of the eye box due to the diffraction limit of the spatial light modulator (SLM) are acknowledged, but we suggest potential solutions such as using the HOE substrate glass as a waveguide and incorporating an array of lenses with an eye tracker for pupil tracking. Our findings offer significant contributions to the holographic display technology landscape and suggest promising avenues for future research.
Holography has been regarded as one of the most ideal technique for three-dimensional (3D) display because it records and reconstructs both amplitude and phase of object wave simultaneously. Nevertheless, many people think that this technique is not suitable for commercialization due to some significant problems. In this paper, we propose an electronic holographic 3D display based on macro-pixel with local coherence. Here, the incident wave within each macro-pixel is coherent but the wave in one macro-pixel is not mutually coherent with the wave in the other macro-pixel. This concept provides amazing freedom in distribution of the pixels in modulator. The relative distance between two macro-pixels results in negligible change of interference pattern in observation space. Also it is possible to make the sub-pixels in a macro-pixel in order to enlarge the field of view (FOV). The idea has amazing effects to reduce the data capacity of the holographic display. Moreover, the dimension of the system is can be remarkably downsized by micro-optics. As a result, the holographic display will be designed to have full parallax with large FOV and screen size. We think that the macro-pixel idea is a practical solution in electronic holography since it can provide reasonable FOV and large screen size with relatively small amount of data.