Recent trends in three-dimensional (3D) display technologies are very interesting in that both old- fashioned and up-to-date technologies are being actively investigated together. The release of the first commercially successful 3D display product raised new research topics in stereoscopic display. Autostereoscopic display renders a ray field of a 3D image, whereas holography replicates a wave field of it. Many investigations have been conducted on the next candidates for commercial products to resolve existing limitations. Up-to-date see-through 3D display is a concept close to the ultimate goal of presenting seamless virtual images. Although it is still far from practical use, many efforts have been made to resolve issues such as occlusion problems.

Recently developed integral imaging techniques are reviewed. Integral imaging captures and reproduces the light rays from the object space, enabling the acquisition and the display of the three-dimensional information of the object in an efficient way. Continuous effort on integral imaging has been improving the performance of the capture and display process in various aspects, including distortion, resolution, viewing angle, and depth range. Digital data processing of the captured light rays can now visualize the three-dimensional structure of the object with a high degree of freedom and enhanced quality. This recent progress is of high interest for both industrial applications and academic research.

The remarkable progress of virtual reality, augmented reality, quantum dot light-emitting diode, and organic light-emitting diode as next-generation displays has overcome the leadership of the liquid crystal display during the last two years. This paper discusses the key technological advancements and performance of these new-generation display devices.

Computer-generated holography (CGH) is a crucial technique in preparing contents for holographic three-dimensional displays. In this paper, the recent progress in the CGH techniques is reviewed, covering the point-cloud-, light-ray-field-, layer-, and polygon-based techniques.

We propose a Maxwellian near-to-eye display implemented using a multiplexed holographic optical element. Maxwellian configuration removes the focal cue of the displayed virtual image completely, presenting an always-focused image to the observer regardless of the focal length of the eye. The transparent property of the holographic optical element enables the optical see-through feature, making the proposed near-to-eye display suitable for augmented reality applications. The multiplexing of multiple concave mirrors into a single holographic optical element enlarges the effective eyebox, relaxing the limitation of the conventional Maxwellian displays. Optical experiment confirms that the proposed display can present always-focused images on top of the real environment with $9.2°(\mathrm{H})\times 5.2°(\mathrm{V})$ field of view, and $9\mathrm{mm}(\mathrm{H})\times 3\mathrm{mm}(\mathrm{V})$ eyebox.

We propose a bar-type three-dimensional holographic head mounted display using two holographic optical elements. Conventional stereoscopic head mounted displays may suffer from eye fatigue because the images presented to each eye are two-dimensional ones, which causes mismatch between the accommodation and vergence responses of the eye. The proposed holographic head mounted display delivers three-dimensional holographic images to each eye, removing the eye fatigue problem. In this paper, we discuss the configuration of the bar-type waveguide head mounted displays and analyze the aberration caused by the non-symmetric diffraction angle of the holographic optical elements which are used as input and output couplers. Pre-distortion of the hologram is also proposed in the paper to compensate the aberration. The experimental results show that proposed head mounted display can present three-dimensional see-through holographic images to each eye with correct focus cues.