Pixel-density and viewing-angle enhanced integral 3D display with parallel projection of multiple UHD elemental images.

This paper presents an integral three-dimensional (3D) display that efficiently enhances both the pixel densities and viewing angles of 3D images with parallel projection of elemental images. In the proposed method, ultra-high-definition (UHD) elemental images are projected and superimposed as parallel light rays from densely arranged compact UHD projectors onto a lens array. Three-dimensional images with enhanced pixel densities and viewing angles can be displayed by optimizing the projector positions and system design. The prototype yielded a horizontal pixel density of 63.5 ppi, approximately 97,000 pixels, and a viewing angle of approximately 30°, making it superior to previous integral 3D display systems.

Aktina Vision: Full-parallax three-dimensional display with 100 million light rays.

Natural three-dimensional (3D) images, perceived as real objects in front of the viewer, can be displayed by faithfully reproducing light ray information. However, 3D images with sufficient characteristics for practical use cannot be displayed using conventional technologies because highly accurate reproduction of numerous light rays is required. We propose a novel full-parallax light field 3D display method named 'Aktina Vision', which includes a special top-hat diffusing screen with a narrow diffusion angle and an optical system for reproducing high-density light rays. Our prototype system reproduces over 100,000,000 light rays at angle intervals of less than 1° and optimally diffuses light rays with the top-hat diffusing screen. Thus, for the first time, light field 3D image reproduction with a maximum spatial resolution of approximately 330,000 pixels, which is near standard-definition television resolution and three times that of conventional light field display using a lens array, is achieved.

Color moiré reduction and resolution enhancement of flat-panel integral three-dimensional display.

Color moiré occurs owing to the subpixel structure of the display panel in the integral three-dimensional (3D) display method, deteriorating the 3D-image quality. To address this, we propose a method for reducing the color moiré and improving the 3D-image resolution, simultaneously, by combining multiple 3D images. In the prototype system, triple 3D display units with lens arrays closely attached to 8K-resolution display panels are optically combined. By controlling the color moiré of the 3D image generated on each display and shifting and combining the elemental lenses constituting the lens array, sufficient reduction in the color moiré is realized, while suppressing the deterioration of the 3D-image quality, at a distant position from the lens array in the depth direction, along with an approximately two-fold enhancement of the resolution near the lens array.

Projection-type see-through holographic three-dimensional display.

Owing to the limited spatio-temporal resolution of display devices, dynamic holographic three-dimensional displays suffer from a critical trade-off between the display size and the visual angle. Here we show a projection-type holographic three-dimensional display, in which a digitally designed holographic optical element and a digital holographic projection technique are combined to increase both factors at the same time. In the experiment, the enlarged holographic image, which is twice as large as the original display device, projected on the screen of the digitally designed holographic optical element was concentrated at the target observation area so as to increase the visual angle, which is six times as large as that for a general holographic display. Because the display size and the visual angle can be designed independently, the proposed system will accelerate the adoption of holographic three-dimensional displays in industrial applications, such as digital signage, in-car head-up displays, smart-glasses and head-mounted displays.

Large size three-dimensional video by electronic holography using multiple spatial light modulators.

In this paper, we propose a new method of using multiple spatial light modulators (SLMs) to increase the size of three-dimensional (3D) images that are displayed using electronic holography. The scalability of images produced by the previous method had an upper limit that was derived from the path length of the image-readout part. We were able to produce larger colour electronic holographic images with a newly devised space-saving image-readout optical system for multiple reflection-type SLMs. This optical system is designed so that the path length of the image-readout part is half that of the previous method. It consists of polarization beam splitters (PBSs), half-wave plates (HWPs), and polarizers. We used 16 (4 × 4) 4K×2K-pixel SLMs for displaying holograms. The experimental device we constructed was able to perform 20 fps video reproduction in colour of full-parallax holographic 3D images with a diagonal image size of 85 mm and a horizontal viewing-zone angle of 5.6 degrees.

Image size scalable full-parallax coloured three-dimensional video by electronic holography.

In electronic holography, various methods have been considered for using multiple spatial light modulators (SLM) to increase the image size. In a previous work, we used a monochrome light source for a method that located an optical system containing lens arrays and other components in front of multiple SLMs. This paper proposes a colourization technique for that system based on time division multiplexing using laser light sources of three colours (red, green, and blue). The experimental device we constructed was able to perform video playback (20 fps) in colour of full parallax holographic three-dimensional (3D) images with an image size of 63 mm and a viewing-zone angle of 5.6 degrees without losing any part of the 3D image.

Integral three-dimensional television with video system using pixel-offset method.

Integral three-dimensional (3D) television based on integral imaging requires huge amounts of information. Previously, we constructed an Integral 3D television using Super Hi-Vision (SHV) technology, with 7680 pixels horizontally and 4320 pixels vertically. We report on improved image quality through the development of video system with an equivalent of 8000 scan lines for use with Integral 3D television. We conducted experiments to evaluate the resolution of 3D images using an experimental setup and were able to show that by using the pixel-offset method we have eliminated aliasing produced by full-resolution SHV video equipment. We confirmed that the application of the pixel-offset method to integral 3D television is effective in increasing the resolution of reconstructed images.

Geometric analysis of spatial distortion in projection-type integral imaging.

In projection-type integral imaging, positional errors in elemental images and elemental lenses affect three-dimensional (3D) image quality. We analyzed the relationships between the geometric distortion in elemental images caused by a projection lens and the spatial distortion in the reconstructed 3D image. As a result, we clarified that 3D images that were reconstructed far from the lens array were largely affected, and that the reconstructed images were significantly distorted in the depth direction at the corners of the displayed images.