Viewing zone enlargement method for holographic displays based on the slanted pixel arrangement on a spatial light modulator.

This study proposes a method for enlarging the viewing zone of holographic displays using the slanted arrangement of pixels on a spatial light modulator (SLM). The pixel arrangement equivalently reduces the horizontal pixel pitch, which enlarges the horizontal viewing zone of displays. Computer-generated holograms (CGHs) were calculated using an asymmetric band-limit filter corresponding to the asymmetric bandwidth of the SLM with slanted pixels. The proposed methods were evaluated through an optical reconstruction experiment using static holograms with a pixel size of 1×1µm, fabricated via electron-beam lithography. The enlarged horizontal viewing zone angle was found to be 41.6°.

Image quality assessment procedure for holographic displays based on exact numerical reconstruction of computer-generated holograms.

We proposed a technique for the computer-based reconstruction of computer-generated holograms and evaluation of the reconstructed 3D image quality. The proposed method mimics how the eye's lens works, thus allowing for viewing position and eye focus adjustments. The angular resolution of the eye was used to output reconstructed images with the requisite resolution, and a reference object was used to normalize the images. Such data processing enables the numerical analysis of image quality. By comparing the reconstructed images with the original image with incoherent illumination, the image quality was quantitatively evaluated.

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.

Integral 3D display using multiple LCD panels and multi-image combining optical system.

We present a method to display an integral three-dimensional (3D) image without gaps between multiple display active areas by using multiple liquid crystal display (LCD) panels and multi-image combining optical systems (MICOS). We designed a MICOS to improve the resolution characteristics and decrease the luminance unevenness corresponding to the viewpoint. Furthermore, we developed a method for correcting the distortion of the integral 3D image by using image processing. We prototyped an integral 3D display using four 8K dual-green (8KDG) LCD panels and the improved MICOSs. The prototype display achieved to magnify the display area about 5.66 times more than when a single LCD panel was used.

Integral three-dimensional image capture equipment with closely positioned lens array and image sensor.

We have developed a compact integral three-dimensional (3D) imaging equipment that positions the lens array and image sensor in close proximity to each other. In the conventional scheme, a camera lens is used to project the elemental images generated by the lens array onto the image sensor. In contrast, the imaging equipment presented here combines the lens array and image sensor into one unit and makes no use of a camera lens. This scheme eliminates the resolution deterioration and distortion caused by the use of a camera lens and improves, in principle, the quality of the reconstructed 3D image. We captured objects with this imaging equipment and displayed the reconstructed 3D images using display equipment consisting of a liquid crystal panel and a lens array. The reconstructed 3D images were found to have appropriate motion parallax.

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.

Numerical estimation of storage capacity in reflection-type holographic disk memory with three-dimensional speckle-shift multiplexing.

Maximum storage capacity in a reflection-type holographic memory with three-dimensional speckle shift multiplexing is investigated numerically. An explicit expression of storage capacity is derived on the basis of interpage crosstalk noise. We fabricate a simulator to evaluate reflection-type holographic data storage by calculating wave propagation, recording a hologram, and reconstruction by scalar diffraction. We calculate the properties of the resultant diffraction efficiency, that is the noise, at the first null in the speckle-shift multiplexing. Numerical results indicate that the storage capacity is proportional to the numerical aperture to the fourth power and to the volume of the recording medium and is inversely proportional to the wavelength to the third power. Achievable storage capacity is discussed.

Three-dimensional shift selectivity in reflection-type holographic disk memory with speckle shift recording.

Three-dimensional shift selectivity of a reflection-type hologram with speckle shift recording is investigated experimentally and numerically. We build an experimental setup consisting of lenses with numerical apertures of 0.28 and an iron-doped LiNbO(3) with a thickness of 0.5 mm. The experimental results show that three-dimensional selectivity has a size of 0.97 microm x 0.97 microm x 8.8 microm in diffraction efficiency. We also develop a volume holographic memory simulator to evaluate the experimental results. The simulator can quantitatively evaluate bit error rate, signal-to-noise ratio, and diffraction efficiency. Numerical results are in good agreement with the experimental results. The experimental and numerical results indicate that three-dimensional shift multiplexing can increase the storage capacity.

Reflection-type holographic disk memory with random phase shift multiplexing.

A reflection-type holographic disk memory system with random phase shift multiplexing is proposed. The experimental results show that a binary data page of 18x17 bits is recorded successfully at intervals of 4 mum in a Fe:LiNbO3 crystal with a thickness of 0.5 mm when six data pages are superimposed. Numerical results show that random phase modulation can improve the shift selectivity in shift multiplexing recording as well as in data security. Experimental and numerical results show that reflection-type holographic disk memory has a high potential for terabyte storage capacity as in transmission-type memory.