Electro-holography System Research Articles

Wide-Viewing Zone Electro-Holography System by Using Switching of Reconstruction Light

Wide-Viewing Zone Electro-Holography System by Using Switching of Reconstruction Light

Review of Fast Calculation Techniques for Computer-Generated Holograms With the Point-Light-Source-Based Model

Computer-generated holograms (CGHs) are a key technology in electroholography systems; however, heavy calculations are required to calculate CGHs. We review fast calculation techniques for CGH calculation of a point-light-source-based model, which is a simple and general model of a three-dimensional object in an electroholography system. To reduce the calculation time, many methods that reduce the temporal and spatial redundancy of the CGH calculation have been developed (e.g., look-up table method, the wavefront recording plane method, and other approximation techniques). The implementation of such methods on parallel computers (e.g., graphic processing unit and field programmable gate arrays) has also been reported.

LEDを用いた動画ホログラフィ表示装置の小型化及び色検討の提案(映像表現フォーラム映像表現に関する特別講演と学生作品・研究発表会)

LEDを用いた動画ホログラフィ表示装置の小型化及び色検討の提案(映像表現フォーラム映像表現に関する特別講演と学生作品・研究発表会)

位相変調型液晶ディスプレイを用いた電子ホログラフィ

There are two types of hologram, an amplitude modulation and a phase modulation ones. Recently, not only amplitude modulation ones but also phase modulation ones have been used in liquid crystal displays. We constructed an electro-holography system with a phase modulation type liquid crystal display and compared it to a system using current amplitude electro-holography. In the amplitude hologram, the reconstructed image darkens because the contrast of the hologram is low when the gray level is increased. It lightens most when binary. However, the phase hologram with high diffraction efficiency has produced an excellent result. The reconstructed image is bright even if the gray level is increased, and all the information of the liquid crystal display can be used at 256 gray levels.

Simplified electroholographic color reconstruction system using graphics processing unit and liquid crystal display projector

We have constructed a simple color electroholography system that has excellent cost performance. It uses a graphics processing unit (GPU) and a liquid crystal display (LCD) projector. The structure of the GPU is suitable for calculating computer-generated holograms (CGHs). The calculation speed of the GPU is approximately 1,500 times faster than that of a central processing unit. The LCD projector is an inexpensive, high-performance device for displaying CGHs. It has high-definition LCD panels for red, green and blue. Thus, it can be easily used for color electroholography. For a three-dimensional object consisting of 1,000 points, our system succeeded in real-time color holographic reconstruction at rate of 30 frames per second.

Interactive color electroholography using the FPGA technology and time division switching method

In this paper, we report an interactive color electroholography system using the field-programmable gate array (FPGA) technology and the time division switching method for color reconstruction. We implemented 30 dedicated-processors for a computer-generated hologram (CGH) into an FPGA chip, and the FPGA chip can generate full-parallax CGHs, on which we record color information for a color 3D object, faster than a personal computer. The time division switching method can reconstruct a color 3D object from the CGHs, to make use of the afterimage effect on human eyes. The system allows us to perform interactive operations for a reconstructed color 3D object using a keyboard, while viewing the reconstructed color 3D object.

３次元映像情報メディア技術 ＧＰＵとプロジェクタを用いた簡易なリアルタイム電子ホログラフィ再生システム

We developed a simple electroholography system consisting of a graphics processing unit(GPU),which has been developing quickly in recent years,and a PC projector,which contains a minute reflective liquid crystal display(LCD).The structure of the GPU is suitable for calculating a computer-generated hologram(CGH).The calculation speed of the GPU is approximately 500 times faster than that of a central processing unit(CPU) alone.We succeeded in reproducing a video of an object,which consisted of 256 points in about 20 frames/s.Reconstruction at the video rate(real time) was almost completely achieved.Moreover,we used a PC projector in which minute reflective LCD panels were included as part of the reconstruction optical system.Three LCD panels for the three RGB colors were built into the inside of a projector.Using them,holographic reconstruction with color was also able to be performed easily.This system,consisting of a GPU and a projector,is simple to make.Therefore,this system is expected to promote reserch in this field.

Electro-holography system using flow controlled nozzle attached water particle screen

Electro-holography system using flow controlled nozzle attached water particle screen

３次元映像情報メディア技術 ＭＩＭ形液晶表示素子を用いた動画ホログラフィ装置の設計と評価

Holography is an ideal technique for 3 D displays. However, since precise modulation of light waves is required, it has long been very difficult to achieve electro-holography. Recently, however, some demonstrations of electro-holography using liquid crystal devices were presented. In this paper, we describe the process, characteristics, and driving methods of a liquid crystal device that aims for a fine pixel structure. Then, we discuss the design of an electro-holography system for the viewpoint of the spatial frequency of the hologram. We also experimentally examine the influence of the pixel structure on image quality by comparing electro-holography and optical holography images.

特集 次世代画像技術 液晶表示デバイスを用いたキノフォームによるカラー立体動画像表示

Attention is being paid to computer generated holograms (CGH) that can be formed by liquid crystal devices (LCD) because of their possible applications in electro-holography. In the research reported here the kinoform of an on-axis type CGH was constructed by using a commercially available TN type LCD as phase modulator, and the basic characteristics of its image were examined. Moreover an electro-holography system for color 3D animated image display was developed by using three LCD panels, RGB three lasers and graphics frame memory. A clear color image was reconstructed by taking into account the wavelength dependence of the size and position of the color image, then the characteristics of color gamut and animation of the reconstructed color image were evaluated in order to determine the feasibility of this system for electro-holography.