Toshio Honda

Electro-holographic display using 15mega pixels LCD

We have been researching holographic 3D displays using a commercially available Liquid Crystal Devices (LCD). However, specifications of the LCD were not enough to holographic display, and we could obtain only small reconstructed image with the narrow viewing zone. In our present research, we are supported by an LCD manufacturer, and planning to use the custom-made LCD which has both minute and numerous pixels. The LCDs pixel pitch is 28 micrometers (horizontal) X 56 micrometers (vertical), and pixel number is 3200 X 960. Five LCDs are horizontally arranged in our electro-holographic display. By using five LCDs, total pixel number becomes about 15 Mega. We can obtain larger image and wider viewing zone compared with our previous experimental display, and can be observed binocularly. The size of the reconstructed image is 50 mm wide, 150 mm high, and 50 mm deep. Viewing zone is 65 mm at approximately 1000 mm from the image. In this display, we discard the vertical parallax and set the 1D diffuser on the vertical image plane. We also discuss the compensation of optical aberrations. Even if a single lens with large aberration is used for the optics system of the reproduction, we can obtain the reproduction image with corrected aberration by adding the compensation phase distribution to the hologram.

Holographic three-dimensional printer: new method.

We propose a holographic three-dimensional (3-D) printer that produces 3-D hard copies of computer data. A new technique for synthesizing a holographic stereogram (HS) has been invented for the purpose of making accurate hard copies of 3-D objects. The flat-format, Lippmann-type HS is printed by one optical step and is ideally suitable for 3-D printer application. This type of HS has both horizontal and vertical parallaxes so that the reconstructed image is free from distortion. The principle and the image quality of this type of HS are described, and a reconstructed image from this type of HS with 160 x 128 elements is experimentally demonstrated. The systematic constitution of a holographic 3-D printer is also discussed.

Color image correlation

Abstract A formulation for color image correlation is proposed. After suitable image transformations the correlator is capable of discriminating between images according to their color as well as their spatial information. A few examples are shown and some applications are suggested.

Expansion of the image size and viewing zone in holographic display using liquid crystal devices

We are researching 3D display using Liquid Crystal Devices (LCDs) as spatial light modulators to control wavefront for reconstructed 3D holographic image. We have tried to expand the image size and viewing zone, especially on vertical direction. The image size depends on the size of LCD pixel, and the viewing zone depends on the number of LCD pixels. So we use half mirror to set up three-fine pixel LCDs continuously in horizontal direction. In our display of first step, we can see 14 mm in width of image size, under +/- 1.2 degree(s) in angle of horizontal viewing zone. But in vertical direction, since the number of LCD pixels are limited, the reconstructed image size and viewing zone become small in full- parallax off-axis holography. So we discard the vertical parallax, which makes the necessity for number of LCD pixels to diffract the wavefront too large. We use cylindrical lens to expand the vertical image size and adjust the image plane, under the condition of discarding the vertical parallax. And we set lenticular sheet on the image plane to get wide vertical viewing zone.

An acylated peonidin glycoside in the violet-blue flowers of Pharbitis nil

Abstract A new acylated anthocyanin was isolated from the violet-blue flowers of Pharbitis nil as a major anthocyanin. The structure of this pigment was determined to be peonidin 3[6″-(4-glucosyl- trans -caffeyl)sophoroside]-5-glucoside. Peonidin 3-sophoroside-5-glucoside was also detected as a minor pigment.

High-quality recording of a full-parallax holographic stereogram with a digital diffuser

A digital diffuser designed for the efficient recording of Fourier holography is applied to the exposure of full-parallax holographic stereograms. From experimental results we confirm that the gray-level characteristic is greatly improved with the digital diffuser. High-resolution three-dimensional imagery is obtained with suppression of speckle noise. The limitation of the resolution is also described.

Multiple current dipole estimation using simulated annealing

A method for estimating electrical current distribution in the human brain using a multiple current dipole model is presented. A cost function for estimating multiple dipoles is proposed and a simulated annealing algorithm is used to obtain an acceptable solution. Computer simulation is used to evaluate the effectiveness of this method.<<ETX>>

Cylindrical 3D video display observable from all directions

We propose a 3D video displaying technique that multiple viewers can observe 3D images from 360 degrees of arc horizontally without 3D glasses. This technique uses a cylindrical parallax barrier and 1D light source array. We have developed an experimental display using this technique and have demonstrated 3D images observable form 360 degrees of arc horizontally without 3D glasses. Since this technique is based on the parallax panoramagram, the parallax number and resolution are limited by the diffraction at the parallax barrier. To avoid these limits, we improved the technique by revolving the parallax barrier. We have been developing a new experimental display using this improved technique. The display is capable of displaying cylindrical 3D video images within the diameter of 100 mm and the height of 128 mm. Images are described with the resolution of 1254 pixels circularly and 128 pixels vertically, and refreshed at 30Hz. Each pixel has the viewing angle of 60 degrees and that is divided into 70 views, therefore the angular parallax interval of each pixel is less than 1 degree. In such a case, observers may barely perceive parallax discretely. The pixels are arranged on a cylinder surface, therefore produced 3D images can be observed from all directions.

Use of color image correlation in the retrieval of gastric surface topography by endoscopic stereopair matching

We propose finding an optimal generalized color plane to carry out digital color image correlation. We seek the optimization of the correlation peaks sharpness and, for the purpose of analysis, we make some assumptions regarding the statistical properties of images to be considered. The analysis leads to a simple solution involving a projection onto the Karhunen-Loeve vectors corresponding to the smallest eigenvalues of the interprimary colors covariance matrix. We use our results in the retrieval of the gastric mucosal surface structure from stereopairs taken through an endoscope. Study of the statistics of the endoscope images shows that the assumptions used earlier can be applied to this type of image. We present some results of stereopair matching with color image correlation. We conclude by proposing a pseudo-3-D surface reconstruction of the gastric surface by mapping the endoscopic image onto the retrieved elevation information.

Three-dimensional display technologies satisfying "super multiview condition"

The 3D research project has been developing the 3D display system in which natural obserbation is realized in Telecommunication Advancement Organization (TAO) in Japan. Here, recent results are mentioned. The researches are mainly classified in three parts. The first research is the development of 3D display apparatus that realizes super-multi-view condition. The second one is the development of image processing system which generates the super-multi-view video signals. The third is the research to measure the eye control states when super-multi-view 3D images are observed, and the development of the measuring system.