This report is concerned with several display systems for making 3D image fluctuate. These systems aim to reconstruct rainbow hologram images moved dynamically. The first method is using small motors for drifting an illumination and swinging a reflection mirror. The second method is using an electric fan for flapping a film hologram hung with rubber strings. The third method is using a liquid crystal display (LCD) projector controlled by a computer and a screen sized reflection panel composed of many small mirrors. In the last case, the small beam out of the LCD projector is reflected on a mirror of the reflection panel and illuminates the hologram panel. The hologram image generated by each small mirror has its particular property that is slightly different each other; shape, position and color. The highlight pattern of the beam projected on the reflection panel is moved by the computer program. When the pattern is fluctuated by the computer program, the position and color of the generated hologram image fluctuate accordingly.
A display system requiring no special glasses is a useful technology for 3D images. In this paper, two types of real- time 3D displays using a holographic screen instead of a lenticular screen are described. One is a stereoscopic 3D display system with viewing apertures such as conventional two-step holographic stereogram. The other is a stereoscopic 3D display system based on a reconstruction of parallax- rays. These systems consist of a liquid crystal device and a holographic screen formed on holographic optical elements. These systems can construct animated 3D images in real-time by updating LCD pixels.
Artistic holograms are usually standstill images. We propose fluctuated fine arts of holograms illuminated by many spot- lights randomly switched on and off. Color of reconstructed image of a rainbow hologram depends on the incident angle of the illuminating beam. A reconstructed image sticking out of a hologram depends on the horizontal incident direction of the illuminating beam. We applied this technique to rainbow holograms to fluctuate the image to fit them to human esthesia. Some illuminating methods and an experimental result are described.
Compact reconstruction of hologram is an important technique to popularize the hologram widely. Edge illumination methods to realize this are reviewed and the features are discussed. The method to illuminate the hologram at large angle in air is also discussed and some experimental results are presented.
A display system requiring no special glasses is a useful technology for 3D images. The lenticular display system has such defects that it has a non-planar screen and views a blur. In this paper, a newly developed, 3D real-time display with a HOE is described. This simple 3D display can improve above-mentioned problems. And the advantage of the screen HOE is that the number of presented views is much greater that of an equivalent lenticular display, because the screen HOE can multiplex pixels both horizontally and vertically to display lateral views. This screen HOE can be made more easily and smoothly. The trial screen HOE is 4' X 5' and consists of 128,000 holograms. Therefore, the image size measures approximately 4' X 5', and the resolution is 200 X 160 pixels X 4 views.
We have been making researches on 3D displays using computer-generated holograms (CGHs). Our CGHs are binary Fresnel holograms that reconstruct point light sources and are recorded by using high resolution laser printers (image setters). The image setters have the resolution of 3600 or 5080 dots per inch (7.1 or 5.0 micron dot width). The resolution is lower than that of photo reduction, but it has wide drawing area, and it is not expensive to draw large CGH patterns on a high contrast film. In this paper, we present an approach to making cylindrical large CGHs and hidden-point removal process. The number of reconstructible point light sources is considered to be restricted due to the low resolution of the printer. To improve this restriction and to make larger displays, we propose a method arranging plural CGHs cylindrically that reconstruct divided objects. For improving the depth of the objects reconstructed from the CGHs, we consider it is necessary to apply hidden-point removal process to our CGH calculation. Whether a certain point object is visible or not from a point of view depends on the existence of the interference fringes on the CGH plane.
A fabrication method for holographic stereograms using a large liquid crystal display panel (LCD) is proposed and experimental results are described. Holographic stereogram is a useful method that can synthesize computer graphics or portraits of 2D perspectives but its process is troublesome. An LCD of a lap top personal computer is applied for perspective display. This method has some advantages, e.g., simple optical layout, no registration mechanism, no aberration by projection lenses and so on. A technique to improve the quality of holograms with a holographic optical element is also proposed.
The holography is a useful technology for 3D images. There are two types of the hologram in the reconstruction; one is a transmission-type and the other is a reflection-type. Especially, the reflection-type hologram that can be hanging on the wall is convenience because it needs no space. Mark Shires presented a flat panel real-time holographic stereogram in his paper. However, his display is unquestionably a transmission-type. In this paper, a 3D real-time display with a holographic optical element (HOE) is described. This display is realized both the transmission-type and the reflection-type. The diffraction efficiency becomes better because this display has a single HOE. This simple 3D display is ideal for both consumer and industrial use.
Visualization of 3D information or 3D displays are important subjects. We have been researching 3D displays using computer-generated holograms (CGHs). We set our sights on making large and high quality 3D displays. In this paper we present an approach to making large CGHs relatively easily, and at low cost, which are binary Fresnel holograms and are recorded by using a high resolution laser printer (an image setter). By using the image setter it is possible to draw large CGH patterns very easily. Furthermore, we found it was possible to reconstruct CGHs with light-emitting diodes or miniature light bulbs. Making good use of this advantage we propose a method of making larger 3D displays by the multiple comstruction using plural light sources and CGHs.
A CAD system with electronic holography is expected to provide ideal designing environments to feel and touch truly 3D images directly. However, interactivity and real-time computation of holographic fringe patterns are the essential requirements to realize it. This paper presents two different types of 3D images creating system. One consists of a 3D pointing device and an electro-holography system with an acousto-optical modulator which was proposed by Prof. Benton in 1989. The other consists of a 3D pointing device and an electro-holography system with a liquid crystal device. We also propose an effective method not depending on the total number of points in the scene and apply it to the designing tool by only appending points in a electro-holography system with a 3D input device.
Holography has made great progress in Japan. There are many `firsts' in holography. Two large research organizations on holography and a working group on moving holography were established. The Conference on Three Dimensional Image separated from The Joint Conference on Imaging Technology. Many exhibitions were opened. An international symposium and a domestic one on holography were held in November.
We propose a new fabrication method of multiplex holograms and present an example made by this method. We studied the possibility to display the perspectives on a liquid crystal panel for a computer display and the convenient way to convert the perspectives to film. The way of conversion is more useful than using liquid crystal panel at the present. We also propose an idea of an attractive object to demonstrate by multiplex hologram. The object is designed with a typical CG technique morphing. Faces of animals are metamorphosed and exposed in a hologram as a sequential image. And then it is divided into two loops and each hologram turns at a different speed. We can look at many different synthesized images from combinations of plural multiplex holograms.
A compact display system using reflection type rainbow hologram is proposed. This hologram is reconstructed by using a large illumination angle in air, not edge illumination. A good reconstructed image is obtained by adoption of a louver film.
This paper presents a new type of the interactive holography display system which features both dynamic and precisely detailed imaging. The main discussion is on synthesis of electronic holograms and optical holograms. Electronic holograms have benefits of dynamic imaging of computer generated 3D objects in essence. On the other hand, conventional optical holograms are known to be suitable for detailed and precise imaging. Considering that many images typically contain objects which dynamically move around on the still background, synthesis of electronic holograms and optical holograms has high potential that the currently limited electronic holograms are applied to a wide range of applications. The second discussion of this paper is about the possibility of producing computed holograms in real time. Computation time of generating holographic fringe patterns with a parallel computer CYBERFLOW is considerably reduced by using techniques such as parallel computation with and within 64 processing elements, vectorized computation, scalar computation simultaneously in parallel with vector computation, and simultaneous computation with data transfer to the output display device. The obtained result is 84.7 times as fast as a conventional computer and promises the possibility of the real time computer generated hologram.
Laser holographic interferometry has been developed to provide a direct optical transonic flow diagnostic tool. It is often convenient, due to the needs of passage instrumentation and blade fixtures, to restrict optical access to one side of the test facility. To overcome this limitation a reflective holographic system has been devised which uses one of the internal tunnel walls as a mirror surface. However, due to the movement of the facility, spurious rigid body vibration information is added to the transonic flow data. A numerical method has been developed by Warwick University and demonstrated on the Laval nozzle flow facility at EPFL which uses a digital fast Fourier transform algorithm to remove the superimposed background information. A further method known as phase unwrapping is used to extract quantitative numerical data from the interferometrically formed images automatically. A complication to the experiment was created by the non-linear deflection of glass window between the two holographic exposures. The deflection was determined experimentally to be of a parabolic nature and has been successfully removed. This was achieved by post processing the unwrapped fringe data.
The method for reconstructing a hologram through an edge of the glass cover plate is discussed from the standpoint of the imaging characteristics. Holograms fabricated by this method do not need large free space for illumination and can be reconstructed compactly. The image blur of the hologram reconstructed with white light is analyzed. Experiments of recording color holograms by this method are also reported.