The authors developed a simple stereoscopic display using the characteristic of inclined polarization of existing LCD panels. The production time of this display is very short and the cost is low price. The screen size of this display becomes about half of the LCD panel. Thus the stereoscopic images are displayed on the slightly small screen. Therefore several distortions often appear as puppet theater effect and cardboard effect. The researchers have not been able to provide the satisfactory solutions to these distortions. The authors propose a geometrical model to describe the relation between the real space of the recording time and the virtual space of the replay time. This model is mainly related to the reduction or the magnification about the screen size and the distance of a pair of cameras. The authors could improve the distortions by considering these conditions. Moreover the authors succeeded in improving 3D images more vividly. The essential point is the construction of multiple layered virtual images. The authors call this complex image "sur-virtual image." In this way the volume of the expressed object and the scale of the virtual space can be easily expanded. The viewer can enjoy more exciting 3D images.
We have already proposed that we could realize the see- through HMD by using the Holographic Optical Elements (HOEs). The HMD using HOE we proposed so far is used the Maxwellian View, which is the direct projection on the human retina. When we see something by the Maxwellian View, we don't need the focusing of the crystalline lens (ocular accommodation) because the depth field is extremely wide. We have been estimated the optical characteristics of this HOE by using still images on the slide mount. In this report, we will show the prototype of Retinal Projection Display, which can provide us the electrical dynamic images on the electrical spatial light modulator.
The authors propose new 3D display system using Holographic Optical Element (HOE) without glasses. The proposed HOE is used as holographic screen in this system. The HOE of proposed method can reconstruct white light in white illumination light. Namely, this HOE can reconstruct color images. The HOE has diffraction efficiency issue. However, we solved this issue, because we considered the Bragg condition when we made the HOE.
A simple diffractive equation representing the Bragg condition is introduced from the pair of grating equations about thick hologram. Usually a color hologram is multiple exposured by 3 lasers; red, green, blue. Each fringe angle can be naturally equal to the others by adjusting 3 beams to the same direction. As the result every Bragg angle is the same value.
KEYWORDS: Holographic optical elements, Head-mounted displays, Virtual reality, Eye, Retina, Holography, Human vision and color perception, Prototyping, Crystals, Head
We will discuss the characteristics of the Head Mounted Display (HMD) using Holographic Optical Element (HOE) in this paper. We have already proposed that using the HOE we could realize the see-through HMD, that is to say the binocular stereoscopic display. This time we evaluate the influence on the human vision system regarding the optical characteristics of the HOE. The HMD using HOE we proposed so far is the Maxwellian View which is the direct projection on the human retina. When we see something by Maxwellian View, we don't need the focusing of the crystalline lens (ocular accommodation) because the depth field is extremely wide. Therefore our binocular crystalline lens will focus at the vergence point when the Maxwellian View is used on the binocular retina. And we can solve the dissociation of accommodation and convergence which is the basic problem of the conventional HMD. We have made the prototype of HOE which can provide the Maxwellian View on our retina and we have proved that our HOE could separate the binocular images onto left and right eye. In this report, we will introduce the Maxwellian View will change the ocular accommodation optionally according to the convergence when we see the real objects and the virtual objects at the same time. We proved that the HOE which provided the Maxwellian View could solve the dissociation of accommodation and convergence.
In recent years, the study of 3D-display is rapid development and many researchers propose many methods. Holography is best method. But, it is difficult that we developed holographic movie in the future tense. At the present time, stereogram method will make practicable in the near future. These methods can easily make animated 3D image. But this method has one problem; this method is conflict between convergence and accommodation. An observer can't watch 3D-display of this method long time. The authors will solve this problem. The authors proposed the 3D-display system that is used holography and stereogram technology. The proposed system has little conflict between convergence and accommodation. The authors developed this 3D-display system. The developed system has four focuses in horizontal direction. The display parts of the developed system are LCD display because the developed system can play 3D movie. Of cause, this display doesn't have special glasses. But, color of this display is single color. It is red. The authors will develop full color 3D-display. The picture size of this display is about 6 inch and the form of this display is very large. The author will develop small size system and show large size picture.
This report is concerned with a stereovision system using holographic optical element (HOE). The authors introduce a natural 3D display system that provides the observer the clear stereoscopic vision without glasses. Even though both eyes of the observer are arbitrary located at the focuses of the stereovision system, he can be satisfied to look at the suitable 3D images. It is important that the focuses are not restricted at the specific points but occupy more broad areas. Such a mechanism is realized by the method of exposing with the diffractive plate. Moreover the authors are interested in a deep stereovision system. The system with four focuses is described to provide the adequate focuses in the accordance with his distance from the object. This system has HOE of multiple focuses that makes two pairs of viewing points in the back and forth locations. In this system four original images are projected from the behind of the HOE. All images join at the HOE and advance for the schemed focuses.
We have been making researches on 3D displays using computer-generated holograms (CGHs). We use an image setter with a resolution of 5080 dots per inch to record the binary CGH patterns. It is possible to reconstruct CGHs with light- emitting diodes or light bulbs which have small emitting segments. In the reconstruction with a light bulb, color- smeared images are observed due to the white light. In order to improve this dispersion, we considered a method to apply a color filter to the CGH. And, we propose a method to make computer-generated color hologram which can reconstruct color point light sources, by combining RGB color filters with the stripe CGHs corresponding to each color.
A display system requiring no special glasses is a useful technology for 3D images. The authors have researched real- time holographic stereogram displays using a holographic screen. In June 1995, we presented the stereoscopic 3D display system with viewing apertures such as conventional two-step holographic stereogram. In 1996, we introduced the stereoscopic 3D color display system using a holographic pseudo-color technique. Last year at the 1997 conference on Practical Holography, the authors presented the stereoscopic 3D display system based on a reconstruction of parallax- rays. These systems consist of a liquid crystal device and a holographic screen formed of holographic optical elements. These systems can construct animated 3D images in real-time by updating LCD pixels. In this paper, the latest result of our study about a stereoscopic 3D display system is proposed. In addition, this paper presents the result of a holographic stereogram movie system as a future 3D display.
We will discuss the prototype of Head Mounted Display using Holographic Optical Element in this paper. It is obvious that a single HOE can record the multiple optical images by the characteristic in itself, that is angular selectivity and wavelength selectivity. Therefore, it is very easy to understand the HOE has the function which can separate the stereoscopic images onto the left and right eyes, like as the conventional HMD. In this report, we propose the prototype of HMD using a single HOE, and we will extract the problem in application of the real industrial field, especially manufacturing and designing. Consequently, we proved that the HMD using Lippmann hologram has the potentiality of miniaturization, lightening, wide field of vision. This HMD can be suitable in the Virtual Reality field. But it is necessary to adjust the pupil distance and the incident angle of conjugate beam precisely.
This paper is concerned with illumination systems for fluctuating the images of rainbow holograms by an LCD projector and a wide mirror array. The authors introduce the early display systems developed for fluctuation holograms. These systems are not enough to fluctuate them arbitrarily because the locations or the angles of their light sources are fixed or cyclically varied. The authors developed an illumination system by which the observer can see the image of the hologram fluctuated like under the natural environment. An LCD projector and a lens-mirror array are used in the illumination system. The lens-mirror array is composed of about 400 small mirrors pasted over with thin concave lenses. The beam projected out of the LCD projector covers the lens-mirror array. The beam reflected by the lens-mirror array is centered for the hologram panel fixed above the LCD projector. When the highlight zone from the LCD projector is continuously moved on the lens-mirror array, the image of the hologram is smoothly fluctuated. In the case of a large holographic optical lens panel instead of the lens-mirror array, the illumination system becomes more simple. The time to adjust the position of the hologram and the angle of the holographic optical lens panel is extremely reduced. Although the bright area is limited around the zone of the mid height, the movement of the rainbow hologram becomes more natural. Next the authors prepared a multiple exposed hologram that was recorded multiple images like a stereogram. This case realized that the image of the hologram is fluctuated more complicatedly because the multiple images are reconstructed by the multiple illuminations.
Holography is a useful technology for 3D images. The authors have researched spatial imaging based on a holographic technology. This paper describes many good results of fundamental study about 3D electronic images--3D TV monitor, 3D fine art, 3D measuring instrument and so on. In addition, this paper presents the latest result of our study about a stereoscopic 3D display system. This system consists of a liquid crystal device and a holographic screen formed of holographic optical elements. This display can construct animated 3D images in real-time by updating LCD pixels.
This paper is concerned with the hologram fluctuating and spinning in a large kaleidoscope. The authors have been studying many display systems for fluctuating the image of rainbow holograms. In the prior systems the authors fluctuated holograms by using several assistant devices. In the new system holograms are fluctuated only by the intention and the operation of the observer. This simple system without surplus is one of the ideal fluctuation holograms. Two types of kaleidoscopes are introduced in this paper. The one is the prism kaleidoscope that has the popular shape made of three rectangles. It provides the observer many colorful reflected images of a rainbow hologram. The other is the pyramid kaleidoscope that has the unique shape made of three trapezoids. It provides the observer complicate and fantastic images of a rainbow hologram.
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.
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.
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.
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.
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.
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