In this report, new recording method of computer generated hologram (CGH) pattern is proposed. CGH pattern is generated as an optical interference fringe pattern with reference light like off-axis hologram. The object wave-front is realized by spatial light-phase modulator (SLPM). One of SLPMs is a liquid crystal panel device. Liquid crystal molecule has very high birefringent characteristics.

A new electro-optic modulator system has been developed by the authors to replay dynamic holographic images. This Active Tiling^TM system offers a route to replay giga- pixel computer generated hologram images with video refresh rates. High speed, medium complexity electrically addressed spatial light modulators are combined with a high resolution optically addressed spatial light modulator to provide ultra-high complexity, video frame rate holographic data suitable for coherent readout.

In this report, computer-generated holograms (CGHs) that are able to reconstruct different 3D images in accordance with moving viewpoints are discussed as an application of electron beam printing CGHs. In previous Practical Holography conferences, image-type CGHs which are able to reconstruct 3D images under white light were reported. This time, utilizing the method of this fabrication, trial making of a CGH which is capable of reconstructing three different 3D images was implemented. To achieve this, the angle selectivity of the incident light to reconstruct the images was applied. In other words, to reconstruct three different images, three reference waves of which each incident angle was varied were selected and three kinds of interferogram data were merged to complete a multi-recorded CGH. The recorded images are horizontal-parallax-only images so that the CGH can be composed of some elemental CGHs which are horizontally-sliced, and so synthesizing three CGHs is achieved by placing elemental CGHs of three CGHs mutually. Therefore, a multi-recorded CGH by space-dividing was fabricated experimentally. As a result of fabricating a 10 mm X 18 mm sized CGH, it has been confirmed that three different 3D images can be observed separately in accordance with moving view points.

This paper discusses certain developments in our understanding of the writing of large-area CGH arrays of the absorption type. The calibration of grey-scale structures is considered, using different forms of the linearization process. It is also pointed out that the feature shape and packing fraction play a dominant role in the achievement of high dynamic range of the holographic recording.

For practical holographic video system, it is important to generated holographic fringe as fast as possible. We have proposed an approximation method that can calculate the Fresnel hologram fast. To compute the hologram, an object is assumed as a collection of self-illuminated points and the fringes from each object point are superposed. To determine the fringe, a distance between object point and sampling point on the hologram is used to obtain phase of the light. Since sampled hologram usually has small pixel intervals, the difference of the distance values between adjacent pixels is also small and its n-th order difference becomes a constant. Therefore, the distance value at certain pixel can be obtained from the neighbor pixel with simple additions. We have investigated approximation errors and computational speed of the method. The numerical results show that the proposed method is quite effective. The distance error can be reduced less that one wavelength with practical parameters and the computational speed becomes 16 times faster than conventional method. With the proposed method, a hologram, which has horizontal parallax only, 1.3 mega- pixels and 1,000 object points, can be calculated less than on second with a personal computer.

Recent advances in high-resolution CCD detectors allow the development of the concept of digital holography that relies on capturing of 2D microinterferograms and their further numerical reconstruction. This approach is valid for optical metrology applications as it gives direct access to the phase and intensity of an object at the selected distance `d'. However it is not convenient for direct 3D display purpose. It is the reason why the authors propose the optoelectronic reconstruction of a hologram that is digitally recorded and transferred to another optoelectronic medium. The application of LCD matrices and optically addressed liquid crystal cells as reconstruction medium are discussed. Their applicability for computer generated and optical holograms is tested by means of simple experiments. The problems connected with limited resolution of the recording (CCD) and reconstruction (LCD, DMD) devices are considered. The comparison of the results obtained by numerical and optoelectronic means are presented, together with a discussion of the limitations and further possibilities of these techniques.

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.

In this paper, the author will look at the origin of an idea as the creative synthesis of experience, technology, concept and form through her holographic light installation, Signature of the Source. This installation attempts to speak to the essentials of creativity.

A new type of Grating Image we dominate as `Sparklegram' is presented. The Sparklegram is characterized because it provides high quality and better design flexibility. These features are achieved by constructing it with shaped dots as desired. Each dot can be designed as an individual shape, for example, a star or a triangle. As dot shapes, we can use not only geometric patterns, but also some kind of symbols. Not only flexibility of each consists dot shape, but also the quality of reconstructed image is remarkably increased too. Because of these features, the constructed image with the new type of Grating Image, Sparklegram has high quality and high flexibility. It can be applied to security use, for example on credit-cards, tickets, etc., and also can be applied to the package of software products, CDs, videos and other kind of items requiring security. And with these features of flexibility and high quality, Sparklegram has also advantages to be applied to other use, for example amusement use, comics and game characters' goods and packages.

This paper is a brief journey from my first introduction to display optics to a career in holography.

Off-Bragg reconstruction of volume holographic grating is known to result in an attenuation of the diffracted beam intensity. In this letter we demonstrate that contrary to the disseminated believe a strong increase of the diffracted beam intensity can be observed when an angular deviation between the grating and reconstruction beam takes place in the direction perpendicular to the dispersion plane. The effect of such `anomalous' behavior of the diffracted beam intensity is studied experimentally.

A new method of wavefronts' cross-correlation by means of so-called Second-Harmonic-Generated Hologram (SHG hologram) is considered. According to this method the interference pattern of an object wave and a reference wave is recorded in nonlinear light-sensitive material using its second order nonlinearity. The SHG hologram generates the wave that forms the reconstructed image of the object without time delay in the moment when interfering wavefronts intersect the image of the object without time delay in the moment when interfering wavefronts intersect the light-sensitive material, the frequency of the reconstructed wave being doubled in comparison with the frequency of the recorded waves. The expression that describes the electrical field of the reconstructed wave is deduced. Basing on this expression the methods for the construction of the image generated by SHG hologram are developed. It is suggested to use the transforming properties of the SHG hologram for constructing the network of changeable interconnection lines, which operates on the principle `light is controlled by light'. The experiment on the recording of the SHG hologram was carried out. The SHG hologram was recorded in BBO I crystal with the help of Nd:YAG pulse laser. The experiment has confirmed the ability of the SHG hologram to form high quality images.

To make holography accessible to high schools and technical institutions, cost, safety, simplicity, scientific content, and usefulness are primary requirements. Herein we introduce the design and function of a real-time holographic interferometer which is capable of obtaining quantitative results with phase subjects. By introducing a phase compensator in the form of an ordinary plate glass, zeroth order interference is routinely attainable.

Holographic Interferometry has been successfully employed to characterize the materials and behavior of diverse types of structures under stress. Specialized variations of this technology have also been applied to define dynamic structural behavior. Such applications of holographic techniques offer some of the most effective methods of structural flaw identification and analysis available. This technology is nondestructive, real-time, and definitive in allowing the identification of anomalous structural and mechanical geometry as well as describing dynamic behavior under stress. Structures and materials can be analyzed with very low amplitude stress or excitation and the resultant data can be used to adjust the accuracy of mathematically derived structural models or as criteria for complete inspection and analysis programs, as well as in developmental analysis.

In making a large size transmission type holographic screen for full color image projection. We revealed several factors that are the main reasons of image performance deterioration. Bragg condition fulfillment and emulsion shrinkage are decisive factors for governing the chromatic performance at the near edge of the screen. By considering these factors, developed optimum geometry for recording the large size holographic screen. The Bragg condition effect was analyzed quantitatively over the whole screen and it shows some colors aren't reproduced satisfactory at the screen edges. Recording condition and image projection condition are balanced properly and image quality is endhenced, by normally aligning line from reference beam source to projector at the screen center. And the recording setup was modified for compensating the photoplate emulsion shrinkage. Transmission type holographic screen of 40 cm X 60 cm was manufactured by using optimum recording setup. The screen has high brightness, and good color reproduction on the whole surface.

Several method have been proposed or used to optimize the phase distribution of a kinoform. In this paper, we propose a new approach for optimization of the kinoform based on simulated annealing to reduce the large computation cost.

Holo-Chidi is a holographic video processing system designed at the MIT Media Laboratory for real-time computation of Computer Generated Holograms and the subsequent display of the holograms at video frame rates. It's processing engine is adapted from Chidi which is reconfigurable multimedia processing system used for real-time synthesis and analysis of digital video frames. Holo-Chidi is made of two main components: the sets of Chidi processor cards and the display video concentrator card. The processor cards are used for hologram computation while the display video concentrator card acts as frame buffer for the system. The display video concentrator also formats the computed holographic data and converts them to analog form for feeding the acousto-optic modulators of the Media Lab's Mark-II holographic display system. The display video concentrator card can display the computed holograms from the Chidi cards loaded from its high-speed I/O interface port or precomputed holograms loaded from a PC through the United Serial Bus port of its communications processor at above video refresh rates. This paper discusses the design of the display video concentrator used to display holographic video in the Mark-II system.

A digital pixel cryptogram technology using e-beam holography is described in this paper. The cryptogram is generated by an electronic beam lithography system and it can be applied to fabrication of embossing hologram for anti-counterfeiting and security.

We have developed a new system based on computer-generated holography using a hologram plane with a sampling structure like a liquid crystal display. This system can eliminate beams from conjugate images and enlarge the viewing zone, which are achieved by combining the following two methods. The first method enlarges the viewing zone by using higher- order diffraction beams generated because of the sampling structure of the hologram plane. If the angle between the object beam and the reference beam is larger than the angle determined by the sampling period on the hologram plane, aliasing occurs in the fringe patterns. In this method, the viewing zone is enlarged by using a spatial filter to extract the object beams from the higher-order diffraction beams generated from aliasing and then combining them. The second method is a modification of the single-sideband method that is known to eliminate the conjugate beams and to restrict the viewing zone to a narrow range. The modified method improves this restriction by dividing the range of the object beams and reproducing each of them. This paper presents the developed system, and the results of experiments that confirmed the effectiveness of this system in enlarging the viewing zone.

A 3D head mounted display (HMD) system is useful for constructing virtual space. The authors have developed a see-through 3D HMD system. This display has no demerit that lightness of real and virtual images is lacking for a spatial viewing. This paper shows that this problem can be solved by using a simultaneous perception of the human vision and a 3D vision system. In addition, we propose a newly developed monocular stereoscopic 3D display system for this 3D HMD system.

A head-up display for cars, which can display full color stereoscopic images, is developed. The display employs a reflective holographic screen having a size of 24 (horizontal) X 18 (vertical) for image projection. The screen is made by laminating two holographic directional diffusers recorded on Du Pont HRF-706 holographic photopolymer, which are tuned to blue (480 nm) and green-red (507 - 630 nm) spectral regions. It shows both properties of a concave spherical mirror and a diffuser. The screen's eye box size in horizontal direction is about 20 cm and stereo images can be perceived within 50 cm to 1 m distance from the screen. No visible color distortions owing to the screen's uniform spectral response and high transparency allow that well distinction between images on the screen and images from outside of the screen even under the sun illumination.

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.

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.

For solving the problem of poor stability that exists in most of the optical dot-matrix hologram fabrication systems. We are now developing a non-optical manner for making dot- matrix hologram by using a pin with a small metal mold made of diamond ruled or electroformed grating on the tip. By rotating the pin and pressing it on a heating plastic plate dot by dot, we can compose a dot-matrix hologram. That's an easy way to make a hologram with the same quality as that resulted from optical interference methodology. We need only a simple motorized rotational stage to rotate the pin that fixed on it instead of using complex optical interference method. The method, which employs mechanical devices, will offer a new concept of implementing a high quality dot- matrix hologram.

In this report, we demonstrate and discuss a holographic storage system, where two holographic multiplexing methods are included: one is angular multiplexing and the other one is random phase multiplexing through a ground glass. The latter is responsible to the optical encryption when the stored pattern needs to be encrypted. We study the tolerance to the displacement of the ground glass in three-dimension. We find that it is a function of both the illumination area of the ground glass and the thickness of the volume hologram.

An optical correlator based on VanderLugt filtering has been constructed using a bitonal spatial light modulator for the transfer function of the matched filter. Because the spatial light modulator can reproduce bitonal magnitude signals only, the filter is introduced as a Lohmann cellular hologram. The traditional additive random phase may not be used, and thus filter functions constructed from uncompensated cellular holograms are inherently lowpass in nature. In the system reported here, improved performance results from an approximation of the ideal reference spectrum and by using error-diffused quantization.

`Everything should be made as simple as possible, but not simpler'--Albert Einstein. We attempt to follow this dictum and apply it to the process of making holograms. The procedures we propose herein are as simple as it is physically possible. In the process, we have made holography not only as simple as possible, but safer, less expensive, and more accessible to young people.

Dai Nippon Printing is the first company in the world to succeed in the mass production of full-color 3D Lippmann type holograms, which are marketed under the name of TRUE IMAGE^TM. TRUE IMAGE^TM labels consist of a panchromatic photopolymer material and pressure-sensitive adhesives (PSAs). This new medium is expected to have wide application in various fields, such as publishing, labels for authentication, and so on. For commercial use, TRUE IMAGE^TM labels require high-quality PSAs. In this study, two new PSAs and a new layer structure were developed. One PSA provides TRUE IMAGE^TM labels with good environmental stability, and the other adjusts the playback wavelengths. These two PSAs together with a new layer structure have enabled the development of a new type of TRUE IMAGE^TM label for security applications.

In the paper we analyze some optical arrangements intended for recording of holograms with optical encoding of the image. In the first section on the basis of the opto- electronic systems theory we are considering the processes of hologram recording and reconstruction with optically encoded images for Fourier and Fresnel hologram recording schemes with encoding mask in reference and subject branches. In the second section the detailed analysis of these schemes with encoding mask consisting of a set of secondary point sources placed in reference branch is made. The results of influence of optical elements installing inaccuracy in the arrangement of image retrieval on a quality of this image are obtained. The hologram recording arrangement for the further studies on the base of the analysis is chosen. In the third section we estimate a signal to noise ratio in the image plane for the arrangements selected. Analysis of multiplexing holograms using possibility with image optical encoding is made.

The paper consider a development of the slitless method of a rainbow holography to the method of generalized holography. The slitless method of a rainbow holography was suggested by the first author in this previous papers.

The polarization properties of the reflection-type holographic recording material, DuPont photopolymer OmniDex^TM 706, have been studied. Depending on the position of photopolymer-Mylar assembly, linearly polarized laser beam alters its polarization state about 40%. Due to the birefringence of Mylar substrate, this phenomenon has been occurred very randomly through a wide range and affected in diffraction efficiencies. In the case of reflection-type hologram, the directions of two beams incident onto the recording materials are not same, the change of the polarization states cause the weak fringe visibility. As a result, reflection holograms have shown low diffraction efficiencies and unstable characteristics.

In the present paper we consider the possibility to obtain highly selective holographic spectral filters operating in near IR range of spectrum. The properties of photopolymer with diffusive amplification as a medium for recording of such filters are analyzed, namely the mechanism of diffusion enhancement of hologram diffraction efficiency, the dispersion dependence of refractive index variations in a wide spectral range, and its influence on the resulting parameters of the holographic filter. The experimental results on the recording of filters optimized for operation at particular wavelengths of 0.85, 1.06 and 1.5 micrometers are presented.

A multiple-level technique suitable to obtain high efficient Optically Variable Device is presented. The target is the realization of a very complex holographic images with various kinetic and dynamic effects, of interest for the application in the security market. The technique, involving the use of a positive and a negative photoresist process, and its application for the fabrication of complex diffraction gratings are described.

Evaluation of the mechanical properties of films of the materials currently employed for recording diffractive optical elements is very important in order to foresee their mechanical behavior during the photochemical processing following recording of the interference pattern. This will also provide information about the mechanical and thermal stability of holograms recorded on these materials, which may be tested in the different environments in which the final application of the optical elements will be used. For quantitative evaluation of these properties in an acrylamide based photopolymeric system, a study was carried out on layers of films of polyvinylalcohol and polyvinylalcohol mixed with triethanolamine. Layers coated on glass substrate were subjected to both a high vacuum and temperature changes. Real time measurements of optical path variations in the film were performed using a vacuum interferometric measurement system.

A variety of environmental exposure tests were conducted on holographic optical elements. Previous reports from our lab have largely been confined to studies on simple mirror holograms in unconverted format. This study was expanded to include slant-fringe diffuse reflectors as well as normal- incidence simple mirrors converted into commercially practical formats with adhesives and different types of support substrates. Holograms were characterized using reflectance as well as transmission spectroscopy. Films were subjected to 30 cycles of 80 degree(s)C to -30 degree(s)C air-to- air temperature cycling, 14 day 70 degree(s)C/95% RH hold, 14 day 100 degree(s)C dry heat hold, 540 hour continuous ultraviolet exposure, and 14 day cycled fluorescent roomlight exposure. Playback wavelength and diffraction efficiency was stable under all conditions. As reported earlier, exposure to intense ultraviolet light increases yellowness of the photopolymer holograms, but this can be prevented by laminating a UV-absorbing layer atop the film.

The results of the synthesis and investigation of two special kinds of thick-layered self-developing glycerol- containing dichromated gelatin are presented. One type was sensitive to blue light while the other type with methylene blue additions was red-sensitive. The thickness of the layers varied from 0.1 to 2 mm. The holographic characteristics are discussed. The method for 3D data storage by means of multiplexing 3D speckle-shift holograms when using counterpropagating beam hologram recording is presented. The method permits hologram multiplexing by shifting a speckle wave by the value equal to its correlation radius. The number of multiplexed holograms and lifetime of holograms are discussed.

Since more than ten years films and cubes made from the halobacterial photochromic retinal protein bacteriorhodopsin (BR) are discussed as storage media for short-term and long- term data storage. The efficient photochemistry of BR, the stability towards chemical and thermal degradation, the reversibility and the polarization recording capability of bacteriorhodopsin films are attractive. The limited storage time of the recorded information implies some restrictions in the use of this material. Because bacteriorhodopsin returns also through a thermal pathway to its initial state recorded information decays with a characteristic time constant which is related to the lifetime of the M-state of the material. By genetic methods and by suitable film compositions this value can be extended up to several minutes which is more than enough for all real-time applications. In some cases a longer storage time is desired, among them optical data storage. Optical modules and components based on bacteriorhodopsin films, which can be thermostated to different temperatures, are presented. They allow very sensitive optical recording and can be photochemically or thermally erased. These bacteriorhodopsin containing modules may be used for high resolution optical recording with extended storage time.

Abstract not available.

Silver halide sensitized gelatin (SHSG) holograms are similar to holograms recorded in dichromated gelatin (DCG), the main recording material for holographic optical elements (HOEs). The drawbacks of DCG is its low sensitivity and limited spectral response. Silver halide materials can be processed in such a way that the final hologram will have properties like a DCG hologram. Recently, this technique has become more interesting after the introduction of the new ultra-high-resolution silver halide emulsions. An optimized processing technique for transmission HOEs recorded in these materials is reported. Diffraction efficiencies over 90% can be obtained for transmissive diffraction gratings. Understanding the importance of the selective hardening process has made it possible to obtain results similar to conventional DCG processing. The main advantage of the SHSG process is that high sensitivity recording can be performed employing laser wavelengths anywhere within the visible spectrum. This simplifies the manufacturing of high-quality, large-format HOEs.

In this article the behavior of thick photopolymer layers as material for holographic recording is studied. The material used is a photopolymer based on acrylamides, consisting of acrylamide as monomer, yellowish eosin as sensitizer and triethanolamine as radical generator, all on a matrix of polyvinyl alcohol. We studied the influence of the thickness of the layer on the behavior of the photopolymer as a holographic recording material. According to Kogelnik's theory, the thickness determines the temporal or energetic evolution of the diffraction efficiency.

Phase holograms in holographic emulsions are usually obtained by two bath processes (developing and bleaching). In this work we present a one step method to reach phase holograms with silver-halide emulsions. Which is based on the variation of the conditions of the typical developing processes of amplitude holograms. For this, we have used the well-known chemical developer, AAC, which is composed by ascorbic acid as a developing agent and sodium carbonate anhydrous as accelerator. Agfa 8E75 HD and BB-640 plates were used to obtain these phase gratings, whose colors are between yellow and brown. In function of the parameters of this developing method the resulting diffraction efficiency and optical density of the diffraction gratings were studied. One of these parameters studied is the influence of the grain size. In the case of Agfa plates diffraction efficiency around 18% with density < 1 has been reached, whilst with the BB-640 emulsion, whose grain is smaller than that of the Agfa, diffraction efficiency near 30% has been obtained. The resulting gratings were analyzed through X-ray spectroscopy showing the differences of the structure of the developed silver when amplitude and transmission gratings are obtained. The angular response of both (transmission and amplitude) gratings were studied, where minimal transmission is showed at the Braggs angle in phase holograms, whilst a maximal value is obtained in amplitude gratings.

Silver halide photographic plates and photosensitive polymers have been utilized for the holographic recording. These materials are available only for recording of still pictures and require complex developing processes and a relatively long time for recording and reproduction of the image. As an alternative, image recording using bismuth silenite compounds has been researched. The BSO and BGO single crystal bulk samples have been used for these studies. We aimed to fabricate BGO and BSO films appropriate for image recording. Films have merits in device integration and mass production. The process condition to obtain a good crystalline film was studied. The film with crystalline phase only was obtained at the substrate temperatures above 200C.

The independent characteristic of the angular selectivity for the writing conditions was presented in photorefractive grating. In general, the incident angle of writing beam and the interaction length determine the angular selectivity of the grating. When the focused probe beam is incident on the grating, we obtain a new relation that the angular selectivity of the photorefractive grating depends on the probe beam incident conditions and is independent of the writing conditions such as writing beam incident angle, wavelength, and interaction length. These characteristics are experimentally investigated as a function of the following parameters; writing beam incident angle, probe beam width and lens focal length. In the experimental results, it has demonstrated that the control parameters are not the incident angles of writing beam but the probe beam width and focal length of the convex lens. Another property of this configuration is to have same value within large angular range that is also determined by the readout conditions.

We present a new material with potential application in holography. We have used a film of mixing ammonium dichromate with rosin resin diluted in isopropyl alcohol. This material can be easily elaborate in the laboratory. A phase grating in this material was recording using Argon-Ion laser at (lambda) equals 457 nm, showing good diffraction efficiency. This material is capable of high resolution when we record some diffraction gratings, observing 2,000 l/mm (grooves). A characteristic of the developed process is their simplicity, takes approximately 25 seconds.

The photorefractive properties of Mn-doped KNSBN crystals, especially the crystal with a higher doping level (0.09 wt.%), was studied. Experiment showed that the properties of Mn:KNSBN crystals with 0.09 wt.% are different from others. This maybe provides a good material to study the electron- hole competition, which exists widely in PR crystals. The high order harmonic properties were also investigated. Five orders of harmonics were observed. It was found that the maximum of the second order index grating shifts towards a small incident angle with respect to that of the fundamental grating. Based on the strong harmonics in this kind of crystals, the recording of harmonic index gratings was achieved by using a novel method in experiment.