External perception of the world implies the detection of the objects to fix. This detection is ensured by the visual field and then by the movement of the eyes that allows localization adjustment : the image of the observed object is pictured on a part of the retina presenting the maximum of sensitivity for details resolution and colours, that is on the macula. Each eye transmits an image to the brain but only one image is perceived : it is the resulting binocular vision. All the process is identical to an image formation by one equivalent cyclopean eye localized between the two eyes at the same height but lightly inside the head. The most important and basic law of the binocular vision is to superpose the to retinas of the eyes at the level of this unique eye or better it the level of the occipital cortex. Binocular vision, starting from to retinal images, gives birth to a new perception with different properties the third dimension is the new sensation which is not in the least suggested in monocular vision.

This paper investigates some concepts for generating 3-D images and tries to classify them. 3-D imagery poses a lot of problems, some of them are "only" technical difficulties, but there are also some fundamental limitations. Among them we consider the restrictions imposed by the wave-equation to 3-D intensity distributions and we study how 3-D information is transmitted by a wavefront or stored by a hologram.

Numerous methods exist to have access at a three-dimensional representation of our environment, and particalary with optics : integral photography, lenticular sheet three dimen-sional picture, integram, ... The holograms appear with an original position. Several holograms are presented : transmission laser holograms, white light transmission, white light reflexion. Their actual possibilities and the recent progress are indicated and their limitations are discussed : size, brightness, angle of view, diffraction efficiency, noise, color. Their futur is evaluated in regards of the actual technical problems.

This paper discusses some of the current knowledge of modulation mechanisms and how they affect the recording of colour reflection holograms in particular and all holograms in general. Recent observations have revealed spurious complexing problems during bleaching of silver halide holograms and these will be discussed in relation to their effect on hologram efficiency.

The replication of holograms on a large scale requires the successful completion of many intricate steps from the initial artistic concept to the finished product. Complicated manufacturing processes must be done efficiently and economically to produce replicas displayed in an esthetically pleasing manner and with the maximum possible optical effect. A description is made of the "high tech laser button" that was designed as a souvenir for the recent World's Fair and the stages involved in its replication. In the basic design, an intricate overlay of multiple holographic gratings onto a recording medium was required. From this a durable metal master was made that was subsequently used to emboss the pattern into a thin plastic sheet. The resulting metallized plastic was die cut and mounted onto a button. The practical and artistic reasons for mounting the holograms in this fashion are discussed. Also considered are subsequent, more advanced designs and the unique optical effects that result from them.

A multiplex hologram is a holographic stereogram synthesized from ordinary photographs, and is going to be used in many fields such as art, advertizing, etc.. However, due to the properties of multiplex holograms, there are some inconveniences to use the hologram for the medical purpose. Among these inconviniences, the distortion of the reconstructed image and the limit of the number of original photographs can be removed by processing the original photographs with a computer. The methods of image processing and examples of the results are presented.

The holographic stereogram has considerable commercial potential as a medium for displaying three-dimensional imagery. Application of the cylindrical holographic stereogram has been limited, however, by format constraints and image distortions and aberrations. This paper discusses these limitations and describes several methods, both demonstrated and proposed, which seek to eliminate these limitations.

The aim of this communication is to describe a visualization technique allowing the reconstruction of holographic images of 3D, colored and animated objects. The technique, using unidirectional multiplexing, consists of dividing a master hologram into several horizontal strips, each of them being one different holographic recording of sequential views of a moving object. The holographic image is reconstructed by the second hologram. This process has been applied to reflection holograms of animated portraits reconstructed in white light. In this case pulsedlaser is necessary. In order to extend the process to polychromatic images, a simulation by motion synthesis has been carried out,allowing the use of CW lasers. Two directions have been explored : i) by adapting the well known rainbow transmission holographic technique, applied to two or three wavelengths. Unfortunately the number of viewers is limited to only one, set close to the second hologram ; ii) by using transmission holograms (master and second ones) recorded and reconstructed in coherent light with two or three different wavelengths. This somewhat restrictive technique (coherent reconstruction) allows therefore to increase the number of viewers. An experimental set-up using two lasers (Argon and Krypton) is developed. The different problems encountered are explained, especially the building of the "Cineholoscopes", i.e. holographic reconstruction apparatus including rotating optics and insuring a vertical scanning of the holograms by the reconstruction beam. The results of this study have led to an exhibition presentation of a multicolor, 3D, animated scene, for six viewers placed at a distance of ~ 2m from a 60 x 50 cm screen-hologram. This realization could be the starting point of a new technique of holographic display.

Diffuse-object holograms in dichromated gelatin (DCG) can be obtained by copying silver-halide gelatin holograms with spectral filtered sunlight. Copies have high efficiency and relatively low noise. The method seems potentially capable of obtaining large size holograms in DCG.

Holographic optical elements (HOEs) have the characteristic of less space-bandwidth product. With this limitation, they cannot be widely used as conventional optical elements. In this paper, we first analyze the cause of this limitation, and then we intend to enlarge this product by using multiple exposures on one hologram. Each exposure records the interference pattern resulted from a fixed pair of object and reference light under different illuminating angle with respect to the hologram plane.

This paper discusses the influence of temporal and spatial coherence of the light source, used in the holographic reconstruction process, on the quality of the image. This quality is estimated by the spread function of the holographic image of an object point, recorded with a coherent source. Different formulas are established successively for a punctual source with partial temporal coherence, a temporally coherent source of finite size and a self luminous source with temporal and partial spatial coherence. Numerical solutions show that, generally, the lack of spatial coherence is more drastic for the image quality.

The principle, configuration and possible application of specially designed spatial 3-D image (color or black and white ) projection system of holograms and objects without the help of polaroid or any other viewing means are described. Optimal scheme of recording projection hologram for obtaining a screen image of the desired quality, the parameters of copying and projecting objectives used for interference copying and projection holograms, the aberrations of holographic screens and its operation condition satisfying paraxial approximation, the limitation of maximal magnification of projection system and its maximal depth perception are discussed.

Auto-stereoscopic displays can be classified into holographic and nonholographic devices. In this review paper we compare several systems in each group on the basis of their information content. Two approaches currently under investigation at Stanford University are discussed. Several investigators have noted a chronological decrease in the diffraction efficiency of sequentially recorded images in a multiple exposure hologram, but no satisfactory explanation for this phenomenon, which we denote by Holographic Reciprocity Law Failure (HRLF), has been presented. We propose a mechanism, based on latent image formation in silver halide films, to explain HRLF and a procedure to equalize the efficiency of all simultaneously reconstructed images. As many as 16 images have been superimposed and reconstructed with equal brightness. Digital holography is an attractive method for displaying discrete volumetric data bases, but present computational methods based on implementing DFT routines for the calculation of Fresnel holograms require large memory and long computational times. We have investigated an alternative method, based on calculating a convolution operation directly (which also uses DFT techniques), but which allows parallel computation of patches of the hologram. This method offers a tradeoff between processors, memory requirements and computation time.

A digital time smear correction algorithm improves the multiplex hologram (MH) as a display device for computerized tomography (CT) data. As it rotates, a corrected MH can display any desired sequence of virtual images. Perspective display and dynamic dissection of a three dimensional data set are fundamental to its visualization. With proper choice of virtual images the corrected MH has both capabilities. This paper explores the correction algorithm, its digital implementation, properties, and application to CT data.

A noncrystalline film of As2S3 is used as a nonlinear recording material of the joint transform optical processor. Real time cross correlation between two transparencies is demonstrated using the optical processor. The authors observed cross correlation peaks between two photographs of identical words. The set-up can be applied to compare fingerprints.

A brief review over the past and present work on stereoscopic and volumetric TV employing the conventional 2-D TV equipments and standards has been made. The earlier 3-D viewing systems such as direct-eye-contact types, color filter based techniques and polarization based systems are critically examined for a successful 3-D TV. A bicircular polarization technique using electrooptic material in the picture tube screen is proposed for a 3-D color TV. Also, a technique involving region-wise periodic illumination of the object for registering blur-free sectional images of the object needed for a volumetric 3-D TV is Proposed.

A simple tri-orthogonal image pickup system for generating 3-D image of an object is analyzed for its performance and characteristics. Some standard solid objects such as sphere, cone and tetrahedran are used for system evaluation. Also an optimal design procedue for tri-depth sectional image pickup system for compatible volumetric 3-D TV is presented. Further, as an alternative to the varifocal mirror technique for volumetric TV, a simple varifocal electrooptic lens system is proposed.

Displays have only one function: the conveying of information to human beings. To do this well, the display must be well suited to the human viewing-comprehending system. Evolving in a three-dimensional (3D) world, humans have an exquisitely tuned system for seeing in 3D. A display capable of providing information in 3D would have a significant advantages over its more common 2D competitors: television, the printed page, etc. The fact that 3D displays are not in common use can only mean that the existing 3D displays have major drawbacks. Indeed that is the case.

Three-dimensional imagery occurs mostly in two different kinds of processes: One-step and Two-step imaging. The One-step process requires specialized equipment,which tends to limit its use to well-equipped and well-trained specialists. Except Worthy Trivision of Hong Kong,nobody sells such apparatus,and most specialists build their own equipment. The Two-step process includes a phase of analysis and a phase of synthesis. The first step can be realized with ordinary photographic equipment,for instance small-frame or medium-frame cameras,Super-8 or 16-mm.cameras,studio cameras up to 5"x7". The second step needs a special device,used in an ordinary darkroom. The purpose of this paper is to indicate some practical means of realizing the first step without failure,the second step being insured by any photographer or by ourselves.

The easiest solution to obtain tri-dimensional pictures to be viewed directly - that is without glasses - consists in using lenticular screens directly associated to matricial scanning. But if we put only with two pictures (as in stereophotography) the right viewing angle is limited. To improve it, the number of pictures must be increased to four at least. The transmission of four pictures is possible on one way only, thanks to the simultaneous use of matricial analysis and numerical modulation. Anyway, we meet the problem of the passing band if we do not want to loose definition. In this point of view, the numerical modulation permits to reduce greatly the passing band, taking into consideration that in several pictures, there are a great number of identical pixels : it is then useless to transmit them on several ways.

Lenticular sheets may be used for observing a couple of stereoscopic pictures, for instance for 3-D TV. This observation is an orthostereoscopic one but areas of correct observation suffer several limitations. These limitations will be studied in this paper and the possibility of reducing them will be discussed. The problem of the accuracy of matching the coded image with the lenticular sheet will also be particu-larly emphasized.

This paper presents a black and white stereoscopic system using a stereo pair of T.V. cameras and an electronic display. The stereo pair of T.V. cameras is first described. A good calibration of observed objects has been obtained by using two rigidly connected solid-state cameras as sensors (Charge Coupled Devices) with 25 mm lenses. A 256 x 256 pixels two-dimensional image is formed by multiplexing two 128 x 256 pixels left and right pictures. The viewing system consists of a 256 x 256 cells liquid cristal display and a lenticular screen. The two dimensional image is displayed on the flat screen and projected in the focal plane of the lenticular screen. The liquid cristal used in this experiment has 32 grey levels and the lenticular screen has 128 half-cylindrical 4 mm lenses. The process requires to transmit only one video signal and digital techniques have been chosen for transmission.

A large number of new display technologies are available for flat panel displays. Currently, each of the technologies has a unique set of features and limitations, which results in that technology being well suited for some applications and inappropriate for the others. After a brief explanation of the problems encounter in flat panel display systems, we will discuss the various categories of flat panel display technologies which can be divided into two groups : - Emissive displays such as flat cathode ray tubes electroluminescent display, plasma panel... - Non emissive displays such as the famous liquid cristal display. When considering any such display it is especially important that we consider the impact of the display on the whole system and particularly the electronic area as all flat panel displays are not driven with equal ease. In conclusion, the choise of flat panel display for 3D imaging will mainly depends on user's requirements and flat panel characteristics.

A sandwich type volumetric screen is proposed for 3-D color image display based on sectional imaging. Each slice of the sandwich displays one section of the image. The slice consists of a back-illuminator and a front liquid crystal matrix screen. A modulated composite color light source of three primary colors illuminates the back-illuminator.

An optical device without moving parts is described which allows the display of standing pictures on the mantle of a drum which rotates with arbitrary angular frequency. The pictures can be seen from all sides without foreshortening and if an observer walks around the drum the picture follows his movements. With a simple variation motion pictures and 3-dimensional images can be shown on this cycloramic display.

X-ray absorbing grids have been proposed for the preparation of composite pictures to be used with lenticular screens for three-dimensional reconstitution. As a first step towards the transfer of this technique to television screen, we have developed the synthesis of the same type of document, starting from conventional pictures taken at various angles with a classical radiographic device. The main advantages so obtained are : - the elimination of the absorption by the grid system, which amounts to a sizeable decrease of the absorbed dose. - the possibility of digital picture preprocessing.

The introduction of a pair of co-ordinated measuring marks into a stereoscopic television display has enabled information to be obtained concerning depth in the preceived image. This is a real time technique which makes use of photogrammetric routines which are normally applied to ordinary photographic cameras. Information relating to the introduction of such measuring marks into the stereo-model, calibration of the system and factors affecting the resolution are presented in this paper.

The display of data in three dimensions overcomes the ambiguity often found in two dimensional displays. A truly objective examination of the display data is allowed while two-dimensional displays require a subjective interpretation of what might exist in the Z direction. Data can occupy a volume of 20 X 25 X 30 centimeters since SpaceGraph allows the display of data in a volume filling manner. The display volume is generated by observing the reflection of a CRT in a circular mirror. The mirror is flexed about a rubber hinge located on a concentric circle several inches from the edge. By exciting this assembly with a hi-fi woofer, the mirror is caused to vibrate and takes on concave and convex optical shapes thus varying the focal length. The varying focal length causes the image of the CRT to sweep out apparent distance in Z of about 30 centimeters. By plotting points on the CRT in X and Y, these points permit us to draw vectors which can describe a wide variety of three-dimensional objects, such as molecules, mechanical subassemblies or total assemblies such as aircraft and ships. In the vector mode, SpaceGraph provides 23 meters of vectors which can appear in as many segments as required by the object being displayed. The three-dimensional display can also be used in a second mode which can be called the image mode. In this mode, X and Y are controlled to generate a raster much like one generated in a conventional home TV. While the raster is being swept, brightness is varied to provide an image in gray shades. As this process takes place, the Z is continuously swept by the mirror as in the vector mode and a volume filling image is created. This mode appears to be of particular interest in computer-aided tomography and to seismologists. Computeraided design, ultra sound analysis, anti-submarine warfare and air traffic control are other applications or views of science which appear promising for 3-D displays.

This report provides a brief, general overview of an ongoing program of research at the Naval Ocean Systems Center (NOSC), Hawaii Laboratory, to assess the value of three-dimensional imagery for the control of remotely operated work systems. The effects of visibility conditions, learning, task demands, pseudo-movement parallax, hyperstereopsis, and isomorphic linkage of camera movements to operator head movements are discussed.

A useful method that makes stereotactic neurosurgery safer, is developed. It yields an integrated stereoscopic image of the cerebral blood vessels, CT view of tumor and simulated electrode trajectory, allowing the surgeon to choose any electrode direction that looks convenient to him, without imminent danger of causing a haemorrhage.

A new and unconventional method for picture representation has been used to produce a fully animated sequence of graphical images. Based on this concept a very fast display processor has been designed with the capability to show coloured surfaces and which also handles the problem of hidden surface elimination at video rate. The purpose of the project is to transfer a picture of a person's face at low bit-rate. This paper focuses on the reconstruction process, which is based on a model for the objects and how they are synthezised into real-time animated pictures at 50 frames/second.

By employing the operator form for the solution of Helmholz equation it is a simple task to discuss the following characteristics of a diffracted wavefield: Its symmetry properties are obtained by simple inspection. The self-imaging phenomena is described in terms of the solutions of simple differential equations. The influence of focus errors is identified with some successive derivatives of the bandlimited version of the object.