Although the two-step holographic technique for producing white-light-transmission, or "rainbow", holograms has proven the most practical for producing display images, one-step apertured-lens techniques can also be useful in producing such holograms. Typically, the diameter of the lens limits the field of view, but not the image size, for pseudoscopic image presentation, or imposes an intermediate vignetting aperture in the orthoscopic case. Here we describe how the combination of conjugate wavefront illumination and conjugate diffraction can be used to produce a large-area, undistorted, orthoscopic image, with only the field of view limited by the lens size. The resulting holograms enjoy very high image contrast, and rival the results of the two-step process in many respects.
The technique of the recording of standing wave pattern near the mirror surface was proposed by the French scientist, G. Lippman, to obtain color interference images. The purpose of this paper is the discription of a similar technique in holography which can give a number of interesting possibilities.
The holographic display recorded in silver halide materials is often problematical in terms of image quality and signal to noise ratio. This paper outlines some of the reasons for the deficiencies and points the way to successful recording and replay. The cases of transmission and reflection holography whilst ostensibly totally different, in fact, depend on the same basic mechanisms. The transmission display is, by its nature, much more tolerant of processing inadequacies but it is of interest to compare the problems between the two modes. Proposals are made as to the mechanisms of modulation and how these may be successfully exploited in the face of emulsion layer difficulties with existing photographic products.
The image quality obtained from a hologram depends to a great extend on the concerned wavefronts correctness. Departures from the assumed ideal wavefront exact profile and geo metry perfection lead to a loss of image resolution and diffraction efficiency. The problem is analysed by recourse to a wavefront representation in terms of the spatial frequency spectrum. The effects derived from the imperfect optical quality of the holographic recording medium and eventually the supporting substrate are considered. The problem is ana-lysed, in particular, for the wedge phase error and the sinuosoidal perturbation. The obtained results permit to derive a tolerance range for wavefront defects and therefore the substrate quality requirements. Relevance of the analysis to different applications are briefly discussed.
A variety of DCG (dichromated gelatin) recipes are already well known. We have developed a useable characterization of DCG and appropriate, reliable tools to manipulate physical Bragg planes. The Graube coagulation or "krinkle" model is useful to demonstrate wavelength and do controls that facilitate the fabrication of a variety of unique optical elements.
The holographic information storage technics and the formation of good optical elements require a high quality recording medium. For any given application, one should take into consideration the material characteristics such as: diffraction efficiency, signal-to-noise ratio, resolution capability, exposure and spectral sensitivity, spatial frequency response, processing requirements, operating environment, chemical and physical stability, and re-procity failure. One of the best holographic materials is dichromated gelatin, because its optical properties as a phase hologram are very close to ideal.
A cylindrical holographic stereogram (CHS) is synthesized by using a series of photographs which have only the horizontal parallax, and the reconstructed image has distortions. Images reconstructed from a CHS of laser reconstruction (LCHS) and a CHS of white light re-construction (WCHS) are calculated under various conditions, and the optimum conditions for making and viewing the LCHS and WCHS are studied.
The sensitivity in holography and in ordinary photography are discussed in terms of the signal-to-noise ratio. It is qualitatively shown that the idea that holographic imagery may be far more sensitive than conventional photographic storage is not correct, at least not for linear recording.
Since the introduction of television, various types of three-dimensional video systems have been used for industrial, medical, educational and entertainment purposes. The systems can be divided into two classes: (1) Stereoscopic Video Systems, which require special glasses or viewing aids; (2) Autostereoscopic Video Systems, which do not require glasses and are viewed by free vision. The two or more images required for these displays are picked-up by stereo optics with a single camera and multiplexed on a single communi-cation channel or they are picked up by two or more cameras utilizing an individual channel for each camera. One or more CRT's with stereo optics are employed in the receiver. The stereoscopic display provides the viewer with added realism and spacial information not available in any other manner. For entertainment purposes, the 3D picture enhances almost any program, including sports, drama and news. Typical industrial applications are for: remote viewing in connection with the remote driving of vehicles or operating manipulators; educational studies of solid geometry and atomic structure; and medical studies of surgical procedures. Stereo video also is being used in connection with microscopic optics to provide a stereo video microscope which has numerous advantages over a conventional optical microscope.
The concept of lenticular sheet 3-D pictures dates from the beginning of this century. This method is responsible of commercial 3-D post-cards and 3-D photographic portraits. New applications are presented in this paper. They concern two domains where direct holographic 3-D reconstructions are impossible. These applications are the 3-D reconstruction of electron microscope pictures and the 3-D projection on a lenticular screen.
Several practical problems which arise in optics are related to achieving a desired three-dimensional signal distribution inside a bounded spatial domain. If we deal with harmonic time dependence, we find an example in integrated circuit microfabrication; if time dependence is arbitrary, we may think of pulse compression in dispersive media. To all of these problems there is a unifying approach based on axiomatic system theory. This theory is well-known to rely on the state space formulation. The way in which the in put acts on the state is quantified by the "controllability" concept. Similarly "observability" relates output data to the state. Strictly related to this approach is the "opt-imal control problem", where the task is to find an input which minimizes a functional consisting of two addenda: a physical term comparing the obtained output with the desired one by some quadratic criterion, and an economical term related to the cost of a given input. These concepts are widely used in signal processing, control theory, etc. Their application to optical problems requires them to be extended to distributed parameter systems. For the cases discussed in the text controllability results will be given and optimal control problems will be stated.
Lets imagine five centuries earlier. Strasbourg. How many people had seen, really seen the cathedral? A few hundred thousand, who from the surrounding area, could see its steeple recisely cast into the air as a signal to be seen from as far away as possible. To these people, add those who knew it from engravings, drawings, colourings, coins perhaps sketches or maybe models-masterpieces, tabernacles, to stipulate a contour over talked about to all of Europe from Alsace, but so rarely seen. Contour social contour, cultural contour, techni-cal contour, etc...locally narrated, abundantly present in the chronicle, at the center of all discussions: oral designation of an object, real, but not really tangible.
Although I don't consider the architectural domain as being on the same level as that of building production, I will voluntarily limit my theoretical approach to architecture within the frame-work of this expose to the branch of production.
The attempt to produce animated, three-dimensional image representations has haunted the occident since the 4th century-the camera ottica and the zograscope have answered the camera obscura as its prolongation and as its amplification -with the invention of photography (Niepoe Daguerre) the same phenomenon occurred: the appearance of stereopho-tography (principals stated by Wheastone and applied by Brewster, then Dubooq). -the same phenomenon happened again with cinema-tography the stereocinematography (screening, embossing, anaglyhic, polaroid glasses processes, etc...), haunt researchers. -finally, holography which, although depending on a space produced by a major technological jump, follows this quest of the reproduction of the effect of stereoscopic vision.
Plato distinguishes the imitation arts, painting and sculpture, and the imaginative arts, reduced as one: architecture. It's a question of imagination, of representation by a dreamt image, of the object as it will be in the future: nature is not dead, it is a project.