Transmission Holograms Research Articles

Interactive computation of holograms using a look-up table

Several methods of increasing the speed and simplicity of the computation of off-axis transmission holograms are presented, with applications to the real-time display ofholographic images. The bipolar intensity approach allows for the real-valued linear summation of interference fringes, a factor of 2 speed increase, and the elimination of image noise caused by object self-interference. An order of magnitude speed increase is obtained through the use of a precomputed look-up table containing a large array of elemental interference patterns corresponding to point source contributions from each of the possible locations in image space. Results achieved using a data-parallelsupercomputer to compute horizontal-parallaxonly holographic patterns containing six megasamples indicate that an image comprised of 10,000 points with arbitrary brightness (gray scale) can be computed in under 1 s. Implemented on a common workstation, the look-up table approach increases computation speed by a factor of 43.

New coding technique to obtain multilevel computer-generated holograms in one step

We used a binary coding scheme based on optical density inside a basic cell to produce a smooth multilevel phase pattern on a photoresist film. This technique, which is as simple as a contact copy, is very easy to control for our type of computer-generated holograms. Preliminary results show that a good blazed profile can be obtained with minimum equipment at low cost. Specialized transmission holograms produced with this technique showed a 40% diffraction efficiency and good quality for 632.8-nm radiation.

Cr(VI)- and Fe(III)-doped polymer systems as real-time holographic recording materials

Volume transmission holograms have been recorded in dichromated poly(vinyl alcohol) (DCPVA), dichromated poly(acrylic acid) (DCPAA), and ferric chloride poly(vinyl alcohol) (FePVA) films using a 488-nm light (from an argon-ion laser), and the hologram development has been monitored in real time using a 647-nm line of the krypton laser. The influence of different chemical parameters (e.g., pH and electron donor) on the holographic efficiency has been determined, and an efficiency value as high as 70% was achieved in all three recording media. Further, the possible primary photoprocesses responsible for the hologram formation are tentatively identified and discussed

Recording of multiple holograms in photopolymer films

Multiple images were recorded in DuPont HRF-150 photopolymer as transmission holograms by using angle multiplexing. Agreement with Kogelnik's two-wave diffraction theory for phase gratings, the time considerations and its effect on dynamic range, the necessity of a pre-illumination pulse, and good image quality at readout are reported.

Projection x-ray lithography using computer-generated holograms: A study of compatibility with proximity lithography

X-ray projection lithography has recently been explored as a method for the manufacture of ≤200 nm linewidth integrated circuits. A method was previously described [J. Appl. Phys. 71, 2993 (1992)] whereby projected lithographic images can be formed with x rays by means of a transmission hologram. The form of the hologram is computed by an algorithm which eliminates the unwanted signals normally present as systematic errors in in-line holographic images. Such an approach to projection x-ray lithography requires an x-ray beam with very little coherence and is thus compatible with high wafer throughput schemes; in addition, image fidelity remains high even when moderately small contaminant particles block the light from small regions of the hologram. Previous example calculations involved using 5 nm x rays to illuminate a 0–1 μm thick carbon hologram located 200 μm from the wafer to produce simulated 0.06 μm linewidth images with good fidelity and with 6 μm depth of field. Presented here are simulations involving holographic masks made of 0–1 μm of tungsten operating at 1 nm wavelength with 50 μm mask-to-wafer gap. Such a configuration can be viewed as a future extension of the existing technology of proximity x-ray lithography to linewidths as small as 0.02 μm.

Influences of Recording Geometry Parameters on Diffraction Efficiency in Bleached Silver Halide Transmission Holograms

Abstract The experimental results of diffraction efficiency as a function of the geometrical disposition of recording beams in bleached silver halide transmission thick-holographic gratings are presented. Two variables have been used to relate these results with certain geometric parameters. These variables are spatial frequency and the slant angle of the interference fringes in the material. The experimental results obtained show that while maximum diffraction efficiency and refractive index modulation depend strongly on spatial frequency, they vary little with slant angle.

Improvements of a spatial frequency analyzer for automated characterization of holographic recording materials

A spatial frequency analyzer was designed to simplify characterization studies for new holographic recording materials. Mechanical movements were automated and a complete informational system gave rapid characterization results. A good fringe stabilization unit was improved by adding simple holographic optical beam combiners. Experimental characterization of two different recording materials shows the versatility of this automated apparatus. Also we present modulation-transfer-function curves of dichromated gelatin between 500 and 3500 cycles/mm obtained with polarization volume transmission holograms.

Interchange Between Reflection and Transmission Holograms Using Mirrors

Abstract Using a single mirror in contact with a hologram in reconstruction leads to a variety of interesting properties. We discuss some of these for very simple transmissive and reflective holograms. One experimental result is also presented for demonstration.

A technique for projection x-ray lithography using computer-generated holograms

X-ray projection lithography has recently been explored as a method for the manufacture of <200 nm linewidth integrated circuits. A method is described whereby projected lithographic images can be formed with x rays by means of a transmission hologram. The form of the hologram is computed by an algorithm that eliminates the unwanted signals normally present as systematic errors in in-line holographic images. Example calculations are shown in which holograms are constructed to generate images of a given test pattern. The holographic images are shown to have excellent fidelity with respect to both resolution and contrast. Such an approach to projection x-ray lithography requires an x-ray beam with very little coherence and is thus compatible with high wafer throughput schemes; in addition, image fidelity remains high even when moderately small contaminant particles block the light from small regions of the hologram. Fabrication limits for the single optic involved are compatible with current technological limits. The approach is applicable over a large range of soft-x-ray wavelengths, indicating the feasibility of a 100 nm resolution system with 6 μm depth of field using a carbon mask system operating at 5 nm, or other materials at shorter wavelengths.

A Discussion of Two Holograms: "Pasqualina" and "Trace"

The back plate contains an imfrom his current body of work, the author briefly discusses each holoage of a glass box with a photogram and the conceptual, esthetic graph of a tree on its back wall. and technical impetus behind it. The face appears to float 13 cm in front of the arch and its surrounding pattern, while the glass box floats 30 cm behind the back plate. Layering the individual plates allows the opportunity to articulate the space between them. This is a space of intense activity, a chasm where light is focused and concentrated. The woman's face is filigreed with the tree's branches, which are convoluted and brain-like as they tangle with her features. The arch encloses the face while the accompanying pattern overlaps the outer edge of the glass box and tree. I manipulated the photographic images of the face and tree prior to making the piece. Cropping, double exposing and making contrast changes helped to further distance the photographs from their concrete referents and analogical sources in nature, allowing the images to point instead to a mysterious quality that stands outside the objects themselves. The front plate was created using two types of holographic techniques-one for the face and another for the surrounding arch and pattern. I used the standard master/transfer rainbow technique for the face. The arch and pattern were created using the one-step rainbow technique, which requires three separate exposures to blend the colors together. Because of the slightly different table geometries used for each of the two techniques, the different images appear shifted in color (e. g. the face appears yellow while the surrounding images appear reddish orange). As the viewer moves, the colors change, relative to one another. The face fades to a deep blue and eventually disappears, Dean Randazzo (holography artist), 2022 West Crystal, Chicago, IL 60622, U.S.A. Received 4 February 1991. LEONARDO, Vol. 25, No. 5, pp. 493-495, 1992 493 This content downloaded from 157.55.39.181 on Thu, 29 Sep 2016 04:54:41 UTC All use subject to http://about.jstor.org/terms Fig. 1. Trace, 5-x-7-in white-light transmission hologram designed for viewing from both sides, 1990. Side 1 (top) contains an animated dog and two walking figures that cross and overlap each other. Side 2 (bottom) contains images of a walking figure, a spinning metal object and a dog. leaving only an arched window through which one can see the glass box and tree visible in the background. The colors mix and blend where the images overlap. The face glows with a softer, less acidic hue than those produced using the rainbow technique alone. The ephemeral images of Pasqualina resonate with spiritual and religious overtones. The piece is a reliquary for light, a 'monstrance for memory', where the very process of photography is reversed. The photograph is freed from its material constraints as light is returned from whence it came, dispersing and fleeing into open space. I have imbued Pasqualina with a potential, a possibility for images to interact and change. None of this potential is realized (or even exists) until the viewer interacts with the work. In a sense, the actual piece comes partially from within the viewer and is drawn out by each one's physical and cognitive interactions with the space and light encoded in the work.

Wide field of view transmission holography

We present a new type of hologram recording geometry employing a waveguide hologram beamsplitter. Due to the unique properties of this configuration, achromatic transmission holograms with wide field of view have been recorded. Modifications of this novel holographic recording procedure may lead to a compact holographic camera.

Magnetic film holder for holography

A simple magnetic film holder for holography is described. Reflection or transmission holograms can be obtained with the film holder.

Double exposure planar transmission holograms recorded in nonlinear dichromated gelatin

A coupled wave model is used to describe the replay of two transmission gratings (G(1) and G(2)) which have been recorded in dichromated gelatin at high exposure energies. As a consequence of material nonlinearities, a third grating G(3) , which has a spatial frequency equal to the difference of the two primary recordings, is also recorded. The model assumes multiple interactions between each of the three gratings and is used to match experimental data where the recording angles were (a) far apart so as to minimize interactions and (b) close together to enhance grating interactions. Good theoretical agreement was found with experiment for both cases.

Dichromated polyvinyl alcohol films used as a novel polarization real time holographic recording material

Real time recording and reading of volume transmission holograms were performed with dichromated polyvinyl alcohol thin solid films (31 microm) that were easy to prepare and use. Real time holograms of high diffraction efficiency were produced without any chemical development, but these films were not erasable. The present holographic study of dichromated polyvinyl alcohol films permits the consideration of many engineering applications.

Photorefractive barium sodium niobate

Abstract Recording of transmission and reflection dynamic holograms, beam coupling, phase conjugation due to backward-wave four-wave mixing, and coherent optical oscillation with frequency degenerate pump have been studied in nominally pure barium sodium niobate crystals.

Holography and Art in a Research Laboratory: A Retrospective

he activity of a research laboratory is like a book divided into several chapters. Each chapter is like a research project with a beginning and an end, evolving in time. What a surprise for a scientist opening this book to come upon some pages dealing with artistic activities! Such activities are not being carried on currently at our laboratory, but for a number of years they were. The laboratory was established in 1947 by P. -M. Duffieux. In 1963 J. Ch. Vi6not succeeded him as the head of the laboratory. At that time, the research activities were focused on studying and developing the laser beam based on the optical concept of the Fourier transform introduced by Duffieux. Since 1963 holography and coherent optics have been carried out with adapted filtering and holographic interferometry. The first holograms (20 x 25 cm) were recorded in 1965. About 1973, a few new lines of research were developed, such as information processing, optical metrology by means of speckle techniques, acoustic holography and flow visualization. During the 1980s, the main research activities have been in new fields such as telecommunications and biomedicine. Computer equipment is curFig. 1. Robe de Qiana, transmission hologram, 60 x 50 cm, 1975. (Photo: Doc. Lab. Optique, Besancon). One of seven holograms of models wearing F. Olivier's ready-to-wear collection shown in a shop window in Paris.

A Journey Towards Creative Holography

his is a description of a personal journey and is therefore largely a subjective account. I am not seeking to define what 'art holography' is, nor am I advancing a holographic aesthetic. Rather, I am interested in examining the distinction that I feel exists between display holography in general and creative display holography. By display holography, I mean the type of hologram that is normally framed and exhibited as a painting would bethough much of my discussion is equally applicable to other forms. In defining 'creative', I do not claim that creative holography is necessarily 'artistically good' holography: 'creative' refers to a certain approach to making display holograms, the end product not automatically having any consequent artistic merit. It is, of course, possible for a creative display hologram to be visually less appealing than a display hologram of the type I would consider noncreative. The question of what makes some holography fundamentally creative is worth consideration if only because such holography requires a different response from the viewer and because it should raise fundamental questions about holography itself. The first holograms I saw in 1983 were of type that I would not now regard as creative; they were essentially spectacular, consisting of forceful demonstrations of certain properties of holography, mainly of three-dimensionality. If I call such holograms spectacular or, borrowing from Graham Greene, describe them as entertainments, this is not in disparagement. It was the impact of seeing such holograms that motivated me to make a hologram for myself-not to make better holograms, not to become a holographer, but quite simply to make a hologram virtually as a self-challenge. I had no background in art or science (such a lack of background was perhaps not to prove a total disadvantage later). I was not handy, nor had I ever shown any signs of the dogged single-mindedness with which I embarked on the necessary background reading [1] and construction work and overcame the difficulties of obtaining optical equipment. Behaviour so atypical can hardly have been provoked only by three-dimensionality; but whatever the other hidden stimuli, it was in fact three-dimensionality that I was after when, about a year after first seeing a hologram, I was ready to try to make one of my own. By then I had read enough about holography, its theory, its applications and its implications in terms of physics and philosophy to be aware that the potential of holography was greater by far than the representational, even re-creational, type of hologram, that I wanted to make. Nevertheless, what I did, and that with infinite pride and sense of achievement, was to make a small transmission hologram of a plastic swan from a Christmas cracker.

"Cosmetic Series" 1985-1987: A Personal Account

N > owadays, whenever I am asked for my thoughts on the future of holography, I become evasive. I think back to the days when I made my first holograms. It may not even occur to those artists now entering the field of holography that there was a long period when it was by no means certain, as it is now, that holography was here to stay. In those days (1968-1973), the only technology available to me, as a lone (and female) artist making holograms in Britain, was the laser transmission hologram, which could only be exhibited with specialized light sources and in darkened conditions. Although I knew that it was necessary for holography to advance beyond such primitive technology in order to have a future, I was so preoccupied with bringing to light as many ideas as I could with the technology available that I tried not to think about this obvious fact [1 ].

Some Thoughts on Holographic Portraiture

to make a hologram of a todlographic studio, the manipulation of visual depth and the technical difdler fascinated by his melting dlecreasmcinae by hisme oftn ficulties in producing a hologram. ice cream cone and one of a 6-year-old, with gold teeth flashing in a happy smile, making a complicated cat's cradle figure, his extended fingers creating an abstract first plane pattern against his white shirt. The laser transmission hologram produced a visual depth of almost a meter, so that when composing the hologram I considered it as a view into a parallel world with its own space, subject to its own optical laws, rather than as a canvas or a painting. Since I was dealing with portraiture, my challenge was to highlight the human subject by bringing out its unique being. At the same time, I had to consider the subject as a sculptural volume made out of light and place it in meaningful relation to other volumes and shapes in the sculptural light-space. In many ways, a pulse laser transmission hologram offers the most versatility for the artist because it offers the most freedom. A wonderful meter-deep holographic space lies ready to be shaped; depth, size and complexity are limited only by the power of the laser and the imagination of the holographer. A great constraint, however, occurs in the viewing of the hologram. The hologram can be seen only by placing behind it an expensive monochromatic point source, such as a helium-neon laser, or more commonly a filtered mercury arc or sodium light. For best viewing the room must be darkened. Green is the most commonly used filter for the mercury arc lamp, and yellow for the sodium. As a result, transmission portraits acquire an eerie green or yellow hue. Ana Maria Nicholson (holographer), 1044 47th Avenue, Long Island City, NY 11101, U.S.A. Received 6 April 1988. LEONARDO, Vol. 22, No. 3/4, pp. 369-373, 1989 369 This content downloaded from 40.77.167.32 on Sun, 04 Sep 2016 04:57:23 UTC All use subject to http://about.jstor.org/terms

My First 10 Years as Artist/Holographer (1968-1977)

but structured patterns, reminiscent of Constructivist art, though my philosophy is unlike that of Constructivism [9]. Ultimately, Holos 17 (1973), a laser transmission hologram (Fig. 3), was the result. A concave hemisphere recorded in the first exposure was turned around in the darkness between exposures so that it became a convex hemisphere. When recorded in the second exposure, the convex hemisphere met the light pattern of the concave hemisphere, whereupon we had a complete sphere, not outlined as such but formed by its own laser light pattern. We intended to use the laser transmission holograms as exhibition pieces, with the best of them as masters for white-light transmission imagery that would project frontally. Although segments of the H 1 (master) pseudoscopic design could be seen from a distance of approximately 30 ft, which I found tantalizing (and have shown this way), the total HI image was too large to emerge through the H2 plates to be seen easily at a moderate distance. Furthermore, the second-generation white-light holograms seemed to have unfathomable problems other than size. After much searching, it was finally determined that the emulsion on the secondgeneration plates was defective (we had been using Agfa-Gevaert 8E75; as all holographers know, it is not unusual to receive a batch of plates with imperfect emulsion). Since we had to redo the H2s, we put Fig. 4. Equivocal Forks I, laser transmission hologram, plate 11x 14 in, pseudoscopic image projecting in front of the plate = 24 to 30 in, 1977. (Photo: Nisham Bichajian) Using a cluster of forks as the object, I placed much effort in the frontally projected imagery so that the glass would not be an obstruc-