For someone who has been occupied with holography for almost 30 years in a variety of ways, it is gratifying to see its nearly 60 year history written and between hard covers. Of course there have been numerous potted histories before, in catalogues, text books and on websites, but none has attempted such a thorough or well-researched treatment previously. A historian of science and technology, and an optical physicist, Sean Johnston was clearly the man for the job.

At the beginning of this book I counted 81 acknowledgements. Johnston personally interviewed 50 assorted researchers, artists and entrepreneurs and consulted another 55 sources. The bibliography occupies 41 pages at the rear of the book and must represent untold hours of reading. The index stretches to 28 pages and is a veritable Who’s Who and What’s What of holography.

Johnston’s timing was fortuitous. Most of the founding fathers of holography, with the exception of Gabor, were still alive while he was doing his research and he was able to question them face to face. By the time of publication, Benton, Leith and Denisyuk had died and a chapter in holography’s history was over – a good moment, perhaps, to reflect on the past and assess the successes and failures of a still developing medium.

In his Preface, Johnston raises the question “Why attempt a history of what some still see as an immature subject?” and answers that “One reason is because notions of maturity carry questionable assumptions. Holography is a young science that illustrates how new subjects come to be. It provides answers to questions such as, How does a scientific subject materialize? How does its content stabilize? How do those who practice it come to recognize themselves as a distinct group? And how do its definitions and products depend on their environments?” He goes on to say that “This visionary subject exemplifies how science, technology and wider culture are woven inextricably in the modern world”.

Later, Johnston observes that “Like the multiple perspectives offered by the hologram… each community had a different vision of its problems and potential and each shaped a history and forecasts to fit”. Depending on your interest in and involvement with holography, different parts of this book may fascinate you more than others but Johnston has explored all its aspects in depth.

Overview of the book

The book is divided into four parts envisaging the development of holography as

1. An intellectual subject
2. A visual medium and scientific technology
3. A social practice
4. An economic and cultural activity

• Creating a Subject—examines the origins of holography in Britain, the Soviet Union and America and argues that it was the particular post-war context of science and industry, combined with a spirit of military exploration in the context of the Cold War, that explains the nurturing and flourishing of the original ideas.
• Creating a medium—focuses on the boom years of 1964–1973 and the frenetic research to extend the technical capabilities of holography.
• Creating an Identity—explores the disparate elements that came to call themselves holographers: Scientist-engineers, fine art or aesthetic holographers and artisanal holographers. The latter coming from ‘a distinct counterculture community to transform the subject during the 1970s with radical methods and goals’.
• Creating a Market—focuses on the commercial sprouting of holography alongside its popular understanding and the co-evolution of both the cultural meaning of holograms and viable commercial products.

My personal involvement with holography begins with the third section so, while I was familiar with many of the names at the beginning of the story, I had not seen their origins and interactions plotted so clearly.

Johnston takes us to an industrial electrical lab in Rugby, England where Dennis Gabor worked for British Thomson-Houston and conducted his original research, to a state scientific institute in Leningrad, USSR where Yuri Denisyuk did his, and to a classified research lab in Willow Run, Michigan, USA where Emmett Leith and Juris Upatnieks made the breakthrough that led to holography as we know it. We meet George W. Stroke, Professor of Electro-Optics at the University of Michigan, an uncongenial figure who constructed the first historical summary of holography and arguably its earliest and most influential packaging. He was influential in the awarding of the Nobel prize to Gabor in 1971 and denying the prize to his Willow Run rivals. (This is possibly the most controversial story to emerge from Johnston’s research).

We see inside the Conductron Corporation who were the first to commercialise holography and meet Kip Siegel the manager whose realisation that what one had to do to make money from holography was “to sell the promise of technology to investors” became the blueprint for many holography entrepreneurs to come. It was there in the late 1960s that mass produced holograms (500,000 laser transmission copies on film for the 1967 Science Year publication) first happened and that an artist, Bruce Nauman in 1968 and Salvador Dali in 1970, had their first chance to use the medium.

It is around this period that we first meet Lloyd Cross, an early worker with pulse lasers, whose subsequent activities as a teacher at the San Francisco School of Holography and manufacturer of holograms at the Multiplex Co would introduce holography to a wider world of artists and entrepreneurs.

Steve Benton makes his first appearance at Polaroid, under the relaxed regime of Edwin Land, and his invention of the rainbow hologram, adopted by artists and eventually commercialised as the ubiquitous embossed hologram, combined with his fostering of a spirit of communication through conferences and collaborations with artists, gets the recognition it deserves. Tung Jeong from Lake Forest College, who taught many workshops and hosted many conferences and Jerry Pethick, who conceived of the sandtable as a way of making holography accessible, are two other names that stand out from the early days.

As holography begins to move further into public consciousness we see the growth of exhibitions and museums, led by Posy Jackson and Jody Burns at the Museum of Holography in New York and later Matthias Lauk in Germany, the subsequent burgeoning of galleries and cottage-industry display holographers and the reluctance of the artworld to accept holography. We encounter Steve McGrew, Ken Haines and Mike Foster who give birth to the hologram embossing industry in the USA and Nick Phillips and Jeff Blyth who kick-start reflection holography in the UK. Testimony is heard from Jim Trolinger, Bill Fagan and others involved in the non-destructive testing applications of holography.

Women feature prominently in the development of art holography so we are introduced to Margaret Benyon, Harriet Casdin-Silver, Anait, Edwina Orr and Eve Ritscher amongst others.

This is not just a tale of relentless progress, however. Johnston recognises that there have been dead-ends and failures too and recounts the falling off in popularity of various aspects of holography.

The insider stories make fascinating reading and brought the book to life for me. As a non-scientist I cannot vouch for the accuracy of all the technical elements of the book, though nothing stood out as inaccurate, but the chapters that dealt with the entrepreneurs and artists in holography seemed to illuminate the whole picture very evenly. Doubtless there will be individuals who feel that their contribution to the story has not received sufficient attention (I was surprised not to see a mention of Walter Clarke as a business man or collector, for example) but I am sure that most would commend Sean Johnston for his thorough and wide ranging history.

Johnston writes well and tells the story persuasively in a way that should appeal to those interested in the sociology of science as well as to holography insiders. There are plenty of amusing passages as the urban myths and popular misconceptions about holography are identified and some of the wideboys and eccentrics attracted to holography make their appearance, and there are moving moments too as when Leith and Denisyuk finally meet in 1989 at the end of the Cold War and share a car journey : “The two, having travelled the same road half a world apart, could do so together at last”.

For the second edition, the misspelled ‘Agfa-Gavaert’ should be amended to ‘Gevaert’ and Pim Giebels would probably rather not be addressed as ‘Goebbels’, but in two readings I did not recoil at any howlers and could not imagine that any of the protagonists would be offended at the way their story has been told.

I think that Johnston has served the holographic community very well and deserves our support. I would hope that at least everyone whose name is in the index buys a copy, and a lot more too. And for all those with an interest in what holography might become, I would suggest that by reviewing the past we are perhaps more able to imagine the future.

There is an omission in the formula at the top of page 471. After the ferric sulphate line, add a new line as follows: ’sodium hydrogen sulfate, crystals…30 g’. Graham offers his apologies to any holographers whose bleach stage took three hours as a result of this omission.

Michael Harrison
www.dragonseye.com/Holography

About the author
Michael was born on an insignificant little blue-green planet orbiting an unregarded yellow sun out in the unfashionable backwaters of the western spiral arm of the galaxy and is a computer programmer currently working in the games industry. He has been interested in holography and has been making holograms since 1984, with a few long breaks for Real Life. He hopes to soon take over the world by combining his experience in 3D graphics with holography.

The release of Graham Saxby’s third edition of Practical Holography shows how well the author understands what people need from a complete book on holography. He takes the reader through what a hologram is, the history of holography, what sort of light sources can be used to make a hologram, what kinds have been made to date and so on through to making and displaying your own images.

The book is written in a clear and concise manner and is augmented by additional tips, definitions, and observations in the margins as well as extensive source references at the end of each chapter.

If you’re new to the field or hobby of holography you should make this one of the first books you buy. Even if you’re an old hand this book will probably show you a few new tricks.

Overview of the book

The first four chapters (What is a hologram, How holography began, Light sources for holography, The basic types of hologram) should be read through by anyone starting out in holography. You don’t necessarily need to understand everything in those chapters right off, but by reading those basics you’ll be better prepared to digest the rest of the book.

The first chapter explains what a hologram is, interference, diffraction, amplitude and phase gratings in a way that most interested readers will have no trouble understanding.

The book continues through the history of holography, the light sources used to make holograms, the basic types of holograms and describes the materials and processing used in making holograms.

It’s in chapter six that Saxby begins explaining how the reader can make their first single-beam hologram using a gas or diode laser. This chapter has complete details on all the equipment needed, how to set it up, shoot it, process the exposed film and view your finished hologram. If you are unfortunate enough to end up with a dim or non-existent image (which is likely to happen the first time) the author takes you through the steps needed to find out what happened and how to fix the problem.

Chapter seven then takes the reader through more advanced single-beam configurations and introduces a few new tools and methods such as using a spatial filter, index matching film and multi-exposure techniques.

The rest of the book shows a similar progression, taking the reader through more complicated steps such as making transfer holograms, building a holography lab, creating master and copy holograms, homemade optical elements and so on.

For those with a mathematical bent, the first three appendices contain information you’ll want to read and digest after going through the first few chapters of the book. These appendices are clearly written and approachable even to those who aren’t particularly adept at mathematics. Saxby also includes an appendix with worksheets for computing the geometries needed for several forms of multicolor holograms.

If you’ve been around the block a time or two (or at least ridden with someone else) you might think that this book would offer little new material. In fact, there is plenty of material for the more experienced holographer. The material ranges from information on fiber optics use, color holography, edge lit holograms and beyond. See the included table of contents from chapter 16 on.

Differences between this and the previous edition

Extensive side notes have been added which expand on and clarify the information given in the main text. These comments could have been left out and the book would not have suffered but by adding them the author gives information that enriches the main text.

The chapter on light sources used for holography has been expanded to include information on diode lasers as well as new information on DPSS (diode-pumped solid-state) and white light laser sources.

The pages devoted to copying holograms have been greatly expanded from one chapter with six pages to two chapters of nearly thirty pages. These cover several techniques for copying both transmission and reflection holograms and close by covering the relatively new technique of edge lighting holograms.

Natural color holography now has a full chapter devoted to it which starts by covering how we perceive color as well as details on how the eye responds to light of differing wavelengths. Details are then given on how individual primary colors are commonly combined to form colors that you won’t find in the natural spectrum. From there the author describes how lasers of differing color may be combined on the table to create a simulated full-color image. While this chapter won’t give you all the details you need for natural color holography it will get you started and there are several references at the end of the chapter that can carry you further.

A chapter has been added covering non-silver processes for making holograms and even includes limited information on coating your own glass plates. This chapter starts out by mentioning the high sensitivity of silver-halide emulsions and discussing the major reasons for its use. Saxby moves on to the details of dichromated gelatin (DCG) use and outlines methods for mixing DCG, coating glass plates, exposure and processing. If you’re interested in extremely bright holograms, this section will definitely whet your appetite for rolling your own plates. From there he moves on to brief discussions of SHSG, photopolymers, photothermoplastics and other processes. He doesn’t go into the same detail in the later sections as he does for DCG but there are plenty of references at the end of the chapter.

Holographic stereograms now have an entire chapter devoted to them. This chapter includes instructions for making several different kinds of stereogram and details for creating good source material, usually photographs. The author even outlines some methods for computer control of a simple holoprinter as well as color control to obtain achromatic and full-color transfers.

A new chapter on the use of holography in biology and medicine includes information on hologram use for dental training, ophthalmology and stereogram use with PET and CAT scan data.

The appendix on processing formulas has been updated and expanded and now includes instruction on creating your own emulsion.

So, the book is perfect is it?

While there are a few typographical errors that the publisher is working to correct in future printings, there really isn’t much that I could find fault with. A few relatively minor complaints are detailed below.

Interferometer testing isn’t introduced until chapter 11 but making your first hologram begins in chapter 6. The reasoning behind this is likely twofold.

1. All the table setups prior to chapter 11 involve using a single beam for the reference and object light and there are less stringent stability requirements for single-beam setups.
2. Setting up an interferometer requires two mirrors, one beam splitter and one lens as well as mounts for all of those elements and Saxby makes an effort to minimize the equipment needed to get going.

Forcing the reader to buy additional optics needed only for the interferometer could be seen as an impediment to bringing people into the field. My only complaint with that reasoning (if that really is what determined where table testing was placed in the book) is that knowing your environment can be critical in understanding your failures when starting out in holography. You will have a few failures in the beginning, especially if you’re not working in a dedicated laser lab. While single-beam setups are less sensitive to vibration problems, they aren’t immune and testing your area with an interferometer can give you invaluable information about what limitations you start out with.

Not all film listed is still available (Kodak no longer makes plates) or available to the general public (most photopolymer material). This is not surprising as this is an area of the field that is in constant change. New materials are appearing as old materials are being refined or disappear completely. You’d be better served by doing an Internet search or checking in the Holography Forum (www.holographyforum.org) for the current state of the art.

My soft cover copy is only three months old and is already coming apart at the binding. This may be a problem with that particular run.

All three editions of Practical Holography have included a hologram of some kind. The first edition actually included two, an embossed hologram on the cover and a silver-halide hologram on the first page. Unfortunately the second and third editions have only included embossed holograms on the cover and while I’m sure that type was selected for the relatively low production cost, they are not the best examples of the art. The depth of field available with embossed holograms is severely limited and while they are visible in almost any light, embossed holograms lack the impressive sense of 3D available from simple reflection holograms on silver-halide or photopolymer.

Summary

I have no trouble at all in recommending the third edition of Practical Holography to everyone interested in holography. There’s something for every holographer in this book.

Table of contents

Following just a few simple rules anyone can shoot a parallax sequence on film or video that can be directly converted into a hologram image. The first consideration is that the motion must be going in the correct direction in order to yield positive stereoscopic parallax in the hologram. The reason for this is very simple: one’s left eye must be presented with the left image and the right eye must see an image in the sequence that is to the right of the first image.

Direction of stereoscopic parallax in a hologram

This is true throughout the parallax sequence, thus if image #12 is seen by the left eye then the right eye must be observing an image that is to the right, such as image #20. If the order is reversed, then the left eye will be seeing a frame that should be seen by the right eye (and vice versa) and the three-dimensional image will be pseudoscopic, i.e. spatially inside-out, with the background seeming to be in front of the foreground subject.

The camera motion must be in the correct direction to make a positive stereoscopic parallax

Luckily with the aid of a computer and video-editing and image manipulation software is it possible to re-arrange the order of the sequence, in the event that the parallax is going in the “wrong” direction, but it is a lot easier to film it correctly in the first place, so that the hologram image is orthoscopic.

This is achieved by having anti-clockwise camera motion when orbiting the scene, or left-to-right camera motion when making a lateral pass by the subject. Alternatively, orthoscopic parallax is produced by having the subject move right-to-left or rotate clock-wise on a turntable in front of a fixed camera [33]. Footage that dates back to a previous century can now be digitally manipulated to extract the temporal parallax information that it contains and to translate it to stereoscopic parallax to produce a three-dimensional image.

Where as the subject moves laterally past the camera or rotates the footage will have some parallax that can often used to create a three dimensional image. To create a three-dimensional portrait just a few frames of temporal parallax are required. Where elements in the scene do not move, such as the background, they can be digitally removed and a new background with parallax inserted.

Once a sequence of images from movie film or video has been digitized it can be manipulated in several ways: to eliminate parts of the image, add new elements, modify size or shape discrepancies, create new intermediate frames between key frames, or even create synthetic 3D from 2D images.

As well as live-action films, temporal parallax is now common in animated feature films like “Toy Story”, “Shrek”, “Monsters Inc”, “Final Fantasy” and others where the animation is made using computer generated models rather than flat artwork.

It is possible to have absolute control over the camera angles within the virtual environment, so adding temporal parallax to increase the realism is now commonplace. Likewise, in computer games temporal parallax has been found to increase the realism of games like “Tomb Raider”. Any animated character that exists as a computer models can be quickly and simply down-loaded to make a three-dimensional hologram image.

The rules governing the use of computer models are the same as for deriving parallax from video or film, in that the model must be correctly moved with respect to the virtual camera.

Computer-generated models are now part of the manufacturing process of a wide variety of commercial products, as well as architectural, aeronautical, pharmaceutical and medical imaging.

From scanning electron micrographs of tiny particles of matter to the NASA images of alien worlds brought to us from outer space, parallax is everywhere and this revolution in digital imaging now permits the data to flow directly from the client’s computer to be be digitally written into a full-colour three-dimensional hologram.

Postscript

My sincere thanks to all the holographers working on dot-matrix and direct-write 3D imaging systems who helped me to compile the final sections of this paper by sending text, images and sample holograms. Your assistance was very much appreciated.

References

[1] Umberto  Eco 1987 Travels in Hyper-reality Picador

[2] Umberto  Eco Ibid

[3] R. V. Pole Jan 1968 3-D Imagery and Holograms of Objects Illuminated in White Light Applied Physics Letters 12 (1) 10–12

[4] Bruce  Lane Stereoscopic displays SPIE 367 20–32

[5] G.  Lippmann March 1908 Comptes Rendus 146 446–451

[6] J. T. McCrickerd and Nicholas George 1968 Scaling and Resolution of Scenic Stereograms SPIE 15, Holography 161–165

[7] D. J. De Bitetto March 1968 Bandwidth Reduction of Hologram Transmission Systems by  Elimination of Vertical Parallax Applied Physics Letters 12 (5) 176–178

[8] D. J. De Bitetto 15 May 1968 Transmission Bandwidth Reduction of Holographic  Stereograms Recorded in White Light Applied Physics Letters 12 (10) 343–344

[9] D. J. De Bitetto August 1969 Holographic Panoramic Stereograms Synthesized from White  Light Recordings Applied Optics 8 (8) 1740–1741

[10] Stephen  Benton October 1969 Hologram Reconstructions with Extended Incoherent Sources Journal of the Optical Society of America 59 1545–1546

[11] S. P. McGrew Diffractive Color and Texture Effects for the Graphic  Arts, Patent WO 82/01595

[12] S.  Smith and T. H. Jueong Method and Apparatus for Producing Full Color  Stereographic Holograms, US Patent No. 5,022,727

[13] June 1994 Munday markets DI-HO System Holography News 8 (5) 1&7

[14] E.  van Nuland and W. Spierings 1993 Development of an Office Holoprinter III SPIE 1914 9–24

[15] Fujio and Kazuhiko Ohuma  Iwata October 12–14, 1988 Grating Images Optical Security Systems Proceedings

[16] S.  Takahashi Method for producing a display with a diffraction grating pattern and a display produced by the method, US Patent No. 5,058,992 (Oct 1991)

[17] S.  Takahashi, T. Toda and F. Iwata Method of manufacturing display having diffraction  grating patterns, US Patent No. 5132,812 (21 July 1992)

[18] Frank  Davis Holographic image conversion method for making a  controlled holographic grating, US Patent No. 5,822,092 (filed  16 May 1988, granted 13 Oct 1998)

[19] Craig  Newswanger Holographic diffraction grating patterns and method for  creating the same, US Patent No. 5,291,317 (filed 12 July 1990,  granted 1 Mar 1994)

[20] Frank  Davis System for making a hologram of an image by manipulating object beam characteristics to reflect image data, US Patent No. 5,822,092 (filed 16 May 1988, granted 13 Oct 1998)

[21] Toppan Bulletin No. 28, pages 5 & 6, May 1994, & Fujio  Iwata, private communication, Toppan Printing Co, Ltd  Technical Research Institute, Tsukuba Research Laboratory, 4-2-3  Takanodai-minami, Sugito-machi, Kitakatsushika-gun Saitama  345-8508, Japan

[22] T.  Hamano and H. Yoshikawa 1998 Image-type CGH by means of e-beam printing Proc. SPIE 3293 2–14

[23] T.  Hamano, M. Kitamura and H. Yoshikawa 1999 Computer-generated holograms with pulse-width modulation  for multi-level 3D images Proc. SPIE 3637 244–251

[24] T.  Hamano, M. Kitamura and H. Yoshikawa 2000 Computer-generated holograms for reconstructing multi 3D  images by space-division recording method Proc. SPIE 3956 23–32

[25] T.  Hamano and M. Kitamura June 2000 Feasibility study for making electron-beam CGHs Holography (SPIEs International Technical Group Newsletter) 11 (1) 3

[26] Chih-Kung  Lee et al. Jan 2000 Optical configuration and color-representation range of  a variable-pitch dot matrix holographic printer Applied Optics 39 (1) 40–53 Julie  Lee private communication. Ahead Optoelectronics, Inc  No. 13, Chin-Ho Road, Chung-ho, Taipei hsien 235, Taiwan

[27] Pawel  Stepien private communication. Polish Holographic Systems s.c., Kazimierzowska 76 m 7, 02-518 Warszawa, Poland. pawel_stepien@wa.home.pl

[28] Rob  Munday private communication, e-mail rob@portraits.co.uk Spatial Imaging Ltd, Shepperton Studios, Shepperton, Middlesex TW17.

[29] Diana  Newcomb private communication. Pacific Holographics Inc 503  Caledonia St. Santa Cruz Ca 95062

[30] Light Impressions International Ltd, 5 Mole Business Park 3,  Leatherhead, Surrey KT22 7SL. TEL: 44-1372-386677 FAX44-1372-386548 http://www.lightimpressions.com

[31] Brian  J. Monagahan and Anthony Heath private communication, International Holographic Paper http://www.ihphologram.com 300 High Point dr., Chalfont, PA 18914

[32] The Matrix ©1999 Village Roadshow Films (B.V.) Ltd  Warner Brothers. Clips from “What is Bullet Time” documentary  from The Matrix DVD & Video

[33] David  Pizzanelli Aspects of Spatial and Temporal Parallax in Multiplex Holograms, a study based on appropriated images, PhD Thesis, Royal Collage of Art, 8 July 1994

David Pizzanelli
DavidPizzanelli@LightImpressions.com

About the author
David is the Sales and Marketing Manager for Light Impressions International Ltd. He has been actively involved in the hologram industry since 1979, as Holographer and Director at Hollusions Ltd Cambridge and at SEE 3 Holograms Ltd London. In 1994 he was awarded a PhD in Holography at the Royal Collage of Art, London. David has served on the Board of the IHMA and as Chairman of the IHMA, and is an acknowledged expert on the subject of security holograms.

Holography has in the past been acknowledged as the most realistic of three-dimensional imaging techniques giving, on occasion, an image of an object that was so life-like that a casual observer might mistake the virtual effigy for the real thing.

Before white light reflection holograms became generally available the only holograms that anyone could see were laser transmission holograms. Looking into a laser transmission hologram was like looking through a window into another world. As one peered through the glass plate one could not only see the subject of the hologram, but the optical components behind it and often the laser table as well. If it was a pulse laser transmission hologram sometimes one could see the whole room, with people standing in the behind the laser table, just by looking through a small piece of glass. It was like looking through a magic letter box into the laser laboratory and was (and still is) quite a magical and uncanny experience.

The only people (apart from scientists and holographers) who actually got to see these early holograms were reporters and journalists writing about the new medium. Looking at these spectacular laser transmission holograms they wrote up very enthusiastic reports in newspapers and magazines about how truly amazing and life-like holograms were and then went on to speculate about how soon we would all be looking at hologram TV and hologram billboards in the sky. Long before the general public ever got to see them it was generally known and accepted that Holography was something new and extraordinary. In his book “Travels in Hyper-reality” Umberto Eco said that holography provided the spectator with an image that is “Absolutely iconic, a perfect likeness, a ‘real’ copy of the reality being represented” [1] he went on to say that “Holography … achieves full-colour photographic representation that is more than three-dimensional” and that “Holography could only prosper in America, a country obsessed with realism, where if a reconstruction is to be credible, it must be absolutely iconic, a perfect likeness, a “real” copy of the reality being represented” [2].

By the time white light viewable holograms were available to the general public it was already widely established that holography was the perfect imaging medium.

“Pencils” by Paul Hubel

What the readers of Eco book, along most members of the public, did not know was that this fantastic “Realism” was actually true under certain circumstances and in fact there were some severe limitations to the medium of “classical” studio holography, such as:

1. Size – The film and plate materials used were so expensive that very few holograms were made that were larger than 30 × 40 cm and the majority were 10 × 8 inches or smaller. All subjects had to be the same size as the final hologram image.
2. Immobility – Unless a pulse laser was used, the subject had to be a solid object, even items that most people would think of as “stationary”, such as a vase of flowers or a bowl of fruit, could not be used because of the severe constraints of immobility.
3. Colour – There have been several multi-colour and even full-colour silver-halide holograms made, but the process was so complex that to date they have served as examples of different holographic techniques rather than established commercial processes.
4. Location – Even if a pulse laser were used to record a moving subject, such as a human portrait, the subject had to be brought into the studio to have the hologram made. All exposures were “in camera”: they had to be made within the darkened studio that was lit only by safelights and thus the subject matter was restricted to what could be physically brought into the studio.

As Dr. Stephen Benton, inventor of the rainbow hologram, once put it, “the disappointing reality for the general public when they go to buy a hologram is that they find them to be three-dimensional images of small dead things”. If a designer or an artist wanted to have a hologram made then his or her concept would have to be interpreted by the holographer, and quite often by a model-maker as well, before the final image was realised.

Figure 2

If one wanted to have a white light rainbow hologram made of a car engine, for example, a 3D scale model would have to be made because the real engine would be far too large to fit onto the holography table.

Figure 3

The 3D model would have to be perfect in every detail but only a tiny fraction of the size of the actual engine. It would have to be carefully painted in grey-scale to reflect the right amount of laser light to produce a realistic image. If the hologram image was to be in more than one colour then the model would have to be painted again in grey-scale for each exposure. The colours in the final image would be determined by the geometry rather than the wavelength of the the laser beams.

Figure 4

The final hologram image would be exactly the same size as the 3D model as all classical holograms have a 1:1 ratio between the image and the object recorded. This meant that even if the object were of a convenient size to put onto the holography table it could not be used directly if the final image was required to be a slightly different size.

This 1:1 ratio is a natural consequence of the way that a classical hologram automatically records every minute detail of the physical object, including its size, but it is seen as a severe limitation by artists and designers who are used to blowing up and reducing photographic images to any size that is required. Artists wanting to use holography to make works of fine Art learned to disguise the limitations of the medium so that observers were unaware of them. What may have seemed effortless beauty was in fact the product of much skill and resourcefulness on the part of the artist.

“Forth Wall”: Artist Dan Schweizer made intricate models like tiny stage sets for his holograms.

“In the Sea of Tranquilly”: Artist John Kaufman made beautiful multi-colour holograms of rocks.

“Exuma”: Artist Rudie Berkhout made colourful abstracts from simple objects. “Motion in Space – Space in Motion” Dieter Jung

“Blueprint for a Metanatural Power Plant” Doris Vila

Artists such as Doris Vila, Rudie Berkhout, Dieter Jung, Kazuo Hatano, Ikuo Nakamura, Shunsuke Mitamura, Setsuko Ishii, Jeffrey Robb and many others created works that used the elements of space, time and colour within the hologram to create images that were far more powerful and beautiful than the sometimes quite humble objects that were used in their creation.

In general display holography the use of solid 3D models and small objects, and the “photo-booth” style pulse laser portraits of people and animals, proved a great disillusionment to the general public who had grown accustomed to the wealth and variety of subject matter offered by cinema, photography and television. In order to provide the same abundance and diversity of imagery that is provided daily by other visual media, Holography has to be used as the means of presentation of sequences of photographs and images from other media and not simply as a direct medium for recording the subjects that could be taken into the dark confines of the the laser studio.

From the very start holographers realised that there had to be a marriage between holography and other imaging techniques, such as photography and cinematography, if holography was to survive beyond the first “era of novelty”, where the innovation of the medium itself was sufficiently interesting to be valued in itself, regardless of the actual subject matter.

As early as 1968, R.V. Pole saw the potential of holography in the context of auto-stereoscopic displays, i.e. the means of providing stereoscopic 3D images without the need for wearing special glasses, or looking through a viewer [3].

There are several forms of auto-stereoscopic displays [4], many of which derive from Gabriel Lippmann’s proposal in 1908 to gather a range of perspective views onto a photographic emulsion by means of an array of spherical lenses, called “fly’s eye” lenses, and then to retro-project them to synthesize a three-dimensional image [5].

Pole wrote that he hoped his technique would “offer a means of closing the “white-light circle” in holography by providing a method of taking a picture of a 3D scene in natural light.” In the same year, George and McCrickerd completed some practical fieldwork in the form of scenic stereograms of the Yosemite Valley and the city of Pasadena using the nine-story Millikan Library building as a platform to take the original footage [6].

In May 1968, D. J. De Bitetto, working at the Phillips Laboratories, described a method of recording a very narrow horizontal strip hologram for viewing of the virtual image of the 3D scene [7, 8, 9].

Then, in October 1969, Dr. Stephen Benton proposed a two-step technique [10], where the second hologram is illuminated to reconstruct a real image of the first hologram the strip that replays the image in each wavelength of the spectrum in turn, to give the bright diffractive colours of a “rainbow” hologram.

In the early 1980’s Benton suggested that a linear pass by the subject (with a movie camera on a linear rail) would give less optical distortion in the image than rotating the subject on a turn-table.

Benton Achromatic Stereogram.

The rainbow hologram was the foundation of the embossed hologram technology, and even prior to the advent of embossing it set the direction that holograms derived from photographic images would go.

Within a short time of seeing the first “rainbow hologram”, Lloyd Cross produced a composite hologram comprising some 1080 image strips, each of which was a one-step white-light viewable rainbow hologram. Collectively the image strips formed a cylindrical display that gave a 360^∘ view of the subject.

“Multiplex” Hologram Display

Whilst the Multiplex Company was making cylindrical displays on silver halide film, other holographers, like Ken Haines, Mike Foster and Steve McGrew were working on methods to mass-replicate “rainbow” holograms onto plastic materials. This was to profoundly affect the economics of producing holographic images and to give rise to a whole new industry.

Steve McGrew’s company, Light Impressions Inc, was the first to bring the embossed hologram to the commercial market with a set of embossed images of 3D subjects. The images were typical of the “classical” studio holography of the silver halide era, one of the best examples being a still life called “Skull and Rocks” by the artist holographer John Kaufman. The hologram is 6′′× 6′′; and the visual depth of the image is a similar amount when the hologram is correctly illuminated with a halogen spotlight.

“Skull and Rocks ” by John Kaufman

Steve McGrew was quick to realise that if commercial clients were to make use of the new medium of embossed holography then there had to be a better way to allow them to specify the image they required.

“ET” – The first embossed 2D–3D hologram

McGrew abandoned full 3D depth in favour of diffractive colour [11] and developed a system now known as “2D–3D”, whereby a client could send in black and white line artwork and this would be converted into a hologram set on two planes, one set on the surface and one appearing a few millimetres behind. With the release of the “E.T.” diffractive graphic stickers in 1982, 2D–3D was launched and became the most popular hologram imaging format of the 1980’s.

“Kelly” – the first embossed stereogram

Although the first embossed stereogram was released soon afterwards, the ease and simplicity of the 2D–3D technique, meant that 3D images originated with a movie camera and a subject on a turntable were both expensive and complicated compared to the new graphic technology which required very little from the client in terms of preparation of artwork. As most clients simply wanted their logo displayed as a diffractive composition, and as company logos were usually in the form of bold graphics designed to look good on letterheads, the 2D–3D system allowed clients to specify custom holograms with ease.

“True-Color” 2D–3D by Light Impressions

When Light Impressions introduced their “True-colour” technique, which permitted 2D–3D holograms to be made from full natural colour photographs and transparencies, by use of diffractive RGB colour control, 2D–3D was given a new boost for promotional contexts where photo-realism was more appropriate than the graphic style of line artwork.

Although there were notable exceptions, such as the portraits of Stevie Nicks and Michael Jackson, by Craig Newswanger at CFC Applied Holographics, and the Clown by Ken Haines, at American Banknote Holographics, there were relatively few full-colour embossed multiplex holograms made in the mid 1980’s and early 1990’s.

Clown Stereogram Ken Haines

This was in part because of the cost of making the original stereoscopic cine film, but also because alignment of the three colour separations from the stereoscopic cine film footage gave rise to significant registration challenges in the holography studio.

The complications of image alignment using cine film were alleviated by the introduction of video that could be manipulated in a computer to correct colour balance and luminosity, whilst still maintaining digital control of the placement of the image within the frame.

Tim Brown Stereogram by Ken Haines

When Ken Haines was at Simian, for example, he produced some beautiful examples of full-colour portraits with small amounts of animation, such as a slight smile, or movement of the eyes, just sufficient to communicate the living presence of the subject.

Steve Smith with linear array of 35 mm SLR cameras

Steve Smith, of Lasersmith, produced a novel way of controlling or eliminating all subject motion, by shooting 35 mm film from a series of still cameras rather than a moving cine camera [12].

In the UK Rob Munday produced a novel system for recording sterograms from an LCD screen rather than from film frames, so that the parallax recording could be done on video, rather than an expensive cine camera, or alternatively data such as 3D computer models could be directly downloaded from computer [13].

In the Netherlands, Walter Spierings developed a system for making colour 3D stereograms, also using an LCD screen, but providing, instead of the conventional H1–H2 system, a one-step imaging process he called the “Office Holoprinter^TM” [14].

Toy Box by Rob Munday

Several holographers were working on methods to exploit the control that image manipulation in computers gave to the process by finding a way to directly output a digital image as a hologram.

In 1988 Fujio Iwata and Kazuhiko Ohuma, of Toppan Printing Co Ltd, introduced their novel process for making animated diffractive patterns by exposing several tiny dots of grating. The system allowed for the variable grating pitch to build up a multi-colour image and, more spectacularly, had the ability to change the orientation of the grating (by rotating the substrate) to provide dazzling animated patterns [15, 16, 17].

“This method needs much time over imagination”, as they put it in their 1988 paper, but the effort was worthwhile, as the tiny animated images were very difficult to achieve by any other holographic method, such as 2D–3D, and were going to be significant in the emerging security market. Within a few months other companies working on similar systems were displaying holograms made by the “dot-matrix” technique [18, 19, 20].

Figure 20

The animated images were bright, colourful and very distinctive. Before long, however, it became clear that the real advantage was that the system required no real holographic skills to operate and that the true skills were in the design of the image.

For the first time it was the designer working at a computer with the latest graphic software who contributed more to the look of the final hologram image than the holographer. The dot-matrix image could be shown on the monitor cycling through the colours, and presenting a good simulation of the final product.

Dot-matrix machine

Designs could be quickly modified and easily displayed to the client for approval. Within a few years dot-matrix had replaced 2D–3D as the most popular imaging technique.

Several of the holographers working on the dot-matrix systems realised that if either the lateral viewing zone of each pixel could be controlled, or the real-estate of the photo-resist divided into a sub-matrix of cells for different viewing zones, then it would be possible to build up a sequence of stereoscopic views using direct-write methods. If the pitch of the grating could be varied for each pixel then multi-colour or true-colour 3D image could be directly written to the hologram.

In May 1994 Toppan published their first multi-colour 3D embossed image made from their high-resolution direct-write technique. Displaying a computer generated scene with at least a dozen perspective views, the tiny image has five clearly discernable colours. One of the most significant aspects of the “3D grating image” is that it is not actually a hologram at all, in that no interference wavefronts, or even lasers, are employed in its fabrication. The images consist of anywhere from several tens of thousands to several hundreds of thousands of minute gratings prepared by an electron beam [21].

Multi-colour “3D grating image” by Toppan

As well as Toppan in Japan, the Dai Nippon Printing Co Ltd also researched methods of using an electron beam to make directly written computer-generated holograms. In 1998 3D images, such as wire-frame models, were fabricated as computer-generated holograms (CGHs) [22]. The following year they extended the technique to make multi-colour 3D images [23] and research is presently underway to make large-format CGHs [24, 25].

In Taiwan, Ahead Optoelectronics Inc developed a dot-matrix system that uses optical exposure methods to provide 3D images in full natural colour with graduated tonal values. Traditional dot-matrix printers did not have the ability to create true colour holograms effectively because they could not vary the pitch of each grating pixel, but the Sparkle^TM machine gets around this limitation and allows one to specify the exact pitch, angle and spot size of every pixel.

Dragon stereogram by Ahead Optoelectronics Inc

The system has the capability to vary the spot size from 150 dpi to 1,300 dpi. The grating pitch can be varied within each pixel from 0.7  to 2.5  to give a wide colour range. In fact it is arguable that technique offers a wider colour gamut than, for example, a 2D–3D true-colour made with single red, green and blue diffractive primaries, because any of the pixels can be set to a wide range of different colours [26]. In practice, a full natural-colour 3D image is presently limited to three stereoscopic channels, but the example of the small stereogram of a porcelain dragon has an authentic realism, reminiscent of “classical” full-colour reflection holograms.

The Kinemax, developed by Polskie Systemy Holograficzne, is another exciting new direct-write technology, whose main distinction from conventional direct-write, or dot-matrix systems is that several “optical interference fields” are recorded at the same time in different areas to give multiple gratings. Thus the “resolution cells” that are written are not separated into discrete dots of diffraction grating, like conventional dot-matrix spots, but form a continuous recording over relatively large areas.

The Kinemax^TM high-resolution direct-write system.

The resolution within each cell is up to 6,000 dpi, with both pitch and fringe direction defined within each cell. The Kinemax^TM technology offers recording of 3D objects as full true-colour stereograms composed of up to 30 stereo views with 3D image resolution of the order of 4000 dpi, with three sets of gratings corresponding to the primary additive colours. The stereogram can be built up from a series of rendered images (in the case of a virtual 3D scene) or a set of digitized photographs (for real objects). Each image represents a view of an object from one direction. Basic colour views from one point in the hologram plane are composed of basic colour components from points at the same locations on subsequent images.

Pawel Stepien, who also worked on the Holomax^TM system, points out some of the advantages of Kinemax^TM are that the basic cell, or pixel, “is composed of a set of diffraction gratings with spatial frequencies corresponding to directions of subsequent views and fringe contrast being responsible for given point-direction combination amplitude. The process does not contain any Fourier transform calculations, and can thus be performed directly by grating recorder in line with recording. It is also possible, unlike in the CGH based stereogram, to scale a 3D image without any additional calculations” [27].

In the UK, Spatial Imaging Ltd saw dot-matrix as having the potential to deliver everything that their earlier Di-Ho^TM stereogram system had done, but without the requirement for specialist skills. “Absolutely no knowledge of holography is required” to originate one-step hybrid 2D–3D and 3D holograms on the new Lightgate 3000 “3Digital^TM” machine [28].

Lightgate 3000 “3Digital^TM” machine

The 3Digital^TM images have several advantages over classical stereogram holograms: they are brighter, with higher contrast and more saturated colours. Imagery is sharper and more detailed, even in semi-diffuse lighting conditions. The grating structures are easier to emboss, and survive application onto substrates that are not rigid or optically flat. Previously stereograms embossed into hot-stamping foil had to be applied to very smooth substrates, such as plastic cards, to avoid degrading the image. 3Digital^TM holograms can be created from up to 64 stereoscopic images in a resolution of up to 3,064 dpi (some 9 million pixels per square inch). Software balances the red, green and blue exposures for each pixel, using a proprietary algorithm, so that the final hologram displays bright saturated colour throughout the spectral range and both the angle of diffraction and the spatial frequency can be continuously varied.

In the US, Pacific Holographics have used their patented SecureText^TM dot matrix system to produce multicolour 3D images at resolutions up to 3200 dpi (over 10 million pixels per square inch). The system allows the operator to control the grating angle, spatial frequency and brightness of every pixel to achieve RGB colour blending as well as gamma control [29].

Three stereoscopic views of “Cube” – a 3D multi-colour dot-matrix hologram

A typical data file for a colour dot matrix hologram contains information from 16 individual frames with a 2^∘ or 3^∘ angular deviation between frames to provide stereoscopic parallax, depending on the hologram size and subject matter. The images are bright and sharp with good colour saturation and wide angle of view.

Light Impressions International Ltd, in the UK, offer two full-colour direct-write technologies, HiMax and BrandMax, both of which allow the designer an artwork resolution of 16,000,000 pixels per square inch.

HiMax Light Impressions

That level of resolution means that each diffractive pixel is like a small white sugar cube on a football pitch. In the case of HiMax each of the diffractive pixels is written at a much higher resolution still, with a point size of just 15nm (over six billion points per square inch).

The BrandMax technology allows designers untrained in holography to make the image on their own computers and control exactly how the final result should look using digital 3D models made with off-the-shelf software.

The 3D model is rotated to give the desired angle of view, yielding up to 50 frames of stereoscopic parallax, in full colour, with animation if required.

As the information is digital and is downloaded directly to make the BrandMax diffractive image, the final result looks very similar to the 3D model as seen on the computer monitor with the colours appearing as they should when the image is viewed at the correct vertical viewing position.

BrandMax – Light Impressions International Ltd.

The BrandMax system also allows designers to make full colour 3D images of live events using digital video either by rotating the subject or by moving the video camera past the subject scene in an orbital or a linear pass.

Other researchers are still keeping their results under wraps. However, it is clear that sufficient work is going on in the field at the moment to make it likely that direct-write full-colour 3D holograms will be the most popular holographic imaging process within the next few years.

The present limitations in the size of direct-write 3D full-colour diffractive images may soon be overcome by pulse laser direct-write systems such as the i-SCAN^TM technology, shown at Holo-Pack in November 1999, exposing pixels at speeds of up to a thousand of dots per second.

The i-SCAN^TM system directly ablates the image into the plastic shims used for soft embossing. Not only does it do away with the holographer, as it bypasses the need for a photoresist plate, but it also dispenses with the electro-former, nickel shims and plating baths. Gone too, is the need to recombine small images together to make larger shims, as large format seamless cylinders can be directly ablated with multiple images. Production time is reduced from a couple of weeks to a couple of hours, a vital factor in making holography a mainstream imaging medium [31].

Conventional printing (left) is combined with an embossed dot-matrix hologram (centre) to provide a dynamic result (right) for a TV guide.

When the i-SCAN^TM system is able to produce full-colour 3D holograms in a similar way to the BrandMax^TM or 3Digital^TM or other full-colour 3D direct-write technologies, then an exciting range of new subject matter will be available that contains full parallax and natural colour.

The capability of directly writing relatively large format full-colour 3D holograms (of a size sufficient to cover a book, magazine or poster, for example) coupled with the ability to combine the image with conventional printing, may finally allow holography to integrate with mainstream publishing.

The recent advances in computing power, software and related digital technology means that far broader subject matter can be imported from other media which already contains parallax data.

There is a vast amount of parallax data available today that is recorded and stored digitally. More parallax is used in television, video and film than ever before, as directors have come to realise that a roving camera can convey far more realism than a static camera.

This is because the phenomena of “motion parallax” (or “temporal parallax”) is feeding 3D depth cues to the viewer even if the motion is only a few degrees and is too subtle to be consciously noticed by the audience.

Not only in action-packed scenes, but also in relatively quiet scenes of dialogue, a small amount of temporal parallax from lateral camera motion adds a three-dimensional feel and a sense of “being there” that a fixed camera shot cannot convey.

As well as fictional dramas and films, shots containing lateral or orbital camera motion are increasingly being used in television advertising commercials and in programmes such as wildlife and nature documentaries.

Hand-held video camera on location

On location, new light-weight video cameras can be hand-held to provide lateral temporal parallax with far more freedom of movement that conventional motion picture cameras, and new Digital Video (DV) formats allow for cameras to be much smaller with very little loss of picture quality.

In the studio, the use of booms and pulleys to move the camera rapidly around allow for more temporal parallax than ever before, both in television and in cinema. It is now more common to shoot a sequence using a camera that can move rather than from one that has a fixed viewpoint, such as on a tripod.

Temporal parallax can be captured with from any laterally moving or orbiting vehicle, such as a car, boat, train, plane, helicopter or hot-air balloon: anything that travels in a smooth motion past the scene will provide parallax data or “look-around”.

Sequences that have temporal or motion parallax in them can be used to make a three-dimensional image as a direct-write digital hologram. The hologram is the means by which the temporal component is translated into a spatial component so the subject can be seen stereoscopically. In other words, the hologram turns a one-eyed view of the world into a two-eyed one, so that the subject can be clearly seen in 3D.

Parallax is increasingly being used in special effects in movies. In the film “The Matrix”, for example, narrative motion is almost frozen by the use of parallax cameras that encircle the subject. The many cameras each take a single image of the scene in sequence to build up a 360 degree (or more) view of the action. The cameras can be triggered to go off simultaneously or with a split-second delay between each one.

Motion Parallax “bullet time” from the film “The Matrix”

Prior to shooting the short scene the camera path is carefully planned for each action. The cameras are embedded in a green wall so that they can be edited out later and a background added into the image.

Camera path and action shot from the film “The Matrix”

The camera path is computer controlled and each view can be matched to a corresponding view of the background, so that the subject and background are always spatially synchronised in the final shot [32].

Since “The Matrix” several films have used this effect and it has also been used on television, for example in the “The X-Files”, and in several commercials. The use of computers and sophisticated video-editing software has changed the movie industry, making possible special effects that could not have been achieved even three or four years ago. The temporal parallax in these scenes can be readily converted to stereoscopic parallax for holography.

Stereoscopic parallax: how we see in 3D

Continue reading Part 2…

Iñaki Beguiristain
ibeguiristain@AOTgroup.co.uk

About the author
Iñaki studied Physics at Imperial College, London. He has been making holograms for the past 15 years, and has perfected an enviable holography studio. During the last 7 years he has concentrated on pseudocolour display holograms. He has worked at various companies involved in security holography.

It has been a while since the release of any new books on practical holography, at least within Europe and the U.S. Despite the wealth of information available on the internet, getting hold of current information on the specifics of the subject, especially from one source, has become increasingly difficult. So the third edition of “Practical Holography” by Graham Saxby comes as a welcome read.

In brief this book is an extremely comprehensive manual on all current aspects of holography, from basic theory to in-depth practical information including commercial and industrial processes. The emphasis from the author’s point of view is of course on the practical techniques, and these are covered in extensive detail. As anyone who has dabbled in the process of making holograms will know, seemingly small and insignificant information at the time of reading can be invaluable at a time of crisis in the lab, when all else seems to have failed! Due to the author’s many years of practical experience this text contains that necessary information so the book can be referred to from the outset as a learning aid and then as a detailed reference for all practical aspects of the subject.

Compared with the two previous editions the layout of the book has been refined, thus improving readability and providing better continuity throughout. There are numerous asides, set as marginal notes, giving topical pieces of useful information. The diagrams throughout follow a clear generic style making them easy to understand, and there are many photographs including some very interesting colour plates of images made by various holographic artists.

The book is divided into four main sections: principles, which covers the very basics of the subject, essentially the building blocks; practical display holography, which comprises the bulk of the book and is detailed enough to cater for all levels; applied holography, which includes commercial and industrial applications; and finally five appendices covering mathematical theories, unusual geometries and processing formulae. So, anyone with a non-scientific background will know which sections to avoid!

The layout of the practical section is organised so that individuals can progressively work from one chapter to the next at their own pace, increasing their knowledge and understanding, and the complexity of the holographic systems they create. There is plenty of advice on corrective measures when things go wrong, and helpful tips on unusual but necessary skills such as cutting glass in the dark. There are many ideas for cost saving as well. A large number of items used in holography can be made from a few basic materials and a little ingenuity. These are fully described throughout the practical section, and there are also references if further information is required. One chapter has been dedicated to producing cheap homemade optical elements including HOE’s for use primarily in the holographic systems described in the book. However, I think a reasonable level of holographic experience has to be achieved before attempting these, as they need to be clean and efficient to work satisfactorily.

There have been significant changes in holography over the past decade since the second edition, some good and some bad; this new edition is completely updated and it expands on areas of increased interest and development such as holographic stereograms and colour work (both natural and pseudocolour). There is an up-to-date report on holographic plates including a useful summary of commercially available recording materials, which will hopefully go a long way towards relieving the concerns about alternative emulsion availability. With the advent of more stable diode lasers there is also information on using these and the necessary criteria they need to fulfil in order to work as well as the more traditional lasers.

There are plenty of good books on theoretical holography but there are very few that focus primarily on the physical processes. This book would suit anyone interested in the making of holograms be it from an artistic, commercial, industrial or research perspective. Taking into consideration the possible savings on equipment and raw materials, and potential time wasted, this comprehensive and extremely informative book will no doubt pay for itself in a very short time indeed, and I can strongly recommend it.