Edwin H. Land (1909 – 1991)

While not an official biography, the following is reprinted with the kind permission of the Royal Society.

by F.W. Campbell, F.R.S.†

Edwin H. Land was born to Harry and Martha Land in Bridgeport, Connecticut. He was
[the only son]. His father was a landowner and prosperous scrap-metal dealer. Edwin’s schooling was at Norwich Free Academy. His yearbook photograph comes with the caption ‘Ed is some star in his studies and we are sure that he will make a name for himself and Alma Mater in college’. He graduated with honours from the Norwich Free Academy.

As a young lad, he was interested in literature and science and slept with a copy of R.W. Wood’s Physical Optics (1st edn 1905, 2nd edn 1911, 3rd edn 1934) under his pillow. Robert Williams Wood (1868-1955) was born in Concord, Massachusetts. After studying at Harvard and Berlin, Wood taught physics at Wisconsin from 1897 until 1901, when he was appointed Professor of Experimental Physics at Johns Hopkins University, Baltimore, where most of his notable work was done. Land would have had the first or the second edition. Wood was an experimenter of great ingenuity in the areas of optics, light, electricity and photography. Did Robert Wood inspire Edwin Land as a child?

Land attended Harvard College and, while still a freshman, set out to find a new way of producing an inexpensive and efficient polarizer which he called Polaroid. He left the freshman physics class of 1926 and intensified his education at the New York Public Library, as had Thomas A. Edison (1847-1931). Harvard University finally awarded an honorary doctorate to him in 1957. For many years he was always called Dr. Land, as he had some 20 honorary doctorates from other universities. His close friends, however, called him Din, his childhood nickname. Bradford Washburn, who knew Land at Harvard, was asked why Din did not finish his physics studies; he replied, ‘He didn’t need to.’

Edwin Land is survived by his wife, Helen (née Maislen) and two daughters, Jennifer and Valerie.

Erasmus Bartholin (1625-1698) was sent, in 1669, a transparent crystal from Iceland (Iceland spar) and, by rotating the crystal, he discovered that objects seen through it appeared double. He correctly deduced that light traveling through the crystal was refracted at two different angles. Today, these are still called the ordinary and extraordinary rays. The explanation required the genius of Thomas Young (1773-1829) to account for them some 150 years later: the two rays were polarized at right angles to each other. William Nicol (1768-1851) had the ingenious idea of cementing two crystals of Iceland spar together with Canada balsam so that each ray was separated at right angles. The resulting Nicol prism could then be used to measure the angle of polarization of compounds, which later resulted in a profound understanding of many aspects of chemistry.

Today, Nicol prisms are still very expensive, bulky and of limited aperture. Edwin Land, when a Harvard freshman, conceived the idea that a polarizer might be made by lining up a myriad of tiny crystals (iodoquinine sulphate) in the same direction and embedding them in transparent plastic which, when set, prevented the crystals from drifting apart. The new polarizer was patented in 1929. With his Harvard physics instructor, George Wheelwright III, he set up the Land-Wheelwright Laboratories in 1932. He established the Polaroid Corporation in Boston in 1937. Thus the word Polaroid was born and entered the dictionary.

The trademark was coined by the Smith College art scholar, Clarence Kennedy, with whom Land collaborated in the early 1930s to produce 3-D photographs of Renaissance sculpture. Like many photographers, Land had a great interest in classical art. (When I watched him taking pictures on a sunny afternoon inside King’s College Chapel, Cambridge, in 1973, I was surprised at how long he took to compose each one; the end result was most impressive artistically. Although a shy person, he did not hesitate to lie on the floor watched by the passing tourists while he photographed the vaulted ceiling. As he stood up, I was handed one of his many shots; it included my eyes looking down at him.)

When Edwin and Helen were reading daily in the New York Public Library, they came across the work of an English physician, Dr William Bird Herapath. In 1852 he had found that dogs treated with quinine had microscopic crystalline needles in their urine. He observed that overlapping perpendicular needles were black where they crossed, whereas parallel needles were clear. From that observation Land invented the first sheet polarizer, the J sheet. The crystals also had a magnetic dipole moment, so that if a suspension is placed in a very strong magnetic field they become oriented to form a uniform dichroic layer. If the aligned crystals are suspended in a polymer, they set.

After making the first samples of synthetic polarizers Land and his wife returned to Harvard. Although still a freshman, he gave a lecture at an invited Physics Colloquium and was given a personal laboratory. Terre (Helen) Land assisted him in this experimental work at a time when women were not normally allowed in Physics Laboratories.

This exciting new polarizer had many advantages: it was inexpensive, thin and could be cut easily to any size and shape to fit the application. When two are crossed a very high extinction coefficient results, suitable for scientific use. For maximum light transmission, a low-coefficient version is available for viewing stereoscopic aluminum screens; these screens preserve the angle of polarization.

Stereoscopic (3-D) cinemas were very popular in the 1950s and were practical only because the Polaroid spectacles were so cheap; the audience liked to steal the magic spectacles believing that they would enhance stereoscopic vision outside the cinema! As television developed, the stereo-cinema became less popular, although the technique still has many important scientific uses.

When I visited Edwin in 1960 he took me to a table covered with all the different types of Polaroid. He handed me a pair of scissors and said ‘ Help yourself, you might come up with a new application.’ I did! This was typical of Land, for he wanted to help the research of others as well as his own.

It was on this occasion that he told me that his original reason for developing Polaroid was to prevent car accidents at night in towns like New York. Before dipped headlamps were devised, the glare from oncoming vehicles obscured pedestrians crossing the street. Headlamps were to be fitted with a visor oriented at 90 degrees. Unfortunately, this meant doubling the headlamp wattage, which would increase fuel consumption. Car makers were not willing to raise the cost of cars, so Land’s humanitarian concern for the safety of pedestrians failed to be implemented.

However, serendipity came to his rescue or, to quote Louis Pasteur (1854), ‘Chance favours the prepared mind.’ One of his colleagues went fishing and took a scrap of Polaroid with him. He came rushing back with a large trout and explained to Land that you could see through the reflection of the sky on the surface of the pool and locate the position of the large leading trout. Initially, Polaroid spectacles were sold only in the ubiquitous fish-and-gun shops in the USA, but they quickly became popular with the public as Polaroid sunglasses, as they are known today.

Another popular use is in photography, as a screw-on filter, to darken the sky and enhance the contrast of the clouds (the blue sky opposite the Sun is highly polarized, the clouds are not). Indeed, his first contract was with Kodak to make Polaroid; Kodak would make the screw-on filter mount. Suddenly Land and his team were faced with all the difficulties of manufacturing optically high-quality Polaroid on a very large scale. After intense activity and ingenuity, they met the deadline. In these early days of making polarizers Land began to work with Howie Rogers. Independently and together they made many significant inventions in polarizers, plastic optics and photographic systems.

The latest wide-scale use of Polaroid is to remove the glare from light falling on the ubiquitous visual display terminal or unit (VDU). A 1/4-wave retardation plate is cemented on one side of a sheet of Polaroid and that side is placed against the terminal screen. Light hits the glass screen and is reflected back through the 1/4-wave plate a second time. It has now undergone a 90 degree shift in orientation and thus is extinguished by the second outgoing passage through the Polaroid. This dramatically reduces the eye-strain due to specular reflection from the convex glass front surface of a VDU. We have come a long way in the history of light (1625-1991) from Bartholin, Young and Nicol to Edwin Land.

Of course, Land had to overcome many human as well as scientific problems to produce the final mass production of Polaroid. For example, to make the first sheet polarizer he had to use the 10000 gauss electromagnet in Columbia Physics Laboratory. After he made the polarizer work, he showed the results to the head of the department who then gave him permission to use the electromagnet as well as a key to the room. Before getting the key, Land had taken the elevator to the sixth floor, walked out of the window and along a ledge on the outside of the building and through another window to gain access to the room containing the electromagnet. It is just as well he did not suffer from acrophobia.

One can speculate that it was this frustration with administrators that led him to set up his own company with himself as Chief Administrator — an elegant and simple solution to a problem that faces all creative scientists and engineers, even to this day!

The Polaroid Corporation was founded in 1937 and located in Boston, New England, where there were very many other optical, camera and film companies. For example, the Harvard physician Dr Oliver Wendell Holmes, M.D. (1809-94), invented in 1851 his portable stereoscope. It was handheld and the two photographs from the two cameras were placed side by side on a card and viewed through two lenses, incorporating prisms to facilitate the divergence of the two eyes. (It was based on the principle of David Brewster (1781-1868, F.R.S. 1815).) Holmes collaborated with a Boston photographer, Joseph L. Bates. For the next century photographers travelled the globe with their stereo cameras recording in three dimensions the Wonders of the World. It developed into a popular parlour pastime of great educational value for parents and their children. The Holmes stereoscope was inexpensive and boxes of photographs could be hired from a local library. Each box contained a very full and accurate description of the country and its culture.

In 1937 Land and his co-inventor, Joseph Mallory, designed the vectograph for creating 3-D images for a wide range of applications. The vectograph could superimpose the two views of a stereoscopic picture on a single sheet of film. It is still extensively used in aerial-photography and satellite reconnaissance. If the two photographs are taken far enough apart, a molehill can be turned into a small mountain by exaggerating the third dimension, using the principle of stereoscopy. Land’s vectography was used to survey the French coast in preparation for the Normandy invasion by UK and USA forces on D-Day (6 June 1944). Maps showing suitable hiding places from the direct fire of the enemy could be supplied. This exaggerated stereoscopy is the ultimate in anti-camouflage warfare. History may show that the technology was also used in the Gulf War (January 1991); much of the battlefield was among featureless sand dunes: hence the operation was coded ‘ Desert Storm’.

In the 1970s the quartz-crystal watch became popular owing to its accurate time-keeping and low cost compared with mechanical versions. Light emitting diodes (LEDs) were used to display the time, but they used a lot of power and battery replacements were frequent, even when a switch was provided to view the time intermittently; a risky action if one was driving. Using Polaroid, the Liquid Crystal Display (LCD) was then introduced; the power requirement dropped to almost zero. Today, many portable computers use this type of display.

Boston contained a wealth of talent and Land could recruit and train almost anyone he wished and develop their talent to the maximum. It was important to Land to situate his business activities in an intensely active scientific environment that included most areas of science. Whenever anyone asked him ‘Where is Polaroid?’, he replied ‘Between Harvard and MIT’.

* CORRECTION * Paragraph Two *   The co-inventor of the vectograph is incorrectly named as Joseph Mallory. The correct name is Joseph Mahler.

Even before Pearl Harbor (7 December 1941), the Polaroid team were thinking well ahead on how to help the Allies and they gave years of advice and service to the US Government over a very wide field of applications. Early contributions were infrared polarizers, heat-stable filters, dark adaptation goggles for night-time fighting and the polarizing ring sight.

In the 1950s Land’s team designed the first of the high-altitude optical surveillance systems, first in the U2 plane and later in satellites, thus helping to maintain military balance and the Cold War peace, which ended with Gorbachev and the destruction of the Berlin Wall (November 1989).

To design a high-quality aerial camera lens requires millions of iterative high-precision calculations, and Land, working with James Baker of Harvard, was able to achieve this using one of the early computers. The camera was so good that the vibrations from a plane’s power unit degraded the resolution. The Lockheed U2 spy plane was a power glider that climbed rapidly to a very high altitude (13 miles); the pilot then switched off the power unit and glided to a lower altitude as the sequence of stereoscopic photographs were taken.

The first flight took place on 4 July 1956. This was such a threat to the USSR that they rushed to develop a high-altitude rocket to destroy it. The West was staggered to learn that the East’s rocket development was so advanced when the pilot (Gary Powers) and his U2 were paraded in Red Square to prove the point in May 1960.

Land did much more than developing the U2 camera — he also helped to design the plane itself. For example, Land and the plane’s designer, Kelly Johnson, were discussing the problems of high-speed, high-altitude flight. They combined two severe problems into an elegant solution. At the desired altitude, the ambient temperature was sufficiently low to increase the viscosity of the fuel, creating fuel-line problems. Furthermore, the friction of the atmosphere on the leading edge of the wing caused it to overheat. Land and Johnson routed the fuel along the wing edge so as to preheat the fuel and, at the same time, cool the wing. As one will learn later, Land was not only a wizard in optics; each of his cameras contained a wealth of ingenious mechanical and electronic parts, albeit hidden from the user.

Land told me, with a chuckle, that he managed to convince golfing President (1953-61) Eisenhower to support the U2 project by describing his new camera’s point-spread-function in terms of detecting a golf ball at 2000 yards, rather than in seconds of arc (4 sec). A golfer can detect a golf ball with difficulty at about 150 yards (60 sec).

In 1963, E.H. Land was awarded the Presidential Medal of Freedom. In 1988 his work for the USA national security service was honoured with the W.O. Baker Award of the Security Affairs Support Association. The Award stated: “It was he whose genius in photography made it possible to conceive a reconnaissance system of extraordinary power [the U2] which he proposed to President Eisenhower, who accepted his recommendation that its development be undertaken. The optics and other features of those original designs became the foundation of advanced systems in use today.”

The origin of this idea is recorded by Land as follows:

I recall a sunny day in Santa Fe, N.M., when my little daughter asked why she could not see at once the picture I had just taken of her. As I walked around the charming town I undertook the task of solving the puzzle she had set me. Within an hour, the camera, the film and the physical chemistry became so clear to me.

The year was 1944, and Land was 35 years old. His daughter, Jennifer, was three years old. This agrees well with what he told me in Cambridge, UK, when he visited my laboratory in 1973.

Land wrote:

It was as if all that we had done in learning to make polarizers, the knowledge of plastics, and the properties of viscous liquids, the preparation of microscopic crystals smaller than the wavelength of light, the laminating of plastic sheets, living on the world of colloids in supersaturated solutions, had been a school both for the first day in which I suddenly knew how to make a one-step dry photographic process and for the following three years in which we made the very vivid dream a solid reality.

Of course, although the ideas were simple in retrospect, it required an enormous research programme to implement them. His energy to experiment, think and organize can be likened to that of William Thomson (Lord Kelvin, 1824-1907) who laid the first successful Atlantic Telegraph Cable and all its associated transmitting and receiving equipment in 1866. Both had a dynamic and charming personality that enabled them to organize talent, benefit mankind and start new industries; both died millionaires.

Strictly speaking, ‘instant’ is a slight exaggeration. The time depends on the ambient temperature. At room temperature you can see, after a few seconds, a low-contrast picture sufficiently well to know that you have aimed the camera correctly and that it was in focus, but it takes several minutes for it to asymptote to a high contrast. When he demonstrated to me this first colour camera (SX-70) he winked and held the emergent print under his arm in order to speed the magic. This immediate feedback meant that the novice quickly learnt how to use the camera correctly. This aim was very important to Land, as he did not want a user to waste the relatively expensive film. It was rumoured that he always took each prototype camera home to find out whether ‘the mothers of America’ could unpack it, understand the instructions, load the film and take perfect photographs with it.

On 21 February 1947, Edwin Land demonstrated his one-step instant camera and film at a meeting of the Optical Society of America. Less than two years later the Polaroid Camera Model 95 and Type 40 Land film were on sale at the Jordan Marsh department store in downtown Boston at a cost of $89.75: it weighed 4 lb. (Today one can buy a Polaroid 635CL Instant Camera for £29.50; Twin pack, 2 x 10 colour prints cost £15.25. The battery for powering the camera and its flash lamp is included in the film pack. The weight of the camera when loaded is 1.5 lb.)

He chose the right year, the right place and, very importantly, the right price. When I first met Edwin I asked him how to be a successful inventor. Land answered: ‘It must retail at just under $100. You see you can’t make money selling to the very wealthy, there are too few of them. You can’t make money selling to the poor either.’

World War II had ended two years earlier and there was a dearth of new household things for the middle-class to buy. Suddenly, there was this magic camera that anyone could operate and afford! You did not even need to know how it worked. Although the film was expensive you could wait until you had a little spare money for the next roll. There were no credit cards in those days. Land had transformed family parties, reunions and weddings; everyone went home with a precious and unique photograph in their pocket. As a result, sales of Type 40 Land film rocketed.

The first Polaroid Camera Model 95 worked as follows. A negative is exposed and then brought into contact with a positive print sheet. Both are drawn through two rollers, by hand, and a pod of chemicals is ruptured and spread evenly across the positive print sheet. If you wanted a copy you just took another photograph. As the negative had to be accurately exposed, it was supplied with a simple but ingenious light meter. The paper sheet and negative were discarded to blow about in the wind; this worried Land as he was very tidy and green-minded.

Land was very proud of the chemistry that made Polaroid black and white images possible. In the first diffusion transfer, silver images were formed by a sepia brown colloidal silver. Polaroid black and white photography required receiving sheets that formed a new kind of silver.

The reagent in Polaroid pods has a pH of 14. The dye image is most stable at a slightly acidic pH. At the time of introduction of Polacolor film, Land and a colleague, Richard Young, rebuilt the film in a six-month period to incorporate a polymeric acid in the receiving layer. The system worked by spreading a basic reagent against a timing layer that disappeared after 30 seconds. Behind the timing layer was an acid polymer that neutralized the base and encapsulated the dye in the mordant layer. All instant colour systems use this principle.

The black and white image behind the coloured strips in Polavision Film was unique in that the entire film has the same amount of developed silver. The white areas in the image are formed by developing the silver halide grain in place to absorb roughly half the light. The black areas in the film contained the same amount of silver but are first dissolved and then developed to create a higher covering power with a transmission of one part in 1000. This was the first photographic system where the image was formed as a function of covering power rather than the amount of developed silver.

A visiting American scientist presented to me a Model 95 in the summer of 1954. I took a photograph of him standing in front of the famous Bridge of Sighs in St John’s College, Cambridge. At that time of year Cambridge is flooded with crowds of foreign tourists, all then equipped with conventional cameras. As soon as I produced the print there was a gasp of astonishment from all the tourists around me and I had to run off the rest of the roll and hand out the prints to them. They wanted to know the cost of each print and where to buy the camera. It was then that I realized that Land had arrived internationally. I must have been one of his first salesmen in Europe! Naturally, I rushed back to my laboratory to find out what I could do with his camera. But Land was already well ahead of me, thinking out the special types of cameras scientists would need.

His series of instant cameras had many uses in science and medicine. One could buy the film packs separately from the camera and attach them to microscopes, telescopes, oscilloscopes, etc., without all the fuss of requiring a dark-room with attendant technicians and messy chemicals. It is not surprising that President (1963-69) Lyndon Johnson presented him with the country’s prestigious technology award, the National Medal of Science, in 1967.

In 1976 when he entertained me one evening at Polaroid in his private study, which he called his ideas-room, he showed me with great pride his dream camera. It was before it was publicly announced and he requested me not to talk about it. It was an instant movie camera. He turned on some floodlights and photographed us toasting his health. (Edwin himself was not a teetotaller but had strong views about alcohol during the working day. A few minutes later we were watching ourselves in colour on a screen. We toasted his health again but, this time, we meant his success. The Polavision instant movie camera was on sale by 1977, but it was not a success in the long run. Why not?

Polavision was introduced in the last days of 8mm photographic movies. It was the most advanced projection system in that it had a cassette that eliminated awkward loading procedure. However, it was only a three minute cassette. It was quickly superseded by magnetic tape recording.

In Britain the BBC and ITV had two TV channels each. The programmes were of high quality and variety. It often happened that in a family there was a dispute as to which channel should be viewed. When videotape recorders became available they sold very well in Britain, for one channel could be viewed while the other was recorded. Videotape recording technology was first introduced to the commercial market in 1965, but the home video market was not born until 1975 when the Sony Corporation took the tape out of large reels and put it into the much more convenient Betamax cassette (weight 205g, playing time 195 minutes). Later, portable Japanese videotape cameras became available and Japan quickly dominated the market using their expertise in electronics and camera-lens design. Their video cameras could operate at much lower light levels, the resolution gave much sharper pictures, the videotape was cheap and could be reused, they could be replayed on one’s own domestic colour television set and, finally, copies could easily be made at low cost for one’s friends. One had a complete television system that bypassed film processing. By pre-setting the programme timer, one did not even have to be at home; the demands of work, entertainment and education became compatible.

On 9 June 1991, Alistair Cooke (1908-), on his radio programme A Letter from America, was discussing how Japan had invested much more on basic research than the USA and how they were supplying more and more technical products to US commerce. In his inimitable way he summarized his argument as follows: ‘The Americans think 10 minutes ahead how to make a buck, the Japanese think 10 years ahead.’ Land could do both. An excellent review of the history of Japanese innovation is given by Akio Morita (1992), Chairman of the Board of Sony Corporation and a close friend of Land’s. He stresses the importance of having engineers in the higher echelons of a modern company rather than accountants. Land was the forerunner of this concept.

W.J. McCune, Jr., and B. Cassell (1991) give a very full account of the complete range of the Land cameras with a list of the key patents. The latest instant colour camera planned by Polaroid is dramatically less bulky than its forbears and resembles the popular 35 mm camera. The shape of the print has been changed from a square to a width to height ratio of 4:3. Instead of ejecting the print as it is developing, the camera bends it around rollers and stores all 10 developed prints in a compartment at the back. These can be left there or taken out. A new film had to be developed, with a coating 23 layers thick, to allow for the tight mechanical turns of the guide rollers. The camera is so small that there is no room for a lens to focus the image; the camera needs to be opened up into a larger unit to take pictures. The new film is so sensitive that the lens aperture can be made small to give a greater depth-of-field. To sharpen the image further, a pulse of infrared light is emitted. If the light reflected back to the sensor is too low, the object must be distant, and a long focus-correcting lens moves into the optical path. The sensor also measures the level of ambient light and sets the exposure time automatically or turns on the built-in flash gun. Polaroid put the new camera (‘Vision’) on sale in Britain in 1993 at a cost of £80. The new film cost £10 for a pack of 10 shots. This compact version of the latest Polaroid camera with its ability to take ten shots rapidly at low cost should enable it to keep abreast of its competitors where small is beautiful but the emergent prints are large and ready for viewing without having to visit a fast processing shop.

Land thrived on the challenges of scientific exploration. His favourite scientific interest was the study of human colour vision in complex, real-life scenes. This began with the study of two-colour projection using red and white light. It extended to Mondrian displays – overlapping rectangles of plain colours, after Piet Mondrian (1872-1944) , leader of neoplasticism — and to computer simulation of real scenes. Later, he worked with David Hubel of Harvard, and Semir Zeki, of University College London, who was the first to realize the physiological implications of the correlation of his colour experiments with Hubel’s neurophysiological findings. A very full account of Land’s contribution to colour vision and, neurophysiological studies is edited by David Ottoson & Semir Zeki (1985).

As a part of his research on making an instant colour film, Land repeated some of James Clerk Maxwell’s experiments. The Maxwell experiment used three black and white transparencies, each taken and projected with a red, green, or blue colour filter. Land loved to experiment. He would study the effect of more red light or less blue light. What happened with different contrast film? To believe any hypothesis Land needed the feeling of certainty that only comes from many probing experiments. At the end of a long evening of experimenting with three projectors, Land decided to go home. A colleague had shut off the blue projector and had put the green filter away, leaving an image of red and white light. Another colleague, Meroè Morse, remarked to Land that the colour was still there. Land replied ‘Oh yes, that’s colour adaptation’. The group went home. At about two o’clock in the morning, Land sat up in bed, saying ‘Colour adaptation, what colour adaptation?’ He got out of bed, went into the laboratory and started three decades of experiments on complex images.

He had assimilated the colour adaptation ideas handed down from Helmholtz (1821-94). He searched for evidence of colour adaptation as the explanation for what he saw. Instead he showed that there was no experimental support for the notion that colour constancy is caused by colour adaptation in complex coloured scenes. Land created a better understanding of how we see the real-world of complex images.

What was special about Land was his passion for doing experiments, along with his quick mind that playfully questioned everything, particularly his own hypotheses. He literally could not sleep when he found an experiment that was trying to tell him something.

I first learnt about Land’s theory of colour vision in 1966 when he gave a demonstration in London. I raised a mild criticism and he said he would have to think about it. About a year later he phoned me in the morning and asked if we could try an experiment in the afternoon. Of course, I agreed. He then spoke to his pilot and asked me to meet him at the local Cambridge airport at 12 noon. We drove to the Physiological Laboratory and a few hours later he said ‘ You are right, I am wrong’. I complimented him on the speed with which he could change his mind and he replied ‘You cannot run a successful company carrying an incorrect fact in your head’.

I returned Edwin to the Cambridge airport and then drove the short distance to my home. I could hear a jet-aircraft taking off and, to my surprise, it flew over my house as it climbed. It then tilted port and starboard twice to say ‘Thank you’ before heading for Heathrow. I suddenly realized that he had planned his itinerary down to the last detail. He must have found out where my home and laboratory were in relation to the airport so that his visit would not inconvenience me. He put his plan into action as soon as he knew he had made a fast time across the Atlantic and could keep his appointment in London. Lastly, he could satisfy his obsession of doing at least one experiment each day. I could almost hear him laugh as he asked his pilot to say ‘Thank you’ or ‘ Au revoir’! The ‘other Cambridge’ had made his day; now back to being Chief Administrator in London.

Land performed thousands of experiments studying two-colour projections. He studied combinations of different filters, different contrast films, positive and negative projections, additivity of stereo projections. He found a 1914 British patent by Fox & Hickey entitled ‘improvements in kinematic apparatus’ which might have contained the gist of Land’s ideas formed many years later.

The experiments on red and white projections fascinated Land. He frequently gave lectures on the subject. His favourite audience was college undergraduates. His lectures were as much on the scientific method as they were on colour. He would not just talk about his experiments, he would bring the experiments to the lecture hall so that the students could do them with him. Around the world, there is an entire generation of scientists in any and every field who recall warmly their fond memories and their great sense of excitement about science that was generated by Land’s lectures on colour.

On 2 November 1972, Land gave the Friday Discourse at the Royal Institution of Great Britain. The experiments used an array of papers with controlled illumination. Later these experiments led to the black and white Mondrian experiments that showed that the same quanta catch at the receptors could generate any level of lightness from white to black in a single field of view. This was followed by the colour Mondrian experiments that showed that the number of quanta caught by any point on the retina could appear in any colour. It demonstrated, in a very dramatic fashion, that the determinant of colour is spatial in nature. It is the relationship of the quanta caught at one point or other points in the field of view that controls the appearance. Lightness and colour are field phenomena, not point phenomena.

Land often quipped that the history of colour vision would have been fundamentally different if Maxwell had studied electromagnetic fields before he invented the colour top – the basis of the science of colorimetry. Colorimetry has extraordinary predictive power for colour matches. But, because all the information used in the calculation comes from a single point in the image, it cannot offer any direct clue as to the appearance of the colour. Both before and after Maxwell, there have been many experiments that pointed out the limitations of single-point colour calculations. If Maxwell had studied colour 30 years later, he might have thought of colour as an array. However, Maxwell did not and Land became the principal proponent of colour as a field phenomena.

To explain the results of various colour constancy experiments, Land proposed the Retinex Theory. He coined the word retinex (made from the words retina and cortex) to de-signate the physiological mechanisms that generate these mathematically independent images: My proposal did not demand that the retinal elements of the same peak sensitivity have to be connected to each other. Instead, somewhere in the retinal-cerebral structure, elements associated with the same wavelength characteristics co-operate to form independent images in terms of lightness.

Land’s rather dramatic demonstrations to the public of his views on colour theory and his lack of references to earlier work in the field generated excessive criticism from the ‘colour establishment’. To them, the dramatic demonstrations that made him appear in the popular mind as an iconoclast challenging accepted ideas were merely vivid examples of the phenomenon of colour constancy that had in essence been described 150 years earlier. Thus, Thomas Young had noted in 1807 that white paper still looks white even when illuminated by the red light from a fire, and earlier still, Gaspard Monge (1746-1818) had demonstrated that patches of colour may dramatically change their appearance as the result of the colouration of their surroundings. The perception of colour was not simply a matter of the physical nature of light, and our sensation of the hue of reflecting surfaces is much more stable — less dependent on the illuminant — than we are normally aware. This is analogous to brightness constancy, the processes of light and dark adaptation that make us unaware of the absolute luminance of a surface unless we use an exposure meter to adjust our camera. Land’s contribution was to formulate a precise model — the retinex theory — that could relate these perceptual phenomena to neural events in the brain.

Why did Land not quote early workers and try to relate them to his own research? He certainly had a very extensive personal library that contained many books on visual science. He had also studied them, for in conversation he often quoted early workers in discussion and he had an extensive knowledge of the current literature. For example, he was very impressed with the recent advances in cortical neurophysiology by Hubel & Wiesel and Zeki and he often flew to London to sit in on Zeki’s experiments. It might be that aphorisms, and dominated his approach to science.

Today we stand on the threshold of understanding neurophysiologically how the visual cortex achieves this colour constancy that is so essential for our survival in our world of frequently changing colour temperature. Maybe the visual cortex has a global colour temperature device that measures the ratio of activity of the short and long wavelength cones and corrects the resulting perception of surface colours. Maybe the diffuse stray light from the cornea and lens (14%) is sampled by the cones and enables the visual cortex to correct for the global spectral properties of the illuminant, but this is speculation and has not been investigated.

Land knew that he could not achieve this with his colour film so he fitted his cameras with a flash lamp and daylight film. If the objects of interest were within the range of his high colour temperature xenon flash, their colour rendering would be acceptable under most circumstances. He once told me that if flesh tones are correctly rendered, a photograph is almost always acceptable. Readers may have noticed that the best way of adjusting the colour control on their TV set is to do so when a face is present on the screen.

There is one unequivocal statement that can be made about Land’s excursion into visual science: he stimulated a widespread research interest in colour and brightness constancy. By 1992 many visual scientists had become involved in research in this field using modern techniques and theories. An excellent review of this upsurge of interest is given by Kingdom & Moulden (1992). It contains 59 references, almost all of them recent. For the reader with an extensive knowledge of colour science, McLaren (1986) should be consulted. It contains the following conclusion: although the Retinex Theory has not yet been subjected to the essential stage in the development of any scientific theory, i.e. experiments designed to prove it wrong, it is tempting to consider its effects on colour vision theory and on the practice of colorimetry should it emerge successfully from such experiments.

A reader who wishes to learn more about the processing of colour in the visual cortex would gain much insight by reading the article by Semir Zeki (1992). The drawbridge between the psychology of perception (psychophysics) and neurophysiology is rapidly being lowered. Land deserves some credit for his prescience that the retina and cortex were both involved and for his many ingenious experiments that aroused so much interest in scientists from other disciplines.

In July 1982 the 74-year-old President of Polaroid retired, but not from work. With more than 500 patents behind him he decided to concentrate on his life-long, although sporadic, fascination with human colour vision. He said on his retirement ‘I look forward to a new period of creative freedom for myself.’

In 1980 Land saw the potential of a vacant lot beside the Charles River at Kendall Square and he decided to build there his Rowland Institute for Science. He retired there to pursue his hobbies and research. I have been unable to establish the reason for the name Rowland, other than that it was a name used among the Land family. Without any outside grant support, Land attracted a small band of kindred spirits to work on a wide range of subjects ranging through artificial intelligence, genetic algorithms, scanning tunnelling microscopy, holography, protein dynamics and, his long-time interest, colour vision.

A colleague of mine, distinguished for his research on colour vision, visited him there in May 1985 and described it as a cross between an art gallery and the private laboratory of a 19th-century gentleman scientist. The recluse Henry Cavendish (1731-1810) resembled Land in many ways and has been described as ‘the richest of the learned and the most learned of the rich’.

The success of the Rowland oasis, Din’s last experiment, will be watched by all scientists as the decades pass through the year 2000.

Patents on the instant colour film process by Land and his associates provided the basis for an infringement suit that Polaroid brought against Kodak in 1976 and won in 1985. Land left Polaroid in the summer of 1982 and he had sold his last stock in the company before the verdict in favour of Polaroid was reached. Land spent a year in court giving detailed evidence about the relevant patents. Kodak had to withdraw the sale of ‘their’ camera and colour film worldwide.

Immediately after Land’s death, and in honour of his contributions, the city of Cambridge, Massachusetts, decided to rename Commercial Avenue, home of the Rowland Institute, as ‘The Edwin H. Land Boulevard’. In Massachusetts, Polaroid today employs more than 7000, including 2000 in Cambridge. Polaroid’s Chief Executive, I. MacAllister Booth, said Land inspired everyone he worked with. ‘He taught us new science, new industry and new ways of working, which together continue to form the very foundations of Polaroid Corporation.’

Land resigned from being Presidential Advisor at the time of the Nixon-Watergate scandal in 1973. I visited him just after he had been listed as one of Nixon’s ‘200 enemies’. I congratulated him. He replied that he was particularly honoured as it was the only honour he had received without working for.

Like his childhood mentor, Robert Williams Wood (1866-1955), Land became a Foreign Member of The Royal Society in 1986. It was an election that pleased him a great deal but, soon after his election, his health began to fail and after a period of hospitalization he was confined to his home in Cambridge. It was almost impossible for him to come to London to sign the Charter Book. Permission was sought from Council by his colleagues for the signature ceremony to be held at Land’s home in America. This was an unusual procedure, not often done. The Charter Book had been taken out of the Society’s apartments only very rarely. It was taken to Whitehall in 1665 to obtain the signature of Charles II, to Sigmund Freud’s home in Hampstead, London, in 1938 (Freud was too ill at the time), to 10 Downing Street in 1941 for Winston Churchill’s signature, and to the Royal Institution in 1948 for the signature of Sir Stafford Cripps. Only once before had a signing ceremony been held overseas, when Professor A.V. Hill obtained the signatures of two Fellows from India in 1944 in the presence of the Viceroy, Viscount Waverley. After some deliberation, Council resolved to send a page of the book (which will eventually be bound into the Charter Book). The Ceremony was held in Land’s home, in the presence of his wife, son-in-law and Mrs. Land’s Secretary. Professor S. Zeki read the citations and both Edwin Land and Edward Purcell, a close friend of Land’s, were admitted as Foreign Members by Professor Hugh Huxley. Ironically, Land’s signature appears on the page underneath that of Paul Langevin, who numbered work on polarizability as one of his achievements. Zeki later wrote: ‘When I looked at Land that day, he appeared to be a man who had led a full and meaningful life. His face reflected serenity, kindness, and the knowledge that he had enriched lives of many people and achieved a great deal.’

This Medal has been established by the Optical Society of America and the Society for Imaging Science and Technology in honour of Land and in recognition of his unique career as scientist, technologist, industrialist, humanist and public servant.

The medal recognizes pioneering work empowered by scientific research to create inventions, technologies and their resulting products. The recipient should share Land’s insatiable scientific intensity and curiosity in optics and imaging and, in part, reflect his image as inventor, scientist, entrepreneur and teacher.

The first Land Medal was awarded at the IS&T Annual Conference in Boston in May 1993. It went to Howard C. Rogers, who had succeeded Land as Director of Research at Polaroid in 1982.

I express my gratitude to John J. McCann, Manager, Vision Research at Polaroid Corporation, for providing me with much useful material about Edwin Land’s life and the history of the Polaroid Corporation. In particular he helped me to convey accurately the personality of Land and his family background. I am grateful to Dr John D. Mollon, Experimental Psychology, University of Cambridge, for providing information about the historical aspects of research in colour vision.

Professor Campbell’s untimely death occurred when this biography was nearly complete, and his work was carried on by Dr R.H.S. Carpenter with advice and assistance from Professor S. Zeki. In addition, Sarah H. Perry, of the Rowland Institute, very kindly provided the bibliography of Land’s works, and a curriculum vitae.

Kingdom, F. & Moulden. B. 1992 A multi-channel approach to brightness coding. Vision Res. 32, 1565-1582.

McLaren, K. 1986 Edwin H. Land’s contributions to colour science. Journal of the Society of Dyers and Colourists 102, 378-383.

Mollon, J.D. 1985 Studies in scarlet. The Listener 113, 6-7.

Ottoson, D. & Zeki, S. 1985 Central and Peripheral Mechanisms of Colour Vision. London: Macmillan Press Ltd.

Zeki, S. 1992 The visual image in mind and brain. Scientific American 267, no. 3, 42-50.