Emmett Leith

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Interviewed by
Sean Johnston
University of Glasgow
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Interview of Emmett Leith by Sean Johnston on 2003 January 22, Niels Bohr Library & Archives, American Institute of Physics, College Park, MD USA, www.aip.org/history-programs/niels-bohr-library/oral-histories/29298

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Interview discusses Leith's early career, including his work at the Willow Run Laboratories of the University of Michigian and his holography research on synthetic aperture radar.


The following notes, not fully transcribed, suggest the scope of the discussion.

Much of the military work was classified. Maybe nobody has bothered to declassify it, but it would be a real goldmine of information for an historian.
Wrote memo for quarterly progress report, written in 1956. Republished in his PhD thesis of 1976.

Early career: background is physics (BSc and MSc). Took a number of electrical engineering courses but mainly physics. He had taken 4 optics courses at University as a physics major, so he became the local expert. Had only a little interest in optics as a student. Optics was spectroscopy, eyeglasses, lens design, etc. — not 'modem optics' as today.

Synthetic aperture radar research with optical processing. Army and Air Force contracts — a lot of people working on it. Chose to work in the optical processing project, although it was very shaky and likely to fail. Sponsor was the Army and the Air Force (a little cagey). It was a big project, a lot of people working on it. At first, Leith just laid the foundations of optical processing. Document 5T — about early synthetic aperture work. Did theoretical analysis on a modulated diffraction grating illuminated by coherent (point-source) light.

Notion of optical reconstruction from synthetic aperture radar:
"The most interesting thing along the way was, when I was looking at the results of the analysis, something suddenly dawned on me, which I thought was most astonishing, if you look at the data record and considered it being illuminated with the beam of coherent light, the field that emanated from it in the first diffracted order was in fact an optical reconstruction of the original radar field which was captured by the synthetic aperture radar as it flew along its flight path.” I developed a whole theory from that viewpoint.

Co-workers: big project, but optics part very small. Wendel A. Blikken supervisor, not technically involved. In 1955 hired Lev Purcello, 2nd person on project, just out of school — we were both pretty junior. Memo didn't get much attention at first, but later, when the airplane was flying, this became a fruitful perspective and eventually in 1956 although nobody paid much attention, but in 1960 it was seen as the dominant view not only at U. Michigan, but in the whole radar community.

Belated PhD thesis:
A reinvention of holography, with some similar and some different features. The thesis section title is the same as the report title. Distributed to sponsor, and still in existence somewhere, but difficult to track down. Suspects that somewhere deep in the archives of someplace, all these reports are still in existence. There were other quarterly reports, but less significant for this story. Tracking them all down would show the continuum of development.

Familiarity with Gabor's work:
Awareness of Dennis Gabor's work: he wrote his report in May 1956. He was acquainted with optical literature at that time via JOSA. In Oct 1956 in JOSA there was an article on wave front reconstruction by Kirkpatrick and El Sum — and he recognized that 'it had already been invented'. He was delighted more than disappointed, because he felt it was worth something. He didn't make contact with them at that point. A couple of years later contacted them. Became rather good friends with El Sum (about Leith's age. Eventually made contact with Gabor, but that was some time later.

The term 'holography':
G. L. Rogers — oldish but still alive in England, 5-6 yrs. older than Leith — writes him letters occasionally. Leith has some letters that might provide an address. Leith thinks Rogers coined the term 'holography' from Gabor's 'holograms'.

Juris Upatnieks:
He joined in 1960. Leith had felt, after the Kirkpatrick-EI-Sum paper, that it would be interesting to take up the optical development of wave front reconstruction. Leith's first thought was that radar couldn't be applied to optics, because in optics you record only the time average, not the real function.
If you record the instantaneous time signal, you have the phase and amplitude but in optics you do not. So he was unsure whether or not it could be done.

Funding from military:
Extra-contractual work in holography: it was a big contract, they let me do pretty much what I wanted... They let me do exactly what I wanted, and I came up with enough good ideas to keep them happy, so... But holography was a sideline. I thought of this way and that way... to record phase and amplitude. Leith thought of various ways - some more complicated — some were published, some not. My first impression was that if you introduced an off-axis reference beam so that the hologram became like a diffraction grating with various diffractive orders, you would have various diffractive orders and within each order you would have all three images that would be totally inseparable, you would have three sets of inseparable images instead of just one; that was my thought, I thought that won't work…

Juris Upatnieks, co-worker:
Juris Upatnieks — 5 yrs younger. He didn't immediately have clearance, so he couldn't work on the classified stuff. He was very junior, and by that time Leith was kind of... not quite so junior. Leith took him in tow, and put him on that. When hired, (staff doesn’t immediately have clearance), so are kept off to one side, and followed around so that they don't look into anything they shouldn't look into… The first thing that they did was to duplicate Gabor's original work, which was straightforward.

It was most fascinating, because here you had a piece of film that had nothing but garbage on it, or very fuzzy images at best, and then you looked downstream where they came to a focus, and there you saw a real, nice sharp image, and there was nothing producing it — there was an image but no optical elements - kind of like a grin without a cat by Lewis Carroll's analogy, you might say... there was an image but there was no source, or no obvious source, and that was most fascinating, even though it was nothing new, it was what Gabor had done, although it was fairly high quality, but...

Photographic materials:
Emulsions — using ordinary film at that time. For off-axis, still used ordinary film because off-axis angle wasn't terribly high. Leith and Upatnieks worked together on this small project. It got exciting, and absorbed more and more of my attention ... and it doesn't mean that it worked at once, it worked out gradually, it worked a little bit, and it worked out better. The first off-axis pictures were pretty lousy... We got some really lousy reconstructions; they were noisy and otherwise pretty lousy, for no good reason that we could think of, but it was just a matter of making the system a little bit better, and the optics a little cleaner and so on, and gradually it got better and better.' They showed people in the lab reconstructions of Gabor's work — it didn't provoke much interest until the images got better. 'The interest rose as the quality got better and that was a slow process'.

First hologram:
Everything came slowly. People ask well, what was your first hologram, which is the first hologram? And museums around the country and private collections and so on, people have enough of the 'very first hologram' around [like pieces of the real cross] back then you could find in crypts and grottos enough pieces of the real cross to start a lumber yard. And some of these holograms that people claim to be the original might be the thousandth... They weren't the first holograms, because there wasn't a first hologram; it was an evolutionary process. It was an incremental process. Things gradually got better. When the laser came along, we switched from the mercury arc to the laser, and then we vacillated between the two... the laser was easier to use, but it was noisy ...

Transition/rom mercury arc to lasers/or holography:
Took several months to decide which was preferable. In the 1962 paper a diffraction grating was used as a beam splitter, quite simply because that is what was available around the lab, they didn't have a Mach-Zehnder interferometer, etc. But this arrangement minimized the coherence requirements, so ideal for a mercury arc source. They were very familiar with mercury arc sources, as the basis for their optical processor.

Optics group at Willow Run:
Optical group and expertise — had about 10 people in the optics group in various aspects. Had 5 or 6 labs, with one or two people in it, and each one had a high-pressure mercury arc source. Had a lot of expertise; undoubtedly the no. 1 coherent optics laboratory in the world. They looked forward to lasers, but then there was controversy about spatial coherence. They had no special access, so they waited until they were procured on the open market around late 1962.
Transition from military contract to holography: had some military applications — could simulate radar ambiguities, which had some military justification. Only Juris and Leith worked on optical holography; other labs were working on other optical aspects of military contracts.

Transition from 2D to 3D holograms:
Got some pretty good pictures — black and white transparencies of letters. Then tried grey scale-disastrous with Gabor's approach, because the noisy background would have obscured the grey scale images.

Published first 2D holograms. Mundane pictures published — "We picked whatever was available lying around the laboratory... they're all mundane or ridiculous in some way or another ... in the 1963 paper we had B& W pictures of a bookmark, my daughter as a little girl, and then there was a picture of Juris's brother... We showed some excellent pictures, in fact one of the reviewers said did you get these pictures mixed up… the reconstruction was indistinguishable from the original…

Reactions to publications:
OSA decided to do a news release on these 2D greyscale pictures. So they came up with the theme of lens-less photography. Leith has a copy of the new releases. Provoked a fantastic, an unbelievable reaction... newspapers around the world picked it up. His employers 'didn't care too much one way or the other. The military people would be far happier if we didn't publish anything ever, at any time! He had to obtain clearance, but not justify why he wanted to publish... people would write, ask what they could do with it... Leith/Upatnieks envisaged x-ray holography, to make x-ray images better. And then there were the crazies, who were convinced that people were shining laser beams at them, and pulling ideas out of their mind ... Leith has scrapbooks of clippings.

Only two thorough publications: New York Times and Wall Street Journal. All the others simply picked up the news release or asked a couple of questions. NYT interviewed him by phone for about an hour. However, proofreading was bad: caption says 'new technique captures PHONE' instead of PHASE. But by the time the paper came out, they had extended to 3D reflective objects. Scientifically, it was not terribly revolutionary (!) but the NYT people didn't pick up this new slant! They ignored the 3D reflective bit, and didn't go beyond the news release. 'I thought that was really funny'.

Step from 2D to 3D:
Gabor said it's three-dimensional... he had always said so, so Leith says it was a trivial one scientifically. We knew it was supposed to happen.

Seeing 3D image:
You saw almost no parallax, you saw no three-dimensionality, no stereo ... we knew that that image that we were looking at was three-dimensional, of course it was, so we cured that by... going to plates that were... strip plates — Kodak sold them... and we cut them to this length so two eyes could get in, and sure enough, they were three-dimensional as prescribed... but the realization was unbelievable ... just seeing it there, seeing it happen, was most astonishing...

First 3D hologram subjects:
First one was a pile of junk — we looked in desperation for an object that would be suitable and found scrap metal, resistors, capacitors, and little piles. But an unstable pile; we had a lot of failures. But they had procured a granite slab for the Mach Zehnder interferometer for another group. Temperature stability was another problem. The slab helped for mechanical stability. They used an oscilloscope to detect fringe stability.
And that's when people really began to take notice... it was a type of imagery that had never before been seen. People sat up and took notice, people in the laboratory looked at it in astonishment, the management came in and looked at it, and the Director came in, people outside the university came and looked at it and Bush, the scientific editor from the Ann Arbor News... He said the plate looked like 'a buttermilk sky' until illuminated by a laser.

Dec. 1963 (?). Electronics magazine picks up story of 3D imagery. This came out before the OSA meeting and paper. Leith has a copy of this. This was the earliest one, and the only one before the OSA paper. This happened because the PR man had close relations with the magazine.
The paper was published in Nov 1964, so Electronics was nearly a year earlier. Showed the holograms to people around Ann Arbor. Engineers and scientists in the area. Showing train hologram at March or April 1964 OSA meeting. That was when the roof blew off. Spectra-Physics had a suite and allowed them to display. The toy train hologram was shown. Juris presented the paper in the afternoon and announced the display. There was a tremendous exodus of people' before the next speaker. There was a long queue out of the suite, down the hall and around the corner. People were confused and these were optical scientists... one guy said oh my, I think my eyes are damaged... although the laser was probably about 2 mW. They all went back to do it themselves, and then Leith and Upatnieks were inundated with telephone calls. They lacked the expertise that Leith and Upatnieks had developed over several years with optical processors.

Meeting Gabor:
After the 1963 news release, Gabor read about it and contacted Leith.

George Stroke:
It probably is best to hear about this from other people, because if I tell you about these things it would be like I was telling you about 3D, that you hadn't seen yourself... Has a George Stroke file 8 inches thick.
He arrived in 1963. He was a consultant for the radar laboratory... he didn't consult much, he came down occasionally... he was on a retainer basis. Stroke did tell them how to build a Mach-Zehnder interferometer, but beyond that Leith doesn't remembering him consulting more than once or twice, and not anything having to do with holography. Then there were Stroke’s course notes, which he wrote up and which made us mad because his notes seemed to suggest that he was involved in the work which he wasn't... but then in subsequent publications, and his book, he referenced his course notes as the first publication, which it wasn't... the course notes themselves reference Leith's papers...

Role as public figure:
It was overwhelming. It sapped a lot of time. Employers were excited about it. Phil Brown, laboratory director, was extremely cooperative. The head of the electrical engineering dept. was extremely cooperative. They liked it. Then Fred Llewellyn, Dir. of the Institute of Science and Technology, of which the Willow Run Laboratories was a part, a very strong supporter, went out to try to get support for it… funding support and patent. He went to Battelle, to try to get them to support it, which they did, and patent it, which they did...
The media role was fun at first, and then tiring — it went on and on.
We got research funds. First of all the air force threw money at us... just to explore it for applications... they gave us $150,000 which was a big chunk of money at that time, just to hunt for applications, and it wasn't really a classified contract, this was a side line from the radar work we'd been doing as we went along, so this was a welcome thing, then the Battelle people gave us some money, so we had a lot of good funding.

Administration at Willow Run:
At about 1962 Leith became head of the Optics Group. Everybody wanted to work in holography, because it was new and exciting, and it was like a plum tree, full of ripe plums, anything you think of would be new and original, so it's easy to write lots of new and original papers, which everybody else was doing and we wanted to do it too... so I said with this money that I have, and in addition Fred Llewellyn, the Director of the 1ST, gave us seed money, so I said everybody can work a little bit, do a little bit of work in holography... Ken Haines was a member of the group and a witness to it all...
Karl STETSON wanted to... This is early 1964, now. Adam Kozma (in Ann Arbor retired now) –- one of the more senior people there at the time. In the Optics Group there were probably 10 engineers and scientists. They had a few technicians, secretaries, professional draftsman and photographer. The largest group in the world, at that time, in coherent optics. There was an outpouring of papers from the group. And the 1ST, of which Willow Run was a unit, made an arrangement that seed money could be used by Leith, and the papers by Willow Run would be expedited and not slowed by clearance — they had been disadvantaged. Competition was enormous. At the next OSA meeting, there was a whole session on holography. Following that, there were three or four sessions...

Yuri Denisyuk:
He published within a month of Leith and Upatnieks, although had worked much earlier, as had Leith. Markov says Russians thought Denisyuk was crazy. Denisyuk's work didn't attract much attention. The OSA had a translation of the Russian Journal, Optics and Spectroscopy. Denisyuk's description made the connections with Gabor and Leith unobvious. Sometime about 1964 or 1965 Leith heard read it, but it didn't ring a bell. A group working out of Boston published a paper on a new way of making holograms — illumination from back side, so can have a wider beam object without the reference beam getting in the way. Afterward, they were totally embarrassed that they had missed that it could reconstruct in white light. Leith decided to try out the same technique. So Juris made a back beam hologram, and went to have it developed in a different building. When he was walking back, in sunlight, he looked at the hologram and saw the most astonishing reconstruction in white light. And he was showing everybody in the laboratory, and everyone was excited about it. But then it struck Leith that this is what Denisyuk had been talking about.

So they were excited about it, and a short time later the Battelle sponsors came down to see what was doing, and they were totally unexcited — they said 'we did this last August, but wanted to keep it quiet for commercial reasons. Then some time in December there were three separate discoveries of white light reflection holography - although Denisyuk had done it years earlier. After dealing with patent application, Leith et al submitted a paper. Stroke and Labeyrie also did something on this around the same time — about Dec 1965. So Americans realized that Denisyuk really had something new. Leith met the Boston people, who felt like kicking themselves at what they had missed.

The patent issue interested the Battelle people — Leith and others were out of it, because their sponsors had done it before they did. Then the Conductron Corporation went to trying to work with Stroke and tried to get patents on his work, so an interference was declared. Patent went to Nil Hartmann of Battelle, but he got little recognition because of Battelle's reticence to publish. Battelle work had preceded the Boston groups, and also Leith.

Rainbow holography:
Leith and Upatnieks saw first rainbows, by Stephen Benton, at a public art exhibition when he went to New York to receive an award. Benton's principal publication was an abstract in the OSA, and he hadn't then shown it to scientists. So art world new about them before scientists did!

Gordon Conference:
In the summer of 1966 or 1967 [SURELY WRONG - 76?], Leith was chairman of the Gordon Conference on holography. He invited Benton, and Lloyd Cross. Cross was remarkable in his way, a free-spirit scientist. He worked at Willow Run, but not in Leith's group. He made the first commercial laser. He disappeared in California, and started making holograms. He began making multiplex holograms. Nick George had made integrals, but Cross had a variant. Cross and Benton had displays side by side, and Cross realized that they should be white-light viewable by viewing Benton's in some exhibit. Cross was working with artists in a kind of communal society, and they were making some fantastic holograms. They were being displayed at the Miramar Hotel in Santa Barbara. The holographers there were astounded by the multiplex and the rainbows.

Artistic holographers:
Benton was a conventional scientific person, Cross a hippie type person. He came down in a broken down van, out of which piled a whole bunch of people, who all piled into one room and showed up for dinner. The director of the conference was hard-boiled and demanded that they pay for the entire conference even if only for one day.
Leith was chairman of Gordon confin. 1970 or 1971, on reflection. [1976, actually] He had met artists earlier at the NY meeting.
Also at opening of the Museum of Holography (but that was much later... Poor memory for later dates, it seems).

Post-seventies holography:
Any big excitements since ? Lots of interesting things, but not the same magnitude for Leith. Holographic portraiture with pulsed lasers was impressive.
(Seems well versed on the early years — presumably oft-told tales and perhaps mythologized as a consequence — but less on 1970 and beyond.

Directions — missed opportunities, etc.:
1965-1966 — holographic interferometry. The first solid application for holography that looked promising, with whole symposia and conferences devoted to it. Karl Stetson, of Willow Run, was central in those activities. He did time-average holography, but others did double-exposure and real time holographic interferometry. Stetson and Powell (?) had priority of publication, but in the next phase, Haines and Hildebrand (in Willow Run) and Jim Burch at NPL, all more or less the same time.
Burch got the patent because he was earliest, but it could have been any of the others.

Relevant publications:
Has given partial accounts. At Jeong symposia he has given papers; History of Display Holography (anecdotal, tongue-in-cheek); he wrote paper on the History of the Optics Group — he is the world authority, because he was its leader half the time, and in it from the beginning.

Dispersal of members of team:
Upatnieks and he drifted to different things. Stroke left in 1967; Leith got professorship in 1965, teaching grad students and optics courses. Juris ran the optics lab for many years. Chuck Vest, now President of MIT, was in the group and later professor of mechanical engineering, and he and Leith had a lab together...

More on publications and wrap-up.
Wrote an historical article for JIST — Journal of the Imaging Science & Technology? Used to be called SPSE. Now they are called... He told some anecdotes in that article.
All the interesting things happened in those early days. Everything was untouched, everything was virgin territory. People just had a field day. You could think of ideas, papers came hard and fast, nowadays it's hard to find a paper... it was a gold mine, you just had to mine it. Now you have to dig deeper... most anything you do hadn't been done before...