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Astronomy

Out of this World

From telescope lenses to extraterrestrial periscopes, Juan L. Rayces discusses his career of innovative lens design.

From telescope lenses to extraterrestrial periscopes, Juan L. Rayces discusses his career of innovative lens design.
31 May 2004, SPIE Newsroom. DOI: 10.1117/2.5200406.0011

Juan L. Rayces was a junior naval officer in Argentina when he developed a chart for graphic calculation of the azimuth of celestial bodies, cementing a lifelong fascination with science. He is the recipient of the 2004 A. E. Conrady Award for his innovative contributions to lens design, and for lifetime dedication to the art and science of optical design. He studied technical optics under Professor Louis Martin (who succeeded A. E. Conrady) at Imperial College in London (London, UK), graduating in 1948. Rayces's distinguished career in lens design has included two stints with Perkin-Elmer (Norwalk, CT, and Costa Mesa, CA) totaling nearly 24 years. He was interviewed by Rich Donnelly and Tim Lamkins. This is an extended version of the interview in the printed magazine.

Rayces taking the first pictures with the "solid cat" at Dana Point Beach, CA in 1975.

SPIE:How did your interest in optics develop?

JR: In 1935 when I was in high school, my brother was ahead of me taking physics already. I saw in his textbook a Porro inverting system and I made one with mirrors instead of prisms inside a shoebox, and it worked. I also saw the picture of a simple telescope and I made one with a lens from my mother's discarded glasses, a newspaper rolled into a tube and a magnifier lens, and it worked. I looked at the moon. I saw part of it; the telescope field was too small. My curiosity in Optics was increased. As for Astronomy that piece of moon I saw was enough for me. A year or two later I visited an observatory and I saw a planet in plain daylight through a large refractor, and that was really intriguing. It was after many years that I understood why that is possible when you look through a long tube. I never again put my eye behind the eyepiece of a telescope, even when years later I worked in that very same observatory. Optics per se was the thing for me.

SPIE:What led you to leave Argentina for work in the U.S. in the early '50s?

JR: This is a long story: I did not take that decision on the spur of the moment.

After high school I attended the Naval School, Rio Santiago. As a Midshipman I visited the U.S. and became fascinated with San Francisco. I received my commission in the Argentine Navy at the end of 1940. I enrolled as a student pilot in the Navy Air Arm.

I crash landed my training plane while my mother was praying for me at the Base Chapel.

Doctors found many good reasons why I should not be allowed to continue my training as a pilot. I was transferred to a light cruiser undergoing a five-yearly period of repairs. When the ship was ready, it joined the fleet and we sailed into high seas. On the second day at sea a catastrophe occurred, the worst in the history of our Navy and I was a participant in it. I was ordered to man a lifeboat and rescue survivors of a sinking destroyer rammed by our own ship in a sudden fog.

After that life in the fleet was rather uneventful. I was a junior officer, not allowed to have duties on the bridge during maneuvers. Instead I had the night watch. I kept myself busy developing a chart for graphic calculation of the azimuth of celestial bodies. I became convinced my true avocation was science: exact science not naval science. When the chart was finished we found that the British Admiralty had just published a similar chart. I was disappointed but the Navy gave me credit anyway. I suspected that, as a mathematical problem, it might have been solved even before that. Sixty years later I finally learned that the device had been invented twice before: by J. J. von Littrow in 1833 and by Patrick Weird in 1890.

Thanks to my new reputation as a scientist in the Navy I was first transferred to the Optics Facility at the Naval Base and then the Navy enrolled me in the Technical Optics Course at the Imperial College of Science in London for a period of two years.

The Head of the Department at that time was Professor L. Martin. He had succeeded professor A. E. Conrady. There were two degrees of separation between the eminent eponym to the SPIE award I am receiving this year and myself.

Juan and wife Maria-Ines Rayces celebrating their 50th wedding anniversary.

I met Maria Ines Niven in London and we had our wedding there.

I returned to Argentina and the Navy after graduation in 1948. Both had changed during my absence. In the Navy there was little or nothing for me to do in optics. I retired from the Navy and I took a position at the La Plata Observatory. Things did not improve there. Juan D. Perón had been elected president of Argentina but for all practical purposes he was a dictator. We were somehow protected in the Naval Base. Not any more in civilian life: we had to attend political meetings to keep our jobs.

Optical work at the observatory was not a challenge at all. Before I joined the most sophisticated thing done by the optical group was a box with test lenses for ophthalmic use that really belonged in a museum. That had been presented to President Perón by the Director of the Observatory in a ceremony at the Government House. I wonder what Perón did with it.

When Perón was elected the Argentine currency was second in strength to the Swiss. Perón dilapidated the Treasury in two years, and started a rampant inflation that lasted 40 years. You never knew if you would have enough to pay the rent on the next month. In 1951 I could not take any more political oppression, inflation and lack of scientific challenging opportunities.

From my school years I had a pen friend, Virginia Jones, a student at Ratcliffe College. Almost by accident I learned in a newspaper that her husband, Dr. Herbert C. Pollock was a prominent physicist at the General Electric Research Laboratory who, with others, in 1940 had isolated U235 for the first time, one of the most important steps in the development of the A-Bomb. I wrote asking Dr. Pollock and his wife their help to come to the U.S. and they were my sponsors to immigrate.

SPIE:You have been a researcher and a lecturer in several countries throughout your career. What have your travels taught you about science and engineering around the world?

JR: When I started traveling I had already decided that the time had come for me to pass on my experience to younger people and doing that gave me enormous satisfaction. I had already developed my own software that helped me a lot in teaching lens design to these younger people. I gained the affection of them and we remained friends for ever after. Receiving a telephone call from one of them, sometimes from almost the opposite end of the world, is every time a tremendous thrill. In particular I enjoyed working with students at my alma mater in London. The mentioning of my help in their Ph.D. theses, are the most cherished mementoes of my professional life. It gives me the feeling that my passing through life was something more permanent than just a gust of wind.

As for science and engineering around the world, I do not think that with today's unbelievable expansion of communications there may be any geographical differences. The difference I perceive is in time. I am under the impression that contributions to conferences and technical magazines, at least in my field, more and more tend to be secretive. Authors seem to be more interested in gaining credit for what they did than in helping others to share their knowledge and experience. Patents are often even more explicit than articles.

SPIE:What do you consider to be some of your most important professional achievements?

JR: I have been extremely fortunate that I was able to develop my own lens design software with the sponsorship of the now defunct Perkin-Elmer Corporation (not related to PerkinElmer Optoelectronics). This program combines the work of two giant scientists of the XXth century: Professor Frits Zernike of Holland, a prominent and famous optical physicist, and Dr. Erhard Glatzel a mathematician and prolific lens designer at Carl Zeiss in Germany.

During the first part of my professional life I gained knowledge and experience in the art and science of lens design. For the second part, while I continued to gain knowledge and experience, I was able to turn knowledge and experience into design software. It was almost like writing a book, except that a book is completely lifeless, while a computer program is alive to some extent.

It is true that this computer program has not gained wide acceptance in the lens design community. It is not easy to use, it requires a solid theoretical background, and as a friend of mine put it, "it is not for the monkeys"

SPIE:You've seen raytracing mature from the simplicity of slide rules to large breadboards to the handheld calculator to the GigaHertz machines in use today. How profound is the difference today from lens design early in your career?

JR: From the beginning of history older generations have complained of the many shortcomings of newer generations such as lack of enthusiasm and lack of ambition. I am no exception, and the newer generation of lens designers is no exception. When you had to spend five minutes in the computation of the refraction of one ray through one surface with a mechanical calculator and you needed many thousands of those rays to complete a satisfactory design you really needed to have dedication, perseverance and love for the profession. Faster computers and developments in software made the task easier, but it has not made better lens designers. Surely, there are today fantastically better optical systems such as those used in microlithography, but these were designed by geniuses like Dr. Glatzel, mentioned earlier, who in addition to his gifted brain had great love for his profession. You can be sure of this: when Dr. Glatzel designed those systems he did not turn the computer on and went to sleep to find the results next morning, as it happened with the winner of the last International Lens Design Conference contest. Dr. Glatzel even developed his own software to achieve his goals and that required considerable intellectual effort.

The sophistication of lens design programs, parallel to the tremendous advances in electronic computers, might be compared to a large aerospace company developing a passenger aircraft that can be piloted by someone who only has experience in driving a car. But it must be admitted that these sophisticated programs benefited the OEM's that needed to meet greater demands in complex optical systems since the space age began.

I should not be that negative, though. I do not really know what percentage of self styled lens designers are just robots that only know how to punch keys on the keyboard and use defaults in the programs. I have been fortunate enough that prospective designers I have associated with were students ready to make sacrifices for the sake of science and to embrace the profession with true love and dedication.

SPIE:What do you foresee will improve future lens design methods, and what do you advise the students you mentor to prepare them for the many revolutions they may experience in their careers?

JR: In this trade there are individuals who develop software, and individuals who use that software. A brilliant student at the Beijing Institute of Technology, recipient of the 2003 Michael Kidger Award, is typical of the former. She is doing research work on intelligent computer-aided design (ICAD), global optimization, use of neural network to handle discrete variables, related topics that will eventually become powerful tools. Users are limited to a great extent by what the developers hand over to them. Yet there can always be creativity in what the user can do. But there cannot be creativity without previous knowledge and training. There are artisans and artists even in lens design. Any one who sets the program defaults and goes to sleep until next morning is not an artist, he can say "my designs" but that is not true, that lens was designed by the program developer.

I have at home a beautiful Chinese scroll. It reads: "Sip the dew dropping from the orchid petal; follow the footprints of the wise, moral men before you". Good advice for lens designers. Try to understand why what you are doing does work or why it does not work. Remember all the great names in lens design, people who came up with remarkable lens systems and did not have the benefit of electronic computers.

SPIE:You have been very involved with space applications from the simulation of the Hubble's primary mirror error to the NIMS Spectrometer on the Galileo Saturn mission. What has been the most fascinating for you?

JR: Probably the most fascinating system I designed was the upside down periscope for the Mercury capsule. Space exploration had just started. Project engineers at Perkin-Elmer shared a big office with the desks neatly aligned. Early each morning new request for proposals were distributed among the engineers, they came in folders. That morning when I opened mine I though it was a joke: a periscope looking down to be fitted to a capsule orbiting the earth with a man inside. The periscope was supposed to render three views of the horizon separated 120 degrees for the astronaut inside to keep the capsule aligned with the vertical, and a fourth view of the earth below. When I recovered from the surprise I made a preliminary design of a dual viewing system, one view looking at a circular area of the earth below as originally requested, and the other a hemispherical view of the entire earth horizon to horizon, with a lens system now known as a "fish-eye objective". There was a switch to go from one mode to the other, and the images would appear on a circular area between the astronaut´s knees. We submitted the proposal to the main contractor, McDonnel Aircraft in St. Louis, Mo., and we won the contract. Eventually the periscope was built, delivered and installed in the capsule. At the time of the proposal the periscope was a very important part of the capsule because the glass window manufacturers had not come yet with a glass that would resist the reentry temperature. A chimp named Sam was the first one to look through the periscope from space: he reserved his opinion. Then Alan Shepard, the first astronaut "observed the woundrous sights below through [the periscope] gray slide [and exclaimed] What a beautiful view!" (Project Mercury Freedom 7 History)

Naturally, taking part in the refurbishing of the Hubble telescope could never be that exciting. Neither monkey nor man, were up there to express admiration. The thrill of participating in that project was instead being required to design an instrument considerably smaller than the Hubble primary mirror and simulating the same flawed wave fronts. For that project I found I had to come up with a lens design method totally different from the standard. The concept of the method was difficult to explain to the management and to my co-workers. I finally took a pair of socks, one representing the telescope mirror and the other representing the simulator. I pulled the inside of one of them and turned it the wrong way, and we called the method "the inside out method". My friends did not ask me to go into details; they accepted the sock model.

Because the periscope was such an important part of the Mercury capsule I had the feeling that I was important in the project. On the other hand in the refurbishing of the Hubble telescope there were so many other important things, like determining with amazing accuracy the amount of flaw in an inaccessible mirror floating in space far above our heads. Instead I had great satisfaction of having developed the inside out method.

I have participated in other space projects but the design work involved was only as exciting as many other instruments that never went too far above our heads, with the exception of the solid catadioptric system discussed below.

SPIE:You've patented some very complex solid catadioptric systems, some with remarkably short lengths compared to their long focal lengths. What was your inspiration for these designs and what did you find the most difficult aspect of optimizing them?

JR: Two years after I joined Perkin-Elmer, in 1960, one of the projects assigned to me was a small star tracker, something of a miniature Cassegrain telescope with a two-inch aperture. It was supposed to stand severe shock and vibration test. Placed on the "shake table" the small telescope completely fell apart.

Someone said casually: "only a solid piece of glass will stand that kind of test", and I heard the comment. Then I designed a 635mm f/9.6 Cassegrain made of two short glass cylinders of different diameters cemented together. It was christened "solid catadioptric" or "solid cat" for short. The primary was 18 wavelengths aspheric. It worked only on axis and it was difficult to align. A year later, in order to alleviate these two hurdles I produced a 355mm f/6.2 aplanatic design (corrected off-axis) with a 12-wavelength aspheric primary.

It was suggested to attach this newer solid cat version to a Minox camera body. In order to fit the camera it was necessary to extend the back focus using a negative (Barlow) lens that further extended the focal length. The results were encouraging and the next design, in 1965, was a 660mm f/11.5 solid cat for a 35mm camera body. It looked like an ordinary 35mm camera lens, nobody would imagine it had a 13x magnification ratio compared to the standard f=50mm objective. This solid cat was manufactured in small quantities and sold to police agencies for intelligence work. The front surface was 12 wavelengths aspheric,(equivalent to 4 wavelength on a primary mirror), but still it was impractical for production in large quantities.

I did some more solid cat designs, always trying to do away with the aspheric altogether. I finally reached my goal with an all-spherical design in 1970, this was a 600mm f/8, with overall length of 84mm, about 1/5 the overall length of a standard 600mm telephoto lens. The Perkin-Elmer Astro-Optical General Manager interested Vivitar in marketing the lens and the lens went into production at a selling price of less than 1/10 the price of the aspheric solid cat. This was a remarkable feat because the division had absolutely no experience in mass producing optics. Another feat was to completely block stray light that always plagues catadioptric systems. Vivitar engineers subjected the solid cat to all kinds of tests, including comparing it to a Nikon 500mm Reflex-Nikkor mounted on the same camera body and taking pictures on the same strip of color film. We took the solid cat to that year's Photokina Exhibition in Cologne. There it was subject to a test that its ancestor, the Cassegrain star tracker could not pass; a visitor to our stand dared one of our people to drop the solid cat onto the floor from a table, he did so and the solid cat survived.

Vivitar was interested on the solid cat mostly for prestige but they lost interest after two or three months and production was halted. Also at that time the price of zoom lenses for 35mm cameras suddenly was within the reach of any pocket. Let us be honest about it: a zoom lens is a lot more fun to use than a fixed focal length solid cat, no matter how short the solid cat may be.

SPIE:Tell me about your family and what you like to do in your spare time. For example, do you have any hobbies, favorite travel destinations, pets, home projects?

JR: A few years ago I gave one of my friends a stereoscopic camera that would qualify for the Antique Road Show. He would not accept it. He said: You only give something like that to your family. I answered spontaneously "my friends are my family also." Having emigrated from my country, my blood relatives, family in the strict sense of the word, are very few indeed. Maria-Ines and I celebrated our 56th wedding anniversary only a few weeks ago, and every day we give thanks to Providence for having allowed us to enjoy each other's company for such a long time. Besides that we have two daughters and three grand children, and I always hope that one of them at least will follow in my footsteps.

For the last four years we have lived in the Tucson area close to our daughters and grand children. Before that we lived far from each other and the children of my friends filled in for our own grandchildren and did a wonderful job showing affection to the two of us as can be expected only from the most loving of grandchildren.

As for our favorite trips abroad, besides visiting our friends and relatives in Argentina, our favorite country is China where we have visited already three times and we are getting ready for the fourth. I became interested in China when I was seven and I learned that my place of birth, Bahia Blanca, and Beijing were antipodes. There were no Chinese in Argentina when I was young. It was here in the U.S. that I became acquainted with Chinese and other Asian Americans. My associates in the development of the computer program were Asian Americans and most of my friends are Asian Americans. And, as you may guess, those adoptive grand children we love so much are their children.

Optical design is still my great pastime. At one time I tried sailing as many people do, but it interfered with my siestas on Saturdays and Sundays, and always there was either too much wind or not enough wind. In the end you wonder if you are sailing because you like it of because you feel you have to justify the expenses of the sport, mainly the rental of a boat slip in a marina. That ended for good when I exchanged a PC for the sailing boat: the weather is always perfect to sail on a PC. Today my favorite pastime is the e-mail, even when I spend several hours each day doing optical design. First thing I do in the morning is to check whether there is any mail from my friends at home and abroad, and last thing in the evening is to answer their letters. Years ago I worried thinking I would be idle most of the time when I retired. I am thankful that it has not happened that way.