Oral-History:Robert Rediker

About Robert Rediker

Rediker was born in Brooklyn in 1924. He went to MIT for his BS in electrical engineering and his PhD in physics. His career was largely at MIT, at its Lincoln Lab and as a regular professor. His research was on circuits, transistor circuits, transistors, gallium-arsenide transistors (he patented the first p-n junction in gallium arsenide), and semiconductor lasers. His research was very important for LEDs, transmitting TV by laser, the technology behind CDs. He retired in 1991, worked for a medical laser company until 2000, doing imaging to detect prostate and breast cancer, and finally retired in 2000.

Rediker was in the Electron Devices Society from the 1950s. He served on the IRE Technical Committee on solid-state devices, and ran the Semiconductor Device Research Conference. He managed to move the Research Conference from the IEEE to the EDS, which allowed private interchange of technical information to continue, without letting commercial secrets into the public domain.

Rediker mentions technologies that never quite got off the ground, such as thermoelectrics, the Esaki diode as a transistor (though it worked well as an oscillator), the Gunn effect, and the gold-banded diode. Silicon transistors and lasers, in contrast, gained great influence.

About the Interview

ROBERT REDIKER: A Telephone Interview Conducted by David Morton, IEEE History Center, 27 July 2000

Interview #404 for the IEEE History Center, The Institute of Electrical and Electronics Engineers, Inc.

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Robert Rediker, an oral history conducted in 2000 by David Morton, IEEE History Center, New Brunswick, NJ, USA.

Interview

Interview: Robert Rediker

Interviewer: David Morton

Date: 27 July 2000

Place: Telephone Interview

Electron Devices Society

Organizational history, 1950s-1960s

Morton:

Much of what I know about your career is from your short biography in the Electron Devices Society directory. You were involved in the group pretty early.

Rediker:

Yes.

Morton:

Did you have any involvement in that group before the mid-fifties?

Rediker:

I got my degree in 1950. I may or may not have been some sort of an associate, but I really started in the fifties. There was an IRE Technical Committee on Solid-State Devices that evolved from a standards committee that went way back. I joined that committee in ’56 and went to their meetings in New York.

Morton:

Was this technical committee specifically on solid-state devices?

Rediker:

It was on solid-state and had three subcommittees. The subcommittee on semiconductor devices, was run under Jim Early. Another subcommittee was on dielectric devices. The biggest subcommittee of the three was the one on thermoelectric devices.

Morton:

That is interesting. What kinds of devices were those?

Rediker:

It has a very interesting history. Pierre Aigrain – a very prominent French professor who became a big wheel in the French government many years later – increased thermoelectric efficiency by a factor of three or four using mixed crystals. In the 1958 World’s Fair in Brussels there was a Russian household refrigerator that used solid-state thermoelectrics. And by the way, it’s quiet.

Morton:

Yes, I’ll bet it is.

Rediker:

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Pierre Aigrain predicted and indicated a way to further increase thermoelectric efficiency to the point that it could compete with conventional electrical generators. I think these mixed crystals were bismuth telluride, and obviously something else mixed in with them. What was very interesting was that the Americans jumped into this field. Three that jumped on it were the U.S. government, Westinghouse and General Electric. In those days Westinghouse was a significant company in the area of power generation.

The charter of the Technical Committee on Solid-State Devices was to have technical meetings and things as well as to do standards. The thermoelectric devices committee got so big and had so many meetings, maybe three or five a year, it requested to the IRE that it secede from the Solid State Committee. I remember as chairman of the SSC writing what I called the “Emperor’s Letter,” explaining why I wanted to keep my clothes. Interestingly enough, all of a sudden and at about the same time the U.S. government, Westinghouse and GE decided their thermoelectric projects were not going to succeed and cut their programs to almost zero. This was in the very early sixties. An interesting name connected with that was Jack Pankove.

Morton:

I’ve heard that name before.

Rediker:

When the Energy Department founded SERI in Colorado to work on new forms of electric power he went there. I’m sure you are well aware that thermoelectricity never succeeded as an efficient power source. Jack did other things too of course – worked on solar cells and so on.

Of the two other subcommittees of the Technical Committee on Solid-State Devices dielectrics was the smallest. The subcommittee on semiconductors was not much bigger. There was a big focus on technical interchange, and one of the major conferences we ran was called the Semiconductor Device Research Conference. The Electron Device Society also held meetings in Washington. It is now called the EDS Conference. I don’t know which conference started first.

Morton:

Where was the Device Research conference held?

Rediker:

It was held in various university campuses. A humorous thing is that there are two ways to get very large attendance at a meeting. One way is to advertise it like mad. The other way is to call it a closed meeting – by invitation only. Everyone wants to get into the closed meetings, because obviously they are very important.

Morton:

Right. Is this still the Device Research Conference?

Rediker:

Yes.

Morton:

Do you remember the title of the Washington meeting?

Rediker:

I think it was called the Electron Device Meeting, basically the same name it has now. However I don’t know when it started.

Morton:

Were the conferences comparable in size?

Rediker:

No. We tried sometimes unsuccessfully to keep our closed meeting small. The EDM meetings were very well advertised and became much larger. They had a wonderful woman in Washington run their meetings. She may still run it. The Electron Device Society Meetings were always held in Washington in those early days and I always attended of course. The Device Research Conference had a real advantage in that we ran our little meeting in such a way that basically there was no overhead, and thus it made a reasonable profit.

We had a kitty. Two or three years ago someone told me that the Device Research Conference still has a kitty. Back in my day there were the two parent organizations – the AIEE and the IRE. I remember telling each of them we were run by the other one so they couldn’t get our money. In that way we kept our own kitty.

Standardization; Zener diodes

Morton:

You mentioned that committee had started out doing standards.

Rediker:

Yes.

Morton:

Was that still the nature of the work on that committee? What exactly did the committee do?

Rediker:

It did a lot of standards, ran the technical meetings and did other technical things. I think all the technical research meetings were run by this committee, but I don’t know. Let me tell you a humorous story about one of our decisions on standards. An important product was what we called Zener diodes, however most of them do not break down by the Zener effect.

Morton:

That’s interesting.

Rediker:

Therefore one of the standards decisions we made was to call them breakdown diodes. A member of our committee named Mort Prince convinced his company to call their devices breakdown diodes. Sales plummeted. No one wanted to buy a broken down diode.

Morton:

Of course.

Rediker:

That’s why they are still called Zener diodes. The Zener effect was discovered by Clarence Zener. Except for diodes that break down at low voltages, these diodes really break down by what’s called an avalanche. That’s an aside, but we did things like that. The big wheels in the field were on that committee and at those technical conferences. We had a lot of fun there and discussed many things. As an example, the vice president in charge at what is now called Sarnoff Labs and then was the research lab of RCA was on the committee.

Technical Committee, Professional Group, and research conferences

Rediker:

When was the Professional Group on Electron Devices formed? Do you know?

Morton:

They’re celebrating their fiftieth anniversary.

Rediker:

Okay, then it must have been around in ’52 and already existed when I joined the Technical Committee on Solid State Devices. I was on the ADCOM of the Professional Group on Electron Devices for six years starting in ’62. In this time frame we were able we were able to transfer this technical meeting of the field from the Technical Committee to the Professional Group. This was a fairly political thing. During this time frame I was chairman of the technical group and I was on the board of the ADCOM of the Professional Group on Electron Devices (now renamed the Electron Device Society).

Morton:

Why was that so important?

Rediker:

At the time, the Research Conference was the meeting. It was a “secret meeting” and where we were able to convince people to reveal things they would not divulge in the open. This made our conference fairly significant, because it had a lot of new stuff in it. The other meeting, the meeting in Washington, was completely open and nobody would disclose anything there that might be the least bit proprietary – where people only said things that were going to appear in publications within the next couple of months. I can’t prove it, but I know that at the Research Conference people used to pay students who were going to the Conference to take notes for them. That was when attendance was truly restricted. That is now illegal. The IEEE cannot have a closed conference.

Morton:

Interesting.

Rediker:

They still do, but that’s neither here nor there. There is a semiconductor workshop that is held on the last day of CLEO that’s essentially by invitation only, however by law if anybody asks to be invited they must be allowed to attend. In the old days the Research conference not only was it by invitation, but we kept the press out. That’s another thing that can no longer be done.

This is maybe a digression, but that was the conference where all the new stuff came out. Then when I ran that conference, subsequent to all this when it was already under the Professional Group on Electron Devices, we were able to convince IBM to disclose the Gunn effect.

Morton:

I’ve heard of that.

Rediker:

That was the first time it was announced. I was involved in talking to their patent lawyers and assuring them that it was definitely a closed meeting and so on. Crawford Dunlap and I had meetings and devised a way to transfer the Research Conference to the Electron Device Society

Morton:

Was that conference growing every year? Was there a point where it really took off in terms of attendance?

Rediker:

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First, let me tell you an anecdote. I was chairman of that conference when it was held in Princeton. I believe it was 1965 and it was by invitation only. If anyone appeared without an invitation the registration fee at the door was significantly higher than for those who had received an invitation and pre-registered. Attendance was tremendous that year, maybe five or six hundred people attended. I remember the vice chairman, Murray Lampert, at the coffee break cutting all the doughnuts in half. The local arrangements chairman arranged to get use of the theater, because that was the only air-conditioned facility in Princeton at that time. It had only one restroom, which was a major problem of course. It was a movie theater and we needed a bigger stage for the conference. Our local arrangements chairman chairmen had his students build a stage. The cost was very little since students built it. We actually gave the local arrangements chairman a set of golf clubs in appreciation.

With the low overhead and high attendance, we made a lot of money. The Transactions of the Electron Devices Society was in something like its second year and had very little circulation. We had so much money left that we wrote everyone and said, “If you’d like, we’ll pay your first year’s subscription.” We paid for maybe 300 new subscriptions to the Transactions. We had a very large surplus of money we didn’t want to keep. We didn’t want to give the money to the IRE and IEEE, but we knew that the more we had of it the more they would try to get it. We thought it was a good idea to give away a fair amount of the money, and we wanted the Transactions to flourish, so we did that. It’s now called the Journal rather than the Transactions.

In hindsight, what happened to me was unfortunate. I became a professor at MIT in 1966 and decided I should reduce my commitments. I was the treasurer and then the vice chairman of ADVISORY COMMITTEE (ADCOM), which meant I was slated to be chairman. That’s the way it worked. At that stage of the game there wasn’t even a pretense of an election. There may have been a piece of paper that went around with one name. However I verbally asked not to be considered for the chairmanship because I was just starting my professorship at MIT. I had previously been at MIT’s Lincoln Lab and felt that for the first year I shouldn’t be going to Washington every other month as I felt the Advisory Committee chairman should. Meetings were held fairly frequently at that time. I should backtrack and say that I was on the Advisory Committee of the Professional Group on Electron Devices.

Research and development areas: tunnel diode, Gunn effect, silicon transistors, lasers

Morton:

You mentioned that it looked like energy conversion was going to be a big thing but then sort of faded away. Were there other areas that seemed to be very promising and exciting but only at the beginning?

Rediker:

Yes. There was something called the tunnel diode, also referred to as the Esaki diode, that was advertised as something that would replace the transistor. Obviously it did not. Someone proposed to use it as an oscillator, and the U.S. government sponsor of this proposal called me and asked, “Aren’t those things completely useless?” I said, “No, that’s exactly what they will do well. The problem was only that they didn’t do well at replacing the transistor.” They may still be in use, I don’t know. However that was a great big thing that sort of went to nothing. The Gunn effect lasted longer, but I don’t hear much about that anymore either.

Morton:

What exactly is the Gunn effect?

Rediker:

The Gunn effect was a way to transfer electrons from one conduction band valley to another. It operated as an amplifier oscillator. Mr. Gunn at IBM invented it. Everybody jokes that the secret of success is, “If you say at the beginning that it cannot be explained any other way, it gets named after you.” In the way the Esaki diode could be called a tunnel diode, the Gunn effect could be called a transferred electron amplifier, but it’s always been called the Gunn effect. Some important effects in physics are named after people because no one really understood what they were. That’s humor. I’ve had very delightful people tell me that the major factor in having effects named after them was “because I had a friend.”

Morton:

Right.

Rediker:

These are nice, modest people. And it’s true.

Morton:

Did other devices surprise everyone by succeeding?

Rediker:

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There were a number from Bell Labs. And of course [[Silicon Transistor|silicon transistors] took off like a rocket when Noyce and also Kilby understood the oxide. Before that silicon devices were extremely expensive and grown only by Texas Instruments. The man on that one was Gordon Teal. Texas Instruments hired him from Bell and they sold a lot of silicon devices to the military at high prices. Basically the silicon oxide business that was discovered or invented at Shockley Labs and Texas Instruments made silicon devices inexpensive.

I could tell you stories. For instance there was the gold-bonded diode Transitron made. The cost of the raw materials, gold and so on was more than the price of the silicon device. That ended that one. One doesn’t hear the name Transitron anymore. All those researchers came to the Device Research Conference. We disclosed the high efficiency that could be obtained in gallium arsenide in the conversion from electricity to light at the 1962 conference. We claimed we got as much as 85 percent efficiency. It became obvious that lasers could be made, and three groups made lasers. This gets back to the Washington conference. The Device Research Conference was always held at a university in the summer in June or July when there were no classes. The Electron Devices Conference used to be held either Halloween or in December. It’s easy to remember when it was at Halloween. My wife had to protect the house.

At the 1962 Washington conference, Bob Hall from GE, Marshall Nathan of IBM and we at Lincoln Laboratory had already submitted papers on the laser to Applied Physics Letters, though they weren’t yet published. And all three of us had “dummy” papers and we had submitted these papers to the conference in case either of the other two announced the laser so that we could match the announcement. I remember Hall, Nathan and I sitting in the anteroom to the conference and saying to each other, “Look, if you disclose it we’ll disclose too.” We were friends, however, and stayed friends. None of us disclosed it. This must have been when the conference was at Halloween, because the papers came out in the November and December issues of Applied Physics Letters – which was a fairly new journal at that point. We felt no compunction in saying, “We’ve obtained very high efficiency” at the closed Research Conference, whereas we would not have revealed anything about it at the very open Electron Device Meeting.

Childhood, family, and educational background

Morton:

Let’s switch gears a bit and go through your career starting from the beginning. I’d like to hear a little about your childhood and how you got interested in a career in engineering.

Rediker:

I was born in 1924 in Brooklyn, New York, though passport says New York City. My family lived for some time in Cuba, and from grade six through high school I went to an American school in Havana called Ruston Academy. I had as math professor Dr. Gundlach who convinced me and my father that I should go to MIT as I did very well in math and science. (I was valedictorian.) Gundlach was a German with a Ph.D., and as many Germans escaping Hitler in the 1936-41 period went to Cuba as the US would not admit them.

I got my undergraduate degree in electrical engineering and my Ph.D. in physics both at MIT. My field of interest was cosmic rays, and that was the subject of my thesis. When I graduated my professor said, “Now you don’t have to go to anymore classes. If you have to learn something new, get a book.” Then I went to Lincoln Laboratory, which was brand new at the time. An associate professor in my professor’s group became one of the founders of Lincoln Lab and he got me to join. My badge number there is 80. Now it’s well above 10,000.

Lincoln Labs

Early work and study

Rediker:

I worked on circuits there. The circuits used in computers are very similar to those I built for cosmic rays, where they are called “coincidence” and “anticoincidence.” In computers their equivalents are called “and” and “or.” Then I was given the job to make the circuits out of [[Transistors|transistors]. They were point contact [[Transistors|transistors] at the time. Following that I worked on cosmic rays for one academic year as a postdoc at Indiana University.

I decided the real problem was not in the circuits made of [[Transistors|transistors] but in the actual [[Transistors|transistors], so I went back to Lincoln Lab and worked on making better [[Transistors|transistors]. Lincoln Lab also sent me to take a course from John Bardeen at the University of Illinois on the transistor field before I returned.

Morton:

I had forgotten that Bardeen went to the University of Illinois. William Shockley went to the west coast.

Rediker:

That’s right. Nick Holonyak, one of Bardeen’s prime students, took an academic position under Bardeen and continues today in the Bardeen chair which us endowed by Sony at the University of Illinois. I have a humorous story. Bardeen and I were once on a two-man committee. I used the law of averages and said, “On the average, each one of us won a Nobel Prize” – because he won two. But that’s just to add humor in this interview.

Narrow base diode patent

Rediker:

Let’s go back to where we were. I took the course from Bardeen, and my copy of Electrons and Holes and Semiconductors, written by William Shockley, is dog-eared. I read it page by page, over and over again. I learned about semiconductors by reading books, and then got involved with semiconductors. I ended up doing research, discovering and inventing. My first patent was on a narrow base diode. Getting the patent was easy because Bell Laboratories put out a number of books that said it couldn’t be done – and so I got a patent. At that time the books were classified “restricted.” The key to getting a patent is prior teachings. If prior teachings say it cannot be done and you do it, you can patent it. As an aside there was early on discussion on classifying transistor work. If that had occurred I wonder where the field would be now?

Gallium arsenide, p-n junction diode development

Rediker:

Back to my career, we at Lincoln were busy working in germanium – because that was where all the action was at that time. Then came silicon. The small group that I led was composed of about three people, so we said, “We can’t compete with the hoards going into silicon. Let’s go into gallium arsenide.” I went to see Professor Welker in Erlangen, West Germany who was the expert on gallium arsenide at that time, he encouraged me and when I returned we worked on making devices using gallium arsenide (GaAs). We developed the technology and made the first p-n junction diode in gallium arsenide. By the way, there is going to be a Millennium issue of the Journal on Special Topics in Quantum Electronics to be published in December 2000 for which I was asked to write a paper. Much of this will be described in this paper. This latter journal is sponsored be the Lasers and Electro-Optics Society (LEOS) of the IEEE.

Morton:

Okay.

Rediker:

You can see I’m moving from semiconductors to optics. However these were all semiconductor lasers obviously.

Morton:

Right.

Rediker:

To repeat, we made the first p-n junction diode in gallium arsenide. All prior ones had been point contacts. These were diffused. Then we made some alloyed diodes and they were very different. We did the smart thing and asked, “What’s the difference? Why the difference?” Too many people don’t do that anymore. We said, “Let’s look at the light output as a diagnostic. Maybe that will tell us the difference.” And then by God the diffused diode had 85 or 95 percent efficiency at the liquid nitrogen temperature (77K). We were only willing to say 85 percent. In the experiment we were looking at the spectrometer output, the meter reading the output gets winged and in order to get it back on scale we have to increase the meter full scale up, up again and up again and up again. We found that, “My God, the diode is really putting out a lot of light.” Then at the Device Research Conference in ’62 at New Hampshire University we gave our paper on high efficiency.

Semiconductor applications; television transmission, CD industry

Rediker:

We transmitted television on a beam of light. Then, not a technical journal, but Time magazine, said, “If you get upset in the future about having a thousand TV channels at home it will be because of these little semiconductors.” I have a copy of that article. I love it.

Morton:

That’s interesting. That reminds me of my earlier question about things everyone thought would be a big deal but didn’t work out. There wasn’t a really big application for lasers at first.

Rediker:

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The problem with semiconductor lasers at that time was that they transmit fine through vacuum or on a clear day, but if for example the night had been foggy or if it had rained or had other weather disturbances television could not be well transmitted by light. Communication never went very far until my friend Charlie Kao told people how to make low loss fibers and my friends at Corning after much hard work commercialized them.

Morton:

Right.

Rediker:

We’re the engine and they’re the transmission. Nowadays that’s a fantastically big field. If I had invested $100 into some of those startup companies in the communications area I’d be rich today. One such company that just entered the S&P 500 has had its initial price go up by a factor of 48,000. Even so if I had put $100 in there initially, I would be a millionaire.

Anyway, the military liked what we had done. They sponsor most of Lincoln Lab. A lot of people came and I broadcasted television for them over a beam of light. By the way, there was no monetary payoff. The patent issued in 1966. The real mass use of semiconductor lasers was not until 1983 with the CD. If you count the years at seventeen that means our patent had already expired.

Getting back to what we were talking about, what happened next was that we went ahead and made lasers for using various other semiconductors. We made semiconductor lasers out of fifteen-odd semiconductors. One group of materials we used were called lead salts PbSe, PbTe. A nice feature of the lead salt lasers is that the laser light they emit is absorbed in the absorption bands of various constituents of the atmosphere. In this way NO and CH4 which are emitted from car exhausts could be detected.

Morton:

In what arena was that useful?

Rediker:

We actually had a contract with the Environmental Protection Agency (EPA). In St. Louis, which is where the project was, we looked at sulfur dioxide. Depending on how much sulfur dioxide was coming and depending on the wind, they would at least partially shut down the plant from where the sulfur dioxide was coming. There were various plants around the periphery of St. Louis. They could tell which. Our experiment with them resulted in their learning that they could shut down that particular plant and let St. Louis get electricity from all the other plants. Then the pollutant sulfur dioxide went away. That is an example of one application.

Morton:

I’ve been trying to find out if the laser was a moneymaking venture in the sixties and seventies – before the consumer applications.

Rediker:

The answer is no. This is unfortunate when one looks at all the products involving the semiconductor laser. The other laser is another issue, because there were patent fights and because it was in court for fifteen or twenty years that patent lasted much longer.

I love to tell this story, and I think it’s correct. The price of the semiconductor laser was $200 and the CD manufacturer said, “Look, we have to sell the CD player for $200. We’ll pay you $2 and we’ll buy a million of them.” The semiconductor laser manufacturers said, “Oooo, we can get $2 million” – and of course this was back when $2 million was worth a lot more than it is now – and the CD manufacturers were able to buy them at $2 apiece. Very soon people were making a profit on $2 apiece. Considering the number of CDs in the world and multiplying that number by two for the lasers, that’s a lot of lasers. That was definitely a moneymaker.

Morton:

I guess it took a long time.

Rediker:

Yes. This is a crazy business. There was a company in Boston called Lasertron that was bought by Oak Industries about two or three years ago. Oak Industries complained that buying it was a big mistake, indicating that a year when their profits were low it was because of Lasertron. Now Corning has now bought Oak Industries – only because they wanted to get Lasertron.

Morton:

Interesting.

Rediker:

Corning is of course in the fiber business.

Morton:

Exactly.

Rediker:

According to a friend of mine who works there now, they are parachuting down big pieces. It is going to be a tremendous expansion. Quite a change from being the dog somebody bought.

Morton:

That’s interesting.

High-efficiency LED (light emitting diode)

Rediker:

Yes. You asked the question about making money, and of course now it’s making money. They wouldn’t patent my light emitting diode (LED) at MIT. They said, “You just discovered the light.” Do you remember what I said about the very high efficiency?

Morton:

Yes.

Rediker:

Look at the traffic signals and taillights on cars. They’re being switched to LEDs. They have been used on indicators for many years, they’re on little clock radios and so on. These LEDs are big business now.

Morton:

Do you consider yourself the inventor of the LED?

Rediker:

We were not the inventors of the LED but of the high-efficiency LED. The issue was that we got the high efficiency.

Morton:

It is something that made the LED practical.

Rediker:

The Patent Office said we didn’t do much. There wasn’t a particular formula of “make it this way, make it that way.” It was very difficult to get MIT to submit for patents at that time, and it would have been an MIT patent.

Morton:

Above and beyond the patent issue, do you feel this was a significant contribution?

Rediker:

Yes.

Morton:

It was more important than the Patent Office or MIT thought.

Rediker:

Yes. Holonyak and Bob Hall, who was the GE inventor of the laser, said it was our paper on the high efficiency that got them to work on making a laser. Therefore we do claim to having presented this information. People following used the information and made the semiconductor laser. If there was no high efficiency there would be no laser – and we presented the high efficiency.

Morton:

Was this discovery more important for the laser field than the LED field in the long term?

Rediker:

Not really.

Morton:

Is it important for both?

Rediker:

They’re still using equivalent material, though not exactly. I have some samples from Hewlett-Packard they claim are extremely efficient and bright.

Roles of individual inventors in semi-conductor lasers and silicon

Rediker:

I make a big point in many of my papers that too much credit is given to inventors and not enough to the people who work like dogs afterwards making inventions practical.

Morton:

That’s a nice point.

Rediker:

There was a whole lot that went into making the semiconductor laser work. The first semiconductor laser that ran at room temperature lasted one minute. I put that in my paper about the Bell Labs work and showed how, with diligent work, they increased the life from one minute to an extrapolated million years. Without that lifetime, it would be useless.

Morton:

Right.

Rediker:

The same thing goes for the people who worked so hard on silicon. Enrico Fermi, who was a cosmic ray physicist, predicted that the first computer – the Eckert-Mauchley of the forties – would last about six minutes between failures. That was because of all the vacuum tubes. We wouldn’t have the computers we have sitting in front of us now if we didn’t have really reliable silicon. Similarly, we wouldn’t have all this communication with gallium arsenide devices unless they were really reliable. I don’t want to deprecate what I did, but it’s those people’s hard work that made it a commercial product. Right now the people who are working extremely hard are at Hewlett-Packard. They sent me some samples, and those traffic light samples are very bright red.

Morton:

I hadn’t realized those had gone to a solid-state product.

Rediker:

Yes. In one town in New Hampshire and one in Massachusetts I know of all the greens as well as the reds in traffic signals are LEDs now also. Each traffic light has about 500 LEDs. If you look, you’ll see their discrete spots. With the red light, I have been told the installation costs is around $200. The electricity savings alone is $70 a year. That means a three-year payback, and that makes them attractive to install.

Morton:

That makes a lot of sense.

Rediker:

You asked when lasers became commercial. MIT did not think it worthwhile to sue anyone until there was a significant usage, therefore no one was sued.

Joint academic appointment at MIT and research appointment at Lincoln Labs

Rediker:

Getting back to my career, when Charles Townes, the inventor of the laser, was the provost of MIT he asked me to become a professor from Lincoln Lab, which is a part of MIT. Therefore when I retired I had forty years at MIT. That is an important thing – no two employers. I was an MIT professor and worked with students mostly on the other materials making lasers. We did some more fundamental work as well. I would need to check the dates, but I believe it was 1970 when I went back to Lincoln Labs I was one of five or eight people with joint academic appointment at MIT and research appointment at Lincoln Lab.

I was head of the Optics Division at Lincoln Lab and we worked on high-power optics. After running a division of 150 to 200 people for a decade I did not want to lose my close connection with the science, so I went back to doing research – at both Lincoln Lab and MIT. I’ve had students at MIT and a program at Lincoln. I retired in 1991.

Consulting work on medical lasers for cancer detection

Rediker:

Then I went to work for a medical laser company, figuring maybe I could do something for mankind. I was a senior vice-president there for five years and then consulted until January 2000.

Morton:

What did you do there?

Rediker:

We had a number of contracts. I was doing imaging, trying to detect cancer. Prostate and breasts were the two areas at which we were looking with appropriate nontrivial imaging. We were doing that with semiconductors in the infrared and so forth. Then we had a program using advanced technology to get more power from lasers by combining them and inputting the combined power in a fiber so that a semiconductor laser could be used in medicine.. The fiber was a “big” medical fiber with a 600-micron diameter. I left Lincoln at age 67. At 72 I decided maybe I should go home and consult part time. At 75 I decided to fully relax and that is where I’m at now.

Morton:

You’ve done quite a lot.

Influence of the Device Research Conference in the Electron Devices Society

Rediker:

If you have any more questions and want to pursue any of these items further, call me at either of my telephone numbers.

Morton:

It sounds like you were right there during the formative years.

Rediker:

Yes. Getting the Device Research Conference into the Electron Devices Society was a significant step, and I think that conference did a lot for the group. It put things at the forefront by presenting things before they cleared the patent office.

Morton:

Right.

Rediker:

There is a meeting called CLEO which gets very big attendance. It’s not a device meeting but is run by a committee of the Lasers and Electro-Optical Society (LEOS) of the IEEE. It begins with four days of presentations – whatever people are willing to present. On the fifth day a workshop by invitation is in some hotel room, but if someone asks for an invitation they must be allowed to attend. However this is where the problems are discussed that no one is willing to publicize but they want interaction from their peers. The differences between the meeting and the workshop are very interesting.

Morton:

Right. It’s a big difference I’m sure.

Rediker:

It’s a very big difference. Thank you so much. It is very nice to be recognized for what I did way back when, and that’s what you’re doing for me.

Morton:

It’s been very interesting. I’m sure we’ll get back with you to clarify a few things. Thank you.