AVS Historical Persons
| Tom Scatchard - 1992
Tom Scatchard - 1992
Oral History Interview with Tom Scatchard
Interviewed by Richard Denton, 1992
: I am a founder member of the American Vacuum Society, along with my former business partner, Tom Scatchard, sitting on my left. We are discussing some of the old time stuff as to how and when we got involved in this. I am a chemist by education. After getting out of college and working for a printing ink company for five years, I went down to the Frankford Arsenal at the beginning of 1942 to help the World War II war effort. After getting involved in a lot of chemical stuff, all of a sudden near the end of the year, they discovered vacuum coatings and told me to get with it and see what I could do. So I did this.
Then I, in the meantime, had met Tom Scatchard at an optics course there that they were giving to enlighten us as to a lot of the business of how they designed lenses. So I met Tom and realized that we had to have more skilled people involved in this job. I got the administration to assign him to the vacuum project. Now, Tom actually was interested in coatings because he was interested in optics a long time before I was. So now I think it's time for Tom to tell us just how he got interested and what he did and what he didn't at that time.
: Well, my interest in optics and consequently in thin-film coating goes all the way back to 1934. I had been a member of the Franklin Institute since 1934, and in 1936, the Franklin Institute had moved into their new building, and I had a specific section dedicated to amateur telescope making. I, of course, was an immediate member of that. Now, when you make an amateur telescope mirror, it isn't much good till you put on aluminum. So that with a bunch of parts donated by RCA-the interesting thing about these parts was that they were the remains of a continuously pumped camera which RCA had used in the World's Fair at Chicago, which I believe was in 19361
. So we took all these parts, including a little two-inch diffusion pump and a Cenco Megavac pump, and we put together a vacuum system in order to be able to pump down far enough to get the aluminum on the mirrors. In those days we had a book, John Strong's Procedures in Experimental Physics. That, I believe, with the exception of the periodic literature which is in the Franklin Institute, constituted the knowledge of thin films at that time.
We had a very interesting technique. We would come in at 9:00 in the morning and plug in the mechanical pump and let it pump till noontime. Now, we had another interesting vacuum gauge, which consisted of an old-fashioned Model T Ford spark coil. There aren't many people who remember what a Model T Ford spark coil was, but you could get a lot of nice, high voltage into our system for the glow. Then we would put this glow on, and a little after we turned on the diffusion pump. When the glow went out in an hour or so, bango, we would fire the aluminum coil.
The other interesting thing was, we didn't own a variac in those days. We were all 1936 amateurs who weren't as loaded with money as they usually are now. So we had a very interesting technique of aluminizing the mirror. We had a step-down transformer, which we plugged into the wall and pulled it out quick. If you left it in too long, you blew the filament out and you had to start over again. We generally took about four to six hours to get the aluminum on the mirror.
We also had a very good test, taken from John Strong. When do we have enough aluminum? When do we have too much aluminum? You were supposed to take the mirror out and look up at the sun. If you could barely see the sun through the mirror, hurray, you had a good coating. That was my vacuum technique!
My interest in working on vacuum pumps-that is, mechanically-was that this Megavac pump, which is an interesting pump because it still exists and is still used in the neon sign industry. But the Megavac pump had a nasty habit of sticking its vanes, so you had to learn right away how to keep a vacuum pump running.
Another point I'd like to bring up about thin films; we had a project, another fellow and I, from the NYA2
to rebuild a four-inch refractor, which was in existence at the University of Pennsylvania observatory. This T. Corkinson3
had the natural bloom, which, when Cook sent to Lord Rayleigh at Cavendish in order to determine how much did this natural blue coating on the surface of the lens cut down the light transmission. And lo and behold, when Lord Rayleigh tested this, it increased it. Fortunately, right in the corner of the Franklin Institute library were the collected papers of Lord Rayleigh. There was his mathematical analysis of the first reason for the increase in transmission through an optical surface when it had this "bloom", which the British called it. He also-although I don't now remember exactly what his results were-had his son work on attempting to duplicate this on optical surfaces by getting thinner and thinner films of collodium. I don't remember whether he was successful or not in that.
Along with this, I had several times gone to Dick. I was an instrument maker, and Dick was at the level above me, being head of the chemistry department, and instrument makers were just people who took orders from the bosses. But my study with that had me go to Dick and ask him a few questions about what I could get, which is how we met. Later on, when I learned from Dick that I was to learn about vacuum coating, again I was fortunate in living around the corner from the Franklin Institute. In preparation for this, I was able to read every article that was in the periodic literature and every patent that had to do with vacuum. It was a fortunate thing that the Franklin Institute at that time had available all the patents that had ever been issued and all of the papers from the periodic literature, so that I went to all of these and made copies of the important things so that I would know, I hoped, as much as I possibly could about vacuum.
: An interesting point here, Tom. You had to make the copies by hand, I guess, because it wasn't just as simple as Xeroxing is today.
: If you had a patent, it was very simple to send the government ten cents and you got a copy of the patent. If you had to make copies of what was in the periodic literature-now, I never studied either German or French, but I had a lot of fun with the German dictionary making inter-linear translations of the German. Fortunately, the Franklin Institute was open two nights a week until ten o'clock and all day Saturday, and also fortunately, I lived around the corner. So I accumulated a pretty big stack of papers on what was then the general knowledge of high vacuum. It subsequently proved useful in the fact that we very quickly became experts. We were the people who knew all about vacuum. So we traveled ourselves around the country to try to bring some sense into a program that needed some sense.
The principle units that we had to work with in those days was a four-inch diffusion pump, a rather casual baffle, an 18-inch bell jar, and a very crude vacuum gauge. We encountered all sorts of fascinating trouble. One of the most interesting things was, the young man who pulled down the vacuum bar, turned on the pump, and ran around and back to prop up the counterweight. I said, "Why'd you do that?" He said, "So the jar won't come open." I said, "Well, don't you realize that that jar is pressed down with a pressure of 3,000 pounds per square inch?" And he looked at me and said, "Is that why they made the legs so strong?" I said, "Now look. It's also pressing with underneath." That's funny today, but that was the man in charge of operating four vacuum units upon which the lens coating-a necessary component of our military optics-was dependent. That was kind of the way that we had to educate. We, as I said, were the half-blind leading the totally blind.
: I might cut in here for a moment to mention that as we got into this, the quarter-wavelength thin film was the thing we had to have in our optics during World War II. As far as I can determine, much more of the technology was discovered in this country by Cartwright and Turner at MIT and John Strong at the California Institute of Technology. Who had the coatings on their lenses in the 1940s? The Germans, not us. So it turns out that many people who were in vacuum in the '30s-erudite types of work now-the fact of the matter is that at that time, at the beginning of World War II and through World War II, we were shooting fire-control instruments and shooting big guns, cannons and so forth, by controlling this. It's the only way they had to see where they were shooting them was optical. If you had these coatings on your instruments, you could see the enemy, and vice versa; whichever way, you had a half to three-quarters of an hour above the threshold where you could see anything, if you had the coatings. And when you're shooting 88- and 105-mm guns at each other, it was very important. This is the time that guys who were in the Marines were in Guadalcanal and shortly after they were in North Africa, so that's why it was very important to do this. I will stop now, because I thought that ought to be in there.
: I want to correct one thing, Dick. John Strong was at Johns Hopkins, not at California. I'm almost certain.
: He was both.
: Well, all right, so he was both. He must have spent a lot of time on a train!
Anyhow, the principal problem, I think, in the war-time aspect of it was that we had, among other things, with due respect to everybody who picked these, just about the worst possible vacuum pump you could have used on thin films. It was a Hypervac 20. It had a very precisely fitted vane, which immediately began to clog up with leftover magnesium fluoride. So the problem was that these vanes stuck. When they stuck, you didn't get a vacuum. It was exceedingly difficult, with the type of people who were put into the job of running these, to get them educated to handle pumps of this technology.
An interesting thing was that every time I thought I was going to get a real tough pump, like a Kinney or a Beach-Russ, somebody sent a directive. Directives beat all, and I had a devil of a time wondering what is this Manhattan Project that's taking every possible pump away from us that are useful to us? Fortunately, I didn't learn about what the Manhattan Project was until the war over! I remember getting an application for the Manhattan Project and tossing it, thinking, "I don't want to work in New York." But I didn't get in the Manhattan Project for a simple reason-I wasn't good enough. If I'd have been good enough, they didn't send you an application; they came and got you. [Laughs]
That, I guess, tells the story of the episodes at Frankford Arsenal. I got out, and they were very happy to get rid of me. I always said I served seven years in the Frankford Arsenal with time off for bad behavior. I don't think it's time to go into the internal politics of the Frankford Arsenal, but frankly, it was a mess. With the exception of Dick, I don't remember any genuine friends I had there. Then, of course, Dick and I, having worked together all during the war with some success, founded a company which we called Optical Film Engineering. The first thing that happened about that company was that we got a letter from the state of Pennsylvania that said, "You can't use the name 'Engineering' unless you have an engineer."
: Professional engineer, registered professional engineer.
: Registered professional engineer. Thank goodness Dick was an engineer. I never considered myself anything but a mechanic. I enjoyed the term "mechanic" because-I'd like to go back again to something personal. That was that I heard the great Ross Kattering say at the Franklin Institute in one of his lectures, "A mechanic with his toolbox is the most independent man on the face of the Earth. He can go anywhere that the political situation will let him put that toolbox down, make a living for himself, and a profit for the man who hires him the day he goes to work. And he doesn't have to understand the language." I had a conversation with a fellow one time in the back streets of Naples when I was traveling in Italy. It involved some kind of machine project he was doing. He invited me into his place and pretty soon I was sketching out how I would do it. He turned to me and he said, "How long you be in Naples? You come to work for me tomorrow?" That was the one proof I found of that. That was a lot of fun because I found that these drill presses and milling machines worked the same way. It doesn't matter if you are running them in the outback of Australia or in places in Malta. If you have a machine project and you can convince the fellow that you can run his machines, you can do the job. Anyhow, that had nothing to do with vacuum. It was just one of the important things that I've had a lot of fun doing in the last 65 years.
Optical Film Engineering began to do two things. We did coating, and we developed a technique of coating camera lenses while they were still in the cells. We also began to make vacuum equipment. We made, I guess, then-Dick and I together-most of the vacuum units that covered the state of the art. I don't know whether there were any we didn't try. But both Dick and I, being research-minded, I think spent more time developing the research aspects of the business, then we might have been a lot wealthier today had we studied the tax laws and we had studied how to make good vacuum units.
I always had hoped, my ambition in making a machine, was that some day 100 years from now, somebody will find one of them in the attic of a physics department and look at it and say, "Boy, those guys in the old days had good material." That was my ambition. It's been a source of pride for me that a couple of times I've gone into plants where I'm doing service work, and there, believe it or not, sitting in a corner was a TV-tube aluminizer that we made 34 years ago still plugging away. We made vacuum furnaces. We made something that made the cookies (we called them) for the nuclear airplane, which they build a reactor, put it in an airplane, and flew it. I've never been sure that they had the reactor critical in the airplane, but I think somebody must have said, "What happens if this airplane crashes?" Somebody said, "Well, we might not have Cleveland, Ohio anymore." So they took that airplane and they hid it in a corner out there where they were working at the time.
: They were working in Cincinnati, Ohio. Yes, it was a General Electric project. Maybe Bill Brown knows more about that than we do and can't talk about it today. But it was next to Evendale, and they have a big GE plant there still. We made these. For two guys that just started, literally in his basement, this system-I've got a picture of it that I found looking for some other things recently. We took a vacuum system and we put these cookies into it. It had to be refractory metal. We had to heat them to 2200 degrees C in vacuum. We made this and introduced them into a lock and then into a jig of the fixture. In those days, they weren't welding tungsten and molybdenum together, like shortly after we did that there were some people who did it. I don't remember how strong it is. But we had to just take tungsten rods and drill holes in them with-Tom will tell you what we did it with; carbide or whatever, diamond drills maybe. And then put wire through to just make this kind of goosey structure and lower it into a lock, evacuate it, drop it down onto a radiation shield that was on a rotary motion, lift it over, and put it up into a hot zone that was about six or more inches in diameter and over probably a foot high altogether, and then cook it up to 2200-degree C and then lower it down again and bring it over and put it into an exit lock. Now the introduction lock was heated mildly and the exit lock was of course cool. We didn't put it into the exit lock at 200-degrees C. But for its time, that was still, in my opinion, quite something.
But what I wanted to get Tom to tell us more about is when we started, we were skilled in optical coating and bigger systems. But then when we got into the electron microscope shadow-casting equipment, which became and still is very important, the specimen preparation for the electron microscope, when we got into that we had to make a smaller unit. At that time, we looked over-we'd worked with all the diffusion pumps. We'd seen them in some of these places where they sent us to help people out. We had done these, and we decided-probably incorrectly-that the four-inch pump we had been buying from CVC or DPI at that time was too big and bulky, so we wanted to have a three-inch pump, and there was no good three-inch pump. So we made up the three-inch pump. I think it was a joint venture. But I know the first one, Tom silver-soldered a copper chimney together. Later we made spinnings of aluminum. And that started a whole series of diffusion pumps that turned out to be pretty good. You may want to mention a few things about that.
: Making the first diffusion pump was a lot of fun because I had had some experience, of course, in the diffusion pump that we had rebuilt at the Franklin Institute. But I took and decided how many jets it would have and how the cone should be arranged. A long, long time ago as a Boy Scout I learned to hammer out copper. As Boy Scouts, we used to make copper ashtrays. Anyhow, there wasn't much difference between a copper ashtray and the necessary umbrellas that we had to make to make a diffusion pump. So I made a good-well, it worked; I guess you could call that good-three-inch diffusion pump with a copper chimney. This worked and did produce a vacuum and we could make good aluminum and good evaporation in this.
Later on, we went to a person who made spinnings and had proper aluminum spinnings made for a three-inch diffusion pump. This was the basis of RSC-3, which became the Model T Ford of the vacuum industry, particularly for use in shadow casting, which was a necessary function if you had an electron microscope. The interesting part about the first one was that the first RSC-3 was put together in my living room. Dick and I and a neighbor carried it down the stairs, and we took it to an exhibit at Convention Hall4
and showed it off at Convention Hall. The most fascinating thing about that was-of course, we had a high-voltage feed-through-you turn on this high voltage and then take a magnet and move the high voltage around. We used to call this our Frankenstein show. [Laughs] I had a rather peculiar house in that the ground floor we made into a shop and the second floor we lived and the third floor was the living room.
: Which became the office. [Laughs]
: [Laughs] Which became the office. Gradually, Optical Film Engineering pushed me out of that house and I bought a house across the way. This is in Cherry Street in Philadelphia. The nice part about this was that nowadays, if we started that, we'd have to go through two or three different political people to just get permission to do anything in that area. In those days, nobody asked us; we just did it.
: We'd have to file an environmental impact statement, probably.
: Well, we didn't have to file anything. I just did the stuff in the house. Of course, we had built a system downstairs and were actually doing coating. I always remember Dick talking about, well, if he were going to advertise to do lens coating on camera lenses-now, everybody had camera lenses, but nobody had coating. Fortunately, being a mechanic I could take these apart and put them together right. So we put an ad in the Sunday paper saying we could coat lens. Dick said, well, if we don't get enough business that I can live, I can get a job somewhere and we'll do it over the weekend. From that first ad, Optical Film Engineering never caught up. [Laughs] One time when we were building units, we had a good mutual friend of ours who was sales manager. Most of the time, we had to have the sales manager telling people, "Please, we're doing your unit as fast as we can and we've got a lot of work to do." But the nice part about Optical Film Engineering was that I don't think we ever had a dull moment until we finally sold it out to New York Air Brake and I became Chief Engineer. I found out that Chief Engineers spend most of their time filling out papers to give to the board of directors. After about two and a half years, I said, "You take your Indian hat and tomahawk. I'm going to quit and go back to work." And that's what I did.
: I think that there are a couple other things we ought to mention. This three-inch diffusion pump that we made new, we had three jets in it. In order to save spinning-- because the spinnings were all right. They didn't cost much, but the tooling cost much, and we started with an extremely low capital. The only reason we were able to start in business was because we had very low expenses, both of us, in our home. I remember at that time, my first house; my taxes and monthly rent together was $30 a month. And Tom had a similar situation there. So in order to make more and better diffusion pumps, bigger ones, we made them bigger in diameter and we added a stage. We added a bottom stage and made the bottom bigger. That went on up to a 10-inch pump, at which point we made a 16-inch but it wasn't like that.
The thing that has always amazed me is that we knew a lot of people with a lot better equipment than we had that were making diffusion pumps, yet in 1959 at the AVS in Philadelphia, John Mark - I think he was working for RCA on a government project up at Princeton at that time - he made a test of all diffusion pumps that he could get for a roughly 10-inch pump to put on an accelerator. At that time, we had sold out to Kinney, but the 10-inch pump was the same. He eventually, I think, picked the Leybold pump for his. But he tested them for speed, he tested them for back-streaming, he tested them for fore-pressure tolerance and that sort of thing, and he balanced all these for what he wanted. But our 10-inch pump, that I guess in 1959 had been designed for six or eight years, that was right in there with the rest of them. It didn't have quite the right characteristics. Since that time, of course, there's been a fantastic amount of difference and incredible thousands of hours of testing done to produce a better diffusion pump that they make today. But that was something that came out of that first little system.
: The three-inch diffusion pump, it gradually got bigger. I always remember, Dick says we figured that if you're going to kick somebody down the stairs, it's much better to give them a boot at every step, which we had a six-inch diffusion pump with five or six stages, and by the time we got to ten we had--
: That was five, and the ten was six.
: Five and the ten was six, and these were actually stages. We had made some pretty good tests on our back-streaming rate, so we knew that was good. But all these other fancy things they come up with, we just knew you put them on a machine and they worked good. Now later on, the people came along and had a lot of beautiful mathematics to prove we were right. But the beautiful mathematics never proved we were wrong, so we just kept doing it that way. What I thought most of all the fun we had-and I always considered it fun at Optical Film Engineering-was that we were able to make such a broad range of different types of machinery. Dick and I were the engineering department, and we did all of the cost accounting calculations that you have to do now, which is, "How much do you think we can get for this one?" [laughs] which was our cost accounting. Mrs. Denton was an excellent bookkeeper. She kept the books.
: At the beginning.
: At the beginning, yes. I was fortunate at that time to be married to a lady who was also an excellent mechanic. So as Dick said, we had lots of help. It just didn't cost very much money. That enabled us-I don't think you could start a company the way we did in today's market with today's technology and get away with it.
: Not unless you had retired and had a pension to support you while you were doing it. I must add, on the diffusion pump business, the four-inch pump that we developed, which had actually a GE Cal Rod [heater] coil inside-hear that GE, Bill?-and that pump had more testing than any pump we made because it became the foundation not of the shadow-caster but of other equipment. We at that time had a bright young guy that approached us. I think Tom dug him up somewhere. Jesse--
: Jesse. Jesse was a member of the amateur astronomers at the Franklin Institute, amateur telescope makers.
: He was going to college at that time in Philadelphia. Anyhow, we paid him a pittance, I guess it was, but he was very happy to come in in the evening and run tests on this pump. So that pump got more engineering than any other pump we ever made. Then we sold a great group of those when television tube aluminizing came in. GE started it I think in '52 or something and then it became a big thing. Then they got these circulating merry-go-round type of things. Due to not, I guess, having a right sales ability, we never got to make those, but a local company near us did. Those pumps, surprisingly enough with the TV alone, I think, are still used today. And they get up to a very fast speed very fast. It's amazing. We're not making any money off of them anymore [laughs], but it's actually, what the heck is it, 40 years or something, they're still using them.
: Yes. As I said, that was always a great thrill to me to go into some company and see a unit that Dick and I built 40 years ago sitting over in the corner still working. I say, "How's it doing?" "All right." I had a fellow call me on the phone from a local college and say he had something and he said I knew something about it, called NSC-3 from Optical Film Engineering. I said, yes, we were responsible for building that. He got it with his electron microscope as a donation. I said, "Is it working?" "Well, it doesn't seem to be working too good." So I gave him a list of things over the telephone to check. And I said, "If it doesn't make it work the way you want it, call me up and I'll come down and fix it for nothing." Because anything that old, I just want to see it working. I called him up about two weeks later and he said, "I made a lot of pictures with it and it seems to be all right."
So these things, as I say, lasted very long. Later on, of course, after we sold to New York Air Brake and I had to work out for a while my non-competing agreement, I did some other things that had nothing to do with vacuum and don't bear on the present subject. But later on when my non-competing agreement was out, I built on my own groups of systems, some of which proved to be very interesting. Because I decided that the general design of the vacuum systems had just become so esoteric that that was not for me. I will build vacuum systems for the peasants.
Strange as it may seem, there are an awful lot of peasants who need vacuum systems, who if they go to some of these fellows building these octopuses that are umpteen long and covered all over with all sorts of gadgetry and cost $90,000, and the fellow says, "I just need a little system to outgas some resin," so they say, "All right. Our engineering charges are $5,000, this, that, and the other thing." So I built a tremendous number, from my standpoint, of resin degassers. Several of these went down to government projects. What happens is I get one of my resin degassers on a government-approved list. That means anybody that wants a resin degasser and the government calls me up and says, "How much is your current number today?" Well, that sold a lot of things because the government put a lot of resins in certain optical components without knowing, with all due respect, what they were doing. And some of these resins what is known in the trade as reverted5
. It wasn't good to have the resin run out of the electronic parts because it was there so long and went back to a liquid and ran out of the part. So there was an awful lot of electronic stuff that had to be rebuilt.
Also, I had, as a consequence of this, an awful lot of very interesting little projects, one of which was a simple problem of pumping the gas out of the electrolyte of the batteries that went to the moon. This is a big project. Many people made a big project out of this. North American Aviation had to send five people from Downey, Colorado to find out whether I could build a system, which is a duplicate of what Dick and I build in 1948 [laughs]. But they all had a reason to come east, and they all came on an airplane and came east and visited their families and cross-examined me as to whether I could build a vacuum system. This is not as simple as it sounds, because you had to pull that down to a vacuum of 28.6 [inches of mercury] or something like that and stop, right there. It couldn't go lower or you boiled your electrolyte.
Now what this involved was a simple project of having a very small orifice solenoid operated from a very precision vacuum measuring [device] so that it pulled down to that point and stopped. If there's a slight increase in vacuum, in pressure, it would start opening the solenoid. You kept your pump running all the time.
: Is this the bypass?
: That's the bypass that we developed. I developed that bypass and it was used on all of my resin degassers because that resin had the same problem. If you just put it onto a real good vacuum system and pumped the resin down, pretty soon you'd boil important components out of the resin. So you had to decide when to stop. It's very easy to make a vacuum that keeps on going. It isn't as easy to make a vacuum that starts at 29.2 [inches of mercury]. And to have it go to 29.2 [inches of mercury] and stop, you've got to have a precision measurement in that area. And that is the area where the most difficult aspect of measuring vacuum really exists.
: The instrumentation, when we first developed that thing, I think it was after 1950 because I know we moved in '50-'51.
: It was up on 6th Street.
: That's right. But today they have more stuff than you could even check on in order to do that. The starting of the Vacuum Society, I might mention, Tom and I had this business that we had ourselves, and his wife worked in it and my wife did the bookkeeping at home at that time. We had like three employees, I think Earl and two girls or something like that. It came time, and we had been to the meeting in Cambridge in 1948, which was the first vacuum meeting post-World War II. We also had been to a French Lick meeting in '51, I think it was, in French Lick, Indiana. Then when we were known well enough, at least, that we got an invitation to this meeting in 1953 up in New York that we just couldn't both go. At that time, Tom was in the place more than I was and it only seemed fair to let him get out. So he went to the meeting and I stayed home and minded the store. That's why we didn't both go. We had to eat. And we're still eating [laughs].
: Yes. Well, that's the story. Being in the vacuum business since 1937 to the present day has been a lot of fun.
1. The World Fair was held in Chicago in 1933.
2. NYA. The National Youth Administration was formed in June 1935. It helped more than 2 million high school and college students stay in school by giving them grants in exchange for work. They worked in libraries and college labs, and on farms. The NYA also found work for 2.5 million young people who were not in school and not working. As World War II approached, NYA youths worked in defense industries where they gained useful job skills.
3. Name is uncertain.
4. Convention Hall, Philadelphia
5. They returned from solid to original liquid state.