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The leading light for lasers

Marco Nero
A diamond scatters coherent green light from a laser. The laser revolution is still

going strong, 50 years after it was invented.

Fifty years ago this weekend, the Laser Age began - an era that has been as revolutionary as the Space Age. It's thought that half of America's gross domestic product is somehow connected with laser technology.

When Theodore Maiman turned on the first pulsed laser at the Hughes Research Laboratory in California on May 16, 1960, few could have imagined how much of an impact the devices would have on communications, manufacturing, medicine (and concert light shows). But Charles Townes had a pretty good idea.

After all, it was his work with microwave amplification by stimulated emission of radiation - masers - that set the stage for the optical lasers to come. In fact, he and others theorized that lasers could be built a couple of years before Maiman did it. Townes' research earned him a share of the 1964 Nobel Prize in physics.

Today, at the age of nearly 95, Townes is still a working scientist at the University of California, doing research in astrophysics. And when you talk with him on the phone, you get the impression that his intellect is still as sharply focused as a you-know-what.

In an interview, Townes looked back at the first 50 years of the Laser Age - and looked ahead to the next phase of the revolution. Here's an edited transcript of the Q&A:

Cosmic Log: Fifty years ago, did you know how significant laser technology would turn out to be - or did you have the sense, like many other people, that the laser was a "solution looking for a problem"?

Charles Townes: I knew it was quite important. I could see many things for which it would be very useful. Some other people said, "Well, it's a solution looking for a problem." Actually, when we were working on the maser for some years, trying to make the first one work, nobody was interested. Once it got working, everybody got interested, and they saw the applications for it.

Nobel laureate Charles Townes is a professor at the University of California at Berkeley.

For quite a while, nobody thought masers could be pushed down to light waves - which is what I wanted to do. My primary object was to get the short waves. After a few years of working with the maser, with all the excitement about that, I decided, "Well, let me see how we can get right on down to light waves." I figured out ways of doing that and wrote a paper about how a laser might be built.

I could foresee a lot of applications, but many people doubted it.

Q: Are there some applications that you saw at the time that have not been done yet?

A: Uh, no, I wouldn't say that's the case. In fact there are many applications that have been done that I didn't foresee. For example, I didn't foresee the medical uses at all. The medical uses are enormous. I saw, oh, communications, and burning and welding and cutting, and a lot of scientific applications. About 10 or 12 Nobel Prizes have been given as a result of people having lasers or masers available to work with. It's produced a lot of good science. And everybody knows how important it's been in industry applications. It's really a very big business right now.

Q: There's an old saying that "success has many fathers," and of course a lot of people were involved in the development of laser technology. Is there a bit of a competitive discussion going on?

A: Oh, sure, everybody would like to claim some of the credit. Actually, the first idea was the maser. Nobody else was much interested in that - only the Russians, Basov and Prokhorov, who got the Nobel Prize with me. They were working on it in parallel, in Russia. I didn't know that at the time, and I don't think they knew just what I was doing. Only two groups in the whole world were working on masers.

Once the maser came along, it became a very exciting field. But nobody seemed to think you could get down to short wavelengths. After Arthur Schawlow and I wrote a paper on how to get down to short wavelengths, then everybody jumped into the field. Lots of different lasers were built. All the lasers were built in industry. I knew there'd be a lot of competition if I indicated that lasers could be built. That's why I wrote a theoretical paper on how to do it, rather than trying to build one, because I felt that people would beat me. And they did.

Q: Are there any lessons in that for future innovation? People have talked about how we'll find future solutions for energy or communication ...

A: Well, I would point out that my research was supported by the Navy. I was doing spectroscopy, and many people questioned whether the Navy should be supporting spectroscopy. One could question that, yet overall, it's paid off enormously. Not all research pays off, but every once in a while, research pays off enormously.

It's hard to predict. When I first started building a maser, the chairman of my department said, "Oh, that's not going to work. You should stop. You're wasting the department's money." Nobody competed. They didn't think it was going to do anything special - until it did work. Then suddenly everybody got excited about it.

New things are new. People don't visualize new things very well. So we've got to be open-minded in order to get new things. We've got to be open-minded, and explore, and that's going to pay off in the long run. Not all of it pays off. Some of it won't work. But some of it will work - and when it works, you can do great things.

Q: Do you feel as if the laser revolution has run its course?

A: No, it's still being developed. And it will continue to develop for years and years.

Q: How do you see the course of development going in the next few years?

A: Oh, boy. Maybe we'll get on down to X-ray lasers. We have some now, but they're not terribly effective. Maybe we'll get some better ones. We can get more power, and higher precision, and just a lot of applications that people will see. They're finding more all the time.

Q: What sorts of applications will X-ray lasers open up?

A: Just think: If you could have an X-ray laser to do X-ray medical work, it could be very sharply focused, you see. You could just affect the part of the body that you wanted to affect, and nothing else.

Q: Would that be for diagnostics, or for treatment?

A: Both. Also, X-rays will penetrate things that light won't penetrate. We could get X-ray lasers penetrating through materials, and focus on areas inside materials to weld or burn something, to cut the inside of the material without affecting the outside very much.

Q: How would that work?

A: You focus the X-rays to a point inside something, and the rays would be weak on the outside before they focus on that inside zone.

Q: Is there anything especially notable about the current generation of laser research? Is science being done differently from how it was when you did your Nobel-winning work?

A: There's a great deal of new science that lasers have produced, yes. Lasers have produced the lowest possible temperatures, and the highest possible temperatures. You may know that there's a big project to do nuclear fusion using lasers. That delivers billions of watts of power using laser beams. It will be the highest concentration of power we've ever had.

Q: People have been trying to achieve that dream of fusion power for many years, but do you feel that they're actually closing in on the goal?

A: I think lasers will produce fusion. Whether it will be economical as a source of energy is another question.

Q: I'm sure a lot of people are wondering what your secret is, to be so hale and hearty at the age of 94. What do you tell people about that?

A: Well, one thing I say is that I have practically never worked in all my life. I just have a good time doing research. I don't work, and for some reason people have paid me for it. It's good fun.

To hear more from Townes about the laser's past, present and future, check out these videos on the LaserFest website:

To learn more about the development of lasers, from fictional death ray to life-saving medical tool, click through "Bright Idea: The First Lasers" at the American Institute of Physics website. Scientific American has a special report about the 50th anniversary, and PhysicsWorld has a special issue.

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