Feld Laser spectroscopy IX

1. Auflage 2012
ISBN: 978-0-323-14695-1
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: 6 - ePub Watermark

E-Book, Englisch, 532 Seiten

Laser Spectroscopy IX documents the proceedings of the Ninth International Conference on Laser Spectroscopy, held in Bretton Woods, New Hampshire, June 18-23, 1989. The scientific program consisted of oral and poster presentations. There were 52 invited talks organized into 14 topical sessions, some with panel discussions. About 60 additional invited contributions were presented in three evening poster sessions. Also included were 15 post deadline oral and poster presentations. These proceedings contain summaries of essentially all of these contributions. The contributions made by researchers at the conference are organized into 14 parts. Part I focuses on laser cooling. Part II presents studies on laser spectroscopy. Part III includes papers on cavity Q.E.D. Parts IV, V, and VI examine noise and coherence, quantum size effects, and surface spectroscopy, respectively. Part VII deals with laser light sources. Part VIII includes papers on trapped ion spectroscopy. Part IX covers ultrafast spectroscopy while Part X takes up fundamental measurements, including those of positronium, the Rydberg constant, and lead and thallium isotopes. Parts XI-XIV cover, respectively, molecular spectroscopy and dynamics, applications in radiation forces, highly excited states and dynamics, and laser spectroscopy for biomedicine.

Autoren/Hrsg.

Feld, Michael

Leseproben

A Laser Commercial; NICOLS After-Dinner Talk

N. Bloembergen,     Division of Applied Sciences, Pierce Hall, Harvard University, Cambridge, MA 02138 USA

Ladies and gentlemen,

We are approaching the end of a busy scientific conference and an equally successful and equally exhausting banquet. You and I deserve a rest. We should simply thank the chairman, Mike Feld, and his staff for all the arrangements and call it a day. However, Mike Feld wanted to fill a much-needed void in the opulent meeting program and appointed me as after-dinner speaker. So here I am, filling the needed void.

There are several reasons and excuses to put me in this predicament. My first name, Nico, resembles the name of the meeting: Nicols. In fact, several colleagues have addressed me in the past as Nicole. Others continue to call me Nikko. This version of my first name caused some hilarity at an International Conference in Japan held in 1953. The Japanese hosts always have a polite smile when a guest is introduced, but I could not help noticing that the smile was a little more pronounced when they heard my first name. When visiting Nikko National Park, 3 hours north of Tokyo, I found out that the Japanese have a saying, “Do not call anything Kekko until you have seen Nikko,” and “Kekko” means “beautiful.”

A second reason why I am up here to speak after dinner is that I had nothing of new scientific interest to present at the regular sessions. When I so informed Mike Feld, he said “Fine, then you can be the after-dinner speaker.” I am rather inexperienced in this new role into which my waning productivity has put me. To prepare myself for this occasion, I went to a bookstore in Harvard Square and found an interesting title, “The ABC and XYZ of After-Dinner Speaking,” I learned that ABC stands for “Always Be Calm,” and XYZ stands for "[e] Xamine Your Zipper.”

NICOLS is the ninth in the series of International Conferences on Laser Spectroscopy. The first one was held in 1973 in Vail, Colorado. The originators of the series were Dick Brewer and Aram Mooradian. Aram as well as many other young and not-quite-so-young faithful are again present at this meeting. The second through eighth in this series of meetings were all held in odd-numbered years, in Megeve, France (1975), in the Grand Tetons at Jackson Lake, Wyoming (1977), Rottach-Egern in the Bavarian Alps (1979), at Jasper in the Canadian Rockies (1981), Interlaken, Switzerland (1983), Maui, Hawaii (1985), Are, Sweden (1987), and now we have settled down at the foot of Mt. Washington in New Hampshire, we have discussed at length where we are going to meet two years from now. It will be in France, but the difficult choice between the Alps and the Pyrenees requires further research.

The ICOLS meetings have been quite successful because they have been restricted in size, as well as in subject matter. They have brought together leaders in the field of laser spectroscopy, which is concerned with the fine features, or fingerprints, of matter, revealing the structure of atoms, molecules and electromagnetic radiation. The interactions and discussions at a truly international level during the ICOLS series have undoubtedly provided a stimulus for the continued growth in this active field of scientific endeavor. At every meeting we have had the opportunity to hear about new developments, admire new blooms and offshoots, but also to give and receive critique, to define areas of disagreement which could only be resolved by further theoretical and experimental investigations.

The restricted nature of these meetings has been criticized by outsiders. This critisism would be justified if ICOLS were the only meetings in the field. There are, however, numerous unrestricted meetings which also cover the field of laser spectroscopy. In fact, there are so many of these, that it would be most undesirable to add another unrestricted meeting to the group that already includes the International Conference on Quantum Electrons, the Conference on Lasers and Electro-Optics, the Interdisciplinary Laser Science Conference, among others. Most of these convene at least once a year. They are big and sometimes brassy, i.e., with large hardware exhibitions. They have a dozen or more simultaneous sessions, and attendance at some of them exceeds five thousand. They certainly fulfill an important function, and their very existence permits the ICOLS series to retain its well-protected niche in the larger spectrum (no pun intended) of activity of Quantum Optics, Opto-Electronics, Photonics, or whatever other nomenclature may be used to denote the field of interest.

We are indeed fortunate that the laser field has so many practical ramifications. Personally, I have always enjoyed my contacts with industry. The direct link between fundamental physics and important practical applications enhances the vitality of our field. It attracts many younger students, scientists and engineers. While the conference program emphasizes issues of basic physics and precision measurements, it may be appropriate in this after-dinner talk to call attention to the enormous industrial development which has taken place concomitant with the ICOLS series during the past two decades. Undoubtedly we derive enormous indirect benefits from these commercial developments.

During the 1960’s a large variety of lasers, employing hundreds of different substances were demonstrated. This period may be considered as the birth of a new technology. At that time, lasers were described as solutions looking for problems. The decade of the 1970’s may be called the period of laser engineering development. The physics of lasers was well understood, possible fields of applications were well recognized, but it proved difficult to turn lasers into economically competitive devices. During the 1980’s sizeable comerical markets for laser products have been established. The businesslike question is now which laser — or other electro-optic device — has the best characteristics at a price that the market will bear.

The total commercial laser industry world market in 1984 amounted to near 3 billion dollars, with an annual growth rate of about 40 percent. So in 1987, the total market exceeded 6 billion U.S. dollars. The main categories of commerical applications are: Materials Working, Communication, Medical-Surgical, Metrology and Inspection, Data Capture, Alignment (Construction Industry), and Printing and Graphics.

In 1984 the last category had the largest commercial importance. While the application of lasers in this field and in construction alignment is reaching maturity, laser applications in communication and medicine are still growing fast, and are about to become the most important segments of the market. It is important to note that the commercial laser market exceeded the military market by a margin of more than two-to-one in ’84 and this difference is even more pronounced at present.

Last year, in 1988, over 200 million semiconductor lasers have been produced. Mass production techniques, similar to those developed for microelectronic chips, are used. In dollar value, the semiconductor lasers now comprise 30 percent of all lasers. They are by far the cheapest and most durable of all lasers. Unit prices are in the 1-10 dollar range. Laser diode production has become a commodity process with commodity-pricing strategies. Small diode lasers (100 µW output) are used in every compact-disk player. Somewhat more powerful semiconductor lasers are used for low-cost laser printing, and for optical communications. More powerful solid state arrays are under development. Integrated opto-electronic, all solid-state devices, useful in optical data processing, are in the prototype design phase. Semiconductor lasers will become serious competitors for the He-Ne lasers. These are the next most numerous lasers with an annual production of one-quarter million in 1988. More powerful lasers, such as argon-ion lasers, CO2 lasers and solid state lasers are produced in much smaller quantities, but their total dollar value is comparable to that of all semiconductor lasers.

Most applications of lasers are based on the concentration of light in time and space. The increase in intensity due to focusing the light was already known and used in Greek antiquity. Lactinius observed and wrote in 303 B.C. that a glass globe filled with water is “sufficiently good to light a fire, even in the coldest of weather,” Archimedes (212 B.C.) proposed to set fire to a hostile fleet of Phoenicians in the harbor of Syracuse by reflecting the sun’s rays from the metal shields of his soldiers. I remember as a young boy using a looking glass to burn shoelaces under the pale sun of the Netherlands.

Laser light can be focused on an area ?2, which is a few hundred times smaller than the cross-section of a human hair. By concentration in space and time, power flux densities of 1012 watts/cm2 equal to those prevalent in the interior of stars are readily obtained. New physics is reported at power levels of 1018 watts/cm2. Thus laser beams can readily drill holes through textiles, metals, through diamond. They can be used for cutting and welding. They can equally well coagulate the vaporize human tissue, or cut into teeth or bone. More importantly, laser light can be concentrated into and guided by optical fibers, with a dimension of a human hair. Bundles of fibers can be inserted into blood vessels or other channels inside the human...