The transistor burst upon the electronic scene in the 1950s

Lasers by Hal Hellman, is part of the HackerNoon Books Series. You can jump to any chapter in this book here. INTRODUCTION

INTRODUCTION

The transistor burst upon the electronic scene in the 1950s. Almost overnight the size of new models of radios, television sets, and a host of other electronic devices shrank like deflating balloons. Suddenly the hard-of-hearing could carry their sound amplifiers in their ears. Teenagers could listen to favorite music wherever they went. Everywhere we turned the transistor was making its mark. There was even a proposal before Congress to require that every home have a transistor radio in case of emergency.

The next development to fire the imagination of scientists and engineers was the laser—an instrument that produces an enormously intense pencil-thin beam of light. Most of us have heard so much about this invention it seems hard to believe that the first one was built only a few years ago. We were told that the laser was going to have an even greater effect on our lives than the transistor. It was going to replace everything from dentists’ drills to electric wires. The whole world, it seemed, eventually would be nothing but a gigantic collection of lasers that would do everything anyone wanted. Roads would be blazed through jungles at one sweep; our country would be safe once and for all from intercontinental ballistic missiles; cancer would be licked; computers would be small enough to carry in a purse; and so on and on.

Yet for the first couple of years the laser seemed able to do nothing but blaze holes in razor blades for TV commercials. Somehow the device never seemed to emerge from the laboratory, prompting one cynic to call it “an invention in search of an application”.

Many of the wild claims came from misunderstandings on the part of the press, others from exaggerations by a few manufacturers who wanted free publicity. But with even less exotic devices than lasers, the road from the laboratory to the marketplace may often be long and hard. Price, efficiency, reliability, convenience—these are all factors that must be considered. It soon became clear that with something as new as the laser, much improvement was necessary before it could be used in science and medicine, and even more before it could be used in industry.

It now seems, however, that the turning point has been reached. We have seen laser equipment put on the market for performing delicate surgery on the eye, spot-welding tiny electronic circuits (Figure 1), and controlling machine tools with amazing accuracy (Figure 2).

Figure 1 A commercial laser microwelder. A microscope is needed for accurate placement of beam energy.

The pace is quickening. At least a dozen manufacturers have announced that they are designing laser technology into their products. These are not laboratory experiments but practical products for measurement and testing, and for industrial, military, medical, and space uses. The Army, for example, has announced that it will purchase its first equipment for use in the field: a portable, highly accurate range finder for artillery observation.

Still, this hardly accounts for the $100,000,000 spent in one recent year on laser research and development by some 500 laboratories in the United States. The U. S. Government alone has spent about $25,000,000 on laser research in a single year. Dozens, and perhaps hundreds, of other applications are on the fire—simmering or boiling as the case may be. Some require particular technical innovations such as greater power or higher efficiency. Others are entirely new applications. One of the most exciting of these is holography (pronounced ho LOG ra phy).

Holography involves a completely different approach to photography. In addition to more immediate applications in microscopy, information storage and retrieval, and interferometry, it promises such bonuses as 3-dimensional color movies and TV someday.

You have to see the holographic process in operation to believe it. One moment you are looking at what appears to be an underexposed or lightly smudged photographic plate. Then suddenly a true-to-life image of the original object springs into being behind the negative—apparently suspended in midair! Not only is the full effect of “roundness” and depth there, but you can also see anything lying behind the object’s image by moving your head, exactly as if the original scene containing the object were really there.

Still another important field of application is that of communications. Perhaps because it is less spectacular than burning holes in razor blades, we haven’t heard as much about it. Yet there are probably more physicists and engineers working on adapting the laser for use in communications than on any other single laser project.

The reason for this is the fact that existing communications facilities are becoming overloaded. Space on transoceanic telephone lines is already at a premium, with waiting periods sometimes running into hours. Radio “ham” operators have been threatened with loss of some of their best operating frequencies to meet the demand of emerging nations of Africa for new channels. Television programs must compete for space on cross-country networks with telephone, telegraph, and transmission of data. The increasing use of computers in science, business, and industry will strain our facilities still further. Communication satellites will help, but they will not give us the whole answer; and much development work remains to be done on satellites.

Why the interest in the laser for communications? In a recent experiment all seven of the New York TV channels were transmitted over a single laser beam. In terms of telephone conversations, one laser system could theoretically carry 800,000,000 conversations—four for each person in the United States.

In this booklet we shall learn what there is about the laser that gives it so much promise. We shall investigate what it is, how it works, and the different kinds of lasers there are. We begin by discussing some of the more familiar kinds of radiation, such as radio and microwaves, light and X rays.

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This book is part of the public domain. Hal Hellman (2021). Laser. Urbana, Illinois: Project Gutenberg. Retrieved October 2022 https://www.gutenberg.org/cache/epub/65512/pg65512-images.html

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