Lasers by Hal Hellman U.S. ATOMIC ENERGY COMMISSION Division of Technical Information _Understanding the Atom Series_ ATOMIC ENERGY COMMISSION UNITED STATES OF AMERICA The Understanding the Atom Series Nuclear energy is playing a vital role in the life of every man, woman, and child in the United States today. In the years ahead it will affect increasingly all the peoples of the earth. It is essential that all Americans gain an understanding of this vital force if they are to discharge thoughtfully their responsibilities as citizens and if they are to realize fully the myriad benefits that nuclear energy offers them. The United States Atomic Energy Commission provides this booklet to help you achieve such understanding. {Edward J. Brunenkant} Edward J. Brunenkant, Director Division of Technical Information UNITED STATES ATOMIC ENERGY COMMISSION Dr. Glenn T. Seaborg, Chairman James T. Ramey Wilfrid E. Johnson Dr. Clarence E. Larson [Illustration: LASERS] by Hal Hellman CONTENTS INTRODUCTION 1 THE ELECTROMAGNETIC SPECTRUM 5 RADIO WAVES 9 LIGHT AND THE ATOM 14 WHAT’S SO SPECIAL ABOUT COHERENT LIGHT? 19 CONTROLLED EMISSION 25 A LASER IS BORN 29 LASING—A NEW WORD 32 SOME INTERESTING APPLICATIONS 34 A MULTITUDE OF LASERS 42 COMMUNICATIONS 48 A LASER IN YOUR FUTURE? 52 SUGGESTED REFERENCES 53 United States Atomic Energy Commission Division of Technical Information Library of Congress Catalog Card Number: 68-60742 1968; 1969(rev.)