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.)
Nothing about lasers is more astonishing than their ability to produce holograms, under arrangements such as shown above. Two laser beams (of different colors) emerge from the curtain (rear). They are optically combined (left center) and the combined beam is then divided by prisms, mirrors and lenses so that part of it shines on the figurines (foreground) and part on the square holographic plate (right center). When the plate is developed (like an ordinary photographic film), it will seem to have only a dull gray surface until it is viewed with spatially coherent light (such as from a laser or a beam through a pinhole) shining through it. Then an amazing, multi-colored, three-dimensional image of the figurines will be visible. (See [page 19] and [Figure 13].)
By HAL HELLMAN