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Spie Press Book

Optics Made Clear: The Nature of Light and How We Use It
Author(s): William L. Wolfe
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Book Description

Have you wondered why the sky is blue? Why the sunset is red? How hummingbirds show us their many colors? Why the road ahead sometimes seems to have water on it, when it does not? Have you wondered how telescopes work to give a magnified image of distant objects? How microscopes provide a magnified image of close objects? How spectroscopes, eye glasses, cameras, binoculars, and similar instruments work? How the simple rear view mirrors in cars dim and provide wide fields of view? In this book, William L. Wolfe describes many of the natural phenomena caused by light and the optical devices that use it in terms everyone can understand.

This book is divided into five major sections. The first is a description of the basic phenomena of optics; the second includes basic optical components and instruments; the third is all about natural optical phenomena; and the fourth part is a collection of applications. The fifth contains descriptions of the above-mentioned great steps in our understanding of the world around us that are directly related to optics.


Book Details

Date Published: 10 November 2006
Pages: 276
ISBN: 9780819463074
Volume: PM163

Table of Contents
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Introduction 1
Chapter 1 The Basics 5
Chapter 2 Components and Instruments 25
Mirrors 25
Lenses 37
Prisms 49
Fibers 52
Cameras 54
Telescopes 63
Detectors and Displays 72
Diffraction Gratings 75
Spectrometers 77
Microscopes and Magnifiers 81
Other Scopes 87
Lasers 90
Frequency Doublers 93
Binoculars 94
Interferometers 96
Round and Round She Goes 100
Lights 101
Other Instruments 103
The Human Eye 108
Interference Films and Filters 112
Chapter 3 Natural Optical Phenomena 113
Chapter 4 Applications 129
Aerospace 129
Agricultural Exploits 135
Art 142
Automotive 145
Communication 153
Dentistry 156
Displays 159
Entertainment 165
Forensics 172
Home Sweet Home 179
Industry 184
Optics in Everyday Life 200
Lighting 202
Medicine 205
Military 224
Transportation 231
Utilities 243
Weather and Climate 249
Chapter 5 Critical Steps in Physics Involving Light 253
Glossary 261
Appendix A Sizes of Things 267
Appendix B Information Sources 271

Introduction

I have spent fifty years of my professional life up to my eyeballs in optics. It has been delightful. It has been enlightening. It has brightened my life. The phenomena are interesting, important, varied, and often beautiful. The evidence of natural occurrences and examples of optical instruments and gadgets are plentiful. So it has been fascinating to learn about how things around us work and develop some of the many things that improve our lives and understanding. I recall one church service in which one of my artistic friends gave thanks for the beauty of the morning's rainbow. I silently added, "and for understanding how it occurs." This book is my attempt to describe many of these natural phenomena and devices in terms that everyone can understand. I want to share the fun and wonder and beauty and insights. You, too, will know how the rainbow is formed, and your appreciation for natural wonders and human creations should improve greatly.

Have you wondered why the sky is blue? Why the sunset is red? How hummingbirds show us their many colors? Why the road ahead sometimes seems to have water on it when it does not? Is global warming real? Is it a natural cycle or as we cause it us? I have attempted to describe these and other natural phenomena in a simple, understandable way, devoid of the "language of the trade." We now use optics to assemble automobiles and airplanes with incredible precision. We flush toilets automatically using optical beams. We turn on garage lights, open doors, spot speeders, provide night vision for cars, improve agriculture, inspect meats and orange groves, analyze distant planets and galaxies, all with light. Optical instruments are used to an incredible degree in medicine. We now have much-improved endoscopes that probe our intestines and other interior parts. We even have one that is a pill. We can perform surgery at great distances from the patient, and do the same with diagnoses telemedicine. Dentists can find tooth decay and operate with optics. This is truly painless dentistry. We can make injections without injecting. I have collected a host of such applications and gadgets that appear in our daily life, be it in medicine, communications, aerospace, manufacturing, or agriculture. I have taken the articles and explained them in a way everyone should be able to understand. Have you wondered how telescopes give a magnified image of distant objects? How do microscopes provide a magnified image of close objects? How do spectroscopes, eyeglasses, cameras, binoculars, and similar instruments work? How do the simple rear-view mirrors in cars dim and provide wide fields of view? Explanations of these are included.

An added delight in the study of optics is that the field has been right in the thick of it for most of the major advances in physics, astronomy, and our understanding of the world around us. Galileo with his telescope proved that the Earth went around the sun rather than the other way around, and he was declared a heretic for that. Max Planck's study of optical radiation created the origin of quantum mechanics. The study of the detection and emission of light from a phototube led Einstein to the concept of the photon. Spectroscopy was essential for Bohr and others to uncover the structure of the atom. The theory of relativity has as one of its cornerstones the tenet that nothing travels faster than light. Recent experiments by John Mather measured the temperature of the celestial background with optics, and thereby helped to verify the Big Bang theory of the origin of the universe. Numerous other experiments have pinned down its age - at least to within a few billion years. Light is important in the many instruments we use in daily life, in nature around us, and in much of the development of physics.

It has been my attempt to keep the math to an absolute minimum, but some very simple equations have snuck in. In each section, I have started with the simplest of concepts and gradually increased the degree of difficulty. For instance, in the section on telescopes, the simplest of two-mirror telescopes, invented by Isaac Newton, are first described. Gradually the descriptions cover more complicated designs, including the Palomar telescope, ending with the complicated Webb telescope that has a thinned, adaptive mirror and will be placed in space at a Lagrange orbital point. The section on mirrors starts with a simple plane mirror and ends with the most complicated of adaptive, liquid and light-weighted, aspherical examples. The section on cameras starts with a pinhole camera and ends with the new digital varieties. This book is divided into five major sections. The first is a description of the basic phenomena of optics; the second includes basic optical components and instruments; the third is all about natural optical phenomena; and the fourth part is a collection of applications. The fifth contains descriptions of the above-mentioned great steps in our understanding of the world around us that are directly related to optics.

The phenomena of optics, as described in the first chapter, can be listed broadly as the emission and absorption of light, polarization, refraction, reflection, interference, diffraction, and scatter. But of course a major question is, "What is light?" That subject is the last one in the first chapter, but unfortunately the answer is not straightforward. The bottom line is that we really do not know what light is. We can describe everything it does, and we can say many things that it is like, but we still cannot say what it is. That should not deter the reading of this book. The descriptions here apply to all the gadgets and phenomena. We do not need to know what light is, just how it behaves.

The applications, the uses of optics in gadgets in our everyday world, have been taken mostly from several "throw-away" magazines that describe advances and uses of optics, but are not very technical nor instructive. I appreciate the fact that the publishers have given me permission to include many photographs from the articles. I have tried very hard to give complete credit for each of them. This also allows the reader to contact any of them for further information. Complete addresses are given for these publications in Appendix B. I have also listed some of the more technical books in Appendix B for those who choose to pursue much more detailed descriptions of the basics and the instruments than I have given here. Appendix A contains some information about numbers and sizes that may be useful in understanding both the astronomical and the microscopic sizes in optics. You need to have a sense of the sizes of nanometers (billionth of a meter) and light years (a distance of almost 6 trillion miles; it is the distance that light goes in a year). There are several ways to read this book. Of course, you can go straight through from the front cover to the back, but this is not a novel (although in one sense, it is a mystery). I do not recommend that approach. You can choose a subject, like mirrors, and start at the front, reading to the back and getting more complicated. In this mode it may be necessary to page back to the earlier chapters to refer to a concept that is used in the descriptions about mirrors. You can also choose any of the applications and approach it the same way. Another approach is to read through the basic chapters and then pick and choose the applications of interest. An interesting pamphlet on optics has been published by the National Research Council. It covers many of these applications and discusses the role of optics in our lives in only 28 pages.

Whatever your reason for getting this book, I hope you find it enjoyable, enlightening, and just plain fun. As you read what I have written, I hope you get the message that I continue to enjoy this subject, and that I feel blessed for having had the opportunity to study the subject and get paid for it!

William L. Wolfe
Tuscon, AZ
June 2006


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