Lasers E-Book

Jean Claude Diels

• Herausgeber: Wiley-VCH
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 452

Veröffentlichungsjahr: 2011

Beschreibung

"Lasers" are active ingredients of our modern life, but they are inconspicuous as they often go unnoticed. This intuitive introductory guide will tell you all you want to know about laser technologies in very diverse fields from nuclear and particle physics to medicine, astronomy and ultra-precise metrology. The book is coherently focused on fundamentals, and is aimed to stimulate intuition about present and future applications, while unveiling the halo of myths around lasers. Written by reputable laser experts who think that science should be entertaining, this useful reference relies on simple analogies and illustrations rather than complex mathematics, and will be suitable for students and end-users of laser technologies, including novices.

Voted a CHOICE Outstanding Academic Title 2012

Leseprobe

Contents

Cover

Half Title page

Title page

Copyright page

Dedication

Preface

References

Chapter 1: A Scenic Route through the Laser

1.1 The Meaning of “Laser”

1.2 Radiation from an Atom

1.3 The Anatomy of a Laser

1.4 Some Examples of Laserws

1.5 Pulsed Lasers

1.6 Properties of a Laser Beam

1.7 How to Make the Shortest Laser Pulse

1.8 Ultrashort Ultraintense Laser Pulses

1.9 Ultrashort Ultraprecise Laser Pulses

1.10 Ultrashort Ultrasensitive Laser Pulses

1.11 The Nonlinear Wizard: Juggling with Frequencies

References

Chapter 2: Laser Coherence at Home

2.1 The Laser Printer

2.2 The Laser Scanner

2.3 The Laser in Data Storage

2.4 Miscellaneous Applications

Chapter 3: The Laser in Medicine

3.1 Introduction

3.2 The Laser in Dentistry

3.3 The Laser and Vision

3.4 Lasers and the Neural Network

3.5 Lasers for the Skin and Cosmetics

3.6 Lasers in Surgery

3.7 Biostimulation Lasers for Ulcer Treatment

3.8 Lasers in Diagnostics

3.9 Ultrafast Peeking

References

Chapter 4: Lasers in Industry

4.1 Laser Machining

4.2 Laser Cutting/Drilling

4.3 Cutting the Forest

4.4 Nanostructure with Lasers

References

Chapter 5: Laser Time Capsule

5.1 Introduction

5.2 Ultrashort Pulses in Microscopy

5.3 Communication

5.4 Frequency Combs

References

Chapter 6: Light in Matter

6.1 Attosecond Science

6.2 Lasers in Nuclear Physics and Accelerators

6.3 Laser Cooling

References

Chapter 7: High Power Lasers (Tazer/Teaser)

7.1 Filaments

7.2 Laser-Induced Lightning

7.3 Laser Tazer–Teaser

References

Chapter 8: Laser Sensors

8.1 Passive Sensors

8.2 Active Sensors

References

Chapter 9: Future Perspectives

References

Index

Color Plates

Jean-Claude Diels and Ladan Arissian

Lasers

Related Titles

Paschotta, R.Encyclopedia of Laser Physics and Technology2008ISBN: 978-3-527-40828-3

Hecht, J.Understanding Lasers An Entry-Level Guide2008ISBN: 978-0-470-08890-6

Smith, F. G., King, T. A., Wilkins, D.Optics and Photonics An Introduction2007ISBN: 978-0-470-01784-5

Meschede, D.Optics, Light and Lasers The Practical Approach to Modern Aspects of Photonics and Laser Physics2007ISBN: 978-3-527-40628-9

Quimby, R. S.Photonics and Lasers An Introduction2006ISBN: 978-0-471-71974-8

The Authors

Prof. Jean-Claude DielsUniversity of New MexicoDept. of Physics & Astronomy1919 Lomas BlvdAlbuquerque, NM 87131USA

Dr. Ladan ArissianUniversity of New MexicoDepartment of Electrical and ComputerEngineeringCenter for High Tech Materials1313 Goddard SEAlbuquerque, NM 87106USA

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ISBN Print 978-3-527-41039-2

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To my mother Maryam and my daughter Vida.

Ladan Arissian

To my daughter Natacha, who taught me that music and lasers can live in harmony and my wife Marlies, for having patiently endured the clickety-clack of a keyboard as evening conversation.

Jean-Claude Diels

Preface

There is no need to convince anyone of the importance of lasers. The growth of this technology and its presence in our daily lives cannot be overemphasized. It can be felt as simply as flipping a switch, like using a laser pointer or a scanner, but there are times that its use is mysterious and glorified, such as in the case of the laser gun, Star Wars and laser induced lightning. The aim of this book is to provide a better intuition about this technology and its applications. We felt that knowing about lasers should not be restricted to scientists and engineers in the field, or to those who are direct users of lasers. It can and has to be shared with everybody. We hope this book will inspire the reader to have meaningful dreams about the future of this technology and its applications, and to alleviate confusion and misuse of science in public media.

We do not believe that science should be boring, or be the prerogative of strange people with unbrushed hair, big glasses, and torn t-shirts. Science is for everyone’s benefit. When a baby rolls a ball or throws a stone she/he starts learning mechanics. With a simple activity, a lot of intuition is established about mass, velocity, and gravity. This is why even in a scientific community a common method to understand a subject is via mechanical analogies. Any physics student has a tough experience at his/her first exposure to quantum mechanics; only a carefree baby can easily assimilate new concepts. We thought that a way to gain a better understanding about optics and in particular about lasers, is to discuss them in an informal way. Some details are kept, some are missed, which is the nature of an imperfect work.

Who cares about lasers? Of course we do, because they are at the center of our job and lives, and we think that others should care as well. Lasers play an important role in the evolution of technology. A wheel, which is a symbol of the mechanical era, served to move objects around, and facilitated transportation. With mechanical technology came another leap in human power and mobility. In scientific aspects it helped us understand the mechanics of the universe, and planetary motions in the sky. In biology it gave a better picture of the mechanics of motion and bone structure. Then came the finer technology of electricity, enabling the transport of energy through electrons in wires. Understanding electricity is not so straightforward, and the experience of an electric shock is not commonly sensed as a knife cut.

Having had electricity around for more than a century, we have gained some intuition about voltage and current, although they are not as clear concepts as speed and position. At the start of the twentieth century quantum mechanics appeared and puzzled scientists for a long time. It brought with it all new concepts, but it was accepted, in the same manner as we have become used to talking to someone over the phone, or meeting a friend on a computer screen, rather than the traditional face to face interaction. We extend our experience and senses with technology. Just like the caveman who lived in bare nature might not have known all the trees and bushes, we may not know all the scientific reasons and backgrounds of the technologies we have at hand.

There is a notion that, after the mechanic and electric eras it is time for a photonic era, and that the laser is the greatest manifestation of it. The laser is not a stand alone subject: it could not have been realized without fine machining, precision optics, and controlled electrical power. It is a magnifying box for photons, not by collecting photons in one position like a lens, but by putting them in phase in a stimulation process. With the power of a laser we can mimic the sun in a laboratory, tame electrons inside molecules and atoms, tatoo a biological cell, have faster and more precise clocks, and eventually guide lightning towards our mean neighbor’s house.

Chapter 1 is a scenic route to the laser. It is an overview of the radiation of light, the properties of the laser, the different types of lasers, properties of the beams and of pulses, the generation of ultrashort pulses, ultra-high intensities, and so on. We have dropped many details and concepts to make this chapter as short as possible. Our purist colleagues may not appreciate our shortcuts and analogies, but this book is not intended for them. We intentionally omitted naming any of the great scientists who have contributed to the birth and growth of the laser. Doing otherwise would have been an unfair selection among the tens of thousands of scientists who have been involved in materializing the dream of creating and understanding laser sources and their applications.

The rest of the book is organized in seven chapters to cover some industrial, medical, military, and scientific applications of the laser, with many important application having been left out in the interest of brevity. The laser has surreptitiously entered so many aspects of our lives, that a comprehensive listing of all its uses may become as boring as reading a dictionary. The history of the discovery of the laser, and anecdotes about ensuing competition in patent recognition, has already been published [1--5]. Instead, we present an informal conversation about lasers, rather than an explanation of their technical and scientific aspects, which has been published by others [6].

In view of all the other contributions, why did we dare to write this book? Because we thought that our “cartoon” approach to science is unique and might reach a different audience than existing textbooks. This book was started as a celebration of the 50th anniversary of the discovery of the laser. For that occasion, we intended to make an overview of all the applications and how they relate to the exceptional properties of the laser.

If you expect to have acquired a textbook, please return this book as fast as possible to the source. Physics is very often explained with simple analogies (which would make a rigorous mind cringe).

No self-respecting science book could be published without exhaustive references. This is not a self-respecting science book. If we had to give credit to all the scientists in the world who have contributed to the field, the content would dwarf the phone directory of New York city. We have purposely omitted citing any names.

This book was started on the initiative of Ladan Arissian, a poet and physicist, as you will clearly sense from the style of various chapters. She has a broad educational background in various disciplines of physics (nuclear, condensed matter, and optical science). In addition to being a research physicist, she dreams of being a teacher and strives to present science in new ways.

This book would not have been published if it had not been ornamented with the name of Professor Jean-Claude Diels, who was willing to sacrifice his reputation as a serious science writer of “ultrafast laser pulse phenomena” [7]. He has decades of experience in tweaking and building impossible lasers and trying to understand the effect of each optical component on the optical pulse. He has never closed the laser box and refused to reduce it to a rectangle in a diagram. He only agreed to coauthor this book if he could insert his cartoons in the text.

Our enthusiasm about lasers and their applications is just a minute reflection of the work of men and women in science, bearing all the frustration and obstacles of conducting research. We are in debt to all scientists, engineers, technicians, and students whose persistence and patience have introduced the laser in all fields of science as well as in our daily lives.

Albuquerque, March 2011

Jean-Claude DielsLadan Arissian

References

1 Hecht, J. (2005) Beam: The Race to Make the Laser, Oxford University Press, New York.

2 Hecht, J. (1992) Laser Pioneers, Academic Press, Boston.

3 Taylor, N. (2000) Laser: The Inventor, the Nobel Laureate, and the Thirty-Year Patent War, Simon & Schuster, New York.

4 Bertolloti, M. (2005) The History of the Laser, Institute of Physics Publications, Bristol, Philadelphia.

5 Townes, C.H. (1999) How the Laser Happened: Adventures of a Scientist, Oxford University Press, New York.

6 Hecht, J. (2008) Understanding Lasers, 3rd edn, IEEE press, John Wiley & Sons.

7 Diels, J.C. and Rudolph, W. (2006) Ultrashort Laser Pulse Phenomena, 2nd edn, Elsevier, Boston.

Chapter 1

A Scenic Route through the Laser

1.1 The Meaning of “Laser”

“Laser” is one of the rare acronyms whose meaning has not been lost over five decades. It stands for Light Amplification by Stimulated Emission Radiation. These words are not sufficient to clarify the meaning, unless we have a picture associated to each of them in our mind. The next few sections will be devoted to unraveling the meaning of each term.

1.1.1 Light (Photon) is a Wave

The first letter “L” tells us that “laser” is “light”. Light is an old known entity originating from the sun and the moon. Once it was associated with fire and thought to be the first essential element. In modern language we say that light actually consists of photons, just as matter is made of atoms. Our intuitive picture of atoms is that they can be nicely classified by their mass in a table – the Mendeleev table. Atoms themselves are boxes filled with electrons, protons and neutrons, and there is a mass associated with each component.

Atoms can combine to make molecules, the ultimate component we expect to arrive at when grinding to its finest constituent any piece of material, from a live leaf to a piece of paper. In a way molecules and atoms are what we deal with on a daily basis, but at such a fine scale that it escapes our direct perception. Photons are as ubiquitous, but quite different from atoms and their constituents. Ubiquitous, because they are associated not only with visible light, but also with invisible radiation (infrared and ultraviolet), x-rays, gamma rays, radio waves, and even the radiation from our electrical network at 50 or 60 Hz. They are quite different because there is no mass associated to the photon. A wave is associated with the photon, which is an oscillation propagating at the speed of light.

What is a wave? There is always a pattern and motion associated to the wave; the ripples of a stone thrown in a pond or folds of a flag. One can imagine more and more examples that the word “wave” is applied to. As physicists we would like to pause and clarify some features of the wave with definitions that can be used to quantify similar observations. If you take a picture from the ripples on the pond you realize that there are regular patterns that repeat in water, and you can possibly count the number of peaks on the water surface, that are separated by a “wavelength”. You can also only consider a fixed point on the surface and monitor its motion as it goes up and down, or oscillates. It takes a “period” for each point on the pond to repeat its position. The pattern on the wave (for example, the peaks) have a certain “speed” or “wave velocity”, and the peaks that are created by the wave have an “amplitude”. It is reasonable to conclude that stronger waves have bigger amplitudes, but there is more to the strength or energy of a wave, as we will see in the following sections.