Optics For Dummies

Galen Duree, Jr., PhD, is Professor of Physics and Optical Engineering at Rose-Hulman Institute of Technology in Indiana, where he is also the Director of the Center for Applied Optics Studies. Duree jointly established the Ultrashort Pulse Laser Laboratory at RHIT and continues to work with the Navy.

Introduction 1

About This Book 1

Conventions Used in This Book 2

What You’re Not to Read 3

Foolish Assumptions 3

How This Book Is Organized 3

Part I: Getting Up to Speed on Optics Fundamentals 4

Part II: Geometrical Optics: Working with More Than One Ray 4

Part III: Physical Optics: Using the Light Wave 4

Part IV: Optical Instrumentation: Putting Light to Practical Use 4

Part V: Hybrids: Exploring More Complicated Optical Systems 5

Part VI: More Than Just Images: Getting into Advanced Optics 5

Part VII: The Part of Tens 5

Icons Used in This Book 5

Where to Go from Here 6

Part I: Getting Up to Speed on Optics Fundamentals 7

Chapter 1: Introducing Optics, the Science of Light 9

Illuminating the Properties of Light 9

Creating images with the particle property of light 10

Harnessing interference and diffraction with the wave property of light 10

Using Optics to Your Advantage: Basic Applications 11

Expanding Your Understanding of Optics 12

Considering complicated applications 12

Adding advanced optics 13

Paving the Way: Contributions to Optics 13

Chapter 2: Brushing Up on Optics-Related Math and Physics 15

Working with Physical Measurements 15

Refreshing Your Mathematics Memory 16

Juggling variables with algebra 16

Finding lengths and angles with trigonometry 18

Exploring the unknown with basic matrix algebra 21

Reviewing Wave Physics 26

The wave function: Understanding its features and variables 26

Medium matters: Working with mechanical waves 28

Using wavefronts in optics 29

Chapter 3: A Little Light Study: Reviewing Light Basics 31

Developing Early Ideas about the Nature of Light 31

Pondering the particle theory of light 32

Walking through the wave theory of light 32

Taking a Closer Look at Light Waves 33

If light is a wave, what’s waving? Understanding electromagnetic radiation 33

Dealing with wavelengths and frequency: The electromagnetic spectrum 36

Calculating the intensity and power of light 36

Einstein’s Revolutionary Idea about Light: Quanta 37

Uncovering the photoelectric effect and the problem with light waves 38

Merging wave and particle properties: The photon 39

Let There Be Light: Understanding the Three Processes that Produce Light 40

Atomic transitions 40

Accelerated charged particles 41

Matter-antimatter annihilation 42

Introducing the Three Fields of Study within Optics 42

Geometrical optics: Studying light as a collection of rays 42

Physical optics: Exploring the wave property of light 43

Quantum optics: Investigating small numbers of photons 43

Chapter 4: Understanding How to Direct Where Light Goes 45

Reflection: Bouncing Light Off Surfaces 45

Determining light’s orientation 46

Understanding the role surface plays in specular and diffuse reflection 47

Appreciating the practical difference between reflection and scattering 48

Refraction: Bending Light as It Goes Through a Surface 50

Making light slow down: Determining the index of refraction 50

Calculating how much the refracted ray bends: Snell’s law 51

Bouncing light back with refraction: Total internal reflection 52

Varying the refractive index with dispersion 53

Birefringence: Working with two indices of refraction for the same wavelength 54

Diffraction: Bending Light around an Obstacle 55

Part II: Geometrical Optics: Working with More Than One Ray 57

Chapter 5: Forming Images with Multiple Rays of Light 59

The Simplest Method: Using Shadows to Create Images 60

Forming Images Without a Lens: The Pinhole Camera Principle 62

Eyeing Basic Image Characteristics for Optical System Design 63

The type of image created: Real or virtual 63

The orientation of the image relative to the object 63

The size of the image relative to the object 64

Zeroing In on the Focal Point and Focal Length 65

Determining the focal point and length 65

Differentiating real and virtual focal points 66

Chapter 6: Imaging with Mirrors: Bouncing Many Rays Around 69

Keeping it Simple with Flat Mirrors 69

Changing Shape with Concave and Convex Mirrors 70

Getting a handle on the mirror equation and sign conventions 71

Working with concave mirrors 72

Exploring convex mirrors 74

Chapter 7: Imaging with Refraction: Bending Many Rays at the Same Time 77

Locating the Image Produced by a Refracting Surface 78

Calculating where an image will appear 78

Solving single-surface imaging problems 80

Working with more than one refracting surface 83

Looking at Lenses: Two Refracting Surfaces Stuck Close Together 85

Designing a lens: The lens maker’s formula 85

Taking a closer look at convex and concave lenses 88

Finding the image location and characteristics for multiple lenses 89

D’oh, fuzzy again! Aberrations 91

Part III: Physical Optics: Using the Light Wave 95

Chapter 8: Optical Polarization: Describing the Wiggling Electric Field in Light 97

Describing Optical Polarization 97

Focusing on the electric field’s alignment 98

Polarization: Looking at the plane of the electric field 99

Examining the Different Types of Polarization 100

Linear, circular, or elliptical: Following the vector path 100

Random or unpolarized: Looking at changing or mixed states 107

Producing Polarized Light 108

Selective absorption: No passing unless you get in line 108

Scattering off small particles 109

Reflection: Aligning parallel to the surface 110

Birefringence: Splitting in two 111

Chapter 9: Changing Optical Polarization 113

Discovering Devices that Can Change Optical Polarization 113

Dichroic filters: Changing the axis with linear polarizers 114

Birefringent materials: Changing or rotating the polarization state 117

Rotating light with optically active materials 121

Jones Vectors: Calculating the Change in Polarization 121

Representing the polarization state with Jones vectors 121

Jones matrices: Showing how devices will change polarization 124

Matrix multiplication: Predicting how devices will affect incident light 126

Chapter 10: Calculating Reflected and Transmitted Light with Fresnel Equations 131

Determining the Amount of Reflected and Transmitted Light 131

Transverse modes: Describing the orientation of the fields 132

Defining the reflection and transmission coefficients 133

Using more powerful values: Reflectance and transmittance 134

The Fresnel equations: Finding how much incident light is reflected or transmitted 135

Surveying Special Situations Involving Reflection and the Fresnel Equations 136

Striking at Brewster’s angle 137

Reflectance at normal incidence: Coming in at 0 degrees 137

Reflectance at glancing incidence: Striking at 90 degrees 138

Exploring internal reflection and total internal reflection 138

Frustrated total internal reflection: Dealing with the evanescent wave 139

Chapter 11: Running Optical Interference: Not Always a Bad Thing 143

Describing Optical Interference 143

On the fringe: Looking at constructive and destructive interference 144

Noting the conditions required to see optical interference 145

Perusing Practical Interference Devices: Interferometers 146

Wavefront-splitting interferometers 146

Amplitude-splitting interferometers 151

Accounting for Other Amplitude-Splitting Arrangements 154

Thin film interference 154

Newton’s rings 157

Fabry-Perot interferometer 158

Chapter 12: Diffraction: Light’s Bending around Obstacles 161

From Near and Far: Understanding Two Types of Diffraction 162

Defining the types of diffraction 162

Determining which type of diffraction you see 163

Going the Distance: Special Cases of Fraunhofer Diffraction 164

Fraunhofer diffraction from a circular aperture 165

Fraunhofer diffraction from slits 167

Getting Close: Special Cases of Fresnel Diffraction 172

Fresnel diffraction from a rectangular aperture 173

Fresnel diffraction from a circular aperture 174

Fresnel diffraction from a solid disk 175

Diffraction from Fresnel zone plates 175

Part IV: Optical Instrumentation: Putting Light to Practical Use 179

Chapter 13: Lens Systems: Looking at Things the Way You Want to See Them 181

Your Most Important Optical System: The Human Eye 181

Understanding the structure of the human eye 182

Accommodation: Flexing some muscles to change the focus 183

Using Lens Systems to Correct Vision Problems 185

Corrective lenses: Looking at lens shape and optical power 185

Correcting nearsightedness, farsightedness, and astigmatism 186

Enhancing the Human Eye with Lens Systems 190

Magnifying glasses: Enlarging images with the simple magnifier 191

Seeing small objects with the compound microscope 192

Going the distance with the simple telescope 194

Jumping to the big screen: The optical projector 195

Chapter 14: Exploring Light Sources: Getting Light Where You Want It 197

Shedding Light on Common Household Bulbs 198

Popular bulb types and how they work 198

Reading electrical bulb rates 201

Shining More-Efficient Light on the Subject: Light Emitting Diodes 201

Looking inside an LED 202

Adding color with organic light emitting diodes 203

LEDs on display: Improving your picture with semiconductor laser diodes 204

Zeroing in on Lasers 205

Building a basic laser system 206

Comparing lasers to light bulbs 211

Chapter 15: Guiding Light From Here to Anywhere 213

Getting Light in the Guide and Keeping it There: Total Internal Reflection 213

Navigating numerical aperture: How much light can you put in? 214

Examining light guide modes 215

Categorizing Light Guide Types 216

Fiber-optic cables 216

Slab waveguides 220

Putting Light Guides to Work: Common Applications 221

Light pipes 221

Telecommunication links 221

Imaging bundles 224

Part V: Hybrids: Exploring More Complicated Optical Systems 227

Chapter 16: Photography: Keeping an Image Forever 229

Getting an Optical Snapshot of the Basic Camera 230

Lens: Determining what you see 231

Aperture: Working with f-number and lens speed 234

Shutter: Letting just enough light through 236

Recording media: Saving images forever 236

Holography: Seeing Depth in a Flat Surface 237

Seeing in three dimensions 237

Exploring two types of holograms 238

Relating the hologram and the diffraction grating 240

Graduating to 3-D Movies: Depth that Moves! 243

Circular polarization 243

Six-color anaglyph system 244

Shutter glasses 244

Chapter 17: Medical Imaging: Seeing What’s Inside You (No Knives Necessary!) 247

Shining Light into You and Seeing What Comes Out 247

X-rays 248

Optical coherence tomography 250

Endoscopes 251

Reading the Light that Comes Out of You 253

CAT scans 254

PET scans 255

NMR scans 256

MRI scans 257

Chapter 18: Optics Everywhere: Exploring Other Medical, Industrial, and Military Uses 259

Considering Typical Medical Procedures Involving Lasers 259

Removing stuff you don’t want: Tissue ablation 260

Sealing up holes or incisions 263

Purely cosmetic: Doing away with tattoos, varicose veins, and unwanted hair 264

Getting Industrial: Making and Checking Products Out with Optics 265

Monitoring quality control 265

Drilling holes or etching materials 265

Making life easier: Commercial applications 266

Applying Optics in Military and Law Enforcement Endeavors 267

Range finders 267

Target designation 268

Missile defense 268

Night vision systems 269

Thermal vision systems 270

Image processing 270

Chapter 19: Astronomical Applications: Using Telescopes 271

Understanding the Anatomy of a Telescope 272

Gathering the light 272

Viewing the image with an eyepiece 273

Revolutionizing Refracting Telescopes 274

Galilean telescope 275

Kepler’s enhancement 276

Reimagining Telescope Design: Reflecting Telescopes 277

Newtonian 277

Cassegrain 278

Gregorian 279

Hybrid Telescopes: Lenses and Mirrors Working Together 280

Schmidt 280

Maksutov 281

Invisible Astronomy: Looking Beyond the Visible 282

When One Telescope Just Won’t Do: The Interferometer 283

Part VI: More Than Just Images: Getting into Advanced Optics 285

Chapter 20: Index of Refraction, Part 2: You Can Change It! 287

Electro-Optics: Manipulating the Index of Refraction with Electric Fields 287

Dielectric polarization: Understanding the source of the electro-optic effect 288

Linear and quadratic: Looking at the types of electro-optic effects 289

Examining electro-optic devices 293

Acousto-Optics: Changing a Crystal’s Density with Sound 295

The acousto-optic effect: Making a variable diffraction grating 295

Using acousto-optic devices 296

Frequency Conversion: Affecting Light Frequency with Light 297

Second harmonic generation: Doubling the frequency 297

Parametric amplification: Converting a pump beam into a signal beam 298

Sum and difference frequency mixing: Creating long or short wavelengths 299

Chapter 21: Quantum Optics: Finding the Photon 301

Weaving Together Wave and Particle Properties 301

Seeing wave and particle properties of light 302

Looking at wave and particle properties of matter 304

Experimental Evidence: Observing the Dual Nature of Light and Matter 306

Young’s two-slit experiment, revisited 306

Diffraction of light and matter 307

The Mach-Zehnder interferometer 308

Quantum Entanglement: Looking at Linked Photons 308

Spooky action: Observing interacting photons 308

Encryption and computers: Developing technology with linked photons 309

Part VII: The Part of Tens 311

Chapter 22: Ten Experiments You Can Do Without a $1-Million Optics Lab 313

Chromatic Dispersion with Water Spray 313

The Simple Magnifier 314

Microscope with a Marble 314

Focal Length of a Positive Lens with a Magnifying Glass 314

Telescope with Magnifying Glasses 315

Thin Film Interference by Blowing Bubbles 316

Polarized Sunglasses and the Sky 316

Mirages on a Clear Day 317

Spherical Aberration with a Magnifying Glass 317

Chromatic Aberration with a Magnifying Glass 318

Chapter 23: Ten Major Optics Discoveries — and the People Who Made them Possible 319

The Telescope (1610) 319

Optical Physics (Late 1600s) 320

Diffraction and the Wave Theory of Light (Late 1600s) 320

Two-Slit Experiment (Early 1800s) 321

Polarization (Early 1800s) 321

Rayleigh Scattering (Late 1800s) 321

Electromagnetics (1861) 322

Electro-Optics (1875 and 1893) 322

Photon Theory of Light (1905) 322

The Maser (1953) and The Laser (1960) 323

Index 325