Acronyms and Abbreviations ix

Preface xi

1 Introduction 1

1.1 Photon Transfer History and Application 1

1.2 Photon Transfer Family 4

1.3 Chapter Review 7

2 Photon Interaction 11

2.1 Photoelectric Effect 11

2.2 Quantum Efficiency 13

2.3 Quantum Yield 17

3 Photon Transfer Noise Sources 21

3.1 Photon Shot Noise 21

3.2 Signal Shot Noise 24

3.3 Fano Noise 25

3.4 Fixed Pattern Noise 30

3.5 Read Noise 34

4 Photon Transfer Theory 35

4.1 Photon Transfer Relation 35

4.2 Sense Node Sensitivities 38

4.2.1 Sense node sensitivity 38

4.2.2 Sense node to source follower sensitivity 40

4.2.3 Sense node to CDS sensitivity 41

4.2.4 Sense node to ADC sensitivity 41

4.3 Interacting Photon Sensitivities 42

4.3.1 Interacting photon sensitivity 42

4.3.2 Interacting photon to ADC sensitivity 43

4.4 Incident Photon Sensitivities 44

4.4.1 Incident photon sensitivity 44

4.4.2 Incident photon to ADC sensitivity 44

4.5 Photon Transfer General Derivation 44

4.6 Effective Quantum Yield 45

4.6.1 Photon event charge sharing 45

4.6.2 Charge collection efficiency 46

5 Photon Transfer Curve 49

5.1 PTC Setup and Generation 49

5.2 PTC Family 52

5.3 PTC Errors 60

5.4 Shutterless (Time-Delayed Integration) PTC 66

5.5 Variance PTC 67

5.6 Example Experimental PTC Data 72

6 e-/DN variance 79

7 Nonlinearity 87

7.1 Introduction 87

7.2 V/V Nonlinearity 87

7.3 V/e- Nonlinearity 93

8 Flat Fielding 111

8.1 Theory 111

8.2 Photon Transfer Verification 115

8.3 Nonlinearity 118

9 Modulation Photon Transfer 127

9.1 Introduction 127

9.2 Sinusoidal Signal 127

9.3 Sinusoidal Noise 131

9.4 Modulation PTC 134

10 Signal-to-noise Performance 143

10.1 Uniform Stimulus 143

10.2 Image S/N Performance 146

10.3 Flat Fielding 150

10.4 Image Averaging 156

10.5 On-Chip Averaging 159

11 Read Noise 163

11.1 Introduction 163

11.2 Pixel Source Follower Noise 163

11.3 Sense Node Reset Noise 165

11.4 Dark Current Noise 167

11.5 ADC Quantizing Noise 175

11.5.1 Linear encoding 175

11.5.2 Nonlinear encoding 182

11.6 Offset Fixed Pattern Noise 186

11.7 System Noise 191

12 Lux Transfer 193

12.1 Introduction 193

12.2 Minimum Detection Limit 198

12.3 Responsivity 200

12.4 Modulation LTC 202

12.5 Acceptable Image 205

12.6 LTC Ratio 207

12.7 LTC Data Sequence 209

Appendix A PTC Data Reduction Example 213

Appendix B PTC Simulation Program with Thermal Dark Current 237

Appendix C PTC Simulation Program with FPN Removal through Flat Fielding 241

Appendix D LTC Simulation Program with Thermal Dark Current 245

Table of Symbols 249

Index 255

Preface

This book was prompted by engineers, scientists, and hardware managers who attended short courses held on CCD and CMOS imagers at UCLA Extension, SPIE conferences, and various seminars. Roughly 15% of course material presented is typically allocated to the photon transfer characterization technique necessary to set the stage for other sessions that require its application. Course evaluation forms generated by students requested more in-depth discussions about the measurement standard, and suggested that a book on photon transfer would also be welcomed. Encouraged by these recommendations, after 25 years of teaching these courses, this short reference book finally materialized.

Photon Transfer is designed for a wide audience—from the novice to the advanced user already familiar with the method. For first-time users, the book's primary purpose is to give sufficient guidelines to accurately generate, calibrate, and understand imaging data products through the photon transfer method. With this purpose in mind, Chapters 2-4 represent background and theoretical material necessary to fundamentally show how the technique works. Chapter 5 then takes the reader into the process of actually generating photon transfer curves, the first objective accomplished by learners before proceeding into more complex photon transfer products.

Experienced users may find the material presented in Chapters 6-12 to be new territory. As this book was written, the author had numerous new insights into photon transfer even after more than 30 years of previous study and use (e.g., Chapter 7 on the subject of V/e- nonlinearity, Chapter 8 on flat fielding, and Chapter 9 on the modulation photon transfer curve). It is very likely that readers of this book will also make new discoveries and find different ways to apply photon transfer on future imaging technologies and applications.

The book contains more than 230 figures that present experimental CCD and CMOS data products and modeling simulations connected to photon transfer. Contents also provide hundreds of relations that support photon transfer theory, simulations, and data presented. For the more important equations, 57 example problems are presented to demonstrate how the relations are used. Appendix A presents a spreadsheet of experimental CMOS data used to exercise the photon transfer method and produce numerous products. Appendices B-D present example computer photon transfer simulation programs utilized throughout the book.

The author would like to acknowledge Margaret Thayer and Timothy Lamkins of SPIE for giving life to my English. Thanks goes to Joseph Altebrando and Rich Lobdill for first seeing and reacting with welcomed criticisms to the manuscript. I wish to express my thanks to Tom Elliott for helping me pioneer the photon transfer technique over the many years we have worked together, and I especially want to thank my wife Linda and daughter Amanda, my sister Barb, and Mom and Dad for their timely support in many ways.