Preface ....................................................... xix
The Authors ................................................... xxi
Part 1. The Source (Infrared-Emitting Diodes)
Chapter 1
Basic Theory .................................................... 3
1.1. Introduction .......................................... 3
1.2. P-N Junction Injection Electroluminescence ............ 3
1.3. Relative Efficiency ................................... 5
Chapter 2
Light-Emitting Diode Fabrication ................................ 7
2.1. Introduction: Epitaxial Growth 7
2.2. Liquid-Phase Epitaxy 7
2.2.1. Gallium Arsenide 9
2.2.2. Gallium Aluminum Arsenide 10
2.3. Metal Organic Chemical Vapor Deposition 13
2.4. Hydride Vapor-Phase Epitaxy 14
2.5. Molecular Beam Epitaxy 15
Chapter 3
IRLED Packaging ................................................ 17
3.1. Introduction ......................................... 17
3.2. Techniques for Improving Photon Emission
Efficiency ........................................... 19
3.3. Packaging the IRLED .................................. 21
3.4. Characterization of the Packaged IRLED ............... 25
3.4.1. Package Side Emission ........................ 28
3.4.2. Package Height ............................... 29
3.4.3. Lens Quality ................................. 30
3.4.4. Chip Centering ............................... 31
3.4.5. Heat Dissipation ............................. 32
3.4.6. Reliability .................................. 32
3.4.7. Storage Temperature Range .................... 34
3.4.8. Operating Temperature ........................ 34
3.4.9. Thermal Shock ................................ 34
3.4.10. Solvent Resistance ........................... 34
3.4.11. Hermeticity .................................. 35
3.4.12. Mechanical Shock and Vibration ............... 35
3.4.13. Optical Consideration ........................ 35
3.5. Understanding Thermal Impedance ...................... 39
3.5.1. Thermal Impedance Calculations ............... 39
3.6. Understanding the Measurement of Radiant Energy ...... 46
3.6.1. General Discussion ........................... 46
3.6.2. Parameter Definitions and Measurement
Techniques ................................... 51
3.7. Reliability .......................................... 52
3.8. Conclusion ........................................... 57
Part 2. The Receiver (Silicon Photosensor)
Chapter 4
The Photodiode ................................................. 61
4.1. Basic Theory ......................................... 61
4.1.2. Photoelectric Effect .......................... 61
4.2. Optimization ......................................... 64
4.3. Characterization ..................................... 66
Chapter 5
The Phototransistor and Photodarlington ........................ 75
5.1. Basic Theory ......................................... 75
5.1.1. Phototransistor .............................. 77
5.1.2. Photodarlington .............................. 78
5.1.3. RBE Phototransistor .......................... 79
5.2. Characterization ..................................... 80
5.2.1. Switching Characteristics .................... 82
5.2.2. Package Lens Effects ......................... 97
Chapter 6
The Photointegrated Circuit .................................... 99
6.1. Basic Theory ......................................... 99
6.2. IC Processing Steps ................................. 101
6.2.1. Starting Wafer .............................. 101
6.2.2. Buried Layer ................................ 101
6.2.3. Epi ......................................... 102
6.2.4. Isolation ................................... 102
6.2.5. Deep N+ ..................................... 102
6.2.6. P+ .......................................... 103
6.2.7. N+ .......................................... 104
6.2.8. Resistors ................................... 104
6.2.9. Contact ..................................... 105
6.2.10. Metal ....................................... 105
6.2.11. Passivation ................................. 106
6.2.12. Backside Processing ......................... 106
6.3. Other IC Devices .................................... 107
6.3.1. Photodiodes ................................. 108
6.3.2. Lateral PNP ................................. 109
6.3.3. Vertical PNP ................................ 110
6.3.4. Capacitor ................................... 110
6.3.5. Summary ..................................... 110
6.4. Characterization .................................... 110
Chapter 7
Special-Function Photointegrated Circuits ..................... 115
7.1. Basic Theory ........................................ 115
7.2. Triac Driver Photosensors ........................... 115
7.3. Synchronous Driver Detector (SDD) ................... 118
7.4. Color Sensor ........................................ 120
Part 3. The Coupled Emitter (IRLED) Photosensor Pair
Chapter 8
The Transmissive Optical Switch ............................... 125
8.1. Slotted (Transmissive) Optical Switch ............... 125
8.2. Encoder Wheel Design ................................ 131
8.3. Performance Characteristics ......................... 131
8.4. Flag Switches ....................................... 136
8.5. Slotted Switch Summary .............................. 136
Chapter 9
The Reflective Optical Switch ................................. 141
9.1. Electrical Considerations ........................... 141
9.2. Mechanical Considerations ........................... 151
Part 4. The Optical Isolator and Solid-State Relay
Chapter 10
Electrical Considerations ..................................... 155
10.1. Background .......................................... 155
10.2. Function ............................................ 156
10.3. Different Types ..................................... 160
10.4. Introduction to Solid-State Relays (SSR) ............ 167
10.4.1. Applications ................................ 168
10.5. Theory of Operation ................................. 168
10.6. DC Input-DC Output SSR Operation .................... 169
10.7. DC Input-AC Output SSR Operation .................... 170
10.8. AC Input-AC Output SSR Operation .................... 171
10.9. Temperature Considerations .......................... 172
10.10.Overvoltage and Overcurrent Surge Protection ........ 173
10.11.Zero Voltage Crossover .............................. 173
10.12.Conclusion .......................................... 175
Chapter 11
Mechanical and Thermal Considerations ......................... 177
11.1. Mechanical Considerations ........................... 177
11.1.1. Discrete Components ......................... 177
11.1.2. Surface Mount Chip Carriers (SMCCs) ......... 177
11.1.3. SMCC Advantages ............................. 178
11.1.4. The Emitter and Photosensor Assemblies ...... 179
11.1.5. Optoisolators ............................... 179
11.2. Managing Junction Temperature of High-Power
Light-Emitting Diodes ............................... 181
11.2.1. Reduced MTTF and Accelerated Degradation .... 182
11.2.2. Generating Heat ............................. 182
11.2.3. Removing Heat ............................... 182
11.2.4. Thermal Equilibrium ......................... 183
11.2.5. Analogy to Electrical Circuits .............. 183
11.2.6. Determining Junction Temperature from
Forward Voltage ............................. 184
11.2.7. Passive Thermal Management .................. 184
11.2.8. Active Thermal Management ................... 185
Part 5. Open Air and Fiber-Optic Communication
Chapter 12
Fiber-Optic Communication ..................................... 191
12.1. Basics .............................................. 191
12.2. Advantages .......................................... 195
12.2.1. Less Expensive .............................. 195
12.2.2. Small Diameter and Light Weight ............. 196
12.2.3. Higher Capacity ............................. 196
12.2.4. Nonconductivity ............................. 196
12.2.5. Low Power ................................... 196
12.2.6. Less Signal Loss ............................ 196
12.2.7. Digital Signals ............................. 196
12.2.8. Security .................................... 196
Chapter 13
Wireless Communication ........................................ 197
13.1. Basic Theory ........................................ 197
13.2. Background .......................................... 200
Part 6. IR Applications
Chapter 14
Pulse Operation ............................................... 205
14.1. The IRLED ........................................... 205
14.2. The Photosensor ..................................... 209
Chapter 15
Driving a Light-Emitting Device ............................... 211
15.1. Introduction ........................................ 211
15.2. Variables ........................................... 211
15.3. Linear Operation .................................... 213
Chapter 16
Interfacing to the Photosensor ................................ 215
16.1. The Photodiode ...................................... 215
16.2. The Phototransistor and Photodarlington ............. 219
16.2.1. Basic Interface Circuits for CMOS ........... 221
16.2.2. Basic Interface Circuits for TTL ............ 222
16.3. The Photo integrated Circuit ........................ 225
Chapter 17
Computer Peripheral and Business Equipment Applications ....... 227
17.1. Copiers and Printers ................................ 227
17.2. Keyboards and Mice .................................. 227
17.3. Touch Screens ....................................... 227
17.4. Data Interface ...................................... 227
17.5. Check/Card Reader ................................... 229
17.6. Optical Couplers/Isolators .......................... 229
Chapter 18
Industrial Applications ....................................... 231
18.1. Safety-Related Optical Sensors ...................... 231
18.2. Hazardous Fluid Sensing ............................. 232
18.3. Security and Surveillance Systems ................... 235
18.4. Mechanical Aids, Robotics ........................... 236
18.5. Miscellaneous Optical Sensors ....................... 238
18.6. Optical Couplers/Isolators .......................... 238
Chapter 19
Automotive Applications ....................................... 241
19.1. Existing Applications ............................... 241
Chapter 20
Military Applications ......................................... 245
20.1. Military Applications for Optical Sensors ........... 245
Chapter 21
Consumer Applications ......................................... 249
21.1. TV and Game Controls ................................ 249
21.2. CD and DVD Discs .................................... 249
21.3. Dollar Bill Changers ................................ 250
21.4. Coin Changers ....................................... 250
21.5. Smoke Detectors ..................................... 251
21.6. Slot Machines ....................................... 253
21.7. Camera Applications ................................. 254
21.8. Optical Golf Games .................................. 254
21.9. Household Appliance Controls ........................ 254
Chapter 22
Medical Applications .......................................... 255
22.1. Introduction ........................................ 255
22.2. Pill-Counting Systems ............................... 255
22.3. Electrical Isolation Systems ........................ 255
22.4. Infusion Pump Application ........................... 255
22.5. Hemodialysis Equipment Application .................. 257
22.6. Fluid and Bubble Sensing for Medical Applications ... 257
22.7. Intravenous Drop Monitor............................. 260
22.8. Pulse Rate Detection ................................ 260
Chapter 23
Telecommunications ............................................ 263
23.1. Telecommunications Overview ......................... 263
Part 7. Visible and Ultraviolet Technologies
Chapter 24
Visible-Light-Emitting Diodes (VLEDs) ......................... 269
24.1. Introduction ........................................ 269
24.2. What Is an LED? ..................................... 269
24.2.1. Chip (Die) .................................. 269
24.2.2. Packaging ................................... 271
24.2.3. Phosphor Coatings ........................... 272
24.2.4. Secondary Optics ............................ 273
24.3. Generating Light .................................... 273
24.4. Optical, Thermal, and Electrical Measurements ....... 274
24.4.1. Measurement of Parameters ................... 274
24.5. Laboratory Testing .................................. 279
24.6. Reliability ......................................... 283
24.6.1. Lifetime and Operation of LEDs .............. 283
24.6.2. Factors Affecting LED Lifetime .............. 284
24.7. Applications ........................................ 287
Chapter 25
Ultraviolet Electromagnetic Radiation ......................... 289
25.1. Overview ............................................ 289
25.2. The UV Spectrum ..................................... 289
25.3. Fluorescent Lamp .................................... 291
25.4. Types of UV Lamps ................................... 292
25.5. UV Lamp Aging ....................................... 294
25.6. RoHS and WEEE Concerns for UV Lamps ................. 295
25.7. Failure Modes in UV Gas Discharge Lamps ............. 295
25.8. Overview of UV Applications ......................... 296
25.9. Germicidal Effects of UV Light ...................... 297
25.10.Ultraviolet LED ..................................... 303
25.11. UV Packaging Technology ............................ 305
25.12.Currency and Document Validation Applications ....... 309
25.13.Industrial UV Curing Applications ................... 310
25.14.Air-Water-Surface Disinfection ...................... 312
25.15.Medical and Forensic Applications ................... 313
Bibliography .................................................. 315
Glossary ...................................................... 317
Index ......................................................... 327
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