List of Figures xv
List of Contributors liii
Preface lv
Acknowledgments lix
Glossary of Symbols and Abbreviations lxi
1 Introduction - Path to Ignition Enabled by Optics 1
Tayyab I. Suratwala
1.1 Ignition 1
1.2 National Ignition Facility 5
1.3 NIF Large Optics 7
1.3.1 Optic Technologies Development 8
1.3.2 Laser Damage Reduction 13
1.3.3 Optics Recycle Loop Strategy 15
1.3.4 Loop Management and Performance 18
1.3.5 Ingredients for Success 20
1.4 Book Organization 22
References 24
Part I Optic Manufacturing Technologies 29
2 NIF Optics 31
Christopher J. Stolz, Kathleen I. Schaffers, Lana L. Wong, and Hoang T. Nguyen
2.1 NIF Optics Functionality 31
2.2 Front-End and Diagnostic Optics 35
2.3 Amplifier Optics 37
2.3.1 Laser Glass 37
2.3.2 Cladding 39
2.3.3 Blast Shields 39
2.4 Vacuum Barriers and Focusing Optics 40
2.4.1 Spatial Filter Lenses (SF1-4) 40
2.4.2 Vacuum Windows (SW, TCVW, and GDS) 42
2.4.3 Off-Axis Wedged Focus Lens (WFL) 43
2.5 Beam-Steering Optics 44
2.5.1 Cavity Mirrors (LM1-2) 45
2.5.2 Transport Mirrors (LM4-8) 46
2.6 Polarizing Optics and Frequency Conversion 49
2.6.1 Polarizing Optics (PL, SC, and PR) 49
2.6.2 Frequency Conversion Crystals (SHG and THG) 51
2.7 Beam-Formatting Optics (Continuous Phase Plates) 52
2.8 Debris-Shield Optics 54
2.8.1 Disposable Debris Shield (DDS) 54
2.8.2 Fused-Silica Debris Shield (FSDS) 55
2.8.3 Grating Debris Shield (GDS) 56
2.9 Short Pulse Optics for Advanced Radiographic Capability (ARC) 58
2.10 Summary 65
References 65
3 Optics Industry, Facilitization, and Sustainability 73
ChristopherJ.Stolz
3.1 Vendor Partnership Strategy 73
3.1.1 Technology Development 74
3.1.2 Facilitization 75
3.1.3 Pilot Production 79
3.1.4 Production 80
3.2 Manufacturing Rate Improvement 82
3.2.1 Continuous Melting of Laser Phosphate Glass 82
3.2.2 Fabrication of Crystal Optics 82
3.2.3 Grinding Technology of Glass Optics (ELID) 85
3.2.4 Computer Controlled Polishing of Fused-Silica Optics 86
3.3 Strategies for Robust Optics Supply 88
3.3.1 Competitive Versus Sole Source 88
3.3.2 Minimizing Optics Supply Risk 90
3.4 Institutional Partnerships 92
3.5 Sustainability for Multi-decade Operations 93
3.6 Summary 94
Acknowledgments 94
References 94
4 Nd-Doped Laser Phosphate Glass 99
Tayyab I. Suratwala and Paul Ehrmann
4.1 Introduction 99
4.2 Glass Composition and Properties 100
4.3 Continuous Melting 102
4.4 OH Content 105
4.5 Fracture 109
4.5.1 Slow Crack Growth 109
4.5.2 Surface Tension via OH Diffusion 112
4.6 Corrosion Resistance 115
4.6.1 Weathering 115
4.6.2 Haze: Ceria Reactivity with Surface 119
4.7 Pt Inclusions 122
4.8 Impurities 124
4.9 Glass Quality, Selection Rules, and Performance 126
Acknowledgments 130
References 130
5 KDP and DKDP Crystals 135
Kathleen I. Schaffers and Tayyab I. Suratwala
5.1 Introduction 135
5.2 Crystal Composition and Properties 136
5.3 KDP and DKDP Growth Technologies 138
5.4 Technical Challenges 142
5.4.1 Crystal Growth to Large Size 142
5.4.2 D/H Exchange (E-Cracking) 145
5.4.3 Reaction with Humidity (Etch Pits) 148
5.4.4 Laser-Induced Surface Roughening in a Vacuum 151
5.4.5 Fracture 152
5.4.6 Liquid Inclusions 155
5.4.7 Bulk Laser Damage and Laser Conditioning 156
5.5 Summary 159
Acknowledgments 159
References 159
6 3¿ Finishing 163
Tayyab I. Suratwala
6.1 Sub-surface Mechanical Damage 164
6.1.1 Grinding SSD Management 164
6.1.2 Polishing SSD Management 167
6.1.3 Scratch Forensics 170
6.2 Role of Chemical Etching 172
6.2.1 Strip Etch 173
6.2.2 Bulk Etching 174
6.2.3 Chemical Impurity Removal 178
6.3 Strategy for 3¿ Finishing and Production Impact 178
References 180
Part II Optic Laser-Induced Damage Reduction Technologies 183
7 Laser-Induced Damage Mechanisms 185
C. Wren Carr
7.1 Laser-Induced Damage Process and Location Implications 185
7.2 Initial Absorption 187
7.3 Types of Laser-Induced Damage 188
7.3.1 Gray Haze 188
7.3.2 Exit Surface Damage on SiO 2 Glass 189
7.3.3 Bulk Damage in KDP and DKDP 191
7.3.4 Damage in MLD Coatings 193
7.4 Initial Absorption Mechanisms 194
7.4.1 Initial Absorption by Intrinsic Mechanisms 194
7.4.2 Initial Absorption by Extrinsic Mechanisms 196
7.5 Secondary Absorption 201
7.6 Material Response 205
7.6.1 Material Response After Damage 205
7.6.2 Material Response Without Damage 210
References 210
8 Laser-Damage Measurement and Analysis Methods 215
David A. Cross and C. Wren Carr
8.1 Introduction 215
8.1.1 Why Are Laser-Damage Measurements Needed? 215
8.1.2 Misconceptions Concerning Laser Damage 216
8.2 Measurement 219
8.2.1 Material Laser Exposure 219
8.2.2 Material Response 221
8.3 Analysis 223
8.3.1 Multimodal Registration 223
8.3.2 Damage-Initiation Measurements 227
8.3.3 Damage-Growth Measurements 232
References 237
9 Parameters Affecting Laser-Induced Damage Initiation and Growth 241
Raluca A. Negres and C. Wren Carr
9.1 Introduction 241
9.2 Initiation 243
9.2.1 Fluence, Wavelength, and Optic Quality 244
9.2.2 Pulse Length and Shape 245
9.2.2.1 Nanosecond Pulse-Width Regime 245
9.2.2.2 Picosecond Pulse-Width Regime 247
9.3 Growth 248
9.3.1 Multi-shot Growth Behaviors 249
9.3.1.1 Fluence, Wavelength, and Location 249
9.3.1.2 Multi-wavelength Irradiation 250
9.3.2 Single-Shot Growth Behaviors 251
9.3.2.1 Probability of Growth 253
9.3.2.2 Growth Rate 257
9.4 Summary 261
References 262
10 Advanced Mitigation Process (AMP) 267
Diana VanBlarcom
10.1 Introduction 267
10.2 Development of the AMP Process 268
10.2.1 Etching to Mitigate Scratches 269
10.2.2 Etching to Mitigate Chemical Impurities 273
10.3 Production Implementation 277
10.3.1 AMP Station 277
10.3.2 AMP Recipes 278
10.3.3 Post-AMP Surface Degradations 279
10.3.4 AMP Production Rates 281
10.3.5 Quality Assurance and Safety 282
10.4 Conclusions and the Future of AMP 283
References 283
11 Debris-Induced Damage Reduction on 3¿-Fused-Silica Optics 285
Rajesh N. Raman, Christopher F. Miller, and C. Wren Carr
11.1 Evidence of a New Damage Source 285
11.1.1 High Online Damage Initiation Rates After AMP 285
11.1.2 Damage Spatial Distribution 286
11.1.3 Debris on Optic and Damage Morphology 288
11.1.4 Debris Morphology and Composition 290
11.2 Sources of Debris 292
11.3 Physics of Debris-Induced Laser Damage 293
11.3.1 Deposition Mechanism 293
11.3.2 Material Type 296
11.3.3 Fluence and Particle Size 302
11.4 Mitigation of Debris-Induced Damage and Impact 303
11.4.1 Antireflection Coating on Grating Surface of GDS 304
11.4.2 Fused-Silica Debris Shield (FSDS) to Protect GDS 305
11.4.3 Metal Barriers to Block Debris Transit 307
11.4.4 Laser Cleaning 308
References 309
12 Silica Sol-Gel Antireflective Coatings 311
StephenH.Mezyk
12.1 Introduction 311
12.2 Single Layer Antireflective Optical Coatings 313
12.3 Stöber Silica Sol-Gel 315
12.4 Chemically Processing Stöber Silica for Enhanced Mechanical and Environmental Stability 316
12.5 Wet-Film Deposition Processes 319
12.6 Ellipsometry for Process Control 320
12.7 Volume Production of Sol-Gel Thin Films 323
12.8 Conclusion 325
References 326
13 Multilayer Dielectric Coatings 329
Colin M. Harthcock
13.1 Introduction 329
13.2 MLD Design Fundamentals 329
13.2.1 Complex Index and Reflectivity 330
13.2.2 Admittance of Optical Thin Films 331
13.2.3 MLD Coating-Design Examples 334
13.2.4 Polarization and Angle of Incidence 337
13.3 Laser-Damage Resistance 340
13.3.1 Electrical-Field Intensification 340
13.3.2 Optical Bandgap 342
13.3.3 Absorbing Precursors and Their Mitigations 345
13.3.3.1 Molecular and Atomic-Level Precursors 345
13.3.3.2 Within Coating Particulate Precursors 348
13.3.3.3 Foreign-Object Debris Precursors 350
13.4 Coating Structure and Deposition Energetics 356
13.5 Coating Deposition Process Variables and Methods 359
References 362
14 Optics Recycle Loop 367
Pamela K. Whitman and Brian J. Welday
14.1 Operation Strategy 367
14.2 Enabling Technologies 372
14.3 Optics Recycle Loop Process 373
14.4 Models to Describe the Optics Recycle Loop 380
14.4.1 Growth Rate of Fused-Silica Glass Damage 381
14.4.2 Analytical Model of Optics Exchange Rate 382
14.4.3 System Initiation Rate 383
14.4.4 Multi-loop Model 384
14.5 Historical Performance and Tailorability 386
14.6 Summary 390
Acknowledgments 390
References 392
Part III Optic Recycle Loop Technologies 395
15 Custom Processing Equipment 397
Vaughn E. Van Note and Henry A. Hui
15.1 Introduction 397
15.2 Systems Engineering Approach 398
15.3 Integrated Product Review Board 400
15.3.1 Failure Modes and Effects Analysis 402
15.3.2 Concept of Operations 404
15.3.3 Work Authorization Process 405
15.4 Advanced Mitigation Process (AMP) Station 406
15.5 Meniscus Coaters 409
15.6 Diffractive Optic Full Aperture System Test (DOFAST) 411
15.7 Assembly Stations 413
15.8 GDS Imprinting System 416
15.9 Sustaining Capabilities and the Future 418
Acknowledgments 421
References 421
16 Optics Inspection and Data Management 423
Laura M. Kegelmeyer
16.1 Optics Inspection Camera Systems on NIF 423
16.1.1 SIDE System for Imaging the Target Chamber Vacuum Window 425
16.1.2 LOIS for Imaging Main Laser Optics and Switchyard Mirrors 425
16.1.3 FODI for Imaging Final Optics and Some Switchyard Mirrors 428
16.2 Finding, Identifying, and Tracking Damage on NIF Optics 430
16.2.1 Image Analysis and Machine Learning 431
16.2.2 Fiducials and Defect Tracking Through Time and Space 436
16.3 Data Management and Applications 438
16.3.1 Integrated Analyses, Databases, and Reporting 438
16.3.2 Tools for Data Visualization 440
16.4 Summary 442
Acknowledgments 442
References 443
17 Online Programmable Shadow Blockers 445
Rajesh N. Raman, Tayyab I. Suratwala, and Pamela K. Whitman
17.1 Programmable Spatial Shaper Device Capability 446
17.2 Blocker Deployment and Optic Exchange 446
17.3 Blocker Constraints 449
17.4 Blocker Distribution Optimization 451
17.5 Production Metrics and Historical Behavior 454
References 455
18 Optic Metrology 457
Mike C. Nostrand
18.1 Full-Aperture Tools 459
18.1.1 Defects in the Antireflective coating using FADLiB 459
18.1.2 Surface Damage and Digs Using DMS 460
18.1.3 Surface Phase Objects 462
18.1.4 General Surface Features Using TID 463
18.1.5 Diffraction-Grating Efficiency and Uniformity Using DOFAST 464
18.2 Sub-aperture Tools 468
18.2.1 Phase and Amplitude of Phase Objects Using PSDI 468
18.2.2 Downstream Modulation Using MMS 470
18.2.3 Removing Coating Defects from Crystals Using FLRT 470
18.2.4 Crystal Phase-Matching Angles Using CATS 472
18.2.5 Threat-Determination Software 473
18.3 Commercial Tools 474
18.3.1 Full-Aperture Tools 474
18.3.2 Reflected and Transmitted Wave Front 474
18.3.3 Sub-aperture Tools 475
18.3.4 Optical-Surface Profiling 475
18.3.5 Optical Microscopy 475
18.3.6 Ellipsometry 477
18.4 Summary 478
References 479
19 Repair of Flaws and Laser-Induced Damage 481
Isaac L. Bass, Todd Noste, and Scott K. Trummer
19.1 Laser-Damage Repair on Fused Silica 481
19.1.1 Damage-Mitigation Requirements 483
19.1.2 Stationary-Beam Mitigation 484
19.1.3 Moving-Beam Mitigation 485
19.1.4 Rapid Ablation Mitigation 486
19.1.5 RAM Applied to Exit-Surface Damage 489
19.1.6 On-Axis Downstream Intensification from Exit-Surface RAM Cones 490
19.1.7 Damage Resistance of RAM Cones 491
19.1.8 Managing Redeposit from RAM Cones 493
19.1.9 Residual Stress from RAM Cones 496
19.1.10 RAM Applied to Input Surface Damage 497
19.1.11 RAM Applied to AR-Coated GDSs 501
19.1.12 RAM Cones Contribution to Obscuration 504
19.1.13 Reliability, Availability, and Maintainability of Mitigation Equipment 504
19.1.14 Investigation of Mitigation at 4.6-¿m Wavelength 505
19.2 Laser-Damage Initiation-Site Repair on KDP Crystals 505
19.2.1 Anatomy of a KDP Mitigation Site 506
19.2.2 Ductile Machining of KDP 508
19.2.3 Crystal Mitigation Station 508
19.2.4 Commissioning the CMS and Mitigation Sites 510
19.2.5 KDP Damage-Site Mitigation Challenges 514
19.2.6 Future Efforts and Upgrades 515
Acknowledgments 515
References 515
20 Laser-Induced Damage Repair Automation 521
Scott K. Trummer
20.1 Repair Process for 3¿ Fused-Silica Optics 521
20.1.1 Preprocessing 522
20.1.2 Software Setup 523
20.1.3 Optic Registration 523
20.1.4 Pre-mitigation Inspection 523
20.1.5 Mitigation and Post-mitigation Analysis 524
20.1.6 Postprocessing and Data Export 524
20.2 OMF Automation 524
20.2.1 Data Handling and Expanded Software Capabilities 525
20.2.2 Pre-mitigation Inspection and Protocol Assignment 527
20.2.3 Mitigation and Post-mitigation Inspection 534
20.2.4 Limitations of Automation 537
20.3 Production Metrics 539
References 541
21 Laser-Induced Damage Identification Using AI 543
Christopher F. Miller and David A. Cross
21.1 Improving Lifetime of Recycled Optics 544
21.2 The All Microscopy Hitlist (AMH) 545
21.2.1 Requirements and Process Strategy 546
21.2.2 Optic Verification and Large-Optic Scan 547
21.2.3 Optic Montage Analysis 550
21.2.3.1 Feature Finding 551
21.2.3.2 Large-Feature Analysis 552
21.2.4 Small-Site Inspection and Classification 555
21.3 Maximizing the Utility of Optic Repairs 556
21.3.1 Optic Triaging 556
21.3.2 End-of-Life Optics 557
References 558
22 On-Optic Shadow Cone Blockers 561
Eyal Feigenbaum, Allison E. Browar, Isaac L. Bass, and Rajesh N. Raman
22.1 Inherent Advantages and Challenges 561
22.1.1 On-Optics Shadowing Approach and Its Advantages 561
22.1.2 The SCB-Resulting Expanding Wave and Subsequent Exit Surface Damage 564
22.1.3 Size Limitations on the Diameter of Conic-Shaped SCB 567
22.2 Approaches for Implementation of Larger SCBs 569
22.2.1 Rounded Sidewalls SCB 570
22.2.2 Larger Shadowed Area Using SCB Arrays 576
22.3 Utilization and Application Considerations 578
22.3.1 FODI "Bleeding" and Potential Solutions 579
22.3.2 Implementation and Testing of SCB Online 580
References 586
23 Contamination Management from Nonoptical Materials 587
Liang-Yu Chen and Tayyab I. Suratwala
23.1 Particle Debris and Residue 588
23.1.1 Surface-Particle Cleanliness Measurement 588
23.1.2 Nonvolatile Residue (NVR) Measurement 589
23.1.3 Gross and Precision Cleaning 591
23.2 Airborne Molecular Contaminants (AMCs) 594
23.2.1 Vacuum-Outgas Test 594
23.2.2 High-Temperature Bakeout to Remove Volatile Organics 601
23.2.3 Polymer Example: Silicone 603
23.3 Summary 605
Acknowledgments 606
References 606
Index 609
