A powerful and up-to-date desk reference for advancements in optic technologies for high energy lasers In Optic Technologies Enabling Fusion Ignition, a team of veteran optics and laser specialists deliver an expert summary of optic manufacturing technologies, laser-induced optic damage reduction technologies, and optic repair & recycle technologies. The authors explore the fundamental scientific phenomena and how they have driven the development of optic technologies as well as the process of transitioning from scientific discovery to large-scale production. The book combines examinations of improving overall optic performance, optic survivability, and laser performance. It also covers novel bulk material developments, yield processing improvement methods, novel metrologies, and advancements in increasing laser-induced damage resistance. Readers will also find: A thorough introduction to the details of optics recycle loop technologies, including the refurbishment and repair of laser-induced damaged optics Comprehensive explorations of advancements in optical fabrication and post-processing reducing laser damaging surface precursors Practical discussions of the fundamental physics of laser-matter interactions related to laser-induced damage Complete treatments of laser-induced damage data management, the use of online shadow blockers, and novel optics metrologies Ideal for optical and laser scientists, engineers, and fabricators of optical materials and components, Optic Technologies Enabling Fusion Ignition is also a valuable resource for graduate students interested in optics, as well as high-energy and high-power laser research.

Table of Contents:
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 3ω 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 3ω 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 3ω-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-μm 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 3ω 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