Kai Wang, Ph.D., Southern University of Science and Technology, Guangdong, China Sheng Liu, Ph.D., Wuhan University, Hubei, China Xiaobing Luo, Huazhong University of Science and Technology, Hubei, China Dan Wu, Ph.D., Nanyang Technological University, Singapore

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• Preface xi1 Introduction 11.1 Overview of LED Lighting 11.2 Development Trends of LED Packaging and Applications 51.3 Three Key Issues of Optical Design of LED Lighting 71.3.1 System Luminous Efficiency 71.3.2 Controllable Light Pattern 71.3.3 Spatial Color Uniformity 81.4 Introduction of Freeform Optics 10References 122 Review of Main Algorithms of Freeform Optics for LED Lighting 152.1 Introduction 152.2 Tailored Design Method 162.3 SMS Design Method 172.4 Light Energy Mapping Design Method 182.5 Generalized Functional Design Method 192.6 Design Method for Uniform Illumination with Multiple Sources 22References 223 Basic Algorithms of Freeform Optics for LED Lighting 253.1 Introduction 253.2 Circularly Symmetrical Freeform Lens – Point Source 253.2.1 Freeform Lens for Large Emitting Angles 263.2.1.1 Step 1. Establish a Light Energy Mapping Relationship between the Light Source and Target 273.2.1.2 Step 2. Construct a Freeform Lens 313.2.1.3 Step 3. Validation and Optimization 333.2.2 TIR-Freeform Lens for Small Emitting Angle 333.2.3 Circularly Symmetrical Double Surfaces Freeform Lens 393.3 Circularly Symmetrical Freeform Lens – Extended Source 423.3.1.1 Step 1. Construction of a Point Source Freeform Lens 453.3.1.2 Step 2. Calculation of Feedback Optimization Ratios 453.3.1.3 Step 3. Grids Redivision of the Target Plane and Light Source 463.3.1.4 Step 4. Rebuild the Energy Relationship between the Light Source and Target Plane 463.3.1.5 Step 5. Construction of a Freeform Lens for an Extended Source 473.3.1.6 Step 6. Ray-Tracing Simulation and Feedback Reversing Optimization 473.4 Noncircularly Symmetrical Freeform Lens – Point Source 483.4.1 Discontinuous Freeform Lens Algorithm 493.4.1.1 Step 1. Establishment of a Light Energy Mapping Relationship 493.4.1.2 Step 2. Construction of the Lens 523.4.1.3 Step 3. Validation of Lens Design 553.4.2 Continuous Freeform Lens Algorithm 553.4.2.1 Radiate Grid Light Energy Mapping 573.4.2.2 Rectangular Grid Light Energy Mapping 583.5 Noncircularly Symmetrical Freeform Lens – Extended Source 603.5.1.1 Step 1. Establishment of the Light Energy Mapping Relationship 613.5.1.2 Step 2. Construction of a Freeform Lens 613.5.1.3 Step 3. Validation of Lens Design 623.6 Reversing the Design Method for Uniform Illumination of LED Arrays 633.6.1 Reversing the Design Method of LIDC for Uniform Illumination 643.6.2 Algorithm of a Freeform Lens for the Required LIDC 66References 684 Application-Specific LED Package Integrated with a Freeform Lens 714.1 Application-Specific LED Package (ASLP) Design Concept 714.2 ASLP Single Module 724.2.1 Design Method of a Compact Freeform Lens 724.2.2 Design of the ASLP Module 734.2.2.1 Optical Modeling 734.2.2.2 Design of a Compact Freeform Lens 734.2.2.3 ASLP Module 744.2.3 Numerical Analyses and Tolerance Analyses 764.2.3.1 Numerical Simulation and Analyses 764.2.3.2 Tolerance Analyses 774.2.3.3 Experiments 814.3 ASLP Array Module 854.4 ASLP System Integrated with Multiple Functions 874.4.1 Optical Design 894.4.1.1 Problem Statement 894.4.1.2 Optical Modeling 894.4.1.3 Design of a Freeform Lens 904.4.1.4 Simulation of Lighting Performance 914.4.2 Thermal Management 914.4.3 ASLP Module 94References 965 Freeform Optics for LED Indoor Lighting 995.1 Introduction 995.2 A Large-Emitting-Angle Freeform Lens with a Small LED Source 995.2.1 A Freeform Lens for a Philip Lumileds K2 LED 1005.2.2 Freeform Lens for a CREE XLamp XR-E LED 1035.3 A Large-Emitting-Angle Freeform Lens with an Extended Source 1085.3.1 Target Plane Grids Optimization 1085.3.2 Light Source Grids Optimization 1085.3.3 Target Plane and Light Source Grids Coupling Optimization 1095.4 A Small-Emitting-Angle Freeform Lens with a Small LED Source 1105.5 A Double-Surface Freeform Lens for Uniform Illumination 1135.5.1 Design Example 1 1145.5.2 Design Example 2 1155.5.3 Design Example 3 1165.6 A Freeform Lens for Uniform Illumination of an LED High Bay Lamp Array 1175.6.1 Design Concept 1175.6.2 Design Case 1185.6.2.1 Algorithms and Design Procedure 1185.6.2.2 Optical Structures 1195.6.2.3 Monte Carlo Optical Simulation 121References 1246 Freeform Optics for LED Road Lighting 1256.1 Introduction 1256.2 The Optical Design Concept of LED Road Lighting 1266.2.1 Illuminance 1276.2.2 Luminance 1286.2.3 Glare RestrictionThreshold Increment 1296.2.4 Surrounding Ratio 1306.3 Discontinuous Freeform Lenses (DFLs) for LED Road Lighting 1316.3.1 Design of DFLs for Rectangular Radiation Patterns 1316.3.1.1 Step 1. Optical Modeling for an LED 1316.3.1.2 Step 2. Freeform Lens Design 1336.3.2 Simulation Illumination Performance and Tolerance Analyses 1346.3.3 Experimental Analyses 1396.3.4 Effects of Manufacturing Defects on the Lighting Performance 1396.3.4.1 Surface Morphology 1446.3.4.2 Optical Performance Testing 1466.3.4.3 Analysis and Discussion 1506.3.5 Case Study – LED Road Lamps Based on DFLs 1526.4 Continuous Freeform Lens (CFL) for LED Road Lighting 1546.4.1 CFL Based on the Radiate Grid MappingMethod 1546.4.2 CFL Based on the Rectangular Grid MappingMethod 1546.4.3 Spatial Color Uniformity Analyses of a Continuous Freeform Lens 1586.5 Freeform Lens for an LED Road Lamp with Uniform Luminance 1646.5.1 Problem Statement 1646.5.2 Combined Design Method for Uniform Luminance in Road Lighting 1666.5.3 Freeform Lens Design Method for Uniform-Luminance Road Lighting 1716.6 Asymmetrical CFLs with a High Light Energy Utilization Ratio 1746.7 Modularized LED Road Lamp Based on Freeform Optics 178References 1787 Freeform Optics for a Direct-Lit LED Backlighting Unit 1817.1 Introduction 1817.2 Optical Design Concept of a Direct-Lit LED BLU 1837.3 Freeform Optics for Uniform Illumination with a Large DHR 1867.4 Freeform Optics for Uniform Illumination with an Extended Source 1917.4.1 Algorithm of a Freeform Lens for Uniform Illumination with an Extended Source 1947.4.2 Design Method of a Freeform Lens for Extended Source Uniform Illumination 1957.4.2.1 Step 1. Calculation of FORs 1967.4.2.2 Step 2. Energy Grids Division for an Extended Source 1977.4.2.3 Step 3. Construction of a Freeform Lens for an Extended Source 1987.4.2.4 Step 4. Ray-Tracing Simulation and Circulation Feedback Optimization 1987.4.3 Freeform Lenses for Direct-Lit BLUs with an Extended Source 1987.5 Petal-Shaped Freeform Optics for High-System-Efficiency LED BLUs 2037.5.1 Optical Co-design from the System Level of BLUs 2037.5.2 Optimization of a High-Efficiency LIDC for BEFs 2037.5.3 Petal-Shaped Freeform Lenses, and ASLPs for High-Efficiency BLUs 2067.6 BEF-Adaptive Freeform Optics for High-System-Efficiency LED BLUs 2107.6.1 Design Concept and Method 2107.6.1.1 Step 1. Finding Out the Best Incident Angle Range 2117.6.1.2 Step 2. Redistribution of Original Output LIDC 2127.6.1.3 Step 3. Construction of a BEF-Adaptive Lens 2137.6.2 BEF-Adaptive Lens Design Case 2137.6.2.1 Basic Setup of a BLU 2137.6.2.2 Design Results and Optical Validation 2147.7 Freeform Optics for Uniform Illumination with Large DHR, Extended Source and Near Field 2197.7.1 Design Method 2207.7.1.1 IDF of Single Extended Source 2207.7.1.2 IDF of Freeform Lens 2217.7.1.3 Construction of Freeform Lens 2227.7.1.4 Ray Tracing Simulation and Verification 2237.7.2 Design Example 223References 2288 Freeform Optics for LED Automotive Headlamps 2318.1 Introduction 2318.2 Optical Regulations of Low-Beam and High-Beam Light 2318.2.1 Low-Beam 2318.2.2 High-Beam 2328.2.3 Color Range 2328.3 Application-Specific LED Packaging for Headlamps 2348.3.1 Small Étendue 2348.3.2 High Luminance 2358.3.3 Strip Shape Emitter with a Sharp Cutoff 2368.3.4 Small Thermal Resistance of Packaging 2368.3.5 ASLP Design Case 2368.3.6 Types of LED Packaging Modules for Headlamps 2388.4 Freeform Lens for High-Efficiency LED Headlamps 2398.4.1 Introduction 2398.4.2 Freeform Lens Design Methods 2398.4.2.1 Design of Collection Optics 2408.4.2.2 Design of Refraction Optics 2418.4.3 Design Case of a Freeform Lens for Low-Beam and High-Beam 2438.4.3.1 Design of a Low-Beam Lens 2448.4.3.2 Design of a High-Beam Lens 2468.4.4 Design Case of a Freeform Lens for a Low-Beam Headlamp Module 2498.5 Freeform Optics Integrated PES for an LED Headlamp 2508.6 Freeform Optics Integrated MR for an LED Headlamp 2558.7 LED Headlamps Based on Both PES and MR Reflectors 2588.8 LED Module Integrated with Low-Beam and High-Beam 262References 2669 Freeform Optics for Emerging LED Applications 2699.1 Introduction 2699.2 Total Internal Reflection (TIR)-Freeform Lens for an LED Pico-Projector 2699.2.1 Introduction 2699.2.2 Problem Statement 2719.2.2.1 Defect of a Refracting Freeform Surface for Illumination with a Small Output Angle 2719.2.2.2 Problem of an Extended Light Source 2729.2.3 Integral Freeform Illumination Lens Design Based on an LED’s Light Source 2739.2.3.1 Freeform TIR Lens Design 2739.2.3.2 Top Surface Design of the TIR Lens 2739.2.4 Optimization of the Integral Freeform Illumination Lens 2799.2.5 Tolerance analysis 2809.2.6 LED Pico-Projector Based on the Designed Freeform Lens 2819.3 Freeform Lens Array Optical System for an LED Stage Light 2839.3.1 Design of a One-Dimensional Beam Expander Based on a Freeform Lens Array 2859.3.1.1 Part 1. Gridding of the One-Dimensional Target Plane 2859.3.1.2 Part 2. Algorithm of a One-Dimensional Freeform Microstructure 2859.3.1.3 Part 3. Optical Simulation Results of the Optical System 2879.3.2 Design of a Rectangular Beam Expander Based on a Freeform Lens Array 2879.3.2.1 Part 1. Algorithm of the Rectangular Freeform Structure 2889.3.2.2 Part 2. Optical Simulation Results of the Optical System 2909.4 Freeform Optics for a LED Airport Taxiway Light 2909.4.1 Introduction 2909.4.2 Requirement Statement 2919.4.3 Design Method of an Optical System 2919.4.4 Simulation and Optimization 2939.4.5 Tolerance Analysis 2949.4.6 Design of an LED Taxiway Centerline Lamp 2959.5 Freeform Optics for LED Searchlights 2979.5.1 Introduction 2979.5.2 Freeform Lens Design of a Small Divergence Angle 2989.5.3 Improving Methods and Tolerance Analysis 3019.5.3.1 The Design of a Freeform Lens and Parabolic Reflector 3019.5.3.2 Tolerance Analysis 304References 30510 Freeform Optics for LED Lighting with High Spatial Color Uniformity 30710.1 Introduction 30710.2 Optical Design Concept 30810.3 Freeform Lens Integrated LED Module with a High SCU 30910.3.1 Optical Design, Molding, and Simulation 30910.3.2 Tolerance Analyses 31210.3.3 Secondary Freeform Lens for a High SCU 31310.3.4 Experimental Analyses 31410.4 TIR-Freeform Lens Integrated LED Module with a High SCU 32310.4.1 Introduction 32310.4.2 Design Principle for a High SCU 32510.4.3 Design Method of the Modified TIR-Freeform Lens 32510.4.4 Optimization Results and Discussions 328References 332Appendix: Codes of Basic Algorithms of Freeform Optics for LED Lighting 335Index 351

Kai Wang, Ph.D., Southern University of Science and Technology, Guangdong, China Sheng Liu, Ph.D., Wuhan University, Hubei, China Xiaobing Luo, Huazhong University of Science and Technology, Hubei, China Dan Wu, Ph.D., Nanyang Technological University, Singapore

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• Preface xi1 Introduction 11.1 Overview of LED Lighting 11.2 Development Trends of LED Packaging and Applications 51.3 Three Key Issues of Optical Design of LED Lighting 71.3.1 System Luminous Efficiency 71.3.2 Controllable Light Pattern 71.3.3 Spatial Color Uniformity 81.4 Introduction of Freeform Optics 10References 122 Review of Main Algorithms of Freeform Optics for LED Lighting 152.1 Introduction 152.2 Tailored Design Method 162.3 SMS Design Method 172.4 Light Energy Mapping Design Method 182.5 Generalized Functional Design Method 192.6 Design Method for Uniform Illumination with Multiple Sources 22References 223 Basic Algorithms of Freeform Optics for LED Lighting 253.1 Introduction 253.2 Circularly Symmetrical Freeform Lens – Point Source 253.2.1 Freeform Lens for Large Emitting Angles 263.2.1.1 Step 1. Establish a Light Energy Mapping Relationship between the Light Source and Target 273.2.1.2 Step 2. Construct a Freeform Lens 313.2.1.3 Step 3. Validation and Optimization 333.2.2 TIR-Freeform Lens for Small Emitting Angle 333.2.3 Circularly Symmetrical Double Surfaces Freeform Lens 393.3 Circularly Symmetrical Freeform Lens – Extended Source 423.3.1.1 Step 1. Construction of a Point Source Freeform Lens 453.3.1.2 Step 2. Calculation of Feedback Optimization Ratios 453.3.1.3 Step 3. Grids Redivision of the Target Plane and Light Source 463.3.1.4 Step 4. Rebuild the Energy Relationship between the Light Source and Target Plane 463.3.1.5 Step 5. Construction of a Freeform Lens for an Extended Source 473.3.1.6 Step 6. Ray-Tracing Simulation and Feedback Reversing Optimization 473.4 Noncircularly Symmetrical Freeform Lens – Point Source 483.4.1 Discontinuous Freeform Lens Algorithm 493.4.1.1 Step 1. Establishment of a Light Energy Mapping Relationship 493.4.1.2 Step 2. Construction of the Lens 523.4.1.3 Step 3. Validation of Lens Design 553.4.2 Continuous Freeform Lens Algorithm 553.4.2.1 Radiate Grid Light Energy Mapping 573.4.2.2 Rectangular Grid Light Energy Mapping 583.5 Noncircularly Symmetrical Freeform Lens – Extended Source 603.5.1.1 Step 1. Establishment of the Light Energy Mapping Relationship 613.5.1.2 Step 2. Construction of a Freeform Lens 613.5.1.3 Step 3. Validation of Lens Design 623.6 Reversing the Design Method for Uniform Illumination of LED Arrays 633.6.1 Reversing the Design Method of LIDC for Uniform Illumination 643.6.2 Algorithm of a Freeform Lens for the Required LIDC 66References 684 Application-Specific LED Package Integrated with a Freeform Lens 714.1 Application-Specific LED Package (ASLP) Design Concept 714.2 ASLP Single Module 724.2.1 Design Method of a Compact Freeform Lens 724.2.2 Design of the ASLP Module 734.2.2.1 Optical Modeling 734.2.2.2 Design of a Compact Freeform Lens 734.2.2.3 ASLP Module 744.2.3 Numerical Analyses and Tolerance Analyses 764.2.3.1 Numerical Simulation and Analyses 764.2.3.2 Tolerance Analyses 774.2.3.3 Experiments 814.3 ASLP Array Module 854.4 ASLP System Integrated with Multiple Functions 874.4.1 Optical Design 894.4.1.1 Problem Statement 894.4.1.2 Optical Modeling 894.4.1.3 Design of a Freeform Lens 904.4.1.4 Simulation of Lighting Performance 914.4.2 Thermal Management 914.4.3 ASLP Module 94References 965 Freeform Optics for LED Indoor Lighting 995.1 Introduction 995.2 A Large-Emitting-Angle Freeform Lens with a Small LED Source 995.2.1 A Freeform Lens for a Philip Lumileds K2 LED 1005.2.2 Freeform Lens for a CREE XLamp XR-E LED 1035.3 A Large-Emitting-Angle Freeform Lens with an Extended Source 1085.3.1 Target Plane Grids Optimization 1085.3.2 Light Source Grids Optimization 1085.3.3 Target Plane and Light Source Grids Coupling Optimization 1095.4 A Small-Emitting-Angle Freeform Lens with a Small LED Source 1105.5 A Double-Surface Freeform Lens for Uniform Illumination 1135.5.1 Design Example 1 1145.5.2 Design Example 2 1155.5.3 Design Example 3 1165.6 A Freeform Lens for Uniform Illumination of an LED High Bay Lamp Array 1175.6.1 Design Concept 1175.6.2 Design Case 1185.6.2.1 Algorithms and Design Procedure 1185.6.2.2 Optical Structures 1195.6.2.3 Monte Carlo Optical Simulation 121References 1246 Freeform Optics for LED Road Lighting 1256.1 Introduction 1256.2 The Optical Design Concept of LED Road Lighting 1266.2.1 Illuminance 1276.2.2 Luminance 1286.2.3 Glare RestrictionThreshold Increment 1296.2.4 Surrounding Ratio 1306.3 Discontinuous Freeform Lenses (DFLs) for LED Road Lighting 1316.3.1 Design of DFLs for Rectangular Radiation Patterns 1316.3.1.1 Step 1. Optical Modeling for an LED 1316.3.1.2 Step 2. Freeform Lens Design 1336.3.2 Simulation Illumination Performance and Tolerance Analyses 1346.3.3 Experimental Analyses 1396.3.4 Effects of Manufacturing Defects on the Lighting Performance 1396.3.4.1 Surface Morphology 1446.3.4.2 Optical Performance Testing 1466.3.4.3 Analysis and Discussion 1506.3.5 Case Study – LED Road Lamps Based on DFLs 1526.4 Continuous Freeform Lens (CFL) for LED Road Lighting 1546.4.1 CFL Based on the Radiate Grid MappingMethod 1546.4.2 CFL Based on the Rectangular Grid MappingMethod 1546.4.3 Spatial Color Uniformity Analyses of a Continuous Freeform Lens 1586.5 Freeform Lens for an LED Road Lamp with Uniform Luminance 1646.5.1 Problem Statement 1646.5.2 Combined Design Method for Uniform Luminance in Road Lighting 1666.5.3 Freeform Lens Design Method for Uniform-Luminance Road Lighting 1716.6 Asymmetrical CFLs with a High Light Energy Utilization Ratio 1746.7 Modularized LED Road Lamp Based on Freeform Optics 178References 1787 Freeform Optics for a Direct-Lit LED Backlighting Unit 1817.1 Introduction 1817.2 Optical Design Concept of a Direct-Lit LED BLU 1837.3 Freeform Optics for Uniform Illumination with a Large DHR 1867.4 Freeform Optics for Uniform Illumination with an Extended Source 1917.4.1 Algorithm of a Freeform Lens for Uniform Illumination with an Extended Source 1947.4.2 Design Method of a Freeform Lens for Extended Source Uniform Illumination 1957.4.2.1 Step 1. Calculation of FORs 1967.4.2.2 Step 2. Energy Grids Division for an Extended Source 1977.4.2.3 Step 3. Construction of a Freeform Lens for an Extended Source 1987.4.2.4 Step 4. Ray-Tracing Simulation and Circulation Feedback Optimization 1987.4.3 Freeform Lenses for Direct-Lit BLUs with an Extended Source 1987.5 Petal-Shaped Freeform Optics for High-System-Efficiency LED BLUs 2037.5.1 Optical Co-design from the System Level of BLUs 2037.5.2 Optimization of a High-Efficiency LIDC for BEFs 2037.5.3 Petal-Shaped Freeform Lenses, and ASLPs for High-Efficiency BLUs 2067.6 BEF-Adaptive Freeform Optics for High-System-Efficiency LED BLUs 2107.6.1 Design Concept and Method 2107.6.1.1 Step 1. Finding Out the Best Incident Angle Range 2117.6.1.2 Step 2. Redistribution of Original Output LIDC 2127.6.1.3 Step 3. Construction of a BEF-Adaptive Lens 2137.6.2 BEF-Adaptive Lens Design Case 2137.6.2.1 Basic Setup of a BLU 2137.6.2.2 Design Results and Optical Validation 2147.7 Freeform Optics for Uniform Illumination with Large DHR, Extended Source and Near Field 2197.7.1 Design Method 2207.7.1.1 IDF of Single Extended Source 2207.7.1.2 IDF of Freeform Lens 2217.7.1.3 Construction of Freeform Lens 2227.7.1.4 Ray Tracing Simulation and Verification 2237.7.2 Design Example 223References 2288 Freeform Optics for LED Automotive Headlamps 2318.1 Introduction 2318.2 Optical Regulations of Low-Beam and High-Beam Light 2318.2.1 Low-Beam 2318.2.2 High-Beam 2328.2.3 Color Range 2328.3 Application-Specific LED Packaging for Headlamps 2348.3.1 Small Étendue 2348.3.2 High Luminance 2358.3.3 Strip Shape Emitter with a Sharp Cutoff 2368.3.4 Small Thermal Resistance of Packaging 2368.3.5 ASLP Design Case 2368.3.6 Types of LED Packaging Modules for Headlamps 2388.4 Freeform Lens for High-Efficiency LED Headlamps 2398.4.1 Introduction 2398.4.2 Freeform Lens Design Methods 2398.4.2.1 Design of Collection Optics 2408.4.2.2 Design of Refraction Optics 2418.4.3 Design Case of a Freeform Lens for Low-Beam and High-Beam 2438.4.3.1 Design of a Low-Beam Lens 2448.4.3.2 Design of a High-Beam Lens 2468.4.4 Design Case of a Freeform Lens for a Low-Beam Headlamp Module 2498.5 Freeform Optics Integrated PES for an LED Headlamp 2508.6 Freeform Optics Integrated MR for an LED Headlamp 2558.7 LED Headlamps Based on Both PES and MR Reflectors 2588.8 LED Module Integrated with Low-Beam and High-Beam 262References 2669 Freeform Optics for Emerging LED Applications 2699.1 Introduction 2699.2 Total Internal Reflection (TIR)-Freeform Lens for an LED Pico-Projector 2699.2.1 Introduction 2699.2.2 Problem Statement 2719.2.2.1 Defect of a Refracting Freeform Surface for Illumination with a Small Output Angle 2719.2.2.2 Problem of an Extended Light Source 2729.2.3 Integral Freeform Illumination Lens Design Based on an LED’s Light Source 2739.2.3.1 Freeform TIR Lens Design 2739.2.3.2 Top Surface Design of the TIR Lens 2739.2.4 Optimization of the Integral Freeform Illumination Lens 2799.2.5 Tolerance analysis 2809.2.6 LED Pico-Projector Based on the Designed Freeform Lens 2819.3 Freeform Lens Array Optical System for an LED Stage Light 2839.3.1 Design of a One-Dimensional Beam Expander Based on a Freeform Lens Array 2859.3.1.1 Part 1. Gridding of the One-Dimensional Target Plane 2859.3.1.2 Part 2. Algorithm of a One-Dimensional Freeform Microstructure 2859.3.1.3 Part 3. Optical Simulation Results of the Optical System 2879.3.2 Design of a Rectangular Beam Expander Based on a Freeform Lens Array 2879.3.2.1 Part 1. Algorithm of the Rectangular Freeform Structure 2889.3.2.2 Part 2. Optical Simulation Results of the Optical System 2909.4 Freeform Optics for a LED Airport Taxiway Light 2909.4.1 Introduction 2909.4.2 Requirement Statement 2919.4.3 Design Method of an Optical System 2919.4.4 Simulation and Optimization 2939.4.5 Tolerance Analysis 2949.4.6 Design of an LED Taxiway Centerline Lamp 2959.5 Freeform Optics for LED Searchlights 2979.5.1 Introduction 2979.5.2 Freeform Lens Design of a Small Divergence Angle 2989.5.3 Improving Methods and Tolerance Analysis 3019.5.3.1 The Design of a Freeform Lens and Parabolic Reflector 3019.5.3.2 Tolerance Analysis 304References 30510 Freeform Optics for LED Lighting with High Spatial Color Uniformity 30710.1 Introduction 30710.2 Optical Design Concept 30810.3 Freeform Lens Integrated LED Module with a High SCU 30910.3.1 Optical Design, Molding, and Simulation 30910.3.2 Tolerance Analyses 31210.3.3 Secondary Freeform Lens for a High SCU 31310.3.4 Experimental Analyses 31410.4 TIR-Freeform Lens Integrated LED Module with a High SCU 32310.4.1 Introduction 32310.4.2 Design Principle for a High SCU 32510.4.3 Design Method of the Modified TIR-Freeform Lens 32510.4.4 Optimization Results and Discussions 328References 332Appendix: Codes of Basic Algorithms of Freeform Optics for LED Lighting 335Index 351

Kai Wang, Ph.D., Southern University of Science and Technology, Guangdong, China Sheng Liu, Ph.D., Wuhan University, Hubei, China Xiaobing Luo, Huazhong University of Science and Technology, Hubei, China Dan Wu, Ph.D., Nanyang Technological University, Singapore

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• Preface xi1 Introduction 11.1 Overview of LED Lighting 11.2 Development Trends of LED Packaging and Applications 51.3 Three Key Issues of Optical Design of LED Lighting 71.3.1 System Luminous Efficiency 71.3.2 Controllable Light Pattern 71.3.3 Spatial Color Uniformity 81.4 Introduction of Freeform Optics 10References 122 Review of Main Algorithms of Freeform Optics for LED Lighting 152.1 Introduction 152.2 Tailored Design Method 162.3 SMS Design Method 172.4 Light Energy Mapping Design Method 182.5 Generalized Functional Design Method 192.6 Design Method for Uniform Illumination with Multiple Sources 22References 223 Basic Algorithms of Freeform Optics for LED Lighting 253.1 Introduction 253.2 Circularly Symmetrical Freeform Lens – Point Source 253.2.1 Freeform Lens for Large Emitting Angles 263.2.1.1 Step 1. Establish a Light Energy Mapping Relationship between the Light Source and Target 273.2.1.2 Step 2. Construct a Freeform Lens 313.2.1.3 Step 3. Validation and Optimization 333.2.2 TIR-Freeform Lens for Small Emitting Angle 333.2.3 Circularly Symmetrical Double Surfaces Freeform Lens 393.3 Circularly Symmetrical Freeform Lens – Extended Source 423.3.1.1 Step 1. Construction of a Point Source Freeform Lens 453.3.1.2 Step 2. Calculation of Feedback Optimization Ratios 453.3.1.3 Step 3. Grids Redivision of the Target Plane and Light Source 463.3.1.4 Step 4. Rebuild the Energy Relationship between the Light Source and Target Plane 463.3.1.5 Step 5. Construction of a Freeform Lens for an Extended Source 473.3.1.6 Step 6. Ray-Tracing Simulation and Feedback Reversing Optimization 473.4 Noncircularly Symmetrical Freeform Lens – Point Source 483.4.1 Discontinuous Freeform Lens Algorithm 493.4.1.1 Step 1. Establishment of a Light Energy Mapping Relationship 493.4.1.2 Step 2. Construction of the Lens 523.4.1.3 Step 3. Validation of Lens Design 553.4.2 Continuous Freeform Lens Algorithm 553.4.2.1 Radiate Grid Light Energy Mapping 573.4.2.2 Rectangular Grid Light Energy Mapping 583.5 Noncircularly Symmetrical Freeform Lens – Extended Source 603.5.1.1 Step 1. Establishment of the Light Energy Mapping Relationship 613.5.1.2 Step 2. Construction of a Freeform Lens 613.5.1.3 Step 3. Validation of Lens Design 623.6 Reversing the Design Method for Uniform Illumination of LED Arrays 633.6.1 Reversing the Design Method of LIDC for Uniform Illumination 643.6.2 Algorithm of a Freeform Lens for the Required LIDC 66References 684 Application-Specific LED Package Integrated with a Freeform Lens 714.1 Application-Specific LED Package (ASLP) Design Concept 714.2 ASLP Single Module 724.2.1 Design Method of a Compact Freeform Lens 724.2.2 Design of the ASLP Module 734.2.2.1 Optical Modeling 734.2.2.2 Design of a Compact Freeform Lens 734.2.2.3 ASLP Module 744.2.3 Numerical Analyses and Tolerance Analyses 764.2.3.1 Numerical Simulation and Analyses 764.2.3.2 Tolerance Analyses 774.2.3.3 Experiments 814.3 ASLP Array Module 854.4 ASLP System Integrated with Multiple Functions 874.4.1 Optical Design 894.4.1.1 Problem Statement 894.4.1.2 Optical Modeling 894.4.1.3 Design of a Freeform Lens 904.4.1.4 Simulation of Lighting Performance 914.4.2 Thermal Management 914.4.3 ASLP Module 94References 965 Freeform Optics for LED Indoor Lighting 995.1 Introduction 995.2 A Large-Emitting-Angle Freeform Lens with a Small LED Source 995.2.1 A Freeform Lens for a Philip Lumileds K2 LED 1005.2.2 Freeform Lens for a CREE XLamp XR-E LED 1035.3 A Large-Emitting-Angle Freeform Lens with an Extended Source 1085.3.1 Target Plane Grids Optimization 1085.3.2 Light Source Grids Optimization 1085.3.3 Target Plane and Light Source Grids Coupling Optimization 1095.4 A Small-Emitting-Angle Freeform Lens with a Small LED Source 1105.5 A Double-Surface Freeform Lens for Uniform Illumination 1135.5.1 Design Example 1 1145.5.2 Design Example 2 1155.5.3 Design Example 3 1165.6 A Freeform Lens for Uniform Illumination of an LED High Bay Lamp Array 1175.6.1 Design Concept 1175.6.2 Design Case 1185.6.2.1 Algorithms and Design Procedure 1185.6.2.2 Optical Structures 1195.6.2.3 Monte Carlo Optical Simulation 121References 1246 Freeform Optics for LED Road Lighting 1256.1 Introduction 1256.2 The Optical Design Concept of LED Road Lighting 1266.2.1 Illuminance 1276.2.2 Luminance 1286.2.3 Glare RestrictionThreshold Increment 1296.2.4 Surrounding Ratio 1306.3 Discontinuous Freeform Lenses (DFLs) for LED Road Lighting 1316.3.1 Design of DFLs for Rectangular Radiation Patterns 1316.3.1.1 Step 1. Optical Modeling for an LED 1316.3.1.2 Step 2. Freeform Lens Design 1336.3.2 Simulation Illumination Performance and Tolerance Analyses 1346.3.3 Experimental Analyses 1396.3.4 Effects of Manufacturing Defects on the Lighting Performance 1396.3.4.1 Surface Morphology 1446.3.4.2 Optical Performance Testing 1466.3.4.3 Analysis and Discussion 1506.3.5 Case Study – LED Road Lamps Based on DFLs 1526.4 Continuous Freeform Lens (CFL) for LED Road Lighting 1546.4.1 CFL Based on the Radiate Grid MappingMethod 1546.4.2 CFL Based on the Rectangular Grid MappingMethod 1546.4.3 Spatial Color Uniformity Analyses of a Continuous Freeform Lens 1586.5 Freeform Lens for an LED Road Lamp with Uniform Luminance 1646.5.1 Problem Statement 1646.5.2 Combined Design Method for Uniform Luminance in Road Lighting 1666.5.3 Freeform Lens Design Method for Uniform-Luminance Road Lighting 1716.6 Asymmetrical CFLs with a High Light Energy Utilization Ratio 1746.7 Modularized LED Road Lamp Based on Freeform Optics 178References 1787 Freeform Optics for a Direct-Lit LED Backlighting Unit 1817.1 Introduction 1817.2 Optical Design Concept of a Direct-Lit LED BLU 1837.3 Freeform Optics for Uniform Illumination with a Large DHR 1867.4 Freeform Optics for Uniform Illumination with an Extended Source 1917.4.1 Algorithm of a Freeform Lens for Uniform Illumination with an Extended Source 1947.4.2 Design Method of a Freeform Lens for Extended Source Uniform Illumination 1957.4.2.1 Step 1. Calculation of FORs 1967.4.2.2 Step 2. Energy Grids Division for an Extended Source 1977.4.2.3 Step 3. Construction of a Freeform Lens for an Extended Source 1987.4.2.4 Step 4. Ray-Tracing Simulation and Circulation Feedback Optimization 1987.4.3 Freeform Lenses for Direct-Lit BLUs with an Extended Source 1987.5 Petal-Shaped Freeform Optics for High-System-Efficiency LED BLUs 2037.5.1 Optical Co-design from the System Level of BLUs 2037.5.2 Optimization of a High-Efficiency LIDC for BEFs 2037.5.3 Petal-Shaped Freeform Lenses, and ASLPs for High-Efficiency BLUs 2067.6 BEF-Adaptive Freeform Optics for High-System-Efficiency LED BLUs 2107.6.1 Design Concept and Method 2107.6.1.1 Step 1. Finding Out the Best Incident Angle Range 2117.6.1.2 Step 2. Redistribution of Original Output LIDC 2127.6.1.3 Step 3. Construction of a BEF-Adaptive Lens 2137.6.2 BEF-Adaptive Lens Design Case 2137.6.2.1 Basic Setup of a BLU 2137.6.2.2 Design Results and Optical Validation 2147.7 Freeform Optics for Uniform Illumination with Large DHR, Extended Source and Near Field 2197.7.1 Design Method 2207.7.1.1 IDF of Single Extended Source 2207.7.1.2 IDF of Freeform Lens 2217.7.1.3 Construction of Freeform Lens 2227.7.1.4 Ray Tracing Simulation and Verification 2237.7.2 Design Example 223References 2288 Freeform Optics for LED Automotive Headlamps 2318.1 Introduction 2318.2 Optical Regulations of Low-Beam and High-Beam Light 2318.2.1 Low-Beam 2318.2.2 High-Beam 2328.2.3 Color Range 2328.3 Application-Specific LED Packaging for Headlamps 2348.3.1 Small Étendue 2348.3.2 High Luminance 2358.3.3 Strip Shape Emitter with a Sharp Cutoff 2368.3.4 Small Thermal Resistance of Packaging 2368.3.5 ASLP Design Case 2368.3.6 Types of LED Packaging Modules for Headlamps 2388.4 Freeform Lens for High-Efficiency LED Headlamps 2398.4.1 Introduction 2398.4.2 Freeform Lens Design Methods 2398.4.2.1 Design of Collection Optics 2408.4.2.2 Design of Refraction Optics 2418.4.3 Design Case of a Freeform Lens for Low-Beam and High-Beam 2438.4.3.1 Design of a Low-Beam Lens 2448.4.3.2 Design of a High-Beam Lens 2468.4.4 Design Case of a Freeform Lens for a Low-Beam Headlamp Module 2498.5 Freeform Optics Integrated PES for an LED Headlamp 2508.6 Freeform Optics Integrated MR for an LED Headlamp 2558.7 LED Headlamps Based on Both PES and MR Reflectors 2588.8 LED Module Integrated with Low-Beam and High-Beam 262References 2669 Freeform Optics for Emerging LED Applications 2699.1 Introduction 2699.2 Total Internal Reflection (TIR)-Freeform Lens for an LED Pico-Projector 2699.2.1 Introduction 2699.2.2 Problem Statement 2719.2.2.1 Defect of a Refracting Freeform Surface for Illumination with a Small Output Angle 2719.2.2.2 Problem of an Extended Light Source 2729.2.3 Integral Freeform Illumination Lens Design Based on an LED’s Light Source 2739.2.3.1 Freeform TIR Lens Design 2739.2.3.2 Top Surface Design of the TIR Lens 2739.2.4 Optimization of the Integral Freeform Illumination Lens 2799.2.5 Tolerance analysis 2809.2.6 LED Pico-Projector Based on the Designed Freeform Lens 2819.3 Freeform Lens Array Optical System for an LED Stage Light 2839.3.1 Design of a One-Dimensional Beam Expander Based on a Freeform Lens Array 2859.3.1.1 Part 1. Gridding of the One-Dimensional Target Plane 2859.3.1.2 Part 2. Algorithm of a One-Dimensional Freeform Microstructure 2859.3.1.3 Part 3. Optical Simulation Results of the Optical System 2879.3.2 Design of a Rectangular Beam Expander Based on a Freeform Lens Array 2879.3.2.1 Part 1. Algorithm of the Rectangular Freeform Structure 2889.3.2.2 Part 2. Optical Simulation Results of the Optical System 2909.4 Freeform Optics for a LED Airport Taxiway Light 2909.4.1 Introduction 2909.4.2 Requirement Statement 2919.4.3 Design Method of an Optical System 2919.4.4 Simulation and Optimization 2939.4.5 Tolerance Analysis 2949.4.6 Design of an LED Taxiway Centerline Lamp 2959.5 Freeform Optics for LED Searchlights 2979.5.1 Introduction 2979.5.2 Freeform Lens Design of a Small Divergence Angle 2989.5.3 Improving Methods and Tolerance Analysis 3019.5.3.1 The Design of a Freeform Lens and Parabolic Reflector 3019.5.3.2 Tolerance Analysis 304References 30510 Freeform Optics for LED Lighting with High Spatial Color Uniformity 30710.1 Introduction 30710.2 Optical Design Concept 30810.3 Freeform Lens Integrated LED Module with a High SCU 30910.3.1 Optical Design, Molding, and Simulation 30910.3.2 Tolerance Analyses 31210.3.3 Secondary Freeform Lens for a High SCU 31310.3.4 Experimental Analyses 31410.4 TIR-Freeform Lens Integrated LED Module with a High SCU 32310.4.1 Introduction 32310.4.2 Design Principle for a High SCU 32510.4.3 Design Method of the Modified TIR-Freeform Lens 32510.4.4 Optimization Results and Discussions 328References 332Appendix: Codes of Basic Algorithms of Freeform Optics for LED Lighting 335Index 351