Freeform Optics for LED Package

Preface xi

1 Introduction 1
1.1 Overview of LED Lighting 1
1.2 Development Trends of LED Packaging and Applications 5
1.3 Three Key Issues of Optical Design of LED Lighting 7
1.3.1 System Luminous Efficiency 7
1.3.2 Controllable Light Pattern 7
1.3.3 Spatial Color Uniformity 8
1.4 Introduction of Freeform Optics 10
References 12

2 Review of Main Algorithms of Freeform Optics for LED Lighting 15
2.1 Introduction 15
2.2 Tailored Design Method 16
2.3 SMS Design Method 17
2.4 Light Energy Mapping Design Method 18
2.5 Generalized Functional Design Method 19
2.6 Design Method for Uniform Illumination with Multiple Sources 22
References 22

3 Basic Algorithms of Freeform Optics for LED Lighting 25
3.1 Introduction 25
3.2 Circularly Symmetrical Freeform Lens–Point Source 25
3.2.1 Freeform Lens for Large Emitting Angles 26
3.2.1.1 Step 1. Establish a Light Energy Mapping Relationship between the Light Source and Target 27
3.2.1.2 Step 2. Construct a Freeform Lens 31
3.2.1.3 Step 3. Validation and Optimization 33
3.2.2 TIR-Freeform Lens for Small Emitting Angle 33
3.2.3 Circularly Symmetrical Double Surfaces Freeform Lens 39
3.3 Circularly Symmetrical Freeform Lens – Extended Source 42
3.3.1 Step 1. Construction of a Point Source Freeform Lens 45
3.3.2 Step 2. Calculation of Feedback Optimization Ratios 45
3.3.3 Step 3. Grids Redivision of the Target Plane and Light Source 46
3.3.4 Step 4. Rebuild the Energy Relationship between the Light Source and Target Plane 46
3.3.5 Step 5. Construction of a Freeform Lens for an Extended Source 47
3.3.6 Step 6. Ray-Tracing Simulation and Feedback Reversing Optimization 47
3.4 Noncircularly Symmetrical Freeform Lens–Point Source 48
3.4.1 Discontinuous Freeform Lens Algorithm 49
3.4.1.1 Step 1. Establishment of a Light Energy Mapping Relationship 49
3.4.1.2 Step 2. Construction of the Lens 52
3.4.1.3 Step 3. Validation of Lens Design 55
3.4.2 Continuous Freeform Lens Algorithm 55
3.4.2.1 Radiate Grid Light Energy Mapping 57
3.4.2.2 Rectangular Grid Light Energy Mapping 58
3.5 Noncircularly Symmetrical Freeform Lens–Extended Source 60
3.5.1 Step 1. Establishment of the Light Energy Mapping Relationship 61
3.5.2 Step 2. Construction of a Freeform Lens 61
3.5.3 Step 3. Validation of Lens Design 62
3.6 Reversing the Design Method for Uniform Illumination of LED Arrays 63
3.6.1 Reversing the Design Method of LIDC for Uniform Illumination 64
3.6.2 Algorithm of a Freeform Lens for the Required LIDC 66
References 68

4 Application-Specific LED Package Integrated with a Freeform Lens 71
4.1 Application-Specific LED Package (ASLP) Design Concept 71
4.2 ASLP Single Module 72
4.2.1 Design Method of a Compact Freeform Lens 72
4.2.2 Design of the ASLP Module 73
4.2.2.1 Optical Modeling 73
4.2.2.2 Design of a Compact Freeform Lens 73
4.2.2.3 ASLP Module 74
4.2.3 Numerical Analyses and Tolerance Analyses 76
4.2.3.1 Numerical Simulation and Analyses 76
4.2.3.2 Tolerance Analyses 77
4.2.3.3 Experiments 81
4.3 ASLP Array Module 85
4.4 ASLP System Integrated with Multiple Functions 87
4.4.1 Optical Design 89
4.4.1.1 Problem Statement 89
4.4.1.2 Optical Modeling 89
4.4.1.3 Design of a Freeform Lens 90
4.4.1.4 Simulation of Lighting Performance 91
4.4.2 Thermal Management 91
4.4.3 ASLP Module 94
References 96

5 Freeform Optics for LED Indoor Lighting 99
5.1 Introduction 99
5.2 A Large-Emitting-Angle Freeform Lens with a Small LED Source 99
5.2.1 A Freeform Lens for a Philip Lumileds K2 LED 100
5.2.2 Freeform Lens for a CREE XLamp XR-E LED 103
5.3 A Large-Emitting-Angle Freeform Lens with an Extended Source 108
5.3.1 Target Plane Grids Optimization 108
5.3.2 Light Source Grids Optimization 108
5.3.3 Target Plane and Light Source Grids Coupling Optimization 109
5.4 A Small-Emitting-Angle Freeform Lens with a Small LED Source 110
5.5 A Double-Surface Freeform Lens for Uniform Illumination 113
5.5.1 Design Example 1 114
5.5.2 Design Example 2 115
5.5.3 Design Example 3 116
5.6 A Freeform Lens for Uniform Illumination of an LED High Bay Lamp Array 117
5.6.1 Design Concept 117
5.6.2 Design Case 118
5.6.2.1 Algorithms and Design Procedure 118
5.6.2.2 Optical Structures 119
5.6.2.3 Monte Carlo Optical Simulation 121
References 124

6 Freeform Optics for LED Road Lighting 125
6.1 Introduction 125
6.2 The Optical Design Concept of LED Road Lighting 126
6.2.1 Illuminance 127
6.2.2 Luminance 128
6.2.3 Glare RestrictionThreshold Increment 129
6.2.4 Surrounding Ratio 130
6.3 Discontinuous Freeform Lenses (DFLs) for LED Road Lighting 131
6.3.1 Design of DFLs for Rectangular Radiation Patterns 131
6.3.1.1 Step 1. Optical Modeling for an LED 131
6.3.1.2 Step 2. Freeform Lens Design 133
6.3.2 Simulation Illumination Performance and Tolerance Analyses 134
6.3.3 Experimental Analyses 139
6.3.4 Effects of Manufacturing Defects on the Lighting Performance 139
6.3.4.1 Surface Morphology 144
6.3.4.2 Optical Performance Testing 146
6.3.4.3 Analysis and Discussion 150
6.3.5 Case Study–LED Road Lamps Based on DFLs 152
6.4 Continuous Freeform Lens (CFL) for LED Road Lighting 154
6.4.1 CFL Based on the Radiate Grid MappingMethod 154
6.4.2 CFL Based on the Rectangular Grid MappingMethod 154
6.4.3 Spatial Color Uniformity Analyses of a Continuous Freeform Lens 158
6.5 Freeform Lens for an LED Road Lamp with Uniform Luminance 164
6.5.1 Problem Statement 164
6.5.2 Combined Design Method for Uniform Luminance in Road Lighting 166
6.5.3 Freeform Lens Design Method for Uniform-Luminance Road Lighting 171
6.6 Asymmetrical CFLs with a High Light Energy Utilization Ratio 174
6.7 Modularized LED Road Lamp Based on Freeform Optics 178
References 178