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- Herausgeber: John Wiley & Sons
- Kategorie: Fachliteratur
- Sprache: Englisch
A practical introduction to state-of-the-art freeform optics design for LED packages and applications By affording designers the freedom to create complex, aspherical optical surfaces with minimal or no aberrations, freeform design transcends the constraints imposed by hundreds of years of optics design and fabrication. Combining unprecedented design freedom with precise light irradiation control, freeform optics design is also revolutionizing the design and manufacture of high quality LED lighting. The first and only book of its kind, Freeform Optics for LED Packages and Applications helps put readers at the forefront of the freeform optics revolution. Designed to function as both an authoritative review of the current state of the industry and a practical introduction to advanced optical design for LED lighting, this book makes learning and mastering freeform optics skills simpler and easier than ever before with: * Real-world examples and case studies systematically describing an array of algorithms and designs--from new freeform algorithms to design methods to advanced optical designs * Coding for all freeform optics algorithms covered--makes it easier and more convenient to start developing points of freeform optics and construct lenses or reflectors, right away * Case studies of a range of products, including designs for a freeform optics LED bulb, an LED spotlight, LED street lights, an LED BLU, and many more Freeform Optics for LED Packages and Applications is must-reading for optical design engineers and LED researchers, as well as advanced-level students with an interest in LED lighting. It is also an indispensable working resource design practitioners within the LED lighting industry.
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Veröffentlichungsjahr: 2017
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Table of Contents
Cover
Title Page
Copyright
Preface
Chapter 1: Introduction
1.1 Overview of LED Lighting
1.2 Development Trends of LED Packaging and Applications
1.3 Three Key Issues of Optical Design of LED Lighting
1.4 Introduction of Freeform Optics
References
Chapter 2: Review of Main Algorithms of Freeform Optics for LED Lighting
2.1 Introduction
2.2 Tailored Design Method
2.3 SMS Design Method
2.4 Light Energy Mapping Design Method
2.5 Generalized Functional Design Method
2.6 Design Method for Uniform Illumination with Multiple Sources
References
Chapter 3: Basic Algorithms of Freeform Optics for LED Lighting
3.1 Introduction
3.2 Circularly Symmetrical Freeform Lens – Point Source
3.3 Circularly Symmetrical Freeform Lens – Extended Source
3.4 Noncircularly Symmetrical Freeform Lens – Point Source
3.5 Noncircularly Symmetrical Freeform Lens – Extended Source
3.6 Reversing the Design Method for Uniform Illumination of LED Arrays
References
Chapter 4: Application-Specific LED Package Integrated with a Freeform Lens
4.1 Application-Specific LED Package (ASLP) Design Concept
4.2 ASLP Single Module
4.3 ASLP Array Module
4.4 ASLP System Integrated with Multiple Functions
References
Chapter 5: Freeform Optics for LED Indoor Lighting
5.1 Introduction
5.2 A Large-Emitting-Angle Freeform Lens with a Small LED Source
5.3 A Large-Emitting-Angle Freeform Lens with an Extended Source
5.4 A Small-Emitting-Angle Freeform Lens with a Small LED Source
5.5 A Double-Surface Freeform Lens for Uniform Illumination
5.6 A Freeform Lens for Uniform Illumination of an LED High Bay Lamp Array
References
Chapter 6: Freeform Optics for LED Road Lighting
6.1 Introduction
6.2 The Optical Design Concept of LED Road Lighting
6.3 Discontinuous Freeform Lenses (DFLs) for LED Road Lighting
6.4 Continuous Freeform Lens (CFL) for LED Road Lighting
6.5 Freeform Lens for an LED Road Lamp with Uniform Luminance
6.6 Asymmetrical CFLs with a High Light Energy Utilization Ratio
6.7 Modularized LED Road Lamp Based on Freeform Optics
References
Chapter 7: Freeform Optics for a Direct-Lit LED BLU
7.1 Introduction
7.2 Optical Design Concept of a Direct-Lit LED BLU
7.3 Freeform Optics for Uniform Illumination with a Large DHR
7.4 Freeform Optics for Uniform Illumination with an Extended Source
7.5 Petal-Shaped Freeform Optics for High-System-Efficiency LED BLUs
7.6 BEF-Adaptive Freeform Optics for High-System-Efficiency LED BLUs
7.7 Freeform Optics for Uniform Illumination with Large DHR, Extended Source and Near Field
References
Chapter 8: Freeform Optics for LED Automotive Headlamps
8.1 Introduction
8.2 Optical Regulations of Low-Beam and High-Beam Light
8.3 Application-Specific LED Packaging for Headlamps
8.4 Freeform Lens for High-Efficiency LED Headlamps
8.5 Freeform Optics Integrated PES for an LED Headlamp
8.6 Freeform Optics Integrated MR for an LED Headlamp
8.7 LED Headlamps Based on Both PES and MR Reflectors
8.8 LED Module Integrated with Low-Beam and High-Beam
References
Chapter 9: Freeform Optics for Emerging LED Applications
9.1 Introduction
9.2 Total Internal Reflection (TIR)-Freeform Lens for an LED Pico-Projector
9.3 Freeform Lens Array Optical System for an LED Stage Light
9.4 Freeform Optics for a LED Airport Taxiway Light
9.5 Freeform Optics for LED Searchlights
References
Chapter 10: Freeform Optics for LED Lighting with High SCU
10.1 Introduction
10.2 Optical Design Concept
10.3 Freeform Lens Integrated LED Module with a High SCU
10.4 TIR-Freeform Lens Integrated LED Module with a High SCU
References
Appendix A: Codes of Basic Algorithms of Freeform Optics for LED Lighting: Based on MATLAB Software
1. Circularly Symmetric Freeform Lens for Large Emitting Angles
2. Noncircularly Symmetric Discontinuous Freeform Lens
3. Reversing the Design Method for the LED Array Uniform Illumination Algorithm of a Freeform Lens for the Required Light Intensity Distribution Curve (LIDC)
Index
End User License Agreement
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Guide
Cover
Table of Contents
Preface
Begin Reading
List of Illustrations
Chapter 1: Introduction
Figure 1.1 Diverse applications for high-power LEDs.
Figure 1.2 Schematic of an industry chain for high-power LED manufacturing.
Figure 1.3 Development trends in LED packaging.
[1]
Figure 1.4 (a) Design concept; and (b) CREE LED light engine.
[1, 9]
Figure 1.5 Illumination performances for LED road lighting with a (left) circular light pattern and (right) rectangular light pattern.
Figure 1.6 Nonuniform light pattern of a high-power white LED and its correlated color temperature distribution.
Figure 1.7 Three key optical issues for LED lighting.
Figure 1.8 Schematic of freeform optics.
Figure 1.9 Freeform optics as an emerging optical design method for LED lighting.
Chapter 2: Review of Main Algorithms of Freeform Optics for LED Lighting
Figure 2.1 Schematic of wavefront reflections from an optical interface.
[6]
Figure 2.2 Freeform lens designed according to the tailored method, and its illumination performance.
[6]
Figure 2.3 Schematic of the SMS method.
[3]
Figure 2.4 Matching relationship between an extended source (
E
1
E
2
) in the SMS method and the target plane (
R
1
R
2
).
[1]
Figure 2.5 Discontinuous freeform lens and its E-shaped light pattern.
[20]
Figure 2.6 Multiple-surfaces discontinuous freeform lens and its rectangular light pattern.
[21]
Chapter 3: Basic Algorithms of Freeform Optics for LED Lighting
Figure 3.1 Schematic of a design concept of a freeform lens for circularly symmetrical uniform illumination.
Figure 3.2 Flowchart of the algorithm of a freeform lens for circularly symmetrical uniform illumination.
Figure 3.3 Schematic of a light energy mapping relationship between the LED light source and target plane for circularly symmetrical uniform illumination.
Figure 3.4 Schematic of light energy distribution of the LED light source with circularly symmetrical division.
Figure 3.5 Schematic of the construction of a freeform curve.
Figure 3.6 Schematic of the construction of a circularly symmetrical freeform lens.
Figure 3.7 A PMMA freeform lens with an emitting angle of 60° and its illuminance distribution on the receive plane 1 m away.
Figure 3.8 A PMMA freeform lens with an emitting angle of 38° and its illuminance distribution on the receive plane 1 m away.
Figure 3.9 Ray exited from the optically denser medium n
1
and refracted into the optically thinner medium n
2
.
Figure 3.10 Schematic of uncontrollable exit rays of (a) 60° and (b) 38° freeform lens.
Figure 3.11 Schematic of a TIR freeform lens.
Figure 3.12 Schematic of a design of surface 2 of a TIR freeform lens.
Figure 3.13 Schematic of a design of surface 3 of a TIR freeform lens.
Figure 3.14 Schematic of a typical light path through a double freeform surface lens. θ
i
is the edge angle of the incident ray.
Figure 3.15 Schematic of (a) point generation on the inner surface when the outer surface is given and (b) point generation on the outer surface when the inner surface is given.
Figure 3.16 Schematic of point generations on the inner and outer surfaces simultaneously.
Figure 3.17 Lighting performance of a circularly symmetrical freeform lens with a (a) single LED source and (b) 3 × 3 LED array source.
Figure 3.18 Flow chart of a feedback reversing optimization design method of a circular-symmetrical freeform lens for an extended source.
Figure 3.19 Poor lighting performance of an LED lamp with a circular-symmetrical light pattern.
Figure 3.20 Schematic of the rectangularly prescribed illumination problem.
Figure 3.21 Flowchart of an algorithm of a discontinuous freeform lens for a rectangular light pattern.
Figure 3.22 Schematic of light energy mapping between the light source and rectangular target.
Figure 3.23 Schematic of points generation on the outside surface of the lens.
Figure 3.24 Deviation between the real unit normal vector (N') and the calculated unit normal vector (N) of one point on the surface.
Figure 3.25 Freeform lens without error control and its lighting performance.
Figure 3.26 Schematic of exit lights of a (a) discontinuous freeform lens and (b) continuous freeform lens.
Figure 3.27 Flowchart of a continuous freeform lens design.
Figure 3.28 Schematic of target plane grid optimization in the radiate grid light energy mapping situation.
Figure 3.29 Schematic of an energy mapping relationship based on rectangular grids.
Figure 3.30 Effect of extended sources on lighting performance of non-circularly freeform lens.
Figure 3.31 Schematic of generation of points on the outside surface of freeform lens.
Figure 3.32 Schematic of a square LED light source array and the target plane.
Figure 3.33 Flowchart of this new reversing design method for LED uniform illumination.
Figure 3.34 Schematic of a light energy mapping relationship between the light source and the required LIDC.
Chapter 4: Application-Specific LED Package Integrated with a Freeform Lens
Figure 4.1 Schematic of the concept of application-specific LED packaging.
Figure 4.2 Schematic of a design target of an ASLP for road lighting.
Figure 4.3 Light intensity distribution curves of an LED chip and an LED chip coated by phosphor layer.
Figure 4.4 A PC compact freeform lens for ASLPs for road lighting.
Figure 4.5 Comparison of detail optical structures between (a) an ASLP and (b) traditional LED packaging.
Figure 4.6 Comparison of size between (a) a traditional LED module and (b) an ASLP for road lighting.
Figure 4.7 Simulation lighting performance of the ASLP at a height of 8 m.
Figure 4.8 Effects of installation errors on lighting performance of the ASLP: (a) horizontal deviation
d
H
; (b) vertical deviation
d
V
; and (c) rotational deviation θ
R
.
Figure 4.9 (a) Traditional SMD LED package based on a ceramic board, (b) its optical performance, and (c) its detailed optical structure.
Figure 4.10 (a) New ASLP SMD LED package based on a ceramic board, (b) its optical performance, and (c) its detailed optical structure.
Figure 4.11 (a) Front view of and (b) left view of a PC domed lens (left) and a PC compact freeform lens (right).
Figure 4.12 White-light ASLP for road lighting.
Figure 4.13 (a) Traditional LED packaging, (b) ASLP, and (c) LED module for road lighting.
Figure 4.14 Light pattern of the blue-light ASLP.
Figure 4.15 Lighting performance of (a) a traditional LED packaging and (b) the ASLP.
Figure 4.16 Illuminance distribution of a radiation pattern of the ASLP.
Figure 4.17 108 W high-power LED road lighting based on a warm white-light ASLP array.
Figure 4.18 Various types of lamps: LED road lamp, LED tunnel lamp, and conventional HPS lamp.
Figure 4.19 A novel 3 × 3 ASLP LED array module based on a ceramic board for road lighting and its optical performance.
Figure 4.20 (a) A novel 3 × 3 ASLP LED array module based on MCPCB for road lighting and (b) its detailed optical structure.
Figure 4.21 Light sources of the 16 W ASLP module.
Figure 4.22 Schematic of a design target of the ASLP module for road lighting.
Figure 4.23 A borosilicate glass freeform lens for the ASLP module.
Figure 4.24 Optical components of the 16 W ASLP module and its lighting performance where illuminance decreases gradually from the center to the side of the light pattern.
Figure 4.25 Simulation lighting performance of 144 W LED road lamps based on the 16 W ASLP modules where illuminance decreases gradually from the area under the LED road lamp to the center of the road.
Figure 4.26 Simulation model of a heat dissipation structure.
Figure 4.27 Temperature field obtained by simulation.
Figure 4.28 An ASLP module for road lighting.
Chapter 5: Freeform Optics for LED Indoor Lighting
Figure 5.1 (a) Philips Lumileds K2 LED optical model, and (b) its Lambertian light intensity distribution curve (LIDC).
Figure 5.2 Illuminance distribution of Philips Lumileds K2 LED at 1 m away from the target plane.
Figure 5.3 Circularly symmetrical PMMA freeform lens with a 120° emitting angle, based on the Philips Lumileds K2 LED.
Figure 5.4 Illuminance distribution at 1 m away from the target plane for a circularly symmetric freeform lens with a 120° emitting angle.
Figure 5.5 Circularly symmetrical PMMA freeform lens with a 90° emitting angle, based on the Philips Lumileds K2 LED.
Figure 5.6 Illuminance distribution at 1 m away from the target plane for a circularly symmetrical freeform lens with a 90° emitting angle.
Figure 5.7 (a) CREE XLamp XR-E LED real object, and (b) optical model.
Figure 5.8 CREE XLamp XR-E LED's LIDC.
Figure 5.9 Circular-symmetrical PMMA freeform lens with a 120° emitting angle based on the CREE XLamp XR-E LED.
Figure 5.10 Illuminance distribution at 1 m away from the target plane for a circularly symmetrical freeform lens with a 120° emitting angle based on the CREE XLamp XR-E LED.
Figure 5.11 Circularly symmetrical PMMA freeform lens with a 90° emitting angle based on the CREE XLamp XR-E LED.
Figure 5.12 Illuminance distribution at 1 m away from the target plane for a circularly symmetrical freeform lens with a 90° emitting angle based on the CREE XLamp XR-E LED.
Figure 5.13 Simulation results of the target plane grids optimization algorithm.
Figure 5.14 Shapes of freeform lenses with the target plane grids optimization algorithm.
Figure 5.15 Simulation results of the light source grids optimization algorithm.
Figure 5.16 Shapes of freeform lenses with the light source grids optimization algorithm.
Figure 5.17 Simulation results of the target plane and light source grids optimization algorithm.
Figure 5.18 Shapes of freeform lenses with the target plane and light source grids coupling optimization algorithm.
Figure 5.19 TIR freeform lens with a 60° emitting angle for the Philips Lumileds K2 LED.
Figure 5.20 Illuminance performance at the target plane locating 1 m for a circularly symmetrical TIR freeform lens with a 60° emitting angle.
Figure 5.21 TIR freeform lens with a 38° emitting angle for the Philips Lumileds K2 LED.
Figure 5.22 Illuminance performance at the target plane locating 1 m for a circularly symmetrical TIR freeform lens with a 38° emitting angle.
Figure 5.23 (a) Schematic of a freeform lens with a cylindrical inner surface and freeform outer surface, and (b) its illumination performance on the target plane.
Figure 5.24 (a) Schematic of a contrastive lens with a cylindrical inner surface and hemispherical outer surface, and (b) its illumination performance on the target plane.
Figure 5.25 Light propagation paths from the light source to the target plane when crossing (a) the present freeform lens, and (b) the contrastive lens.
Figure 5.26 (a) Schematic of the second freeform lens with a freeform inner surface and cylindrical outer surface, and (b) its illumination performance on the target plane.
Figure 5.27 (a) Schematic of the second contrastive lens with a spherical inner surface and cylindrical outer surface, and (b) its illumination performance on the target plane.
Figure 5.28 A double freeform-surface lens designed (Lens II) by providing the distribution of the deviation angle. The ratios of the first and the total deviation angles are (a) 0, (b) 0.25, (c) 0.33, (d) 0.50, (e) 0.66, (f) 0.70, (g) 0.75, (h) 0.80, and (i) 1.0.
Figure 5.29 Schematic of a high-power LED high bay lamp.
Figure 5.30 Optimized LIDC.
Figure 5.31 Illuminance distribution on the target plane with optimized LIDC.
Figure 5.32 Schematic of a CoB LED array module.
Figure 5.33 Freeform lens outer shape (left) and the cross-sectional view (right).
Figure 5.34 Silicone filled the gap between the LED light source and the secondary freeform lens.
Figure 5.35 Outer shape of the designed freeform lens array.
Figure 5.36 30° lampshade for the LED high bay lamp.
Figure 5.37 Whole optical model of the LED high bay lamp.
Figure 5.38 Simulated LIDC of the whole LED high bay lamp.
Figure 5.39 Optical model of the 8×8 LED high bay lamp array.
Figure 5.40 Illumination pseudo-color map of the whole lighting area.
Chapter 6: Freeform Optics for LED Road Lighting
Figure 6.1 Poor lighting performance of LED road lamps with (a) zebra stripes, and (b) anti-zebra stripes on the road.
Figure 6.2 Schematic of a road luminance calculation.
Figure 6.3 Schematic of the observed point of the maximum glare threshold increment .
Figure 6.4 Schematic of the design target of LED tunnel lighting.
Figure 6.6 Cree XLamp XR-E LED: (a) material object and (b) practical optical model.
Figure 6.5 (a) Schematic of a light intensity distribution curve (LIDC) tester and (b) LIDC of a Cree XLamp XR-E LED.
Figure 6.7 Experimental LIDC versus (a) simulation and (b) fitting for the Cree LED.
Figure 6.8 Seed curves of a one-quarter discontinuous freeform lens.
Figure 6.9 (a) A PMMA discontinuous freeform tunnel lens and (b) a numerical model for a Cree LED module with this lens.
Figure 6.10 Numerical illumination performance of the freeform lens with a point light source.
Figure 6.11 Numerical illumination performance of the freeform lens with a practical Cree LED.
Figure 6.12 Effects of installation errors in the vertical up direction: (a) schematic of vertical deviation ; and (b) numerical illumination performance when , (c) when , and (d) when .
Figure 6.13 Effects of installation errors in the horizontal direction: (a) schematic of horizontal deviation ; and (b) numerical illumination performance when , (c) when , and (d) when .
Figure 6.14 Effects of installation errors of rotation: (a) schematic of rotation angle ; and (b) numerical illumination performance when , (c) when , and (d) when .
Figure 6.15 Comparisons of the effects of increasing size of light source and installation errors on illumination performance.
Figure 6.16 A PMMA discontinuous freeform lens for LED tunnel lighting.
Figure 6.17 (a) Rectangular light pattern of the discontinuous freeform lens, and (b) an 84 W LED tunnel lamp integrated with these freeform lenses.
Figure 6.18 (a) Point clouds, and (b) a model of the PMMA discontinuous freeform lens.
Figure 6.19 (a) A numerical model for an LED module with a PMMA discontinuous freeform lens and (b) its illumination performance in simulation.
Figure 6.20 (a) A numerical model for an LED module with a BK7 optical glass discontinuous freeform lens and (b) its illumination performance in simulation.
Figure 6.21 (a) The PMMA discontinuous freeform lens and (b) the BK7 optical glass discontinuous freeform lens.
Figure 6.22 (a) Microphotograph of the PMMA lens and (b) a numerical optical model of the PMMA lens.
Figure 6.23 Micrographs of different parts of the PMMA discontinuous freeform lens.
Figure 6.24 (a) Microphotograph of the BK7 glass lens, (b) a numerical optical model of the BK7 glass lens, and (c) a partially enlarged view of the BK7 glass lens.
Figure 6.25 The LED discontinuous freeform lenses test modules.
Figure 6.26 Light pattern of the PMMA lens at 70 cm away from the LED.
Figure 6.27 Light pattern of the BK7 optical glass lens at 70 cm away from the LED.
Figure 6.28 Schematic of lights propagation at (a) smooth and (b) rough optical surfaces.
Figure 6.29 Schematic of lights propagation at (a) the sharp transition surface and (b) the smooth transition surface.
Figure 6.30 Lighting performance of an 112 W LED road lamp with a freeform lens array.
Figure 6.31 (a) One 112 W LED road lamp based on the PMMA discontinuous freeform lenses, and (b) a PMMA freeform lens array.
Figure 6.32 LIDC of the 112 W LED road lamp.
Figure 6.33 (a) Good lighting performance of the 112 W LED road lamp integrated with a discontinuous freeform lenses array, and (b) lighting performance comparison between the 112 W LED road lamp and one 250 W HPS lamp. (Supplied by Guangdong Real Faith Enterprises Group, www.gd-realfaith.com)
Figure 6.34 Optical model of the PMMA continuous freeform lens (radiate grid mapping) for road lighting.
Figure 6.35 Simulation lighting performance of a continuous freeform lens (radiate grid mapping): (a) without optimization and (b) with optimization.
Figure 6.36 (a) A PMMA continuous freeform lens (radiate grid mapping) for road lighting, and (b) its light pattern.
Figure 6.37 (a) A 168 W high-power LED road lamp based on the PMMA continuous freeform lenses (radiate grid mapping), and (b) its road lighting performance. (Supplied by Guangdong Real Faith Enterprises Group, www.gd-realfaith.com)
Figure 6.38 Optical model of the PMMA continuous freeform lens (rectangular grid mapping) for road lighting.
Figure 6.39 (a) Simulation and (b) experimental lighting performance of a single continuous freeform lens (rectangular grid mapping).
Figure 6.40 (a) A PMMA continuous freeform lens (rectangular grid mapping) for road lighting; and (b) another lens on the market, for comparison.
Figure 6.41 CCT spatial distribution of the traditional LED module where CCT decreases gradually from the center to the side.
Figure 6.42 ⊿
u
'
v
' spatial distribution of the traditional LED module where increases from the center to the side.
Figure 6.43 Optical model of the PMMA continuous freeform lens (radiate grid mapping) and its blue-light and yellow-light patterns where illuminance decreases gradually from the center to the side of the light pattern.
Figure 6.44 CCT spatial distribution of the LED module integrated with the PMMA continuous freeform lens (radiate grid mapping) where CCT decreases gradually from the center to the side.
Figure 6.45 spatial distribution of the LED module integrated with the PMMA continuous freeform lens (radiate grid mapping) where increases from the center to the side.
Figure 6.46 Optical model of the PMMA continuous freeform lens (rectangular grid mapping) and its blue-light and yellow-light patterns where illuminance decreases gradually from the center to the side of the light pattern.
Figure 6.47 CCT spatial distribution of the LED module integrated with the PMMA continuous freeform lens (rectangular grid mapping) where CCT decreases gradually from the center to the side.
Figure 6.48 spatial distribution of the LED module integrated with the PMMA continuous freeform lens (rectangular grid mapping) where increases from the center to the side.
Figure 6.49 Distribution of the equivalent luminance coefficient on asphalt pavement.
Figure 6.50 Distribution of the equivalent luminance coefficient on concrete pavement.
Figure 6.51 Simulated road (a) illuminance distribution and (b) luminance distribution of an LED road lamp based on a freeform lens with a uniform-illuminance light pattern.
Figure 6.52 Flowchart of the combined design method for uniform-luminance road lighting.
Figure 6.53 (a, b) Flowchart of the combined design method for uniform-luminance road lighting.
Figure 6.54 Simulated road (a) illuminance distribution and (b) luminance distribution of an LED road lamp based on the combined design method.
Figure 6.55 Road-lighting performance of an LED lamp based on the optimized LIDC designed by the combined method. (Supplied by Guangdong Real Faith Enterprises Group, www.gd-realfaith.com)
Figure 6.56 Flowchart of the freeform lens design method for uniform-luminance road lighting.
Figure 6.57 (a) A freeform lens for road lighting with uniform luminance, and (b) its LIDC.
Figure 6.58 Simulated light pattern of the freeform lens for road lighting with uniform luminance.
Figure 6.59 Practical road-lighting performance of an LED road lamp with the uniform-luminance freeform lenses. (Supplied by Guangdong Real Faith Enterprises Group, www.gd-realfaith.com)
Figure 6.60 A PMMA freeform lens to achieve uniform-luminance distribution in tunnel lighting and its lighting performance.
Figure 6.61 Schematic of road lighting with (a) symmetrical and (b) asymmetrical light patterns.
Figure 6.62 Schematic of the light energy mapping relationship of an asymmetrical freeform lens.
Figure 6.63 (a) An asymmetrical freeform lens for road lighting with uniform luminance, and (b) its LIDC.
Figure 6.64 Simulated light pattern of the asymmetrical freeform lens for road lighting with uniform luminance.
Figure 6.65 Comparison of symmetrical and asymmetrical freeform lenses for LED road lighting: (a) surrounding ratio and (b) average luminance.
Figure 6.66 Practical road lighting performance of an LED road lamp with the asymmetrical uniform-luminance freeform lenses. (Supplied by Guangdong Real Faith Enterprises Group, www.gd-realfaith.com)
Figure 6.67 An LED road-lighting engine integrated with multiple functions and various kinds of LED road lamps based on this module. (Supplied by Guangdong Real Faith Enterprises Group, www.gd-realfaith.com)
Chapter 7: Freeform Optics for a Direct-Lit LED BLU
Figure 7.1 Market development of CCFLs and LEDs for LCD backlighting.
[1]
Figure 7.2 Schematic of an LED (a) edge-lit and (b) direct-lit backlighting unit (BLU).
Figure 7.3 Development of size of an LED TV.
Figure 7.4 (a) A side-emitting LED module and (b) a direct-lit BLU based on this LED module array developed by Lumileds.
[2]
Figure 7.5 Direct-lit LED BLU using an SMD LED array.
Figure 7.6 Lighting performance of an SMD LED module array on the plate 10 mm away when the distance between the two adjacent LED modules is (a) 10 mm, uniformity = 0.902; and (b) 20 mm, uniformity = 0.446.
Figure 7.7 Schematic of a co-design concept in a direct-lit LED BLU.
Figure 7.8 (a) Optical model of a traditional 0.068 W LED module for direct-lit backlighting and (b) its LIDC.
Figure 7.9 Lighting performance of a traditional LED module array on the receiving plane 10 mm away when DHR increases from 1 to 3: (a) DHR = 1,
U
= 0.902, CV(RMSE) = 0.0167; (b) DHR = 2,
U
= 0.446, CV(RMSE) = 0.2201; and (c) DHR = 3,
U
= 0.155, CV(RMSE) = 0.5688.
Figure 7.10 (a) Optimized LIDC and (b) its lighting performance on the receiving plane when DHR = 2:
U
= 0.936, CV(RMSE) = 0.0097.
Figure 7.11 (a) A new LED module integrated with a special silicone freeform lens for direct-lit backlighting when DHR = 2; (b) a comparison of LIDCs between the simulated and the optimized results; and (c) lighting performance of these new LED module arrays,
U
= 0.915, CV(RMSE) = 0.0128.
Figure 7.12 (a) A new LED module integrated with a special silicone freeform lens for direct-lit backlighting when DHR = 3; (b) comparison of LIDCs between the simulated and the optimized results; and (c) lighting performance of these new LED module arrays,
U
= 0.887, CV(RMSE) = 0.0224.
Figure 7.13 Experimental comparisons of illumination performance of the traditional LED module and the new LED module integrated with a freeform lens of DHR = 3.
Figure 7.14 When DHR = 3, the average uniformity decreases with the light source size increasing. The size of the light source is: (a) 0.28 × 0.28 mm,
U
= 0.89, CV(RMSE) = 0.02; (b) 0.4 × 0.4 mm,
U
= 0.74, CV(RMSE) = 0.05; and (c) 1 × 1 mm,
U
= 0.54, CV(RMSE) = 0.15.
Figure 7.15 Schematic of the LED array and receiver plane.
Figure 7.16 Flow chart for a feedback optimization design method for an extended source.
Figure 7.17 Schematic for the light intensity distribution of a light source.
Figure 7.18 Energy mapping relationship between input and output light.
Figure 7.19 LED array with an extended source: (a) single LED light source, and (b) LED array optical model.
Figure 7.20 Illuminance distribution of a 0.28 × 0.28 mm point source LED array at the receiver plane.
Figure 7.21 Illuminance distribution of an LED array consisting of 1 × 1 mm extended chip size LEDs at the receiver plane.
Figure 7.22 Illuminance distribution of an LED array consisting of 1 × 1 mm extended chip size LEDs with a feedback-optimized freeform lens at the receiver plane.
Figure 7.23 Light intensity distributions before and after application of the feedback optimization method.
Figure 7.24 Schematic of BEF: (a) optical, (b) structures, and (c) function.
[11]
Figure 7.25 Division of a Lambertian LED in the latitudinal θ direction and longitudinal ϕ direction.
Figure 7.26 Relations of transmittance of BEFs on (a) latitudinal and (b) longitudinal incident angles corresponding to specular reflection walls.
Figure 7.27 Relations of transmittance of BEFs on (a) latitudinal and (b) longitudinal incident angles corresponding to diffuse reflection walls.
Figure 7.28 A petal-shaped freeform lens and its light intensity spatial distribution.
Figure 7.29 ASLP integrated with a petal freeform lens for a high system optical efficiency direct-lit BLU: (a) 2835, (b) 5050, (c) 5730, and (d) its light intensity spatial distribution.
Figure 7.30 Under the situation of specular reflection walls. (a) Normalized luminance distributions of the central point produced by an LED array. Upper or down solid line denotes an array with or without lenses corresponding to 0° in the longitudinal direction; upper or down dotted line denotes array with or without lenses corresponding to 90° in the longitudinal direction. (b) Illuminance distribution produced by an LED array with freeform lenses.
Figure 7.31 Under the situation of completely diffuse walls. (a) Normalized luminance distributions of the central point produced by an LED array. Upper or down solid line denotes an array with or without lenses corresponding to 0° in the longitudinal direction; upper or down dotted line denotes an array with or without lenses corresponding to 90° in the longitudinal direction. (b) Illuminance distribution produced by an LED array with freeform lenses.
Figure 7.32 A PMMA petal freeform lens for a high system optical efficiency direct-lit BLU.
Figure 7.33 Brightness comparisons of BLU with the lens (left) and without the lens (right).
Figure 7.34 Flowchart of the BEF-adaptive design method for a high luminance LED backlight.
Figure 7.35 Segmental light sources within a different latitudinal incident angle θ.
Figure 7.36 Optical model of a traditional direct-lit BLU.
Figure 7.37 (a) Simulated BEF transmittance produced by each latitudinal segmental source; (b) luminance distribution produced by a segmental source of θ = 45∼50°; (c) luminance distribution produced by a segmental source of θ = 50∼55°; and (d) luminance distribution produced by a segmental source of θ = 55∼60°.
Figure 7.38 Models of a BEF-adaptive lens under a different constriction factor: (a)
C
m
= 1; (b)
C
m
= 0.6; and (c)
C
m
= 0.1.
Figure 7.39 Output efficiency and axial luminance of BLUs under different
C
m
.
Figure 7.40 (a) Horizontal axial luminance distribution and (b) vertical axial luminance distribution under different
C
m
.
Figure 7.41 Horizontal viewing angle and vertical viewing angle of BLUs under different
C
m
.
Figure 7.42 (a) Spatial luminance distribution of a BLU without a BEF-adaptive lens and (b) spatial luminance distribution of a BLU integrated with the optimal BEF-adaptive lenses.
Figure 7.43 Illumination uniformity: (a) far field target with point source,
U
= 0.89, CV(RMSE) = 0.02, (b) near field target with point source,
U
= 0.67, CV(RMSE) = 0.09, (c) far field target with extended source,
U
= 0.55, CV(RMSE) = 0.15, and (d) near field target with extended source,
U
= 0.45, CV(RMSE) = 0.24.
Figure 7.44 Schematic of fitting IDF and reference point illuminance.
Figure 7.45 Fitting IDF of extended source and freeform lens.
Figure 7.46 Comparison of profiles of the traditional freeform lens and the new freeform lens.
Figure 7.47 Illuminance distribution of 0.2 mm × 0.2 mm point source at the 1000 mm far field receiver plane, (a) LED array with traditional lens, and (b) LED array with new lens.
Figure 7.48 Illuminance distribution of 0.2 mm × 0.2 mm point source at the 10 mm near field receiver plane, (a) LED array with traditional lens, and (b) LED array with new lens.
Figure 7.49 Illuminance distribution of 1 mm × 1 mm extended source at the 1000 mm far field receiver plane, (a) LED array with traditional lens, and (b) LED array with new lens.
Figure 7.50 Illuminance distribution of 1 mm × 1 mm extended source at the 10 mm near field receiver plane, (a) LED array with traditional lens, and (b) LED array with new lens.
Figure 7.51 Comparison of uniformity and CV(RMSE) between traditional lens and new lens for four different simulation condition.
Chapter 8: Freeform Optics for LED Automotive Headlamps
Figure 8.1 Low-beam pattern on the measuring screen provided by ECE R112 Regulation (reproduced from Ref.
[1]
).
Figure 8.2 Sketch diagram of a gradient of the horizontal cutoff line.
Figure 8.3 White-light color coordinate range for an LED automotive headlamp.
Figure 8.4 Schematic diagram of overlapping images of a light source on a test screen.
Figure 8.5 Schematic diagram of LED packaging.
Figure 8.6 Simulation results on thermal resistance and heat distribution of LED packaging.
Figure 8.7 Picture of an ASLP sample with a sharp cutoff line.
Figure 8.8 Three different LED packaging modules for headlamp application in the market. Pictures from (a) OSRAM, (b) Lumileds, and (c) Nichia.
Figure 8.9 Sketch diagram of the lens' structure.
Figure 8.10 Calculation of the points on the inner surface's curve.
Figure 8.11 Calculation of the points on the TIR surface's curve.
Figure 8.12 Control of the incident collimating rays.
Figure 8.13 Sketch diagram of meshing the target plane.
Figure 8.14 Calculation of the freeform surface.
Figure 8.15 Cross section of the low-beam lens and LED.
Figure 8.16 (a) Simulated illuminance distribution on the measuring screen, and (b) vertical sectional curve.
Figure 8.17 Schematic view of (a) low-beam lens, and (b) low-beam light.
Figure 8.18 Radii of the rounded edges of the low-beam lens facets.
Figure 8.19 Simulated beam pattern of a low-beam lens with rounded edges.
Figure 8.20 (a) High-beam lens, (b) simulated beam pattern of a high-beam lens on a measuring screen.
Figure 8.21 (a) Freeform lens that generates a horizontal rectangular light pattern, (b) freeform lens that generates a 15° inclined rectangular light pattern, and (c) schematic of a low-beam headlamp module with freeform lenses.
Figure 8.22 Illuminance of a smooth top surface freeform lens.
Figure 8.23 (a) LED low-beam freeform lens integrated with a spherical lens, and (b) light pattern of this freeform lens.
Figure 8.24 (a) PES-based headlamp module, and (b) schematic of a PES system.
Figure 8.25 Base ellipsoid cross section size and segmentation method.
Figure 8.26 Designed reflector for an LED PES.
Figure 8.27 Baffle of the PES optical system.
Figure 8.28 LED PES low-beam module with multiple functions.
Figure 8.29 Simulated beam pattern for low-beam light with an improved PES system.
Figure 8.30 Diagram of LED location and MR optics for low-beam light.
Figure 8.31 Simulated beam pattern on a measuring screen with MR optics for low-beam light.
Figure 8.32 MR optics for an LED high-beam light.
Figure 8.33 Simulated beam pattern on a measuring screen with MR optics for high-beam light.
Figure 8.34 LED headlamp module integrated with improved MR low-beam and high-beam modules.
Figure 8.35 Fabricated MR reflector module for an LED headlamp.
Figure 8.36 MR LED (a) low-beam and (b) high-beam light pattern.
Figure 8.37 Schematic diagram of an active cooling system in an LED headlamp.
Figure 8.38 Simulated heat distribution on a heat sink when the ambient temperature is 85 °C.
Figure 8.39 Design model of the LED headlamp.
Figure 8.40 Practical prototype of the LED headlamp.
Figure 8.41 LED low-beam light engine for headlamps.
Figure 8.42 (a) LED low-beam illuminated performance and (b) LED low-beam light pattern on the vertical wall.
Figure 8.43 LED headlamp low-beam lighting performance.
Figure 8.44 (a) LED high-beam illuminated performance and (b) LED high-beam light pattern on the vertical wall.
Figure 8.45 Schematic of ray tracing of the LED PES optical system.
Figure 8.46 (a) Front view and (b) side view of the integrated LED module (design model).
Figure 8.47 Simulated (a) low-beam and (b) high-beam beam pattern of the integrated LED module where the highest illuminance is at the center area of the light pattern.
Figure 8.48 (a) Front view and (b) side view of the integrated LED module (prototype).
Figure 8.49 Lighting performance and beam pattern of the (a) low-beam and (b) high-beam of the integrated LED headlamp module.
Chapter 9: Freeform Optics for Emerging LED Applications
Figure 9.1 Schematic of construction components of an optical engine.
Figure 9.2 (a) Light pipe illumination system and (b) microlens array illumination system.
Figure 9.3 Light rays out of control.
Figure 9.4 Effect of an extended light source.
Figure 9.5 Cross section of a freeform TIR lens.
Figure 9.6 Slicing of the light source.
Figure 9.7 Intersections of the edge rays with the top surface of TIR.
Figure 9.8 Slicing of a rectangular target plane.
Figure 9.9 Construction of the seed curves of a freeform top surface.
Figure 9.10 Validation of the freeform top surface.
Figure 9.11 Cross section of an integral freeform illumination lens with light rays traced.
Figure 9.12 Illumination distribution on the target plane based on a point light source.
Figure 9.13 Illumination distribution on the target plane based on an extended light source.
Figure 9.14 Match the area grids of the target plane with illumination distribution.
Figure 9.15 (a) The final optimized illumination lens and (b) its illumination distribution.
Figure 9.16 (a) Vertical deviation, (b) horizontal deviation, and (c) rotational error.
Figure 9.17 (a) Curves of light efficiency versus
dh
and
dv
; (b) curve of light efficiency versus
d
θ; (c) curves of illumination uniformity versus
dh
and
dv
; and (d) curve of illumination uniformity versus
d
θ.
Figure 9.18 Optical engine inside the LED pico-projector.
Figure 9.19 (a) LED lighting module of the pico-projector and (b) illumination distribution on the target plane with a 70 mm distance.
Figure 9.20 PMMA freeform lens for a high-efficiency LED pico-projector.
Figure 9.21 Illumination distribution at the target plane, 70 mm from the LED illumination module with freeform lines.
Figure 9.22 Schematic of light pattern control of a large-distance color LED array by an LED freeform lens.
Figure 9.23 Hexagonal arrangement of the collimator lens array.
Figure 9.24 Collimating lens array board of front view (left) and back view (right).
Figure 9.25 Schematic of a one-dimensional freeform microstructure beam-extending algorithm.
Figure 9.26 Schematic of (a) a freeform microstructure groove, and (b) the optical system consisting of a one-dimensional freeform microstructure array beam expander and collimating TIR lens board.
Figure 9.27 Illuminance distribution of a freeform array optical system on the receiver plane: (a) without beam expander, (b) expanding the beam in the vertical direction, (c) expanding the beam in the horizontal direction, (d) and expanding the beam in both the vertical and horizontal directions.
Figure 9.28 Schematic of a freeform lens algorithm for a rectangular target plane.
Figure 9.29 Schematic of a rectangular beam expander based on a rectangular freeform microstructure array.
Figure 9.30 (a) Light intensity distribution and (b) illuminance distribution of the optical system with the rectangular beam expander.
Figure 9.31 Isocandela diagram for a runway centerline light with 15 m longitudinal spacing and a rapid exit taxiway indicator light.
[17]
Figure 9.32 Schematic diagrams of collimation and control of rays.
Figure 9.33 Schematic of (a) LCAP source module and (b) optical system of a runway centerline light.
Figure 9.34 (a) Simulation luminous intensity distribution result and (b) primary optimization curve in a two-dimensional plane.
Figure 9.35 Effects of rounded edges and installation errors on lighting performance of the LED runway centerline light. (a) Perfect edge; (b) rounded edge; (d) vertical deviation
d
; (f) focus of rays; and (c, e) average luminous intensity variation in area I.
Figure 9.36 Schematic of an LED taxiway centerline lamp: (a) top view and (b) cross-sectional view.
Figure 9.37 LED taxiway centerline lamp with adjusting angles of (a) 0°, (b) 7°, and (c) 9°, which can satisfy different illumination requirements.
Figure 9.38 Light distribution of an LED and the searching light.
Figure 9.39 Ray trace of the freeform lens at the cross section.
Figure 9.40 The critical circumstance of a freeform lens for collimation.
Figure 9.41 Illumination distribution on the target plane of three size freeform lenses with (a)
h
= 10 mm, (b)
h
= 15 mm, and (c)
h
= 20 mm.
Figure 9.42 The curve of light efficiency to the height of a freeform lens.
Figure 9.43 Schematic of parabolic reflectors with the LED locating on the focus.
Figure 9.44 Optical design of a freeform lens and parabolic reflector.
Figure 9.45 (a) Illumination distribution on the target plane and (b) light distribution curve of the combined optical design.
Figure 9.46 LED search light constructed by 56 optical units.
Figure 9.47 Installation errors of (a) horizontal deviation, (b) vertical deviation, and (c) rotational error.
Figure 9.48 (a) Curves of light efficiency to
dv
and
dh
when they range from 0 to 0.5 mm; (b) curve of light efficiency to
d
θ as it changes from 0° to 10°.
Chapter 10: Freeform Optics for LED Lighting with High SCU
Figure 10.1 Schematic of light output of (a) the traditional LED and (b) the modified LED.
Figure 10.2 Schematic of optical power of center and edge points in the far field of (a) the traditional LED and (b) the modified LED.
Figure 10.3 Optical models of (a) the traditional LED and (b) the modified LED.
Figure 10.4 2D SCU distribution of the traditional LED and the modified LED.
Figure 10.5 3D SCU distribution of (a) the traditional LED and (b) the modified LED.
Figure 10.6 LIDs of the traditional LED and the modified LED.
Figure 10.7 Effects of radii of phosphor layers on the SCU of LEDs.
Figure 10.8 Effects of heights of phosphor layers on the SCU of LEDs.
Figure 10.9 Optical model of the new LED module based on the secondary freeform lens with a combination of freeform and spherical surfaces.
Figure 10.10 SCU comparison of a traditional LED packaging module with a new LED packaging module (freeform surface and spherical) (2D).
Figure 10.11 SCU comparison of (a) a traditional LED packaging module with (b) a new LED packaging module (freeform surface and spherical) (3D).
Figure 10.12 SCU freeform lens with a combination of freeform and spherical surfaces.
Figure 10.13 LED packaging modules of (a) sample 1, (b) sample 2, and (c) sample 3.
Figure 10.14 Light pattern for sample 1's LED at a distance of 1 m: (a) no lens is added, and (b) a freeform lens is added.
Figure 10.15 Spatial CCT distribution comparison of sample 1's LED.
Figure 10.16
⊿u'v
' distribution of the sample 1 LED (a) without a lens, and (b) with a freeform lens.
Figure 10.17 Light pattern for the sample 2 LED at a distance of 1 m: (a) no lens is added, and (b) a freeform lens is added.
Figure 10.18 Spatial CCT distribution comparison of the sample 2 LED.
Figure 10.19
⊿u'v
' distribution of the sample 2 LED (a) without a lens, and (b) with a freeform lens.
Figure 10.20 Light pattern for the sample 3 LED at a distance of 1 m: (a) no lens is added, and (b) a freeform lens is added.
Figure 10.21 Spatial CCT distribution comparison of the sample 3 LED.
Figure 10.22
⊿u'v
' distribution of the sample 3 LED (a) without a lens, and (b) with a freeform lens.
Figure 10.23 (a) Classic TIR lens; (b) traditional white LED packaging; and (c) YBR distributions of a traditional LED and the LED integrated with a classic TIR lens.
Figure 10.24 Design principle of the modified TIR-freeform lens. (a) Original YBR distribution; and (b) desired YBR distribution.
Figure 10.25 Sketch map of designed ray paths through the modified TIR-freeform lens.
Figure 10.26 Sketch map of (a) the generation method of the discrete points of the top surface; and (b) a designed TIR lens with (θ = 60°, γ = 45°, β = 65°). The modified TIR-freeform lens has a larger divergence half angle than the classic TIR lens.
Figure 10.27 (a) Optimization processes of minimizing modified TIR-freeform lens dimensions as well as maximizing the SCU; and (b) YBR distributions of the traditional LED and modified TIR-freeform lens with β = 65.
Figure 10.28 (a) Detailed structure of the packaging. (b) Relative illuminance distributions on a 700 × 700 mm target based on the extended light source 1 m away. Uniformity of illuminance is enhanced by 10.6% from 53.1% to 63.7%. The larger divergence angle of the modified TIR-freeform lens results in lower central illuminance compared with the classic TIR lens, while the marginal illuminance of the modified TIR-freeform lens on a large enough receiver is higher (not shown here).
List of Tables
Chapter 4: Application-Specific LED Package Integrated with a Freeform Lens
Table 4.1 Simulation comparison of system optical efficiencies between a traditional LED module and an ASLP for road lighting
Table 4.2 Experimental comparison of system luminous efficiencies between the traditional LED module and the ASLP for road lighting
Table 4.3 Comparison of the road-lighting performance of the 144 W LED road lamp with the national standards
Table 4.4 Comparison of system optical efficiencies between a traditional LED road lamp and a new LED road lamp based on the ASLP modules
Chapter 5: Freeform Optics for LED Indoor Lighting
Table 5.1 Output efficiency simulation results of an LED source and LED high bay lamp
Chapter 6: Freeform Optics for LED Road Lighting
Table 6.1 A city road-lighting standard
Table 6.2 Comparisons between simulation results and experimental results
Table 6.3 Simulated road-lighting performance of a lens with a uniform-illuminance light pattern
Table 6.4 Simulated road-lighting performance using the combined design method
Table 6.5 Simulated road-lighting performance using a freeform lens with uniform luminance
Table 6.6 Simulated road lighting performance using the asymmetrical freeform lens with uniform luminance
Chapter 7: Freeform Optics for a Direct-Lit LED BLU
Table 7.1 Detailed configurations of optical stacks in the BLU
Chapter 8: Freeform Optics for LED Automotive Headlamps
Table 8.1 Value of ECE R112 (Class B) for low-beam light
Table 8.2 Value of ECE R112 (Class B) for high-beam light
Table 8.3 Test results of the ASLP sample
Table 8.4 Simulated illumination result compared with the corresponding value of ECE R112 (Class B) for low-beam light (sharp edges)
Table 8.5 Simulated illumination result compared with the corresponding value of ECE R112 (Class B) for low-beam light (rounded edges)
Table 8.6 Simulated illumination result compared with the corresponding value of ECE R112 (Class B) for high-beam light
Table 8.7 Simulated illumination result compared with the corresponding value of ECE R112 (Class B) for low-beam light with improved PES system
Table 8.8 Simulated illumination result compared with the corresponding value of ECE R112 (Class B) for a low-beam light with an improved MR system
Table 8.9 Simulated illumination result compared with the corresponding value of ECE R112 (Class B) for a high-beam light with an improved MR system
Table 8.10 Comparisons of test results of an LED headlamp with the GB requirements
Chapter 9: Freeform Optics for Emerging LED Applications
Table 9.1 Simulated illumination result compared with the corresponding value of ICAO for a runway centerline light
Freeform Optics for LED Packages and Applications
Kai Wang
Southern University of Science and Technology Guangdong, China
Sheng Liu
Wuhan University Hubei, China
Xiaobing Luo
Huazhong University of Science and Technology Hubei, China
Dan Wu
Nanyang Technological University Singapore
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Preface
Light-emitting diodes (LEDs), having superior characteristics such as high luminous efficiency, low power consumption, compact size, long lifetime, high reliability, and being environmentally friendly, have been widely accepted by the industry as the new-generation light source in the 21st century as well as the future developing trend in lighting technology, possessing great market potential. With increasing luminous efficiency (e.g., more than 300 lm/W in lab and 150 lm/W in market in 2014) and cost performance in recent years, LEDs have more and more applications in general and special lighting, such as LED indoor lighting, LED road lighting, LED backlighting for liquid crystal displays (LCDs), and LED automotive headlamps. The LED market is growing rapidly. Optical design, thermal management, and power supply are three key issues for LED lighting. With the development of LED lighting, high-quality LED lighting has attracted more and more attention from customers, which means that higher optical efficiency, more controllable light patterns, and higher spatial color uniformity will be needed for the optical design of LED packages and applications. Freeform optics is an emerging optical technology in LED lighting, with the advantages of having high design freedom and precise light irradiation control, and it provides a more promising way to realize high-quality LED lighting. In the next 5 years, with the development of LED chip and packaging technologies, the luminous efficiency of high-power white LEDs will reach a higher level, which will broaden the application markets of LEDs furthermore and also will change the lighting concepts in our lives. Moreover, people also will pay more attention to the quality of LED lighting. Therefore, more new algorithms of freeform optics and advanced optical design methods will be needed to meet the requirements of LED lighting in the future. Thus, a book discussing freeform optics for LED lighting is expected and needed by LED researchers and engineers at present.
This book will introduce the freeform optics for LED packages and applications, from new algorithms of freeform optics to detailed design methods and then to advanced optical designs and case studies. A series of basic freeform optics algorithms specialized for LED packages and applications will be introduced in detail in this book, such as circular symmetry, noncircular symmetry, point sources, extended sources, array illumination, and so on. Most algorithms have been validated by the industry. Many algorithms and designs will be proposed systematically for the first time in this book, and there is no similar book in the market yet. Moreover, besides these core algorithms, detailed and practical freeform lens design methods derived from these algorithms also will be introduced. Novel and advanced optical designs for various LED packages and applications will be introduced in detail, too, such as noncircularly symmetrical freeform lenses for LED road lighting, application-specific LED packaging (ASLP) integrated with petal-shaped freeform lenses for direct-lit large-scale LED backlighting, Fresnel freeform lenses for low-beam automotive LEDs, total internal reflection (TIR) freeform lenses for an LED pico-projector, and a freeform lens for high spatial color uniformity. Moreover, codes of fundamental freeform optics algorithms will be included as appendices.
Chapter 1 gives an introductory basic background in the area of LED packages and applications, especially the three key issues of optical design of LED lighting. Chapter 2 reviews existing major algorithms of freeform optics. Chapter 3 demonstrates a series of basic freeform optics algorithms and design methods specialized for LED packages and applications. Following chapters will apply these algorithms in specific LED packaging and applications, including ASLP in Chapter 4, LED indoor lighting in Chapter 5, LED road lighting in Chapter 6, LED backlighting for large-scale LCD displays in Chapter 7, LED automotive headlamps in Chapter 8, emerging LED applications in Chapter 9, and high spatial color uniformity of LED modules in Chapter 10.
From this book, readers can gain an overall understanding of the application of freeform optics, which is regarded as one of the
