Freeform Optics for LED Packages and Applications

Kai Wang, Sheng Liu, Xiaobing Luo, Dan Wu, Shen Liu

• Publisher: Wiley
• Year: 2017
• Print ISBN:
  9781118749715
• Edition: 1
• eBook ISBN:
  9781118750032
• Topic: Technology & Engineering
• Subtopic: Electrical Engineering & Telecommunications
• Index: Technology & Engineering

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.

Chapter 1
Introduction

1.1 Overview of LED Lighting

Solid-state lighting is a new type of lighting technology based on the high power and brightness of LEDs (light-emitting diodes), and it is commonly known as LED lighting. LED is a semiconductor luminescence device based on the P–N junction electroluminescence principle. Compared with conventional light sources, LED has advantages such as low power consumption, high luminous efficiency, long lifetime, compact size, low weight, high reliability, and being environmentally friendly; it is regarded by the industry as the twenty-first-century green light source as well as a future developing trend in lighting technology, possessing great market potential.^[1–5]

For the past two centuries, natural and energy resource consumption by human beings has increased, and the corresponding environmental pollution and ecological damage have drawn much attention. Reducing energy consumption and adopting energy conservation and environmental protection products are becoming common beliefs of international society. Lighting alone consumes around one-fifth of the total electricity generated globally. In the current energy shortage situation, adoption of energy conservation and environmentally friendly LED-lighting products is meaningful for conservation of energy and reduction of petroleum imports.

To cope with development trends of the semiconductor lighting industry, the United States, the European Union, Japan, and China have given high priority to LED as a primary and strategic industry. They have unveiled their national solid-state lighting plans and devoted huge labor and material resources to research and development (R&D). Take the United States as an example: in 2000, they promoted the National Solid State Lighting Research Program, which invested $500 million for the development of the solid-state lighting industry from 2000 to 2010. In July 2000, the European Union constructed the Rainbow Project, which grants commissions by six large companies and two universities to promote the application of LED. In 2003, China launched the National Solid State Lighting Project. China also announced officially in 2006 that the Solid State Lighting Project will be included in the Tenth Five-Year Plan, and China expected to invest 350 million RMB for semiconductor lighting technology development and promotion. In 2010, solid-state lighting was listed as one of the most important strategic emerging industries in China; there are nearly 30 research institutes and more than 2000 companies nationwide that will focus their research and development on LED lighting related to epitaxial growth, chip fabrication, packaging, and application. In the meantime, the world's three lighting giants, General Electric (GE) in the United States, Philips in the Netherland, and OSRAM in Germany, not only established respective solid-state lighting divisions or subsidiaries, but also carry out a wide range of global cooperative efforts and strive to seize the high ground of the future market.

Under the government's strong support and guidance, as well as large investments in R&D from both institutes of companies and universities, solid-state lighting technologies (including epitaxy growth, chip manufacturing, and packaging technologies) are developing very fast, and the performance of LEDs is increasing dramatically. The luminous efficiency of an LED module reached more than 300 lm/W in the lab^[6] and 150 lm/W in the market in 2014, much higher than the luminous efficiencies of most traditional light sources (e.g., 15∼25 lm/W for incandescent, 70∼100 lm/W for fluorescent, and 100∼120 lm/W for high-pressure sodium) and creating significant energy saving of more than 50% for lighting power consumption. Moreover, with rapid improvements in the cost-effectiveness of LED packaging modules and application products, the global solid-state lighting market is growing rapidly. Take China's LED-lighting market as an example. In 2014, the gross output of the LED industry of China reached as high as 344.5 billion RMB (about US$55.1 billion), an increase of 30.6% compared with the gross output in 2013 of 263.8 billion RMB (about US$42.2 billion).^[7]

In Figure 1.1, high-power LEDs have been vigorously developed in general lighting and specialty lighting applications. For example, through the 10 City 10,000 Lamps project, LED road lighting and LED tunnel lighting are currently being promoted nationwide in China. LED-backlighted cell phone screens, computer monitors, and large-size TVs are gradually becoming familiar to a huge number of families. Emerging LED automotive headlamps and LED-based pico-projectors are under rapid development. A variety of LED lamps for indoor lighting (e.g., LED bulbs, spotlights, downward lights, and panel lights) are applied in commercial lighting, factory lighting, office lighting, museum lighting, house lighting, and other lighting occasions to get more and more applications. Also, LED lamps also are widely used in urban lighting, military and police special lighting, and other occasions for a large number of applications.

Figure 1.1 Diverse applications for high-power LEDs.

The solid-state lighting industry chain includes upstream LED substrate material, epitaxy growth, chip design, and manufacturing; midstream includes LED packaging and testing; and downstream is reserved for specific applications, including LED general lighting and special lighting as shown in Figure 1.2. The ultimate LED lighting product performance is closely correlated with every aspect of upstream, midstream, and downstream: from epitaxy growth, chip manufacturing, packaging, and testing to application product design and manufacturing, where each process step will exert important impacts on the system's lighting efficiency, the lighting quality, and the reliability of LED lighting products. In the meantime, for a high-power LED manufacturing process, each process step is interrelated that will have a coupling impact on LED output efficiency, reliability, and so on.

Figure 1.2 Schematic of an industry chain for high-power LED manufacturing.

Therefore, solid-state lighting technology is a combination of the semiconductor, physics, optical, thermal, mechanical, materials, electronics, and other interdisciplinary research fields. For LED packaging and applications, optical design, thermal design, drive control, and reliability are the four key factors. Among them, the lighting performance is the ultimate design purpose of LED lighting, and good heat dissipation and high reliability design offer a guarantee for long-life LED lighting products. Moreover, in the LED industry chain, packaging is the key connecting link between the upstream and downstream, and application is the major driving force for the whole LED industry. According to GG-LED, the gross output of LED packaging and applications accounts for more than 90% of the total LED industry's gross output.^[7] This book will focus on the emerging freeform optics technologies for LED packaging and various applications.

1.2 Development Trends of LED Packaging and Applications

To gain a better understanding of the design concept of freeform optics, which will be discussed in later chapters in this book on LED lighting, we will first have a brief introduction to the development trends of LED packaging and applications in this section.

As shown in Figure 1.3, brighter, smaller, smarter, and cheaper are always the development trends of LED packaging. With ...

Table of contents

• Cover
• Title Page
• Copyright
• Table of Contents
• Preface
• Chapter 1: Introduction
• Chapter 2: Review of Main Algorithms of Freeform Optics for LED Lighting
• Chapter 3: Basic Algorithms of Freeform Optics for LED Lighting
• Chapter 4: Application-Specific LED Package Integrated with a Freeform Lens
• Chapter 5: Freeform Optics for LED Indoor Lighting
• Chapter 6: Freeform Optics for LED Road Lighting
• Chapter 7: Freeform Optics for a Direct-Lit LED BLU
• Chapter 8: Freeform Optics for LED Automotive Headlamps
• Chapter 9: Freeform Optics for Emerging LED Applications
• Chapter 10: Freeform Optics for LED Lighting with High SCU
• Appendix A: Codes of Basic Algorithms of Freeform Optics for LED Lighting: Based on MATLAB Software
• Index
• End User License Agreement