Articles & Interviews

Resources | LpR Article | Technologies | LiFi | Oct 31, 2017

LiFi - What It Is, How It Works, What It Provides, How to Apply, and Its Future Prospects

The acronym LiFi (Light Fidelity) was born at the beginning of the 2010s. Its name derives from the very well-known WiFi (Wireless Fidelity). The term VLC (Visible Light Communication) is used in the restricted instances of visible light. Mr. Luc Chassage who works for Oledcomm and the Versailles University is also Scientific Committee President of the Global LiFi Congress that offers 20 lectures dealing with all aspects of LiFi. He is a profound expert in this technology field. Mr. Chassage explains the functionality, pitfalls and hurdles to overcome, the disadvantages and advantages, and best practice to apply LiFi. Read more »

LpR Article | Jun 07, 2016

Light-Emitting Surface (LES) Concept Enables Comparison of Photometric Properties by Osram GmbH

The concept of the light-emitting surface (LES) has been developed by the Zhaga Consortium to enable comparisons of the photometric properties of different LED light engines. Stefan Lorenz, a Systems Architect with Osram GmbH, describes the theory behind the LES and how it applies to the different Zhaga Books. Read more »

LpR Article | Jun 20, 2016

Light Guide Technology for Obtaining a Different Bi-Directional Direct/Indirect Light Emission Pattern

Market requirements ask for a solution for use in suspended light fixtures that will allow the light to be distributed upward, for indirect illumination, as well as downward, for direct illumination. However, existing light guide technology typically produces fairly indirect light and relatively uncontrolled distribution. Brett Shriver, Vice President at Global Lighting Technologies, explains a new approach with individual light extraction features used within the light guide in order to control light in multiple directions and provide the required semi-Lambertian distribution in the downward direction with low glare while obtaining a bat-wing type distribution in the upward direction. Read more »

Lighting and Emergency Dept. Clinician Wellness and Performance Improvement

LpR 70 Article, page 38: Short wavelength ("blue") light is known for its strong impact on humans covering "visual" function, wellness and performance of humans. Lighting has been recognized to have an effect on clinician wellness and performance as well as the occurence of medical errors. In a pilot study, Octavio L. Perez, Ph.D, WELL Accredited Professional and Adjunct Researcher at the Department of Population Health Science and Policy, and his team of scientists and physicians, Christopher Strother, Richard Vincent, Barbara Rabin and Harold S. Kaplan, from the Mount Sinai Hospital, New York, systematically investigated if and how a radically new lighting concept could improve wellness and performance in an emergency department. Read more »

LpR Article | Jun 20, 2016

Lighting & Building Automation Technologies

The transition from traditional lighting technology to LED is old news. People in the lighting business no longer talk about the “LED Revolution”. Today’s revolution, perhaps spurred on by LED technology, is in building automation and lighting controls. Lighting experts know that while LED products have the potential to achieve terawatts of power savings worldwide over the next decade, even larger power savings might be achieved through effective lighting control and building automation systems. Greg Galluccio, Director at Leviton Manufacturing discusses lighting load-shedding strategies, such as daylight harvesting, occupancy sensing, task management and demand response as well as the trends towards the interaction of lighting control with other building functions. Read more »

Lighting Delivering Increased Value To Society - A Strategy For Growth

In recent years we have seen energy efficiency as the key driver for regulation as well as growth. Thanks to the arrival of LEDs the industry is already providing energy savings greater than any other sector. As the LED revolution rapidly continues, where next for the EU lighting industry? LightingEurope, the European industry association for the lighting industry has developed a strategy for growth which aims to fundamentally deliver value to society while aligning with the need to move towards a circular economy. Read more »

LpR Article | Sep 05, 2016

Lighting Fabrics - A New Approach for Flexible Light Sources

Different groups from the lighting business have been dreaming of truly flexible light sources for a long time. OLEDs are being promoted as the solution of the future but there are other solutions already on the market. Managing Director R&D at Carpetlight GmbH, Mr. Till Sadlowski, takes a look at the common history of light and fabrics, the evolution of flexible circuity and the latest development in form free scalable light sources. Read more »

Resources | LpR Article | Quality | Perception | Sep 12, 2017

Lighting to Achieve Optimal Appearance

Visual appearance of an object or space depends on the characteristics of the lighting applied. The objective definition of light quality often doesn’t tell the whole story. Light intensity, its spectral composition and distribution in space, as well as individual preference, must be considered. Nevertheless, aiming for the absolute optimum is only recommended when private rooms are concerned. As visual appearance is key in driving consumer demand, it is important to tune the light to maximize effectiveness and visual pleasure for most consumers. Markus Reisinger, owner and CEO of the Lighting Research Studio, discusses this complex situation with examples. Read more »

Commentary | Smart Lighting + IoT | Resources | LpR Article | Jan 26, 2017

Lighting Up Smart Cities, Dr. Wu Chou, Huawei

Although streetlights have been associated with cities for more than a thousand years, they are rarely considered for functions other than luminary purposes. One of the distinct features of streetlights is their geographic location. In particular, streetlights follow the roads and streets that are the arteries of the city, and at night they outline the city so it can be seen from many miles away. Read more »

LpR Article | May 06, 2016

Lighting with LEDs – More than just Illuminating Objects, by Bartenbach Lichtlabor

Light is more than just vision. It includes aspects of well-being, health and emotions. Dr. Wilfried Pohl, Markus Canazei and Christian Knoflach from Bartenbach report on their experiences and discuss the requirements for LED lighting. They also write about physiological effects and make recommendations for improvements. Read more »

Resources | LpR Article | Technologies | Thermal Management | Mar 13, 2017

Looking for the Best Thermal Solution for CSP Module Designs

Chip Scale Package (CSP) LED technology is not new but while it has been used for a while in TV backlighting applications, it is relatively new to lighting applications. In many respect CSPs are a new world for lighting module manufacturers as they are smaller, usually don’t have any ESD protection, have different light distribution, and, last but not least, have a smaller heat dissipation area. The latter asks for re-thinking the traditional thermal design for modules. Dr. Giles Humpston, Applications Engineer at Cambridge Nanotherm, explains in detail why CSP LEDs present a significant thermal challenge for module designers and outlines some fundamentals in calculating the thermal flow required to keep CSP LEDs cool. Read more »

LpS Gets a Younger Sibling to Foster a Holistic System Approach

For the most part our readers are aware of the fact that the LpS has a strong focus on the component level, but after the 6th event, the Luger Research team realized that it was time to find a way to push the more holistic system approach. After much consideration and careful planning, the Trends in Lighting (TiL) Forum and Show was initiated and took place in conjunction with the LpS 2017. Arno Grabher-Meyer, Editor-in-Chief at LED professional took a close look at both exhibitions and the lectures to find out what the audience thought of the extension and broader outlook. Read more »

LpR Article | Research | Jun 03, 2016

Luminescent Glasses and Glass Ceramics for White Light Emitting Diodes by the Fraunhofer Institute and the South Westphalia University of Applied Science

Luminescent glasses or glass ceramics represent an interesting alternative to LED phosphor due to their high thermal and chemical stability. A series of rare-earth doped glasses are investigated for their potential application as photon converters for solid-state lighting applications. Franziska Steudel, Sebastian Loos, Bernd Ahrens, and Stefan Schweizer from the Fraunhofer Institute and the South Westphalia University of Applied Science respectively, show that the color coordinate of double-doped glass can be varied over a broad spectral range by changing the rare-earth doping ratio accordingly. In addition, double-doping allows for a change in the color coordinate by using different excitation wavelengths. Read more »

LuxLive and SILE Sharpen Focus on End-Users

On November 23rd and 24th, as in previous years, LuxLive was held in the Excel Center close to London’s City Airport. This year, for the second time since the merger of Revo Media and Pennwell, LuxLive and Strategies in Light Europe were co-located. Arno Grabher-Meyer, Editor-in-Chief at LED professional, summarizes his impressions of the event, picking out the more technical oriented lectures held in the different "arenas". Read more »

Trends | LpR Article

Making Light Work – Light Sources for Modern Lighting Requirements

Solid state light sources are the core of modern lighting installations. To get in the right mood for the IYL 2015, Dr. James Gourlay, Chief Technology Officer with Design LED Products, looks at the ways to make LED lighting more efficient, satisfy user demands and to bring SSL design to the next evolutionary level. Read more »

LpR Article | Jun 20, 2016

Managing Manufacturing and Supply Chain Challenges in LED Luminaire Design by Sanmina

Today’s luminaires are often complicated lighting systems and have a wide range of applications from in-home luminaires and retail to very high power outdoor lighting. This causes several challenges in both design and manufacturing. Some of these problems may have already been solved by design and manufacturing firms having expertise with LED luminaire design and manufacturing. Gelston Howell, Senior Vice President at Sanmina explains how to manage some of these design, manufacturing and supply chain challenges by using examples. Read more »

LpR Article | Technologies | Jun 08, 2016

Mastering Thermal Issues in LED PCB Design & Laminate Selection by Ventec Europe

LED applications are not the only applications that are driving the need for thermal issues to be considered and mastered in PCB design, but they are certainly amongst the most challenging. Designing LED PCBs requires many considerations and key are those that arise from multiple heat sources in close proximity. Martin Cotton, Director OEM Technology of Ventec Europe describes the process and criteria used when designing PCBs (Printed Circuit Boards) for use in LED applications using thermally conductive IMS (Insulated Metal Substrates). He goes into technical detail with charts and diagrams that explain everything the designer would need to consider when selecting a laminate and commencing a design. Read more »

Resources | LpR Article | Technologies | Thermal Management | Feb 01, 2019

Materials, Manufacturing and Technologies for Designing Passive Cooling Devices

Until recently, incandescent bulbs and fluorescent lights were the dominant light sources. Today it’s the energy efficient, durable and, in the meantime, cost effective, LED. But to achieve these attributes appropriate cooling is still necessary and due to progress over the last few years the need for active cooling solutions is limited to a few high power applications as long as the material and technology is carefully chosen. John Broadbent, Managing Director at Columbia-Staver Ltd., describes the different technologies and materials and gives practical advice on how to find the right solution for an application. Read more »

Measurement of Angular and Spatial Resolved Spectral Rayfiles

The enhanced complexity of modern lighting systems has increased the importance of realistic light source models during the optical design process of LED-based luminaires. I. Rotscholl, Research Associate, K. Trampert, C. Neumann, I. Leopoldo Sayanca from the Karlsruhe Institute of Technology, U. Krüger and F. Schmidt from the TechnoTeam Bildverarbeitung GmbH, propose a method to enhance the often used LED light source model “rayfile” towards a “spectral rayfile”. A spectral rayfile would be a model that associates each ray with its own spectrum and therefore describes varying spectra as a function of angular direction and spatial starting position. The PMBS (physical motivated basis spectra) method is based on the assumption that each LED spectrum consists of a weighted sum of individual basis spectra, for instance those of individual semiconductors and phosphors. There is no need for any special measurement equipment but a classic nearfield goniophotometer and some off-the-shelf optical filters. This method requires at least one spectral measurement and just a minimum of goniophotometric measurements with different optical filters. Finally, the authors demonstrate the potential of this method by applying the concept on a typical LED and compare the results to the often used Blue/Yellow approach in terms of accuracy and applicability. Read more »

Melanopic Green - The Other Side of Blue

LpR 71 Article - page 74: For years now, there has been a controversial discussion about the amount of blue light in LEDs. Medical studies have shown that, depending on the amount, blue light at night disrupts the circadian rhythm. As a result, warm white (<3000 K) light sources are often touted as a solution for street lighting as well. Ian Ashdown, P. Eng. (Ret.), FIES Senior Scientist at SunTracker Technologies discusses whether or not it is sufficient to only look at the CDT or if other wavelengths and aspects should be considered. Numerous medical studies have shown that exposure to blue light at night suppresses the production of melatonin by the pineal gland in our brains and so disrupts our circadian rhythms. As a result, we may have difficulty sleeping. It is therefore only common sense that we should specify warm white (3000 K) light sources wherever possible, especially for street lighting. - True or false? Read more »

LpR Article | Jul 04, 2016

Mesopic Photometry - An Accurate System of Road Lighting Evaluation by Surya Roshni Ltd.

For a long time, photopic vision was the basis for all light measurement tasks, but today this approach is challenged. According to several research results, it seems that mesopic vision should be used as a basis to evaluate street lighting applications or other low level lighting applications. Prija Jain from the Executive Design and Development (Photometry & Optics) department of Surya Roshni Ltd. in India gives us an overview on the recent status of the discussion, explains it and shows the resulting consequences. Read more »

Method and Circuit to Maintain Constant Light Output for LED Luminaires

Article from LpR 66 | page 80: It is difficult to accurately predict the lifetime or the light output degradation of LED luminaires. A Constant Light Output (CLO) operation is implemented in some of the latest drivers. However, there are many factors that require a different algorithm in terms of time rate and forward current values that are usually not taken into account. Prof.Dr.Eng. Stelian Matei, from the Photometry and Electromagnetic Compatibility Laboratory at Electromagnetica SA, proposes and explains a new method is maintaining the luminous flux over the lifetime of the LED luminaire, considering the luminaire global light degradation. Read more »

LpR Article | Technologies | Jun 28, 2016

MOCVD Platform for Cost-Effective Production of GaN-based HB LEDs

GaN-based blue and ultraviolet light emitting diodes (LEDs) are steadily becoming more widely used in solid-state lighting (SSL) applications [1-3]. Enabling dramatic energy savings when compared to contemporary incandescent bulbs and fluorescent lamps, these high-brightness LEDs (HB-LEDs) have a market potential in the billions of dollars. Yole Development estimates that by 2017, the market for LEDs will be approximately $75 billion [4, 5]. Shiping Guo, the Senior Technology Director of Advanced Micro-Fabrication Equipment Inc. presents a new approach to support this goal with a cost effective MOCVD solution for HB-GaN LED manufacturing. Read more »

LpR Article | Jun 03, 2016

More Efficient Plant Growth with Quantum Dots by Nanoco Lighting

Using LEDs for plant growth lights is nothing new, nor is the use of QDs in LED lighting. While it is already proven that LED systems have big advantages over conventional plant lighting technologies, it is not common knowledge that Cd-free QDs are ideal candidates for optimizing the light spectrum for plant growth systems. Dale Needham, Business Development Director-Lighting at Nanoco Lighting, explains the opportunities and advantages based on Nanoco’s proprietary and patentprotected CFQD® cadmium-free quantum dot LED grow lighting systems. Read more »

Resources | LpR Article | Technologies | Applications | Jan 15, 2018

Multi-Pixel LED Technology Opens New Horizons for Smart Lighting Applications

The evolution of Multi-Pixel LED technology has initiated a giant leap in the development of intelligent lighting systems which are most visible in the automotive industry. Now the first hybrid LED provides smart headlights with more than 1000 individually controllable pixels. Ralph Bertram, who is working on advanced LED device concepts, and Norbert Harendt, who is developing optics solutions for general lighting at Osram Opto Semiconductors, show that automotive lighting is just one of the potential areas in which intelligent selective pixel control can be applied. Options for the use in general lighting, such as information display for outdoor, indoor, retail or industrial applications, are very versatile. Read more »

LpR Article | Jun 28, 2016

Natural Design for Heat Sinks

The luminous flux of LEDs decreases with the rise of the operating temperature. Therefore the dissipation of the heat is, aside from the efficiency of the LED chip itself, an essential part in the development of efficient LED systems. Christian Herbold and Cornelius Neumann from the Light Technology Institute at the Karlsruhe Institute of Technology analyzed natural inspired shapes and show an approach to heat sinks that combine high thermal performance with a high aesthetic value. Read more »

LpR Article | Technologies | Jun 07, 2016

New Class of Siloxane Polymers for Advanced LED Packaging

Packaging presents a major challenge to further improve LED device efficiency and reliability. A novel class of high stability siloxanes forms a technology platform to address such opportunities in die attach, encapsulation, and light outcoupling applications. Dr. Juha Rantala, CEO & Founder, Dr. Joerg Rockenberger, Director Application & Business Development, Dr. Jyri Paulasaari, Vice President Technology, Dr. Jarkko Heikkinen, Director Inks & Pastes. Markus Laukkanen, Application Manager, and Dr. Janne Kylmä, Vice President Engineering & Production at Inkron Oy explain the material properties and give examples of how these new materials in combination with novel nanomaterials enable products fully compatible with current process tools and flows while having superior properties. Read more »

LpR Article | Jun 09, 2016

Form Factor Luminaires and Light Effects

If luminaires designed for traditional light sources are simply retrofitted with LED light sources like it occurs in the so-called “1st wave of LEDification”, they will always fall short of expectations in many points. Herbert Weiß and Thomas Noll from Osram GmbH, Martin Möck from the University of Erlangen-Nuremberg, Martin Creusen from Philips Lighting, and Friedhelm Holtz from Insta Elektro GmbH explain why these shortcomings were addressed and which solutions were developed in the EnLight project. Read more »

Resources | LpR Article | Research | Light Conversion | May 16, 2017

New Glass-Based Phosphors for White Light-Emitting Diodes

Phosphors were always the key component of high quality white LED light. With the increased effîcacy and the higher power capabilities of blue high power LEDs, the phosphors become even more important for reliability, color consistency and overall light quality. Franziska Steudel, Florian Wagner, A. Charlotte Rimbach, Bernd Ahrens, Peter W. Nolte and Stefan Schweizer, scientists at the Fraunhofer Application Center for Inorganic Phosphors, a Branch Lab of Fraunhofer Institute for Microstructure of Materials and Systems IMWS, investigated different glass and ceramics based phosphors for white LEDs. Read more »

Offline Lighting Voice Controller — An Alternative to Voice Assistants

The historical evolution of light control by users started with a mechanical switch followed by potentiometer and dimming, touch panels and touch screens, gesture and movement detection control, and ending with voice. Voice control are mostly online speaker independent like Alexa, Google Home and Siri. But there are privacy and security concerns. Filip Michalski, Electronic Engineer, and Cezary Skotak, CEO, from Cezos describe a speaker independent offline voice controls system, explain the technology and discuss the pros and cons. Read more »