Articles & Interviews

LpR Article | Technologies | Jun 28, 2016

OLED Technology in Lighting Applications

Prototypes and niche applications with OLEDs for lighting have been demonstrated over the past few years. Now there are indications that OLED technology is ready for mass production or at least will be ready very soon. Franco Musiari, Technology Specialist at ASSODEL analyzed the current status and future perspectives of OLED technology. Read more »

LpR Article | Innovation | Nov 24, 2016

On-Chip Beam Forming Optics Paves the Way for New Luminaire Designs

An LED luminaire’s optical system usually consists of primary and secondary optics. This concept always causes a trade-off between light quality, system size, efficiency and light distribution. New concepts to make secondary optics obsolete have already been researched. Paul Drosihn, Head of Modular Products, and Samir Mezouari, Optics & Lighting Design Specialist at Plessey Semiconductors present the first of its kind chip scale beam forming technology, StellarTM. They explain how it works and how it helps to overcome the limitations of traditional optical solutions for LED lighting. Read more »

On Life Cycle Assessment to Quantify the Environmental Impact of Lighting Products

The lighting industry has made great efforts to increase energy efficiency around the world with a strong participation from governmental organizations, multilateral organizations and agencies. However, energy consumption is not the only aspect that needs to be considered for transforming the lighting industry. Víctor Ferreira, Deidre Wolff, and Cristina Corchero from Catalonia Institute for Energy Research (IREC) will explore relevant environmental metrics to help inform the reader about circular economy and Industry 4.0 strategies to achieve a sustainable lighting product. Read more »

Optical Designs to Improve LED Lighting Efficiency of Medical Endoscopes

Lighting efficiency for endoscopic instruments has been deemed very poor, at only about 20%. While laboratory tests demonstrate that fiber optics bending is not problematic, optical simulations clearly show that lighting efficiency is strongly limited by the Étendue. Because of strong geometrical constraints in the light coupling area of an endoscope system, only a radical new optical design can provide significant improvement. Alexander Gaertner and Paola Belloni from the Faculty of Mechanical and Medical Engineering and the Steinbeis Transferzentrum Lichttechnik und Beleuchtungsoptik at the University Furtwangen discuss these issues and propose possible approaches. Read more »

LpR Article | Technologies | Jun 29, 2016

Optical Lithography Method for Advanced Light Extraction in LEDs

Objective material selection for various target applications is key for successful product development. Efficient light extraction features are crucial for highly efficient LEDs. Thomas Uhrmann and Harun Solak, et.al* from EV Group and Eulitha AG will demonstrate a novel lithography method, PHABLE™, that enables the printing of sub-μm patterns in a non-contact, proximity process. Read more »

Technology | LpR Article | Apr 05, 2013

Interview - Optics Production Technology for Customizing LED Luminaires

Siegfried Luger and Arno Grabher-Meyer from LED professional discuss future trends and challenges of the LED lighting business with Richard van de Vrie, CEO of LUXeXceL, a young company that is growing quickly. Van de Vrie owes much of his 25 years of experience in the lighting business to the family owned lighting company that he worked in. Read more »

Optimization of Freeform Optics Using T-Splines in LED Illumination Design

Freeform optics is the game changer in the illumination industry in terms of its ability to redirect the light into the target area. Non-Uniform Rational B-splines, commonly known as NURBS are widely used to represent freeform curves and surfaces. There are certain optical systems where local modification of the surface is necessary during the design or optimization phase. In such cases, NURBS cannot offer such transformations. But a new mathematical representation called T-splines make this feasible. Though its potentiality is well described, this has not been implemented in any optimization routine so far. Annie Shalom Isaac, Jiayi Long and Cornelius Neumann from the Karlsruhe Institute of Technology demonstrate the advantage of the local refinement ability of T-splines by implementing it in the optimization routine and the results are evaluated. Results show that T-splines provide more uniform and homogenous light distribution as compared to NURBS at a faster convergence rate. This makes optical design or optimization using T-splines an intuitive approach for future freeform design tasks. Read more »

LpR Article | Technologies | Jun 21, 2016

Optimization of SSL LED Devices by Osram Opto Semiconductors

There are different levers to improve LED performance. Ralph Bertram, application engineer for SSL products, and Alexander Wilm, key expert in the SSL application engineering department at Osram Opto Semiconductors, have a look into the device itself and explore the principal limitations of the different contributors to device efficacy. They show how to balance driving current and chip size to define the right LED, and explain the impact on performance and system costs of LED packages for the intended lighting task approaches for lighting strategies. Read more »

LpR Article | Jun 03, 2016

Potting Processes as a Part of LED-Based Lighting Module Manufacturing Methods by ViscoTec Pumpen and Dosiertechnik GmbH

Many manufacturing processes need very accurate dosing. One such dosing process concerns the potting of LED-modules. Numerous parameters affect the potting quality. Willi Huber from the Business Unit Adhesives & Chemicals at ViscoTec Pumpen- u. Dosiertechnik GmbH explains casting equipment, critical parameters and appropriate potting methods. Read more »

LpR Article | May 24, 2016

Power over Ethernet Lighting for Commercial Buildings by Molex

Today, information technology (IT) and lighting are separate worlds. It is necessary to create a bridge between these worlds, not only from a technical standpoint but also from the perspective of understanding what is important to each industry. Giovanni Frezza, Group Product Manager at Molex, discusses how LEDs and PoE may pave the way with new power standards: LEDs far outperform the lumens output of older lighting technologies. Today, the PoE standard for LED is 30 W. An UPOE standard for 60 W is in the works, and an expansion called BP is in progress for up to 95 W. Read more »

LpR Article | Jul 04, 2016

Practical Results of a Gas Station Refurbishment with LED Luminaires by the Electromagnetica SA Semiconductor Lighting Centre

Perfect lighting at a gas station is very important for competitiveness. But a conventional lighting system is also a costly and energy demanding installation with high maintenance costs. Stelian Matei from the Electromagnetica SA Semiconductor Lighting Centre shows how a well-planned upgrade of conventional lighting to LED lighting lowers energy consumption and maintenance and, therefore, costs. Read more »

LpR Article | Jul 04, 2016

Practical Results of a Gas Station Refurbishment with LED Luminaires by the Electromagnetica SA Semiconductor Lighting Centre

LpR Article | Jun 06, 2016

Predictive Simulation to Virtually Test Product Design and Reduce Time to Market by Trinseo

With technical progress and new regulations, shorter product cycles are a continuous challenge for OEMs. Modelling is one measure to cut time to market efficiently without compromising product quality. Trinseo Technical Service & Development specialists Kersten Terry and Berend Hoek explain the process of computer-based simulation, specifically applied to injection molded plastic parts. Through case studies, they showcase how Trinseo’s Application Engineering Development resource facilitates more effective LED-lighting development relative to part design, tool design and material selection by modelling “real world“ performance. Read more »

Resources | LpR Article | Feb 20, 2021

Reader's Question About "Short-Pulse Testing"

In reference to the article "Short-Pulse Testing Eliminates Self-Heating Errors to Produce True L-I Graphs" in issue LpR#83, a reader has asked why one measures with these short pulses, since this differs very much to the conditions in real application. Read the author's answer below. Read more »

Qualified Bluetooth Mesh – Making Lighting Controls Future-Proof

LpR 69 Article, page 88: At Lightfair USA, Siegfried Luger met with Patrick Durand, Worldwide Technical Director at Future Lighting Solutions. One of Mr. Durand’s striking statements was: “Basically, what we need is to future-proof lighting control.” This was the first time that this important aspect was so clearly addressed by a representative of the industry. This led us to asking Mr. Durand to provide LED professional with a technical article to clarify the current situation, explain the technical background that led him to making that statement and to give an idea of which requirements a controls solution must fulfill to be truly future-proof. Read more »

LpR Article | Research | Aug 11, 2016

Quality and Health Aspects of LED Lamps for the European Residential Lighting Market

Because of shortfalls in regards to consumer information about high quality, energy efficient, substitute products for incandescent lamps, there has been a significant amount of irritation on the side of the consumer. As part of the Intelligent Energy Europe Program of the European Union, Prof. Dr. Georges Zissis from the Paul Sabatier - University Toulouse and his team investigated 370 LED lamps. All relevant parameters of 95 different lamp types from store shelves in 12 European countries were measured and evaluated regarding quality and health issues. Read more »

Quantum Dot Based White LEDs for General Illumination

Colloidal quantum dot based white LEDs can be integrated into commercial products meeting the stringent reliability requirements for general illumination and providing LED efficiency gains of 5% to 15% over commercial phosphor based LEDs at CCT’s ranging from 5000 K to 2700 K. Unlike earlier demonstrations, the QD material is applied in an on-chip configuration resulting in drop-in fit, form, and function compatibility to existing LED based luminaires and lamps. Ken T. Shimizu, Director, Novel Technologies and Devices, Research and Development, M. Böhmer, D. Estrada, S. Gangwal, S. Grabowski, H. Bechtel, E. Kang, K. J. Vampola, D. Chamberlin, O. B. Shchekin, and J. Bhardwaj from Lumileds showcase the advantages of on-chip QD LEDs: A commercial lamp at 3000K color temperature and 90 CRI is substituted with QD based LEDs resulting in a system level efficiency gain up to 17%, attributed to the reduced blue LED droop from the lower drive current and the lower heat sink temperature when compared to the standard phosphor based LED lamp output. Read more »

LpR Article | Technologies | Jun 28, 2016

Reliability Oriented Design of LED-Based Light Sources

The transition from traditional light sources to SSL systems requires a different design philosophy to achieve the advantages offered by LED light sources. The key approach is based on the parallel design of thermal, electrical, optical and spectral properties of the light source. Matteo Meneghini, Gaudenzio Meneghesso, Enrico Zanoni and Matteo Dal Lago from the Department of Information Engineering at the University of Padova, and Nicola Trivellin from LightCube SRL explain this approach including the importance of the electrical management of LEDs, comparing modulation techniques to constant current, differentiating between versatility and efficiency. Read more »

LpR Article | Jul 01, 2016

Reliable Thermal Management of High-Power LEDs by Haeusermann

Stefan Hörth believes that FR4 PCBs can easily replace IMS PCBs and even open new fields of LED applications. Haeusermann’s HSMtec Product Manager demonstrates that common FR4 laminates, including special copper filling, will sufficiently withstand the heat of HB LEDs. Read more »

Repro-Light - Looking for a Sustainable and Modular Luminaire Architecture

The Repro-light project aims to re-conceptualize the European lighting industry towards more sustainability and competitiveness in terms of production and time to market. This will be achieved through the implementation of modular luminaire architecture and a smart production scheme, demonstrated by the development of a reconfigurable customized LED luminaire designed to improve the customers’ health. Read more »

Rethinking the Photometric Data File Format

With increasing computing power, engineering disciplines cannot be imagined without simulations anymore. In lighting, photometric data and electronic processing of this data has become one of the most important tools for luminaire design and lighting design. This data is today provided in IES LM-63 format, a format that meanwhile has come to its limits. P. Eng. (Ret) Ian Ashdown, Senior Scientist at SunTracker Technologies Ltd., explains why the time for a change to a new standard has come and discusses the newly proposed standard and its properties in detail: ANSI/IES TM-33 respectively UNI 1603054. Read more »

Roadway Lighting Optics for Environment Adaptive Spatial Light Distribution

Roadway lighting for different environmental conditions is a challenging task. But even more challenging is to find a solution with outstanding task efficiency for both dry and wet tarmac surface conditions. The drawback of these types of solutions is that they are usually made up of two different lighting systems. Since the two systems are not usually used to an equal degree, they age at a different rate. Solving this problem is very complex. Viktor Zsellér, PhD student, and Dr. Krisztián Samu, Senior Lecturer, both from the Budapest University of Technology and Economics, propose an optical system that solves this conundrum. Read more »

Roll-to-Roll UV Nanoimprint Lithography for Large-Area Nano- and Micro-Structuring of Flexible Substrates

LpR 67 Article, page 50: Cost and time-efficient methods for the fabrication of optical elements are highly desirable in the field of lighting. Imprinting optical structures in combination with large area fabrication turns out to become an effective approach in this regard. In particular roll-to-roll UV nanoimprint lithography (R2R-UV-NIL) has a large potential to set new benchmarks for the fabrication of miniaturized, low-cost and low-weight optics that can be applied in many fields of applications. In the following, the Joanneum Research Forschungsgesellschaft m.b.H team, Claude Leiner, Stephan Ruttloff, Dieter Nees, Anja Haase, Ladislav Kuna, Wolfgang Nemitz, Franz-Peter Wenzl, Christian Sommer, Barbara Stadlober and Ursula Palfinger, led by Paul Hartmann, demonstrates the maturity of the related process chain, combining optical design, direct laser lithography, step&repeat imprinting for shim fabrication and R2R reproduction. Read more »

LpR Article | May 24, 2016

Safety Concept for LED Street Lighting by Phoenix Contact

Street and building lighting has profited greatly from the advantages of LED technology. While modern LED lampposts have dielectric strengths of up to 6 kV, surge currents and voltages occurring in the grid can be significantly higher. Andreas Schamber, Product Manager for surge protection at Phoenix Contact, presents and discusses a comprehensive power surge protection concept to prevent blackouts during power surges and to protect investments in LED lighting based on the company’s product portfolio. Read more »

LpR Article | Technologies | Jun 21, 2016

Safety Issues for LED Drivers with PWM Operation Modes by Product Approvals Ltd.

In many cases LED drivers manage their output power with PWM controlled switched mode power supply-topologies. The output voltages are filtered and normally DC voltages with low ripple apply at the output connectors of LED drivers. During dimming these circuits can behave very differently and therefore safety issues may arise. Siegfried Luger, CEO at Luger Research e.U. and John Showell, Product Safety Consultant at Product Approvals Ltd. have a closer look at those operation modes and the requirements on voltage limits. Read more »

Resources | LpR Article | Research | Micro-Optics | Aug 13, 2019

Semi-Empirical Characterization of Freeform Microlens Arrays

LpR 72 Article - page 42: Microlens arrays (MLA) have been used for imaging and non-imaging applications for a long time as cost-effective solutions. Non-symmetrical beam shapes require more advanced non-symmetrical freeform microlens arrays (FMLA). The required FMLA molding tools convey a high cost and an iteration process is required for the final design. Oscar Fernández, Tamara Aderneuer, Rolando Ferrini from the Centre Suisse d'Electronique et de Microtechnique, CSEM, and Julien Duchene from ANSYS proposed a method to overcome these limitations based on 3D surface sampling, computer generation of a ray-traceable model and ray-tracing performance simulation and demonstrate feasibility for several commercially available freeform asymmetric thin-film diffusers. Read more »

LpR Article | Jul 04, 2016

Sensors and Feedback Control of Multi-Color LED Systems by MAZeT GmbH

To obtain stable and consistent lighting conditions within the black body range with LED systems, especially RGBx systems is a challenging task. Feedback controlled systems are expensive, but the best solution. Here, the question of which type of sensor accomodates the given application best, arises. Thomas Nimz, Fredrik Hailer and Kevin Jensen from MAZeT GmbH discuss different options based on their scientific studies on LED systems with four or more different LEDs considering secondary conditions like color rendering index. Read more »

Resources | LpR Article | Research | Micro-Optics | Jan 15, 2019

Smart Design of Freeform Micro-Optical Elements for Thin Direct-Lit Luminaires

LpR 69 Article, page 64: Direct-lit LED luminaires consist of LED arrays. In order to achieve homogenous light distribution a diffuser sheet is placed at a certain height above the LED array. Usually the distance between the LEDs and the diffuser has to be greater than the distance between the LEDs on the array. To overcome this limitation, additional optical elements like freeform lenses are necessary. Christian Sommer, scientist at the Institute of Surface Technologies and Photonics of the Joanneum Research Forschungsges.m.b.H and his colleagues, Claude Leiner, Ladislav Kuna, Paul Hartmann and Franz P. Wenzl propose a smart design concept for an extremely flat, direct-lit lighting system, making use of mask-less laser direct write lithography. Read more »

Smart LED System in Package through Wafer Level Integration Approach

It is believed that LEDs will dominate all lighting applications in the near future. Integration and packaging are the two critical issues that, if resolved, will enable efficient and reliable solutions for lighting requirements. Z. Kolahdouz, H. van Zeijl, and G. Q. Zhang from the Institute of Microsystems and Nanoelectronics (DIMES) at the Delft University of Technology, and M. Kolahdouz from the Thin Film Laboratory and Nano-Electronics at the Department of Electrical and Computer Engineering of the University of Tehran show that wafer level packaging is a promising method to ensure lower cost, higher scale, and superior yield. A new integration approach of a smart unit of LED lighting is introduced: LED System in Package (SiP). Read more »

Trends | Smart Lighting + IoT | Resources | LpR Article | Nov 28, 2016

Smart Lighting Market and Technology Trends

Intelligent lighting technology that enables its users to control lighting through connected devices such as smart phones or remote controls is a big topic in the industry. A new report sheds light on different aspects of this business including drivers, restraints and opportunities. Jasmine Hinduja, Research Analyst at The Insight Partners, summarizes the major findings and how the trend to intelligent systems affects the companies regarding technology skills and strategies. Read more »