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.
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Issue 63 | Challenges in UV Measurement
Over the past decade UV LEDs have emerged as a highly attractive alternative to conventional
UV emission sources. They are cost effective and energy efficient devices in a small housing.
These advantages allow new fields of applications and access to a larger group of users - even in
the consumer market, e.g. water purification. Dr. Tobias Roesener, Product Manager at Instrument
Systems, explains what makes accurate measurement of UV LEDs so complicated and what the
crucial requirements on the measurement equipment are. In addition, he discusses calibration
and stray light issues.
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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.
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Challenges when Designing LED-Based Illumination Systems in Medical Applications and Diagnostics
LEDs have become indispensable in medical technology and dentistry. But the requirements placed on these lighting products are very high: Minimized size, high, application specific color rendering index, efficient temperature management, usability and excellent disinfection opportunities are all extremely important. Prof. Paola Belloni from the Steinbeis Transfer Center Illumination Optics and Lighting Engineering and Furtwangen University, and Alexander Gärtner from the Faculty of Mechanical and
Medical Engineering of the Furtwangen University discuss the requirements for different applications such as endoscopy, surgeries, dental devices, and photodynamic therapy. Further topics are the development of a self-disinfecting operation interface with edge-lit UV-A LEDs, and a new optimization approach, taking into account the reflection and absorption properties of human tissues.
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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.
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Tech-Talks BREGENZ - Dr. Wilfried Pohl, Research Director, Bartenbach GmbH
Bartenbach is one of the pioneers in light planning and lighting research. Since Christian Bartenbach
Senior founded the engineering office in 1976, the company has been dedicated to light and visual
perception. Several lighting inventions made over the years, can be attributed to Bartenbach.
Dr. Wilfried Pohl, as a member of the Managing Board and Director of Research at Bartenbach GmbH,
has played a substantial role in many developments. LED professional talked with him about
Bartenbach’s history, education in the lighting business, the lighting parameters he deems very
important, the quality of light, "Human Centric Lighting" and "Biodynamic Lighting“, and how LEDs
have changed the light planning and lighting research company, in general.
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CIE Calls for Focused Research Efforts to Support Healthful Lighting Recommendations
Not so long ago, vision scientists thought that light detection - photoreception - was exclusively
performed by rod and cone cells in the retina. Photobiologists, however, conclusively demonstrated
otherwise with the identification of the intrinsically photoreceptive retinal ganglion cells (ipRGCs) [1].
Whereas rods and cones detect pattern and color, and send this information to the visual cortex,
ipRGCs (of which we are learning there are several subtypes) detect irradiance, and route their
information to many brain structures. The most thoroughly studied of these is the suprachiasmatic
nucleus of the hypothalamus, location of the central circadian clock, where the light and dark signals
trigger the offset and onset of production of the hormone melatonin. As shown in figure 1, however,
ipRGCs also project to other structures, about which, as yet, we have little information.
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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.
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Technology Challenges in Professional Tunnel Lighting Applications
The guide for tunnel lighting CIE 088:2004 is the most established international standard for the illumination of road tunnels. However, Switzerland’s ASTRA (Bundesamt für Strassen) and the ASFINAG in Austria both provide guidelines that go well beyond these requirements. Maximilian Herzig, Product and Key Account Manager Lighting at SWAREFLEX GmbH shows solutions to satisfy these requirements and explains why the commonly used value of "lumen per watt" is not a perfect method of evaluating system performance and efficiency.
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CIE Research Strategy on Defining New Calibration Sources and Illuminants
In photometry and radiometry, traceability of measurements requires appropriate calibration sources
and transfer detectors. A major challenge is the technological revolution of lighting products towards LED
lighting and the ban of incandescent lamps. This raises concern about the availability of incandescent
photometric standard lamps in the future while the prices of such standard lamps are already increasing.
In addition, calibration conditions should ideally be chosen to be as close as possible to the
measurement conditions. Furthermore, the number of LED lighting measurements in laboratories and in
the field has significantly increased, while the calibration of photometers is still done using incandescentbased
standards. Therefore, it is important to investigate the pros and cons of replacement of
conventional standard lamps with new solid-state technology. Peter Blattner and Tony Bergen, Division 2
Director and Secretary respectively, explain how CIE has defined the research topic “New Calibration
Sources and Illuminants for Photometry, Colorimetry, and Radiometry” to address these concerns.
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Brave New World and the Dualism of Light(ing)
The lighting business has been quite
predictable over a long period of time.
Technical changes were introduced
slowly, dominated by a handful of leading
companies, and mostly due to new,
but not disruptive light sources. The life
of engineers was mainly determined by
a manageable number of parameters:
Lighting requirements, light source
parameters, costs, product dimensions,
and the odd, required feature.
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Variability in LED Production and the Impact on Performance
LEDs are subject to manufacturing deviations, which have an impact on the end product. Benoit Bataillou and T. Merelle, guest authors from Pi Lighting, review the surprisingly large impact on LED performance and light quality. They used traditional as well as modern indicators like CRI and TM-30 as well as the latest circadian indices to measure. The results are explained by spectral modeling and a variability study. They show the large impact on CRI, even with small deviations inside the same bin.
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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).
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Ultrathin Direct-Lit LED Module with Beam Shaping Thin-Film Optics
Thin, high quality, LED light panels are still a challenge. LED professional’s scientific partner,
CSEM, investigated and developed a new approach with its partners, GAIKER-IK4 and BASF-SE.
The authors, Oscar Fernández and Rolando Ferrini, from CSEM, Leire Barruetabeña, from GAIKER-IK4, and Sorin Ivanovici from BASF SE, present a solution that uses low-cost and spectrally poor, ultra-cool white LEDs in conjunction with optical color conversion foils, to transform the output to a high-quality light. They also describe a combination with added lime and red LEDs for a color tunable solution.
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Tech-Talks BREGENZ - Jamie Singerman, Future Lighting Solutions
We recently sat down with Jamie Singerman, Worldwide Corporate Vice President, and Patrick Durand,
Technical Director for Future Lighting Solutions, a leading provider of Solid-State Lighting technologies,
engineering expertise and online simulation and design tools, to discuss the company’s differentiators
and their views on the ever changing lighting market.
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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.
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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.
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Enabling Total Control in the Next Generation of Outdoor Lighting
Outdoor lighting is certainly one of the applications with the greatest potential for energy saving. Although many approaches are discussed, they all end up with a smart lighting solution. In order to accommodate this, intelligent software and electronics are required as well as standardized, robust interfaces. Ronald Weber, Global Industry Manager, Building Automation and Benjamin Nelson, Business Development Manager, Intelligent Buildings, both from TE Connectivity, present a Zhaga compliant solution.
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A Lighting Designers Relativity of Light Performance
The LED will always be the superstar
of light sources. Their precise and clear lighting possibilities have been targeted by lighting planners and architects for the past ten years. The coming years will see the performance of the LED getting progressively closer to the spectrum of daylight and that will, in turn, generate biologically effective LEDs that are even higher in contrast and promise a new kind of feel-good light.
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Tech-Talks BREGENZ - Philipp Henrici, President and Managing Director at BJB
It’s unusual for a lighting company to be older than electric lighting itself, but BJB in Arnsberg, Germany is celebrating their 150th anniversary this year. LED professional’s Siegfried Luger and Dr. Günther Sejkora spoke with Philipp Henrici, the President and Managing Director at BJB about disruptive technology changes, starting from petroleum lamps to electric lighting as well as conventional lighting versus solid state lighting. They also touched on the subjects of chances and drawbacks of LED component standardization, modular systems and automated production processes.
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CIE Fosters Co-Ordination of Global Research and Standardization on Temporal Light Modulation
Dr. Jennifer Veitch, recently convened the CIE Stakeholder Workshop for Temporal Light Modulation Standards for Lighting Systems. Below is the exclusive report she provided on the workshop findings and the attitude of the CIE towards this important issue.
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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.
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A Standardized Open Platform Is Key to the Future of Smart Lighting System Design
The LED industry’s pace of evolution is more prevalent now than it has ever been. The shift from traditional
standalone LED bulb lighting to fully connected digital LED systems is upon us and is transforming the
industry for the better. For years, LED manufacturers have focused on driving cost down rather than
focusing on improving quality, but with the advent of connected lighting, smart lighting and human-centric
lighting, the focus has shifted back onto quality. Dr. Kyeongik Min, Principal Engineer in the LED business
team at Samsung Electronics, explores how the LED industry can accelerate the transition from
standalone lighting to fully connected lighting through a deeper understanding of current market trends.
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Lead Halide Perovskite Nanocrystals - A New Promise for Light Emitting Devices
Perovskites structured materials have attracted scientific and technological interest in the last four years.
Recent studies have shown that these materials could deliver high photoluminescence efficiency at any
desired wavelength in the visible spectrum. Mirko Prato and Francesco Di Stasio, Technologist and
Marie Curie Fellow of the Institute of Photonic Sciences at the Istituto Italiano di Tecnologia focus on the
application in single color LEDs (red, green and blue) and white emitting color-converting layers. They
discuss what limits their application in everyday technology like toxicity and limited functional stability.
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SSL Growth Strategies and USDA Corn Breeding Objectives
The SSL horticulture lighting industry has become one of the fastest growing branches of lighting
worldwide. Much research has already been done in regards to horticultural SSL technology and
continues to be rigorously explored. While most other inputs for plant growth are monitored and
controlled based on plant needs, it is still common practice for light control to be rudimentary (on/off).
Brandon Newkirk, Marketing Communications Manager at LumiGrow Inc., gives a short overview on the
current state of dynamic LED lighting with a focus on USDA corn breeding trials and objectives.
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Bio-Effective Lighting for Humans, Livestock and Plants
Mood lighting is often misleadingly interpreted as HCL. But HCL is much more because it includes
biologically effective light that is beneficial or dangerous, depending on the correct application.
While the relevant parts of the radiation spectrum may differ, light is also biologically effective for
plants and animals and it is used to achieve well-defined effects. Volker Neu, General Manager
LED at Vossloh-Schwabe Lighting Solutions, presents examples, discusses similarities and
differences between humans, animals and plants in respect to the relevant spectra, and
scrutinizes possible consequences.
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Tech-Talks BREGENZ - Norman Bardsley, President of Bardsley Consulting
Professor of Physics, Dr. J. Norman Bardsley, has become an internationally recognized expert in SSL
through his activities as an advisor for DoE and ISA. Dr. Bardsley has a profoundly deep knowledge and
understanding of OLED technology, which includes the manufacturing thereof, cost structures and
research activities. LED professional talked with him about the different aspects of OLED lighting
technology and asked for his thoughts on future perspectives.
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Lifetime Calculation of White HP-LEDs from 16,000 Hours Aging Data
Accurate models are a relevant tool for correctly calculating the so-called useful lifetime predictions of
LED lighting products. Until recently, only the efficiency decay and related reduced lumen output was
taken into account. Max Wagner, Research Assistant, TU Darmstadt, and his co-authors, Alexander
Herzog, Hristo Ganev, and Prof. Tran Quoc Khanh asked themselves if there are other lifetime limiting
factors that can be modelled and predicted. Their findings showed that color shift might be more critical
and in the following, propose a method to simulate and predict this behavior.
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From Component to System, Andreas Weisl, CEO at Seoul Semiconductor Europe GmbH
The history of Light-Emitting Diodes
(LED) is quite short compared with
some other electronic device industries.
However, it has changed and
revolutionized the entire world of light
within a very short period of time. The history of Light-Emitting Diodes (LED) is quite short compared with some other electronic device industries. However, it has changed and revolutionized the entire world of light within a very short period of time.
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Technical Aspects Regarding the Equipment of Show Caves with Modern LED Systems
Caves have an almost magical attraction over people, drawing them again and again into their depths.
The first electrification started in the 19th century, culminating in today’s digitalization and “LEDification”.
Vladimir Vashkevich, Technical Manager at Cave Lighting CL GmbH & Co KG, describes the tough
requirements on luminaires and the whole installation. He explains the advantages for the operators
and the ecosystem and finally discusses solutions, practical examples and future prospects.
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