10th Biennial Joint CNC/CIE and CIE/USA Technical Conference
University of Toronto, Toronto, Ontario
19 October 2015
Papers
Exterior lighting with low blue content
André Laperrière
Institut de recherché d’Hydro Québec (IREQ), Québec City, Québec, Canada
The attached paper has been kindly provided by André Laperrière fof those individuals interested in more detail on the work he presented at the Technical Session.
Presentations
Custom color matching functions: extending the CIE 2006 model
Mark Fairchild1 and Yuta Asano2
1Munsell Color Science Laboratory, RIT, Rochester, N.Y., USA,
2Motorola Mobility
Mean color matching functions, averaged across a number of observers, such as the CIE 1931and 1964 Standard Colorimetric Observers, have proven very useful in a wide range of colorimetric applications. However, they are less useful for describing the color matching responses of individual observers. In 2006, CIE TC1-36 published a physiologically-based mathematical model of mean color matching functions with dependency on age and field size. The CIE 2006 model is immensely helpful in beginning to quantify individual differences in color vision, but does not go far enough. It does not predict individual differences for any given age or field size. We have extended the CIE 2006 model with a physiological model of color vision and observed variances in the components of color matching functions (lens, macula, cones). This presentation describes formulation of the individual observer model and its application in practical colorimetry of means and covariances.
Erwin Schrödinger’s two color spaces
Keith Niall
Defence Research & Development Canada (DRDC), Toronto, ON, Canada
Erwin Schrödinger wrote extensively on the theory of color, specifically about color space. He divides the subject into basic colorimetry – the foundation – and advanced colorimetry. Color matches are the data of basic colorimetry, while advanced colorimetry may incorporate judgments of color difference, similarity, or contrast. The space of basic colorimetry has an affine geometry of at least three dimensions. Only affine properties count for that geometry. The color diagram which results from its projection onto a plane has a two-dimensional projective geometry. Schrödinger’s advanced colorimetry introduces the line element for color space. Schrödinger considered advanced colorimetry incomplete, though he gave it a Riemannian geometry. He identified a tension between the consolidation of empirical data in advanced colorimetry, and adherence to Fechner’s law for color difference. Fechner’s law should not take precedence. Schrödinger speaks to our time: he presents an viable and synoptic framework for the geometry of color space.
A new metric for lighting preference
K. Vick and G. Allen
New Technology Introduction, General Electric Lighting, 1975 Noble Road, East Cleveland, OH 44112, USA
Existing color quality metrics struggle to accurately quantify consumer preference of lighting products. The development of a new metric, Lighting Preference Index (LPI), is discussed that accounts for both preferred color appearance (saturation and hue distortion) as well as preferred shifts in color point away from the Planckian locus. The formula for LPI and calibration of the coefficients will be provided. A strong correlation has been found with preliminary observer testing, and the optimization capability of an accurate preference metric is proven through additional studies. Trends between LPI and other color metrics are highlighted through a computational study on modeled three-component LED spectra. Extension of the LPI metric to a broader range in CCT and Duv will be discussed.
Why the Planckian radiator remains the ideal low CCT color rendering reference illuminant
Lorne A. Whitehead
University of British Columbia, Vancouver, Canada
Since an object’s tristimulus values depend on the illuminant SPD, it is not generally possible to predict its tristimulus values under one illuminant based upon its values under another. However, if two illuminants differ in color temperature but both have a high CRI, such a prediction can be made fairly accurately. A related useful fact is that metameric matching is fairly well preserved in this case, due to the smooth SPDs of the CRI reference illuminants. These are under-recognized advantages of the CRI reference illuminants. Recently, some who may be unaware of them have suggested that at a low CCT, such as 3000K, the selection of the Planckian radiator as the standard for color rendering was arbitrary and should be reconsidered. However, because the Planckian radiator has the important characteristic of conserving daylight color information and preserving metameric match, it was, and remains, the ideal low CCT CRI reference illuminant.
Vision experiment II on white light chromaticity – Duv range perceived most natural
Yoshi Ohno1 and Semin Oh2
1National Institute of Standards and Technology (NIST), Gaithersburg, MD, USA
2Ulsan National Institute of Science and Technology, Korea
Traditionally the white chromaticity points of light sources for general lighting have been designed to be around the Planckian locus, as specified by the standards for fluorescent lamps for many years as well as by the recent Standard for solid state lighting products (ANSI C78.377). However, these specifications have not been based on experimental data on visual perception. Some experimental studies on white light perception were reported only recently. Vision experiments were conducted at NIST in 2013 for white points perceived most natural in a simulated interior room environment using NIST spectrally Tunable Lighting Facility. The results showed that lights with Duv? - 0.015 on the average, much below the Planckian locus, appeared most natural. This experiment used broadband spectra, and the gamut area for saturated object colors naturally increased as the Duv shifted to the negative direction. A discussion was published recently on this NIST research questioning that the results might have been affected by the increase of gamut area in addition to the shift of chromaticity. The 2013 experiment consisted of a number of comparisons of light pairs. To address this question, another series of vision experiments was conducted at NIST in July 2015 using the same facility and the same procedures but with the spectra of each pair of lights adjusted so that the gamut areas (CQS Qg) and the chroma of the red and green samples (used in CQS) were kept nearly equal, to eliminate any effects other than the chromaticity. The experiments were done with 21 subjects at six different Duv levels (-0.03, -0.02, -0.01, 0, +0.01, +0.02) and at four different CCTs (2700 K, 3500 K, 4500 K, 6500 K). The results are similar to 2013 at all CCTs, indicating that the effect of gamut area in the NIST 2013 results was insignificant. The 2015 result has verified that lights at negative Duv in a certain range are generally preferred for interior lighting and this effect is fairly consistent at all CCTs from 2700 K to 6500 K.
Organic light-emitting diodes for solar grade lighting
C. Nguyen and Z.H. Lu
Department of Materials Science & Engineering, University of Toronto, Toronto, ON, Canada
In addition to retain high efficiency at high luminance, white OLEDs have to produce a color rendering index (CRI) suitable as general illumination sources. Over the last two decades, traditional inorganic semiconductor device physics has guided the OLED research community in device structure design and selection of materials. Various types of organic and inorganic materials have been progressively introduced in device fabrication. Many of these multilayered device structures have worked well, in particular for low luminance applications such as flat-panel displays. However, efficiency roll off (similar to efficiency droop in LED) at high luminance has become a major challenge for OLED lighting applications. In this talk I will review potential problems in these multilayered devices and its correlation with efficiency droop. In order to reduce this efficiency droop, considerations in design of device structure and in selection of materials will be discussed. This talk will also review the various device structures used in constructing WOLED, and will discuss the pros and cons of these device structures in addressing two equally important parameter, device efficiency and color rendering index (CRI). Device engineering methods using inter-zone and intra-zone exciton harvesting for improved efficiency and CRI will also be presented.
Goniometric measurement of light sources using an integrating sphere
Yuqin Zong
National Institute of Standards and Technology (NIST), Gaithersburg, MD, USA
A new and fast method for measuring the angular luminous or radiant intensity distributions of light sources has been developed at NIST. Instead of using a slow conventional goniophotometer this new method uses a fast integrating sphere that is commonly used for the calibration of light sources, but only for total luminous flux or total radiant flux. A fisheye camera with a large field of view is used to measure relative luminance/radiance distribution of a light source over the entire surface of the integrating sphere, which is then used to derive the relative luminous/radiant intensity distribution of the light source based on the characterisation of the integrating sphere for its point spread function and spatial non-uniformity. The absolute angular intensity distribution of the light source is obtained with the calibration of the light source for total luminous/radiant flux. The measured angular intensity distribution of the light source not only provides additional valuable information but also makes it possible to correct the measurement error resulting from the spatial non-uniformity of an integrating sphere, which is often the dominant source of uncertainty and is the fundamental limit of achievable uncertainty using the integrating sphere method. The theory of the method and experimental results will be discussed.
Measurement complications of high frequency electricity
Cameron Miller and Yuqin Zong
National Institute of Standards and Technology (NIST), Gaithersburg, MD, USA
Traditional lamps and linear fluorescent tubes using magnetic ballast are operated on 60 Hz or hZ hrelatively low frequency AC electricity. Most laboratories do not have difficulties in measuring these traditional lamps and low frequency fluorescent tubes. With the development of rapid start and instant start ballasts the 60 Hz electricity is up converted to 20 KHz electricity (even as high as 85 KHz). Measurement of such high frequency lamps is much more difficult; however, only few laboratories need to measure such high frequency linear fluorescent tubes or luminaires and they are aware of this situation and accounted for the higher frequency electricity in their measurement systems.
Solid-state lighting products, which often have a very fast reaction time, may induce high frequency electricity showing up in measurement facilities unexpectedly, which may result in a large measurement error. For example, AC power supplies that use a digital waveform generator to create the 60 Hz AC electricity have a small high-frequency component that is on the order of 30 – 60 KHz. Some solid-state lighting products can react to this small component creating a high frequency current wave. This high frequency current wave is susceptible to capacitance and inductance in the electrical wires or cables of the measurement system. Examples of these problems will be discussed along with potential solutions.
Challenges and opportunities for OLED lighting
Michael G. Helander
OTI Lumionics, Toronto, ON, Canada
Organic light emitting diode (OLED) is a new high-efficient lighting technology that is just starting to emerge on the market. OLED offers a paradigm shift in lighting design as it is the first thin, light and flexible source of light. Feature and benefits of OLED lighting will be discussed in comparison to incumbent lighting technologies. The current development roadmap for the technology and initial wave of product applications will be highlighted. Finally a case study of the challenges bringing an OLED lighting product to market, the aerelight A1 OLED lamp will be discussed.
Solid-state lighting measurement assurance program: summary with analysis of metadata
Cameron Miller and Maria Nadal
National Institute of Standards and Technology (NIST), Gaithersburg, MD, USA
In January 2010, the National Institute of Standards and Technology (NIST) began to offer a Measurement Assurance Program (MAP) for solid-state lighting (SSL) products to customers of the National Voluntary Laboratory Accreditation Program (NVLAP) under the support of the Department of Energy (DOE). The MAP program provided proficiency testing complimenting laboratory accreditation to ensure that as SSL products became more prevalent, capable testing laboratories would be available to handle the volume of measurement work. At the request of the Energy Star program, in January 2011 the MAP was opened to any testing laboratories that wanted to participate, independent of accrediting body. As of December 2014, the first version of the MAP was closed with 118 participant laboratories representing 13 countries.
The results of the comparison provide a snapshot of the capabilities of accredited laboratories worldwide. In general, all the laboratory results are within +/- 4 % for total luminous flux and luminous efficacy measurements. In addition to the photometric, colorimetric and electrical comparison the results were analyzed against metadata. The metadata includes sphere versus goniometer along with size and manufacturer, calibration lamp vendor, traceability to national metrology institutes, power supply, and power analyzer manufacturers. This analysis leads to insights that will allow improvements to the documentary measurement standards.
Lighting for life: update on CIE activities
Jennifer Veitch
National Research Council Canada (NRC), Ottawa, ON, Canada
Recent years have revolutionized not only lighting technologies, but also our understanding of the complexity of ocular light detection and the physiological and behavioural responses that follow: light enables vision, but also affects quality of life in myriad other ways. There has been, and continues to be, widespread interest in applying this fundamental knowledge – and countervailing opinions from those who argue that our understanding is not yet adequate to support responsible applications. As the international body responsible for scientifically founded, consensus-based guidance and standards related to light and lighting, CIE has taken several actions to foster understanding of this important topic. Most recently, CIE took an important step in publishing an official statement titled “Proper Light at the Proper Time”, outlining its evaluation of the state of knowledge and its plans for sound guidance in the use of light and lighting to support health and well-being in an integrated way. Taking the official statement as the starting point, this presentation will summarize CIE’s activities in this domain, including the state of knowledge concerning photoreceptor action spectra, research priorities to support applications, and new technical committees that currently seek expert members.
Everyone has a home – how LEDs are changing the way we light it
Terry McGowan
Lighting Ideas Inc., Cleveland, OH, USA
Since 2003, an unusual record of high-performance residential lighting products has been documented by the Lighting for Tomorrow Competition. This competition, which is sponsored by Canadian and U.S. electric utilities and energy programs, seeks to identify and recognize products that meet efficacy and other performance standards and which are also particularly suitable for residential lighting applications. A panel of judges consisting of lighting retailers, lighting designers, interior designers, utility program managers, testing laboratory technical experts and residential lighting media people judges the entries, typically over 100 products each year, and rates them on a numeric scale for performance, appearance, price, innovation and marketability.
LED luminaires have been included in the competition since 2006. LED replacement lamps, lighting controls, retrofit kits and decorative lamps have since been added so that the competition is now a yearly record of LED lighting product innovations and developments.
This presentation looks at how the technology, performance ratings and product features are changing as manufacturers work to incorporate LEDs into their designs in ways that not only take advantage of the new technology, but also result in affordable and energy-efficient products that consumers want to buy and have in their homes.
Exterior lighting with low blue content
André Laperrière1, Patrick Martineau2 and Chrisnel Blot3
1Institut de recherché d’Hydro Québec (IREQ), Québec City, Québec, Canada
2Hydro Québec
3Spectralux
On some critical sites, such as observatories and wild life locations, specialists recommend to limit light emission for wavelength below 500 nm. In fact, fears are raised for light emission in the wavelength region from 450 to 470 nm. In the province of Québec, the Réserve internationale de ciel étoilé du Mont-Mégantic (RICEMM) and the ASTROLab are also very concerned by the blue content of some luminous source. The goal of this study is to address such concerns since blue content can also impact this type of environment. Recently, few street LED luminaires that are equipped to filter out blue light (less than 2 %) were installed in the town of Sherbrooke. The study presents the cumulative spectral power density energy as a function of the wavelength and the light source type. Computer simulations were also performed to assess the light quality.
Uthayan Thurairajah
MMM Group Ltd., Toronto, ON, Canada
Driving safely at night can be challenging because most of a driver’s reaction depends on vision, and vision is severely limited at night. A good roadway lighting design can improve visibility that leads to increasing operational efficiency, health and safety of drivers and people on the go. The proper application of roadway lighting increases visual performance and visual comfort and promotes safety and security. In addition, roadway lighting draws attention, beautifies and enhances space and architectural forms, nurtures mood and atmosphere, and improves satisfaction and health. This also facilitates communication and influences social interaction among people who otherwise may feel less safe and secure in the absence of good outdoor illumination. The roadway lighting design process has abundant complications with several variables and input that are needed to prepare for safe lighting solutions. A logical and systematic approach is necessary for selecting luminaires and poles, mounting heights, arrangements, and spacing. The introduction of solid-state light sources (LEDs) has provided the possibility to design innovative, genuinely sustainable lighting installations that are adaptable to changing circumstances such as traffic and pedestrian density, and weather conditions. LED luminaires are manufactured with optical elements (lenses, diffusers, and reflectors) to look bigger, to distribute the light over a larger area to reduce the brightness and increase eye comfort and safety. A holistic lighting design will emphasize the need for various factors including the physical measurement of light levels for different roadway classifications. The visual performance and visual comfort of a road user are directly influenced by the complex pattern of luminance existing in his/her view of the road ahead. The reflection properties of vehicles, bicycles, pedestrians, obstacles and other objects in the field of view vary widely. Human vision is a complex system with much implication for roadway lighting design. The nighttime driving safety is correlated with increased visual performance and visual comfort from roadway lighting. Safety can be increased by increasing visibility.
The presentation will review the science of vision and visual and non-visual receptors, and the effect they have on visibility and human health. The presentation will also propose a new holistic roadway lighting design method to calculate the lighting design including visual and biological evaluation and various other factors. The presentation may include the accident data, case studies, and latest research finding on this topic including the impacts of vehicle headlights on visibility and glare.
Posters
Light exposure before bedtime in individuals with delayed sleep schedule
Solenne Van der Maren P, Vincent Fulham-Léonard, Christophe Xavier Moderie, Véronique Daneault, Jean Paquet, Marie Dumont
Sacre-Coeur Hospital of Montreal, Montreal, Québec, Canada
Delayed sleep phase disorder is characterised by an inability to advance the timing of the sleep episode to accommodate a standard work schedule. Excessive light exposure before bedtime, especially blue light exposure, may contribute to delayed sleep. To test this hypothesis, individuals with a complaint of delayed sleep schedule (n=14) were compared to individuals with an adapted sleep schedule (n=14). Subjects of the delayed group reported a complaint about interference between their sleep and work/school schedules and had a habitual bedtime later than midnight. Subjects of the adapted group had no complaint and a habitual bedtime before midnight. Light exposure was measured for 8 consecutive days using the Actiwatch Spectrum. Subjects had to maintain a stable sleep schedule, chosen to reflect their habitual sleep time, and had to fill a sleep diary every day. Preliminary results based on ten participants tend to support the hypothesis. Extended analyses are in progress.
Sensitivity to blue light in individuals complaining of delayed sleep schedule
Christophe Xavier Moderie, Solenne Van der Maren P, Vincent Fulham-Léonard, Marie Dumont
Sacre-Coeur Hospital of Montreal, Montreal, Québec, Canada
It was hypothesized that individuals suffering from an excessively late sleep schedule may have an increased sensitivity to evening light. This ongoing study compares individuals complaining of a late sleep schedule to adapted individuals. Subjects, admitted to the laboratory 5h before their habitual bedtime, are kept in dim light (<5 lux) for 6h then exposed to polychromatic blue light (~500 lux) for 1.5h. In preliminary analyses (n=20), averaged salivary melatonin concentration during light exposure was compared to concentration before exposure to estimate melatonin suppression. Dim light melatonin onset (DLMO) was later in the delayed than in the adapted group (23:03±1:38h vs. 20:44±1:09h, p=0.002). There was no difference for melatonin suppression (late: 44.2±24.7%, adapted: 36.2±33.3%, p=0.55). However, correlation with DLMO approached significance in the late group (Rs=0.62, p=0.06), which may reflect higher sensitivity to blue light in the more phase-delayed subjects. This remains to be confirmed on the entire dataset (n=28).
Cameron Miller
National Institute of Standards and Technology (NIST), Gaithersburg, MD, USA
For goniometric data, a critical aspect of the uncertainty analysis is the uncertainty from the algorithm that interpolates the solid angle data between the measured points. To determine the uncertainty of the interpolated solid angle, the relative uncertainty between measured points along with a model to approximate the data is required. Typically, software uses a linear average for the model without considering the uncertainty introduced. Results will be provided using experimental data as examples.
NRC solid state lighting lab and OLED measurements
William Neil and Arnold Gaertner
National Research Council Canada (NRC), Ottawa, ON, Canada K1A 0R6
The NRC Measurement Science and Standards (MSS) portfolio is developing measurement facilities to provide accurate, SI-traceable, photometric and radiometric measurements of solid state lighting (SSL) devices, in response to the increased scientific and commercial requirements for accurate SSL component measurement. This includes the measurement of both calibration standards and modules used in commercial lighting products. These facilities include 1.6 m and 0.50 m diameter integrating spheres and linear optical tables with a diode-array spectroradiometer and a fibre-coupled scanning spectroradiometer (200 nm to 1700 nm) for total luminous flux, total spectral flux, radiance/luminance, intensity/irradiance and correlated colour temperature measurements. Mechanical set-ups are available to provide both goniometric and surface positional measurements of the radiation from SSL devices. Measurements are traceable to the SI through the NRC basic standards of luminous intensity, luminous flux and spectral irradiance. Measurement procedures have been successfully tested through NRC participation in the IEA 4E SSL Interlaboratory comparison of LED products. We present some recent goniometric and position-dependent measurements of OLED samples.
Color Vision Deficiencies, Mild Hypoxia, and the Stroop Effect
Jeffery K. Hovis1, Nelda J. Milburn2 and Thomas E. Nesthus2
1University of Waterloo, Waterloo, ON, Canada
2 FAA Civil Aerospace Medical Institute Oklahoma City, OK USA
Previous studies reported that color defective (CVD) individuals were slower to respond to colored stimuli in a Stroop experiment, but the interference effect was similar to the color normal (CVN) group. We reexamined this effect and expanded our experiment to include mild hypoxic environments. Red, green, and blue colors were used in the Stroop test. The test was administered at ground, simulated 3,780 m, and 20 min after returning to ground. Twelve CVN individuals and 17 CVDs participated. Older CVD subjects were slightly slower than the older CVN group; except after returning to ground. The mean reaction times for the younger CVD subjects were always faster than younger CVN subjects. The interference values averaged across all altitude conditions were lower for the CVD subjects. CVD individuals may not be slower in identifying if the colors are easily distinguishable. Interference may also be less for CVD subjects.
New product evaluation and rating protocols are needed for optically complex fenestration
Neall Digert1, D. Charlie Curcija2, and Todd Maerowitz1
1Solatube International Inc.
2Lawrence Berkeley National Laboratory
Optically-complex daylighting products have become common tools for daylighting buildings. These products incorporate highly-engineered, optimized, refractive and reflective optical technologies to provide variable Visible Light Transmittance (VLT) to selectively maximize daylight harvesting performance under varying sky and daylight resource conditions. Common standards for determining a fenestration product’s VLT using a single homogeneous illuminant condition do not provide sufficient data to accurately represent optically-complex daylighting product performance under the broad range of sky conditions and solar positions that characterize the real-life daylight resource. Reliance on existing VLT data results in overlighting daylit spaces under clear sky and partly cloudy daylight conditions, yielding occupant discomfort and reduced building energy-efficiency. This poster session provides an overview of new daylight harvesting technologies, the need for detailed VLT performance data, and global trends to deploy effective product testing and rating protocols that should be used to guide the development of new CIE standards.
Artificial light and health: a human-centered approach to indoor and outdoor lighting design to synchronize with our circadian rhythms using LED technology
Uthayan Thurairajah
MMM Group Ltd., Toronto, ON, Canada
The non-image forming optical radiation affects the human health and well-being as well as quality of life. This complicated issue will be solved by a new method using the source, modifier and receiver level approaches or any combination of these for any indoor and outdoor lighting application using LED technology. The human eye sensitivity to light varies based on age, alertness, physical and mental conditions of a person. The light intensity, quantity, distribution, direction, color, time, duration, history, etc. also play a significant role in the visual, circadian, neuroendocrine and neurobehavioral responses. The various scholars and scientist that have carried out these experiments throughout the world have not produced any single objective result to mitigate this disorder. In this juncture, I would like to propose a new method to light indoor and outdoor built environment as well as new approaches for the future lighting design that accommodate the human health and well-being.
Near Field Photometry for OLED Characterization
Kaijie Zhang1, Krishnan Harikumar1 and Venkat Venkataramanan1,2
1Lumentra Inc., 150 Frobisher Dr. Unit 5, Waterloo, ON, N2V 2B1
2Impact Centre, University of Toronto, 60, St. George St., Suite 331, Toronto, ON. M5S 1A7
Lighting-class Organic Light Emitting Diodes (OLEDs) are rapidly emerging as commercial products. However Photometric standards for these are just evolving. Currently manufactures either adapt semiconductor LED lighting test methods or standards used by the display industries, both of which could be insufficient. Spatial uniformity and angular variation of brightness and colour are important for OLED lighting panels. This necessitates advanced test methods to obtain meaningful data for fundamental understanding, lighting product development and deployment. We present near field imaging goniophotometer method for characterizing lighting-class white OLED devices, where luminance and colour information of the pixels on the light sources were measured at a near field distance for various angles. This method enables collection of extensive data that can be analyzed to obtain angle dependent luminous intensity, CIE chromaticity coordinates, and correlated colour temperature (CCT) in the far field. Our results show that early OLED panels have poor luminance and CCT uniformity. Most recent panels have vastly improved characteristics.
Imaging System for Measurements of Beam Patterns
Chad Greene and Paul Prior
Westboro Photonics, 1505 Carling Ave. #301, Ottawa, ON, Canada K1Z 5P8
Beam pattern measurements are important to characterize the luminous intensity distribution for lighting products in industries such as indoor/outdoor lighting, automotive, avionics, and medical, which are regulated by global standards. A traditional beam pattern measurement method involves the use of spot-detectors and a goniometer. Although computationally straightforward, this time consuming measurement technique provides information limited to the number of spot-detectors and test angles used. An innovation in beam pattern measurements now involves a calibrated imaging colorimeter and a diffuse surface, whereby an imaged beam pattern projection is used to characterize the luminous intensity distribution of the light source under test. A test lamp was measured using the imaging technique and compared to the goniometer method, referred to as the gold standard. The imaging technique provided results within 5% of the gold standard at locations corresponding to the spot-detector measurements. Furthermore, the measurement throughput was increased by a factor of 30.