White LED-based Integrating Sphere Offers Superior Luminance Calibration of Imaging Sensors

LED Integrating Sphere

G&H’s white LED-based integrating sphere

 

The light measurement instrumentation and imaging detector industry relies heavily upon conventional single line spectrum and continuous sources. Typically incandescent, they provide only limited utility in terms of reliability, accuracy, control of spectral content and serviceable life. A new product under development by Gooch & Housego will allow an unprecedented level of flexibility in terms of uniformity and linearity testing for designers, integrators and end-users.

The source addresses the needs of engineers, scientists and technicians who currently work with conventional incandescent-based line and filtered broadband sources but desire a cost-effective, wavelength-selectable, NIST-traceable radiant light source. In such applications, the LED Integrating Sphere Source provides more versatility and better performance than filtered sources and is a significantly lower cost alternative to monochromators and similar instruments. Main application areas include product testing and detector, imaging system and photometric instrument calibration. Also unlike tungsten halogen lamps, LEDs will not heat parts significantly due to radiation, so the optical cavity can be small. It does not require air flow, so the cavity is easily rendered light tight. The heat can be conducted to a heat sink and dissipated using inexpensive, readily available assemblies. Calibrations will be available in luminance, radiance and illuminance/irradiance.

here are a few white LED-based luminance sources in the market place but until now they have only been able to generate a uniform spectral output across a limited range. The proprietary design of this new system from G&H is unique in overcoming that limitation, offering a true broadband output as good or better than conventional sources. For more information on the G&H White LED-based Integrating Sphere; specifications and applications, contact Alex Fong or orlandosales@goochandhousego.com.

New website showcases Light Measurement Solutions Portfolio for Industrial and R&D Applications

Multicolored LEDSTo showcase this exciting line of solutions, G&H has recently launched a website dedicated to light measurement instrumentation. This new dedicated site is designed to serve the industrial and research light metrology community. It is application driven and allows visitors to explore all the options G&H has to offer along with rich content such as a wealth of product information, application notes and video tutorials. Links to social networking tools and forums will help to create dialogs between our experts and the user community regarding technical and commercial trends of importance. New innovations to be introduced in 2015 will also be announced on the site as part of product spotlights and case studies.

In addition to its trusted and popular OL 770 Series lighting LED and display test platforms, research systems such as their OL 750, HSi-440C spectral imagers and calibration standards and services, Gooch & Housego (Orlando), the company’s Instrumentation division, recently announced that it has added ultra compact and rugged spot photometers, colorimeters and luminance spectroradiometers from Colorimetry Research to its line-up. In addition G&H now distributes the Techno Team family of LMK5 Imaging Photometers and RiGO801 goniophotometers in the Americas. “Both of these lines are welcome additions, enabling G&H to better serve the production test community”, commented Senior Vice-President, Alex Fong.

The Instrumentation division of Gooch & Housego, located in Orlando, Florida, is a world leader in light measurement solutions, such as spectroradiometer, radiometer / photometers, calibration standards and services, integrating spheres and hyperspectral imaging and multi-imaging solutions. Instruments and systems provide accurate, repeatable, research-grade measurements in the UV-VIS-NIR-IR wavelength ranges for research, academia, industry, and the military. Light measurement systems are designed to provide consistent, precise, and repeatable measurements throughout the long life of the instrumentation.

For more detail on G&H’s light measurement solutions please visit the Instrumentation website or e-mail us at sales@goochandhousego.com.

White LED-based Integrating Sphere Offers Superior Luminance Calibration of Imaging Sensors

Alex Fong, G&H (Orlando)

The light measurement instrumentation and imaging detector industry relies heavily upon conventional single line spectrum and continuous sources. Typically incandescent, they provide only limited utility in terms of reliability, accuracy, control of spectral content and serviceable life. A new product under development by Gooch & Housego will allow an unprecedented level of flexibility in terms of uniformity and linearity testing for designers, integrators and end-users.

G&H’s white LED-based integrating sphere
G&H’s white LED-based integrating sphere

The source addresses the needs of engineers, scientists and technicians who currently work with conventional incandescent-based line and filtered broadband sources but desire a cost-effective, wavelength-selectable, NIST-traceable radiant light source. In such applications, the LED Integrating Sphere Source provides more versatility and better performance than filtered sources and is a significantly lower cost alternative to monochromators and similar instruments. Main application areas include product testing and detector, imaging system and photometric instrument calibration. Also unlike tungsten halogen lamps, LEDs will not heat parts significantly due to radiation, so the optical cavity can be small. It does not require air flow, so the cavity is easily rendered light tight. The heat can be conducted to a heat sink and dissipated using inexpensive, readily available assemblies. Calibrations will be available in luminance, radiance and illuminance/irradiance.

There are a few white LED-based luminance sources in the market place but until now they have only been able to generate a uniform spectral output across a limited range. The proprietary design of this new system from G&H is unique in overcoming that limitation, offering a true broadband output as good or better than conventional sources. For more information on the G&H White LED-based Integrating Sphere; specifications and applications, contact Alex Fong or orlandosales@goochandhousego.com.

LighTimes:CALiPER Publishes New Report on Retail-Bought LED Lamps

March 18, 2014…Since the second retail lamp study was published, in early 2012, the U.S. DOE says it has seen substantial progress in all aspects of LED lamps available from retailers. CALiPER again purchased a sample of LED lamps from retail stores including a total 46 products–focusing on A19, PAR30, and MR16 lamps — and has published a new report on the findings. The products were not chosen randomly, but were picked to answer specific hypotheses about performance to expanding ranges of LED equivalency, improving the accuracy of lifetime claims, and examine their efficacy and price trends, as well as changes to product designs.

The CALiPER testing found very good LED-based alternatives to 60W, 70W, and 100W incandescent A19 lamps and 75W halogen PAR30 can now compete performance wise. The testing found that LED-based MR16 lamps have shown less progress, but now 35W/12V and 50W/120V halogen MR16s have acceptable LED-based alternatives. However, lamps for other uses, such as in enclosed luminaires, were found to need more development to be competitive.

The lamps purchased in 2013 at the same price point had higher output and slightly higher efficacy than those purchased in 2011 or 2010. Greater than 30 percent of the products purchased in 2013 exceeded the maximum efficacy measured in 2011 (71 lm/W). The most efficacious product purchased in 2013 operated at 105 lm/W.

The testing revealed apparently increasing consistency in color quality, with the vast majority of products having a correlated color temperature of 2700 K or 3000 K and a color rendering index between 80 and 85. Fewer poor-performing products were tested, and more high-performing products were available in 2013 than in previous years. While the accuracy of equivalency and performance claims improved compared to 2011, it remains a concern. About 43 percent of tested products failed to meet their equivalency claims, and 20 percent failed to match the manufacturer’s performance data.

The testing found insufficient lumen output was becoming less of an issue than previous testing indicated Other issues such as reducing cost, improving electrical/dimmer compatibility, eliminating flicker, and improving color quality still need work. The DOE notes that multiple high-quality, sub-$10 products are now available, and the availability of vastly superior products in 2013 is undeniable.

The DOE gives the example of 800-lumen A lamps that are now common, but were a rarity just two years ago. The testing found that a substantial portion of the products tested for the new report exceeded the lumen output and efficacy performance of the very best products from 2011.

The DOE warns that poor-performing products are still on the market, and the accuracy of equivalency claims and data remains a problem. Despite the progress, LED lamps available through retail stores continue to exhibit a range of quality. Therefore consumers, contractors, and specifiers have to be more educated than ever before to purchase products based on the performance of conventional products.

LighTimes: Market for AMOLED Light-Emitting Materials to Surge in 2014

January 16, 2014…A flood of new competitors set to initiate or increase the production of active-matrix organic light-emitting diode (AMOLED) panels next year, according to IHS. Therefore IHS predicts that demand for materials used to make AMOLEDs is forecast to rise by nearly 27 percent in 2014. IHS predicts that the global market for AMOLED light-emitting materials will expand to $445 million in 2014, up from $350 million this year, according to IHS Inc. While growth next year will moderate compared to the 49 percent rise in 2013, the market will swell by about $100 million in 2014, as presented in the attached figure.

“South Korea’s Samsung Display Co. Ltd. has successfully pioneered the AMOLED business during the last five years, attaining major success in the market for smartphone panels ranging in size from 3-inches to 5-inches,” said Doo Kim, principal analyst, display component and materials research. “Now other panel manufacturers are seeking to cash in on the expanding demand for AMOLEDs in smartphone, televisions and other products. This phenomenon will spur the continued increase in sales of materials used to create AMOLEDs in 2014.”

IHS notes that the organic light-emitting materials utilized in AMOLED panels can be largely divided into two categories: common functional layer materials and color-emitting materials. The common layer materials include hole transport layer (HTL), hole injection layer (HIL), electron transport layer (ETL), electron injection layer (EIL), capping layer (CPL), charged generation layer (CGL), electron blocking layer (EBL), efficiency enhanced layer (EEL) and RGB prime layer materials. Of these, the EBL and EEL materials are hardly used at this time, while the CGL material is used only in white organic light-emitting diode (WOLED) panels. Materials such as PIN dopant are also adopted to improve efficiency.

The color-emitting materials are red, green and blue host and dopant materials. Also, yellow-green materials are used in white OLEDs. Samsung Display reportedly started the AMOLED market when it began large-scale mass production in 2008 and has since led the AMOLED market’s expansion. In 2013, LG Display Co. Ltd. of South Korea launched a WOLED TV panel and a flexible AMOLED panel. Meanwhile, AU Optronics Corp. (AUO) of Taiwan introduced samples of small- to medium-sized AMOLED panels. Next year, LG, AUO and Japan Display Inc. (JDI) are poised to begin increasing AMOLED panel production. As a result, IHS forecasts that light-emitting material makers will compete in a more diverse market environment with increased demand and a broader base of customers. This will represent a marked change from the last five years, when they depended wholly on demand from Samsung Display.

LighTimes: DOE Publishes Gateway Report about LED Lighting for Pedestrians

January 14, 2014…The U.S. Department of Energy has published the results of the Gateway demonstration of Pedestrian Friendly Outdoor Lighting. The DOE notes that outdoor lighting has mostly focused on vehicles, and has rarely focused on the needs specific to pedestrians. The U.S. Department of Energy GATEWAY Demonstration Program followed two pedestrian-focused projects at sites where the pedestrian-scale lighting needed improvement: Stanford University in California and the Chautauqua Institution in upstate New York. The results from these demonstration projects reveal that pedestrians may have different criteria for lighting than drivers, especially in areas where cars are subordinate to bicycles and users on foot. Further the results indicate retrofit modules with optics are not created equally, and not all modules work in all applications. Additionally, the demonstrations concluded that not all optics are ideally suited for all applications.

At both sites, an iterative process was used to evaluate luminaires; collect feedback from residents, homeowners, and/or campus facilities groups; and use that feedback to try other options. In both cases, it became clear that users cared about the daytime appearance of the luminaire, found luminaire glare to be a significant factor in luminaire acceptability. Users clearly preferred luminaires that produced a soft-edged pattern of light on the ground, and they preferred a warm color of light (2700K to 3000K) given the character of their neighborhood and the fact that they were used to either incandescent sources or high-pressure sodium as a baseline The projects found that horizontal illuminances could be at the low end of IES-recommended levels as long as luminaire glare was reduced.

The demonstration projects found that smoothing out the luminance transition from high to low resulted in responses of greater visual comfort, even though glare metrics do not take this into account. Pedestrians found glare to be most uncomfortable when they were closest too the light source when walking within the zone of 0 to 75 degrees.

The DOE report notes that conventional lighting design for outdoor applications focuses on: illuminance or luminance on pavement; contrast of irregular paving and objects in the path of travel; uniformity (e.g., maximum-to-minimum illuminance or average-to-minimum illuminance); vertical illuminance on faces and targets; pole spacing and mounting height for economy and uniformity; luminaire distribution (“Cutoff” or BUG (backlight, uplight, glare) system ratings) for dark-sky considerations and some degree of glare control; and lighting system efficacy.

However, the DOE found that additional criteria that are needed for evaluating pedestrian lighting applications might also include: safety from tripping/falling; safety from being hit by vehicles, bicycles, or skateboarders; personal security from harm or intimidation by others; minimizing unwanted light in residential windows; appearance of the neighborhood/campus/area; minimizing glare that causes discomfort, is disabling, or affects viewer adaptation level.

The demonstration projects found that smoothing out the luminance transition from high to low resulted in responses of greater visual comfort, even though glare metrics do not take this into account. Pedestrians found glare to be most uncomfortable when they were closest too the light source when walking within the zone of 0 to 75 degrees.

The DOE report notes that conventional lighting design for outdoor applications focuses on: illuminance or luminance on pavement; contrast of irregular paving and objects in the path of travel; uniformity (e.g., maximum-to-minimum illuminance or average-to-minimum illuminance); vertical illuminance on faces and targets; pole spacing and mounting height for economy and uniformity; luminaire distribution (“Cutoff” or BUG (backlight, uplight, glare) system ratings) for dark-sky considerations and some degree of glare control; and lighting system efficacy.

However, the DOE found that additional criteria that are needed for evaluating pedestrian lighting applications might also include: safety from tripping/falling; safety from being hit by vehicles, bicycles, or skateboarders; personal security from harm or intimidation by others; minimizing unwanted light in residential windows; appearance of the neighborhood/campus/area; minimizing glare that causes discomfort, is disabling, or affects viewer adaptation level.

LighTimes: Lighting for Tomorrow 2014 Competition Launched

January 16, 2014…Lighting for Tomorrow launched its twelfth consecutive annual competition at the Dallas Market, January 15-19. In 2014, Lighting for Tomorrow is looking for products that meet market price points such as LED A-lamps under $10, fixtures under $50, and high lumen LED A-lamps as part of the solid state lighting competition. Similar to last year, Lighting for Tomorrow awards bonus points for lighting designed to meet the needs of the growing senior population and invites submissions of organic LED (OLED) luminiaires as part of the SSL competition.

The Lighting for Tomorrow continues to examine lighting control products, including stand alone, system, and whole house devices. Additionally, the competition continues to evaluate LED luminaires for specific applications, retrofit kits, and replacement lamps.

In 2008, the fluorescent fixture competition requested that all CFL-equipped chandeliers be able to dim. Following this advance, a fluorescent dimming competition in 2009 sought good quality dimming in both fixtures and CFLs. From 2010 to 2013, Lighting for Tomorrow held a lighting controls competition that required lighting control devices to be compatible with fluorescent or LED technology. This lighting controls competition will be continued in 2014.

The judging panel will be evaluating products based on functionality, ease of installation and use, innovation, and ability to work with other systems and existing luminaires. Lighting for Tomorrow seeks a broad range of residential LED products such as fixtures, retrofit kits, and replacement lamps. The competition increased its scope in 2013 with the inclusion of OLED fixtures, and plans to continue with this category in 2014. Entries will be judged on lighting performance, marketability, and energy efficiency. In 2013, ten winners, five honorable mentions, and two noteworthy products were selected including manufacturers Acuity Brands, Edge Lighting, Evolution Lighting, Juno Lighting, LEDnovation, Legrand, LITON lighting, Nesora Lighting, Philips Lighting, Prism Co. Ltd, Samjin Lnd Co. Ltd, SWITCH Lighting, and WAC Lighting.

The first deadline for intent to submit for this year’s competition is April 18, 2014. Winners will be announced during an award ceremony at the ALA Conference,September 16, 2014 in Nashville, Tennessee and will be eligible to be promoted by energy efficiency programs across the US and Canada during the following year. For complete guidelines and rules for the 2014 competition, see www.lightingfortomorrow.com.

AOTF Spectral Imaging for Cancer Detection

Alex Fong, VP, Life Sciences

High throughput screening of multiply stained clinical pathology samples is currently a difficult and laborious task requiring expert review. In examining a patient slide, pathologists rely primarily on examination of cellular morphology and tissue architecture. While this approach has been the backbone of pathology for many decades, the discovery of numerous molecular biomarkers of disease has lent increasing importance to the role of biomarkers in detecting abnormalities and determining proper treatment. However, individual biomarkers generally do not have sufficient sensitivity and specificity to identify disease and there has been growing recognition that the use of multiple biomarkers is highly desirable. Optimally the pathologist would like to see the multiple biomarkers of interest and the morphology of interest simultaneously throughout the slide. But multiply stained slides can be very difficult to interpret by eye. We have therefore applied our Acousto-Optic tunable filter (AOTF) based HSi-440C Hyper-Spectral Imaging system to imaging traditionally stained clinical pathology samples to which additional transmission stains labeling multiple specific biomarkers have been added.

For spectrally imaging a multiply stained sample the number of different wavelengths required is in principal the same as the number of independent stains, and therefore spectra, in the sample. Our experience has been, however that that many more wavelengths than this are often needed for highest quality results. The actual number required depends on the number of stains used, the degree to which they spectrally overlap, and the complexity of the sample being imaged.

The figure below illustrates this important point. On the far left is a color image of Pap-stained cervical cells co-stained for the biomarker p16 with Deep Space Black. The Pap stain itself is actually a combination of four separate stains (Hematoxylin, Eosin, Fast Green, and OG6), each of which stains different parts of different types of cells, for a total of five stains in this sample. Hematoxylin is the main nuclear stain of primary importance for morphologic evaluation. The best possible unmixed Hematoxylin image for various number of unmixing wavelengths is shown in the four images to the right. It can be seen that analysis results using 6 wavelengths is far from adequate, and approximately 30 wavelengths are required for best results

Pap-stained cervical cells co-stained for the biomarker p16 with Deep Space Black
Pap-stained cervical cells co-stained for the biomarker p16 with Deep Space Black

Spectral imaging of Hematoxylin in a traditional Pap slide requires nearly 30 wavelengths to be accurate. The high speed and flexibility of the AOTF make this practical.

A clinical sample often requires many hundreds of fields of view in order to cover an entire slide under a microscope, even at low magnification. A multi-stained sample therefore requires dozens of wavelengths and thousands of wavelength changes per slide. In high-throughput clinical applications, it is essential that the slide scan time be reduced to a minimum. For multispectral high-throughput scanning, it is therefore necessary that the wavelength switching be accomplished fast enough so as not to slow down the native frame rate of the camera. The AOTF’s ~100 microsecond switching time and spectral flexibility together with their superior imaging quality make them an ideal choice for this application.

The AOTF based HSi-440C has now been applied to cervical cancer detection and shown to provide the pathologist with significant additional information to aid in more accurate interpretation. More details of these results will be in the next newsletter. For more information please contact alex.fong@goochandhousego.com.

LighTimes: GaN-on-Silicon LEDs Forecast to Increase to 40 Percent of Market Share by 2020, According to IHS

December 10, 2013…IHS Inc predicts that the penetration of gallium nitride-on-silicon (GaN-on-Si) wafers into the LED market will increase at a compound annual growth rate (CAGR) of 69 percent from 2013 to 2020. IHS forecasts that by 2020, GaN-on-Silicon LEDs will account for 40 percent of all GaN LEDs manufactured.

In 2013, 95 percent of GaN LEDs will be manufactured on sapphire wafers. However, only 1 percent will be manufactured on silicon wafers. This will soon change according to IHS. The growth in the manufacturing of GaN-on-Si LEDs between 2013 and 2020 will take market share from both sapphire and silicon carbide wafers, according to IHS predictions. The accompanying figure shows the GaN-on-Si LED market share outlook in terms of revenue for the packaged LED market.

“Manufacturing large ingots made from sapphire is difficult, whereas silicon wafers are available from 8 inches up to 12 inches and are generally cheaper and more abundant,” said Dkins Cho, senior analyst for lighting and LEDs at IHS. “There is a large pre-existing industry for silicon-based manufacturing that is leveraged to create economies of scale and reduce the cost of an LED.”

IHS says that the shift to producing GaN-on-silicon LEDs is generally accepted to require minimal with manufacturers only having to repurpose their facilities. IHS notes that companies that previously manufactured CMOS semiconductors already own legacy 8-inch CMOS fabrication units that can be converted for LED production with a small modification. Furthermore, IHS says that these companies already have in-house expertise and technology associated with silicon-based processes.

“Many of the CMOS semiconductor manufacturers already have excellent inspection tools, unlike traditional LED companies,” Cho said. “This could help increase their process yield through in-situ monitoring. However, it is unlikely the repurposing will happen overnight; instead we forecast a shift during the coming years.”

LighTimes: The DOE Office of Science Announces SBIR/STTR Funding Opportunity

November 26, 2013…The U.S. Department of Energy (DOE) Office of Science has announced a funding opportunity for its Small Business Innovation Research (SBIR) and Small Business Technology Transfer (STTR) programs that may be of interest to the solid-state lighting (SSL) community. The DOE is requesting that the SSL community submit grant applications for fiscal year 2014 SBIR/STTR Phase I, Release 2 funding opportunities with the release of the announcement (FOA) DE-FOA-0001046. Specifically, the DOE SBIR/STTR funding opportunity announcement, (FOA) DE-FOA-0001046 seeks applicants for research and development of the subtopic: “integrating energy-efficient solid-state lighting with advanced sensors, controls, and connectivity.”

According to the DOE, other possible areas of interest related to SSL in the funding opportunity include: the use of advanced manufacturing processes such as 3-D printing and digital metal forming to create SSL lamps and luminaires in ways that were previously not possible; the use of fully automated assembly, advanced printing, and integrated electronics designs that may provide substantial opportunity to inexpensively and quickly manufacture high-quality SSL products; inexpensive and easily integrated components, sensors, control hardware, or control software.

The DOE is offering a free webinar to review the SBIR/STTR programs and the award process as it relates to this announcement on Tuesday, December 3, at 2:00 p.m. ET. Those interested in listening to and participating in the webinar must register. Letters of intent to submit proposals are due with the DOE’s Office of Science December 16, 2013. Full proposals are due February 4, 2014, with award notifications anticipated in April. For more information, visit http://science.energy.gov/sbir/funding-opportunities/.