Bright, laser-based lighting devices

New low-heat, high-efficiency white lighting options described in the journal 'AIP Advances'

2013-09-27

(Press-News.org) WASHINGTON D.C. Sept. 27, 2013 -- As a modern culture, we crave artificial white lights -- the brighter the better, and ideally using less energy than ever before. To meet the ever-escalating demand for more lighting in more places and to improve the bulbs used in sports stadiums, car headlights and street lamps, scientists are scrambling to create better light-emitting diodes (LEDs) -- solid state lighting devices that are more energy efficient than conventional incandescent or fluorescent light sources.

Just one thing stands in the way: "droop," the term for a scientific problem related to LEDs currently in use. Droop refers to the fact that LED efficiency falls as operating currents rise, making the lights too hot to power in large-scale applications. Many scientists are working on new methods for modifying LEDs and making progress toward cooler, bigger and brighter bulbs.

Now investigators at University of California, Santa Barbara, led by material scientists Kristin A. Denault and Michael Cantore, have devised an alternative means of creating high-power white light by using a different excitation source -- a laser diode in combination with inorganic phosphors, instead of the traditional LEDs.

Their laser-based lighting options are high in efficiency and high in performance metrics, according to their study, which is described in the journal AIP Advances, which is produced by AIP Publishing.

"We found two ways to create high-intensity 'cool' white light, explained Denault. "In one we used a blue laser diode and yellow-emitting phosphor powder with a luminous flux of 252 lumens, which is comparable to current high-brightness white LEDs. For our second method, we used a near-ultra-violet laser diode and a combination of red-, green-, and blue-emitting phosphors."

They also achieved a variety of other color temperatures with high color rendition, broadening the range of applications for these new lights, she said.

INFORMATION:

The article, "Efficient and stable laser-driven white lighting" by Kristin A. Denault, Michael Cantore, Shuji Nakamura, Steven P. DenBaars, and Ram Seshadri appears in the journal AIP Advances. See: http://dx.doi.org/10.1063/1.4813837

ABOUT THE JOURNAL

AIP Advances is a fully open access, online-only, community-led journal. It covers all areas of applied physical science. With its advanced web 2.0 functionality, the journal puts relevant content and discussion tools in the hands of the community to shape the direction of the physical sciences. See: http://aipadvances.aip.org

ELSE PRESS RELEASES FROM THIS DATE:

3-D models of electrical streamers

2013-09-27

WASHINGTON D.C. September 27, 2013 -- Streamers may be great for decorating a child's party, but in dielectrics, they are the primary origin of electric breakdown. They can cause catastrophic damage to electrical equipment, harm the surrounding environment, and lead to large-scale power outages. Understanding streamers and the mechanisms behind their initiation, acceleration and branching is necessary to devise better solutions to avoid them. As recently reported in the Journal of Applied Physics, a team of researchers at MIT have developed an accurate 3-D model of streamer ...

A new paradigm for nanoscale resolution MRI has been experimentally achieved

2013-09-27

A team from the University of Illinois at Urbana-Champaign and Northwestern University has devised a novel nuclear magnetic resonance imaging (MRI) technique that delivers a roughly 10¬nanometer spatial resolution. This represents a significant advance in MRI sensitivity -- modern MRI techniques commonly used in medical imaging yield spatial resolutions on the millimeter length scale, with the highest-resolution experimental instruments giving spatial resolution of a few micrometers. "This is a very promising experimental result," said U. of I. physicist Raffi Budakian, ...

Folic acid deficiency has multigenerational effects

2013-09-27

Researchers from the universities of Calgary and Cambridge, UK, have discovered that a mutation in a gene necessary for the metabolism of folic acid not only impacts immediate offspring but can also have detrimental health effects, such as spina bifida and heart abnormalities, on subsequent generations. The animal study, published this week in the journal Cell, also sheds light on the molecular mechanism of folic acid (also known as folate) during development. About one in 1,200 children are born with spina bifida. The detrimental effects of folic acid deficiency during ...

Joslin identifies immune cells that promote growth of beta cells in type 1 diabetes

2013-09-27

BOSTON - (September 27, 2013) - Joslin researchers have identified immune cells that promote growth of beta cells in type 1 diabetes. This study provides further evidence of a changed role for immune cells in type 1 diabetes pathology. The study appears online today and will also appear in the January issue of Diabetes. In type 1 diabetes, the immune system infiltrates pancreatic islets and destroys insulin-producing beta cells. However, previous studies in non-obese diabetic (NOD) mice have suggested that immune cells can also contribute to preserving beta cells. This ...

Study: New medical device extremely effective at preventing HIV in women

2013-09-27

It's often said that the HIV/AIDS epidemic has a woman's face. The proportion of women infected with HIV has been on the rise for a decade; in sub-Saharan Africa, women constitute 60 percent of people living with disease. While preventative drugs exist, they have often proven ineffective, especially in light of financial and cultural barriers in developing nations. A new intravaginal ring filled with an anti-retroviral drug could help. Developed with support from the National Institute of Allergy and Infectious Diseases by Northwestern University visiting associate professor ...

Oncogenic signatures mapped in TCGA a guide for the development of personalized therapy

2013-09-27

New York, September 27, 2013 -- Clinical trial design for new cancer therapies has historically been focused on the tissue of origin of a tumor, but a paper from researchers at Memorial Sloan-Kettering Cancer Center published on September 26 in Nature Genetics supports a new approach: one based on the genomic signature of a tumor rather than the tissue of origin in the body. It is well known that the emergence of cancer is a multi-step process, but because of the efforts of The Cancer Genome Atlas (TCGA), funded by the US National Institutes of Health, and other large-scale ...

Setting blurred images in motion improves perception

2013-09-27

Philadelphia, Pa. (September 26, 2013) - Blurred images that are unidentifiable as still pictures become understandable once the images are set in motion. That's because of a phenomenon called "optic flow"—which may be especially relevant as a source of visual information in people with low vision, reports a study 'With an Eye to Low Vision: Optic Flow Enables Perception Despite Image Blur' (published online ahead of print, September 3, 2013) in the October issue of Optometry and Vision Science official journal of the American Academy of Optometry. The journal is published ...

Study examines health of kidney donors

2013-09-27

Washington, DC (September 26, 2013) — The short-term risks associated with kidney donation are relatively modest, but because many donors have additional medical conditions, it is important to evaluate their ongoing health. That's the conclusion of a study appearing in an upcoming issue of the Clinical Journal of the American Society of Nephrology (CJASN). In more than a third of kidney transplantations performed in the United States, the transplanted organs come from live donors. Research suggests that there are minimal health consequences for donors, but only a few ...

NASA Mars rover Curiosity finds water in first sample of planet surface

2013-09-27

Troy, N.Y. – The first scoop of soil analyzed by the analytical suite in the belly of NASA's Curiosity rover reveals that fine materials on the surface of the planet contain several percent water by weight. The results were published today in Science as one article in a five-paper special section on the Curiosity mission. Rensselaer Polytechnic Institute Dean of Science Laurie Leshin is the study's lead author. "One of the most exciting results from this very first solid sample ingested by Curiosity is the high percentage of water in the soil," said Leshin. "About 2 ...

Wildlife face 'Armageddon' as forests shrink

2013-09-27

Singapore, 27 September 2013 – Species living in rainforest fragments could be far more likely to disappear than was previously thought, says an international team of scientists. In a study spanning two decades, the researchers witnessed the near-complete extinction of native small mammals on forest islands created by a large hydroelectric reservoir in Thailand. "It was like ecological Armageddon," said Luke Gibson from the National University of Singapore, who led the study. "Nobody imagined we'd see such catastrophic local extinctions." The study, just published ...

Bright, laser-based lighting devices

ELSE PRESS RELEASES FROM THIS DATE:

LAST 30 PRESS RELEASES: