This post was written by Keith Dawson for UBM Tech’s community Web site All LED Lighting, sponsored by Philips Lumileds. It is archived here for informational purposes only because the All LED Lighting site may go dark at any time. This material is Copyright 2013-2015 by UBM Americas.


Monday Roundup: Strawberry Shelves Forever

This week: LED headlights in our future, a push by brick-and-mortar lighting showrooms, and extending the shelf life of strawberries with UVB LEDs.

Graded refractive index LEDs win $30,000 prize
They're called GRIN LEDs, and it's possible the technology will be bringing a grin to the faces of LED engine makers. The invention certainly brought a grin to the judges of the Lemelson-Renssalaer Student Prize at Renssalaer Polytechnic Institute. They awarded the $30,000 annual prize to Ming Ma, an RPI PhD student in materials science and engineering whose thesis work revolves around GRIN.

Ming Ma (photo: RPI)

We wrote about a "factory roof" coating for LEDs, inspired by firefly lanterns, that increases light extraction from an LED. GRIN is another approach to increasing extraction efficiency. It uses nano-scale, star-shaped towers with a graduated refractive index to mate the transmissivity of the LED itself with that of the surrounding medium (e.g., air). LED light extraction efficiency is typically in the 25 percent range; GRIN has demonstrated an efficiency of 70 percent. Ma also demonstrated how the far-field emission pattern of GRIN LEDs could be tuned by shaping the geometry of the pillars -- their height, spacing, and diameter.

LED headlights to 2020
Strategy Analytics has a new report out on the market for LED headlights for automobiles and small trucks, to the year 2020. The low end of the estimate calls for 13.7 million light vehicles to be outfitted with LED headlights by that year; that's 12 percent of the market. On the high end, if LED cost reductions live up to the more optimistic estimates, 24 million vehicles (21 percent) might sport the LED lights. In order to reduce costs, many designers of LED headlights are falling back on older lighting technologies such as halogen for high beams, according to Strategy Analytics.

UVB LEDs extend strawberry shelf life
Using ultraviolet LEDs in refrigerators could more than double the shelf life of fruit and vegetables, according to a study carried out by the US Department of Agriculture. A company called Sensor Electronic Technology (SETi), from Columbia, SC, makes the UV LEDs used in the study. SETi's website hosts a summary of the USDA study's conclusions.

Tubs of strawberries under refrigeration remained free of both mold and decay after nine days, when illuminated by UVB light with wavelength in the range from 280 to 305 nm. Strawberries not so illuminated showed both mold and decay after four days. SETi says it has been working with USDA for three years to optimize the wavelengths of UV light that result in the longest preservation times while not harming anti-oxidant levels or drying out the food.

Brick & mortar lighting vendors get industry attention
The owner of a lighting showroom noticed a discarded container in his neighbor's trash. It was packaging for a chandelier -- one the showoroom owner had in stock -- and it had been purchased from an online store. The neighbor was fully aware of what this man does for a living.

The showroom owner, who prefers to remain anonymous ("It's about all of the brick-and-mortar showrooms, not me"), was understandably upset. He channeled his ire at the lighting manufacturers that feature a prominent "Buy Online" button on their websites. He figured that the manufacturers should be supporting the local showrooms that had been supporting them for decades.

After consulting with colleagues, this retailer launched Brick & Mortar Lighting, a campaign to get lighting manufacturers to stop sending visitors to online big-box stores -- or at least to offer them the option of visiting a local lighting showroom instead. Here is the open letter the campaign addresses to lighting manufacturers.

Residential Lighting magazine did not say what the reaction has been from the lighting industry.

How about you -- do you buy your LED products locally, or from one of the big online retailers?

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