Soraa Discusses Strong Effect of Whiteness Rendering on Lighting and Object Preference

Understanding that quality of light is essential to the widespread adoption of LED lighting, Soraa discussed this week at SPIE Photonics West 2014 how whiteness rendering has a strong effect on lighting and object preference.

Soraa explained that the brilliant, shimmering appearance of bright white objects, whether man-made or natural, is not simply a result of their reflective optical properties. The apparent whiteness of teeth in a smile, for instance, is arrived at by virtue of fluorescence: short wavelength light from the sun is absorbed by human teeth and re-emitted in the blue. This causes an increase in apparent brightness and whiteness to the eye of the beholder.

In the mid-20th century, textile manufacturers developed a similar process to create clothing that appears truly white. Without the fluorescence effect, white materials were not particularly conspicuous and did not evoke a lustrous appearance. Chemists developed Optical Brightening Agents (OBA's) that were incorporated into textiles and perform the function of absorbing short wavelength light and re-emitting in the blue, thus enhancing their whiteness. This approach was extremely successful and was transferred beyond textiles to several different industries including detergents, paper, plastics, and cosmetics.

Until recently, electric light sources such as incandescent and fluorescent exhibited some short wavelength emission and interacted with OBA's to render whiteness in a familiar and pleasant manner. However, most LED manufacturers in their race to maximally efficient, low cost light sources skipped the short wavelength regime altogether, resulting in blue-LED based lighting products that cannot excite OBA's and thus cannot render whiteness.

Uniquely, Soraa's full visible spectrum GaN on GaN™ LED lamps are engineered to emit all colors of the rainbow, including violet, which excites OBAs and perfectly render whiteness. The company unveiled independent psychophysical research, conducted at Penn State University, that showed participants overwhelmingly preferred its full visible spectrum LED lamps to LED lamps that lacked the short wavelength range of the spectrum in rendering whiteness. In fact, whether looking at a white dress shirt or their own smile, 90% of users preferred the whiteness rendering of Soraa's lamps. The details of the research will be published in an upcoming article in LEUKOS, the journal of the Illuminating Engineering Society of North America.

"Because our lamps beautifully render the entire visible spectrum, white fabrics and paper goods pop, plastics are brilliant and people's smiles are whiter," said Mike Krames, CTO of Soraa. "That's good news for consumers and retailers, who want the enormous economic and environmental benefits of LED lighting, but are unwilling to sacrifice light quality in return."