A new lab at the National Institute of Standards and Technology (NIST) is dedicated to improving the quality of light that light-emitting diodes (LEDs) produce. NIST vision scientists Wendy Davis and Yoshi Ohno and a team of physicists created the NIST Spectrally Tunable Lighting Facility (STLF).
“Everyone wants light that appears natural and is pleasing to the eye, but with LEDs we’re not consistently there yet,” Davis says. “LEDs offer a lot of advantages over incandescent and fluorescent lighting, but they don’t always emit light that looks ‘right.’”
The STLF distinguishes itself from most optical technology labs in that it concentrates on the relationship between physical measurements of light and human perception of light and color. Here, scientists experiment with combining LEDs of different hues to produce an overall light color that pleases the eye.
One section of the lab space is decorated with couches, tables, and food-filled plates, just like a living room — but above, hundreds of LEDs cover the ceiling. Adjusting the level of different colors demonstrates the effect lighting has on the appearance of the food and furniture below. Learning from efforts like this is helping the team develop a way to quantify how LEDs affect the colors of objects in ways meaningful to the lighting industry. They are currently developing a measurement tool called the Color Quality Scale to help manufacturers develop LEDs for general lighting.
“Because the light emitted by LEDs is different from the light we get from other lighting technologies, the way that we measure color quality doesn’t always work for them. At this point, LED manufacturers don’t have a reliable way to determine the color performance of their products,” Davis says. “If we don’t handle this issue now, it could create big problems for future LED lighting products, because bad color means unhappy consumers. We want to use measurement, which is a NIST specialty, to nip this problem in the bud.”