New facility enables color rendering experiments for solid-state lighting sources

Imagine sitting on a comfortable couch in a well-lit room in NIST’s Vision Science Laboratory.  A vase of red flowers sits on a table before you.  Suddenly, the lighting spectrum changes, and the red flowers become intensely vivid.  You think this lighting is fabulous until you look in a mirror – your face appears flush and blotchy.  Although the room appears to be illuminated with white light in both cases, your color perception has changed.  This makes you wonder.  How do we perceive colors under different lighting spectra?  Why do some people dislike the white light produced by fluorescent lamps? Which spectral combination gives the best color quality and energy efficiency?

NIST’s new Spectrally Tunable Lighting Facility will enable this research.  The facility consists of two room-size, furnished cubicles in which observers can be completely immersed in a real-life setting.  Each cubicle is illuminated by a spectrally tunable light source (STLS) composed of 1,800 high-power LEDs under computer control.  Organized into 22 wavelength channels, the LEDs span the visible spectral range of 440 to 640 nm and can be set to simulate the spectra of various types of broadband lighting. 

LEDs, both semiconductor and organic, have the potential to dramatically reduce energy costs due to their energy efficiency and longevity.  Indeed, recent legislation promotes energy savings through standards for lighting and the further development of solid-state lighting technology.  However, current color-rendering standards, developed for traditional lamps, are problematic when applied to LEDs.  Recognizing this issue within the lighting community, researchers in the Optical Sensor Group began building the Spectrally Tunable Lighting Facility as an IMS program in 2005. 

Now that the facility is completed, researchers will use it to test a new color quality scale, investigate optimum spectral compositions of white light to achieve superior color quality, and achieve high energy efficiency.  The results of these experiments will lead to new international standards and provide manufacturers with knowledge they need to develop products that are widely accepted by consumers.