formatting link
"Human vision is adversely affected by light fluctuations at frequencies up to 200 Hz, even though people can only directly perceive fluctuations at frequencies up to about 70 Hz. The fundamentals of the sensitivity of the human eye to rapidly changing light (transient light artifacts or TLAs) as a function of frequency have been well known to science for a decade or more. Despite this, the lighting industry has so far limited itself to only characterizing light sources over the range of frequencies which the human eye can perceive directly. This range is below 100 Hz. However, it is well documented that human visual performance is degraded by the presence of light fluctuations at frequencies in the range from 100 to 200 Hz. Here we will describe a new flicker metric/tool that includes consideration of higher frequencies and further discuss an AC-LED light engine relative to performance against the new metric."