The National Electrical Manufacturers Association (NEMA) Lighting Systems Division published Temporal Light Artifacts (Flicker and Stroboscopic Effects), a position paper on temporal light artifacts (TLAs) that addresses what is commonly referred to as flicker and stroboscopic effects.

Temporal light artifacts (TLAs) are undesired changes in visual perception induced by a light stimulus whose luminance or spectral distribution fluctuates with time, for an observer in a certain environment. Depending on the details of the fluctuations, TLA consists of flicker and/or stroboscopic effect.

According to James Gaines, PhD, senior principal engineer, Philips Lighting, and chair of the

NEMA Working Group on Temporal Light Artifacts (TLAs), IEEE (Institute of Electrical and Electronics Engineers) 1789-2015 proposes limits that appear to be overly strict for many applications, which could add unnecessary cost to the electronics in LED products. He notes that even incandescent lamps do not fall within the low-risk or no-effect regions in the recommended practices. 

In this position paper, NEMA asserts that current TLA standardization is hampered by lack of adequate TLA assessment metrics and that new flicker metrics and associated measurement methods for lighting are required. Currently applied metrics do not quantify TLA correctly because they do not fully account for the effects of both the frequency and the wave-shape of the light stimulus. The human eye is sensitive to both wave-shape and frequency effects and a metric or specification that does not allow for them will be too strict for some cases and/or too lax for others.

Building on the position paper, NEMA is presently working to produce a standard for TLA measurement and define application-dependent recommendations.

Temporal Light Artifacts (Flicker and Stroboscopic Effects) may be downloaded at no charge on the NEMA website.