Flicker:
It’s Not Just Annoying. New Results of Work on the Phantom Array Effect

You might see it at the Paris Opera House, or your favorite bistro, or your home bathroom, or the car driving toward you. Or, you may see no repeating patterns (i.e., the phantom array effect) from flickering lights at all. Therein lies the quandary: A chunk of observers see nothing; while others may experience headaches, migraines, disorientation, or worse from this flavor of temporal light modulation (“flicker”). In the effort to ensure energy-efficient lighting technologies also provide comfortable environments, PNNL completed an experiment comparing the sensitivity of migraineurs and non-migraineurs. There was a wide range of visibility to surprisingly high frequencies of modulation, as well as differences in sensitivity and in post-experiment outcomes between the groups. Beyond these experimental results, this presentation will discuss new data on the prevalence of flicker in schools, the forthcoming specification guidance in IES TM-39, and the new phantom array visibility metric. Whether you see flicker or not, come to learn why this is an increasing concern with LED systems and how it can be fixed.

Knowledge of basic lighting terminology, especially temporal light modulation is recommended.

Learning Objectives

• Comprehend why LED lighting systems are more prone to flicker than conventional sources.
• Be able to list potential health implications of temporal light modulation (headaches, nausea, migraine, disorientation, etc.)
• Experience what the stroboscopic effect looks like, as well as the phantom array effect. Articulate the four principal waveform characteristics contributing to flicker visibility and detection.
• Understand the three recommended metrics that apply to different frequency ranges, and target values for these ranges in different applications and for different populations.