Did you ever see a scientist waving her finger to a lamp? It is a quick way to find out whether the lamp causes flicker or stroboscopic effects. Cheap low-quality lamps then let you see a multitude projected fingers in stead of a single one.

Our electricity grid provides power as 50 Hz alternating current. LED lamps run on DC. The conversion from AC to DC may cause flicker in the light. Gosia Perz reports not only on what she sees happening in the market (LEDs have improved) but also on innovations and technical progress reported at LS24. These temporal light effects were the topic a special session at LS24.