stroboscopic effect visibility meter specification and verification method, and test procedures a.o. for dimmer compatibility. NEMA 77-2017: amongst others, flicker test Methods and guidance for acceptance criteria. Dangers in workplaces Stroboscopic effect may lead to unsafe situations in workplaces with fast moving or rotating machinery. If the frequency of fast rotating machinery or moving parts coincides with the frequency, or multiples of the frequency, of the light modulation, the machinery can appear to be stationary, or to move with another speed, potentially leading to hazardous situations. Because of the illusion that the stroboscopic effect can give to moving machinery, it is advised that single-phase lighting is avoided. For example, a factory that is lit from a single-phase supply with basic lighting will have a flicker of 100 or 120 Hz (depending on country, 50 Hz x 2 in Europe, 60 Hz x 2 in US, double the nominal frequency), thus any machinery rotating at multiples of 50 or 60 Hz (3000–3600rpm) may appear to not be turning, increasing the risk of injury to an operator. Solutions include deploying the lighting over a full 3-phase supply, or by using high-frequency controllers that drive the lights at safer frequencies or direct current lighting. See also 3D zoetrope Temporal light artefacts Temporal light effects Flicker (light) Flicker fusion threshold References External links https://www.youtube.com/watch?v=3_vVB9u-07I A clear example of this effect. Interactive Strobe Fountain – lets you adjust the strobe frequency to control the apparent movement of falling droplets. Yutaka Nishiyama (2012), "Mathematics of Fans" (PDF), International Journal of Pure and Applied Mathematics, 78 (5): 669–678. Film and video technology Optical illusions Articles containing video clips