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Flicker and stroboscopic effect

Flicker is a periodic, rapid and directly visible change in brightness of a light source, its photometric values (luminous flux), which can be due to fluctuations of the light source, which is varying (aperiodic). Flicker can cause visual discomfort at work. It can also cause migraines and even epileptic seizures.
The stroboscopic effect means a change in the perception of movement by the observer in lighting conditions changing over time. These changes can be periodic and non-periodic and can be caused by the light source itself, the power source. In an industrial environment it can cause accidents involving people, because the stroboscopic effect caused by light changes leads to a disturbance in the perception of the speed of rotating objects, such as machine parts.

New measures: PstLM and SVM

PstLM is a flicker metric introduced in the Regulation, where “st” (short term) means short term and ‘LM’ the method of measuring flicker, as defined in the standards. A value of Pst LM = 1 means that the probability that the average observer will notice flicker is 50 per cent; Table 4 of the Regulation specifies the required level of Pst LM <= 1 at full load and applies to LED and OLEDs.
SVM is a new Stroboscopic Visibility Measure – it is a new measure of the probability of a stroboscopic effect. The threshold of visibility of a stroboscopic effect is the value of SVM equal to or greater than 1. If the value is less than 1, the stroboscopic effect will not be visible for the observer. The minimum required level of SVM at full power is 0.4.


Measurements of these quantities must be made with photometric instruments. Such instruments consist of a high-performance photo-sensitive system (photodiode with transimpedance amplifier) supplemented by a V-lambda optical filter to adapt the sensitivity curve of the system to the characteristics of the human eye

Extended information -> here


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