Flicker (light)

Twinkling, also called scintillation, is a generic term for variations in apparent brightness, colour, or position of a distant luminous object viewed through a medium.

Light meters and image sensors can potentially detect flicker at much higher frequency bands than human vision.

[3] Various scientific committees have assessed the potential health, performance and safety-related aspects resulting from TLMs, including light flicker.

[4][5][6] Adverse effects of flicker of include annoyance, reduced task performance, visual fatigue, headache and epileptic attack by photosensitive persons.

The magnitude, shape, periodicity and frequency of the TLMs will depend on many factors such as the type of light source, the electrical mains-supply frequency, the driver or ballast technology and type of light regulation technology applied (e.g. pulse-width modulation).

TLMs and resulting flicker can be seen also while driving with a certain speed along a street or through a tunnel lit by lighting equipment positioned with a regular spacing.

There are much more factors that determine the visibility of TLMs as flicker: All observer-related influence quantities are stochastic parameters, because not all humans perceive the same light ripple in the same way.

The perceptibility scale of PstLM (and PstV) is chosen such that a value of 1.0 corresponds to a level at which 50% of human test subjects judge the flicker to be both noticeable and irritating (Figure 1).