What is Light Flicker?

Light Flicker is the term used to refer to rapid, repeating changes to the brightness of light over time. Flicker can be identified through a light that appears to flutter and is unsteady. It can be caused by the lights voltage supply changing, or when the voltage of the power line itself fluctuates.

Flicker can vary in severity, there are multiple factors that affect this such as:

  • How often the voltage fluctuates
  • The amount the voltage changes
  • The type of light – fluorescent, incandescent, HID (high intensity discharge lighting systems) or LED (light emitting diodes)
  • The gain factor of the lamp (how much the light intensity changes when the voltage fluctuates – % relative change in the light levels) divided by (% relative fluctuation in voltage)
  • Ambient light levels (amount of light in the lighted area)

Health Effects of Flicker

Theoretically, humans are incapable of detecting the flicker from florescent lights, yet studies have shown individual’s sensory systems detecting flicker. Since the introduction of fluorescent lighting into workplaces, there has been an increase in the reports of headaches, eyestrain and other forms of discomfort from those exposed.

These complaints have been associated with the light flicker from fluorescent lights. When compared to regular fluorescent lights with magnetic ballasts, the use of high frequency electronic ballasts (20,000 Hz or higher) in fluorescent lights resulted in more than a 50% drop in complaints of eye strain and headaches. There tended to be fewer complaints of headaches among workers on higher floors compared to those closer to ground level; that is, workers exposed to more natural light experienced fewer health effects

Detecting and Measuring Flicker with GL Optic’s GL SPECTIS TOUCH + FLICKER

If you are looking for reliable, precise and intuitively operated spectral instrument for light assessment, the GL Optic state-of-the-art light measuring tool, the GL SPECTIS 1.0 Touch + Flicker, is the best answer to all your spectral light measurement needs.

GL SPECTIS 1.0 Touch + Flicker is an intuitively operated touch screen version of the successful SPECTIS 1.0 product line. If you need to measure light output and colour together with optical flicker quantities the highly portable and precise GL SPECTIS 1.0 Touch + Flicker is the perfect solution. This device combines spectral illuminance instrument with flicker measurement electronics.



  • Light sources quality control and flicker measurement. Flicker impacts workplace comfort and effectiveness while reducing visual task performance and productivity
  • Lighting flicker measurement at sports arenas, public events and commercial activities. Slow motion video recordings are significantly affected by flickering lights, which have a strong impact on video quality


Optical flicker metrics:

  • flicker frequency
  • flicker index
  • flicker ratio
  • flicker graph and FFT graph available

To find out more about our GL SPECTIS 1.0 Touch + Flicker click the button below or learn more about our other Light Measurement Solutions.


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