Flicker (light)

Flicker (Light)

Flicker sensitivity curves

Flicker in lighting refers to the rapid and repeated change in the brightness of a light source. This phenomenon can be caused by fluctuations in the power supply, the design of the lighting fixture, or the characteristics of the light source itself. Flicker can be imperceptible to the human eye or can manifest as a visible strobing effect, depending on the frequency and amplitude of the light fluctuations.

Causes of Flicker

Flicker can arise from several sources:

• Electrical Supply Variations: Changes in the voltage of the electrical supply can cause variations in the light output of lamps, particularly those that are not designed to handle such fluctuations.
• Lamp Design: Certain types of lamps, such as fluorescent lamps and LED lamps, can exhibit flicker due to the way they are powered and controlled. For example, fluorescent lamps can flicker if the ballast is malfunctioning.
• Dimmer Switches: The use of dimmer switches can introduce flicker, especially if the dimmer is not compatible with the type of lamp being used.

Effects of Flicker

Flicker can have several effects on both humans and equipment:

• Human Perception: Flicker can be perceived as a nuisance or discomfort, and in some cases, it can lead to headaches or eye strain. In extreme cases, flicker can trigger photosensitive epilepsy in susceptible individuals.
• Equipment Performance: Flicker can interfere with the operation of sensitive equipment, such as cameras and other optical devices, leading to artifacts in images or video recordings.

Measurement of Flicker

Flicker influence quantities

Flicker is typically measured using metrics such as the flicker index and the percent flicker. These metrics quantify the extent and frequency of light output variations:

• Flicker Index: This is a measure of the cyclic variation in output of a light source. It takes into account the waveform of the light output and is a more comprehensive measure than percent flicker.
• Percent Flicker: This is a simpler measure that calculates the difference between the maximum and minimum light output as a percentage of the sum of the maximum and minimum.

Mitigation of Flicker

To reduce or eliminate flicker, several strategies can be employed:

• Use of High-Quality Ballasts and Drivers: Ensuring that lighting fixtures are equipped with high-quality electronic ballasts or LED drivers can minimize flicker.
• Stable Power Supply: Maintaining a stable electrical supply with minimal voltage fluctuations can help reduce flicker.
• Compatible Dimmers: Using dimmers that are specifically designed for the type of lamp being used can prevent flicker when adjusting light levels.

Related Pages

• Fluorescent lamp
• LED lamp
• Photosensitive epilepsy
• Ballast (electrical)