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Since 2009, DOE has conducted research on the visual phenomenon known as flicker. Flicker is defined as rapid variation in light source intensity, which can cause visual effects ranging from uncomfortable to harmful or dangerous. In response, the Institute of Electrical and Electronics Engineers (IEEE) formed an industry standards committee on flicker, co-chaired and staffed by DOE technical experts, among others. The work of this committee produced IEEE recommended practice P1789-2015 for evaluating flicker risks, and ENERGY STAR® and California’s Title 20 are requiring the reporting of flicker performance and/or considering the adoption of flicker criteria. Some manufacturers appear to be giving flicker increased design priority, as evidenced by the improved performance of new product generations.

An understanding of why flicker matters and how much it varies across commercially available products is increasingly becoming essential to proper lighting design. Specifying the right product for a given application and risk sensitivity further requires the ability to quantitatively characterize flicker. At this time, however, there is no standardized test procedure for measuring photometric flicker from light sources, and manufacturers rarely report flicker characteristics.

Ideally, a test-and-measurement procedure would facilitate the capture of light-source intensity or luminance over time and potentially describe how to characterize periodic waveform characteristics (e.g., amplitude modulation, shape or duty cycle, frequency) using one or more metrics. DOE continues to contribute expertise and technical support by participating in the Illuminating Engineering Society (IES) Testing Procedures Committee on a Method of Measuring Optical Waveforms for use in Temporal Light Artifact (TLA) Calculations and the International Commission on Illumination (CIE) Technical Committee 1-83: Visual Aspects of Time-Modulated Lighting Systems, both of which are considering the development of standardized test and measurement procedures for flicker.


The growing awareness of flicker has led to a profusion of handheld flicker meters that have come on the market to help users determine in the field if flicker is occurring and, if so, whether the level is acceptable for the application in question. These handheld meters range from simple smartphone applications to scientific-grade meters. DOE has conducted two studies of flicker meters – one on the handheld variety and the other on benchtop models – to determine how they perform and to identify any issues.

  • Characterizing Photometric Flicker: Handheld Meters
    2018 Study documents the capabilities and accuracy of eight newly available handheld meters capable of measuring flicker in the field, compared to a reference benchtop meter.
  • Characterizing Photometric Flicker
    2016 Study compares three benchtop laboratory meters against a reference system to evaluate their performance and accelerate development of standard test and measurement procedures.

The increased availability of more-affordable and easier-to-use measurement devices in the previous two years reflects the growing awareness of flicker by lighting technology developers, and improved ability to address it through emerging measurement methods and recommended practices.


Flicker Basics
A DOE Solid-State Lighting video about flicker, featuring commentary by Naomi Miller of Pacific Northwest National Laboratory.
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Flicker Measurement and Standards
A DOE Solid-State Lighting video about flicker measurement and standards, featuring commentary by Naomi Miller of Pacific Northwest National...
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Flicker Demonstration
A DOE Solid-State Lighting video demonstrating visible flicker, featuring commentary by Naomi Miller of Pacific Northwest National Laboratory.
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2019 Webinar: Metrics in Motion: Flicker & Glare

2018 Report: Characterizing Photometric Flicker: Handheld Meters

2016 Report: Characterizing Photometric Flicker

2013 Technology Fact Sheet: Flicker

2015 CALiPER Report  22.1: Photoelectric Performance of LED MR16 Lamps

2014 CALiPER Report 20.2: Dimming, Flicker, and Power Quality Characteristics of LED PAR38 Lamps

2013 CALiPER Exploratory Study: Recessed Troffer Lighting

2014 CALiPER Retail Lamps Study 3.1: Dimming, Flicker, and Power Quality Characteristics of LED A Lamps

2012 Presentation: LED Dimming: What You Need to Know

2014 Presentation: SSL Flicker Fundamentals and Why We Care

2015 Presentation: Flicker: Understanding the New IEEE Recommended Practice

IEEE Standard 1789-2015: IEEE Recommended Practices for Modulating Current in High-Brightness LEDs for Mitigating Health Risks to Viewers

2010 Conference Abstract: LED Lighting Flicker and Potential Health Concerns: IEEE Standard PAR1789 Update

1989 Journal Abstract: Fluorescent Lighting, Headaches and Eye-Strain

1995 Journal Article: Modulation of Fluorescent Light: Flicker Rate and Light Source Effects on Visual Performance and Visual Comfort

2012 Report: ASSIST Recommends… Flicker Parameters for Reducing Stroboscopic Effects from Solid-State Lighting Systems

2015 International Electrotechnical Commission Technical Report 61547-1: Equipment for General Lighting Purposes - EMC Immunity Requirements - Part 1: An Objective Voltage Fluctuation Immunity Test Method

2014 Presentation: Objective Testing of Flicker and Stroboscopic Effects Resulting from Mains Voltage Fluctuations

2014 Journal Article: Modeling the Visibility of the Stroboscopic Effect Occurring in Temporally Modulated Light Systems