Review of photometric flicker metrics and measurement methods for LED lighting

Adoption of LED lighting in large scale has opened a debate on how to evaluate performance of commercially available LED lighting products. In this paper a review of existing photometric flicker metrics and measurement methods for LED lighting products is discussed. There is an urgent need to characterize potentially visible temporal light artifacts, or popularly known as flicker from light sources. Conventional light sources like incandescent and discharge lamps modulate light output, but the severity and diversity of light modulation exhibited by LED lighting products has generated curiosity in quantifying and understanding flicker and its impact on human health and productivity. Flicker metrics like flicker index and percentage flicker are not made available in datasheets of LED lighting products. It is critical for lighting designer to obtain this important information from LED luminaire manufacturers or conduct independent testing of LED luminaires to measure flicker metrics. The data reported in this paper show great inconsistency in flicker profile waveforms (flicker profiles) of some typically commercially available LED lighting products. Flicker is hence an important characteristic that the lighting designer needs to consider in assessing LED products. This paper presents a traditional method to develop a minimum suggested performance criteria for flicker measurement and reporting, understanding the performance needs of known lighting applications and including results from significant researchers in the field. It is important to minimize the chance of mismatching LED lighting products is installed in areas where flicker can be very serious health hazard or where it can hamper productivity and human comfort.