IES LM-90-20

Cyclic variations in luminous output from a light source or lighting system are known as temporal light modulation (TLM). TLM is known to affect visual perception, cognition, and brain activity. The variety of TLM patterns of solid-state lighting has brought these effects to the attention of the lighting community. Research seeks to create new metrics that predict the occurrence of visual, cognitive, and neurological effects based on measurements of the physical stimulus, the luminous flux waveform. This document describes the procedures to be followed and precautions to be observed in performing reproducible luminous flux waveform measurements for use in temporal light artifact (TLA) calculations under standard conditions. It provides a description of the method of measurement, equipment requirements, and formulation of luminous flux waveforms for use in the calculations of temporal light artifacts from light sources. Luminous flux waveforms utilized in TLA calculations are for luminous flux frequencies between 1 Hz and 3,000 Hz under various control conditions. In addition, data reporting formats are described. Intentionally flashing or signaling lights outside the defined frequency range are not included within the scope of this document.