A study to assess the detection and acceptability of flicker and stroboscopic effects under different lighting conditions was conducted. Frequencies from 50 Hz to 300 Hz were assessed, as well as different modulation amounts, duty cycles, waveform shapes and correlated colour temperatures. For the range of conditions evaluated, direct perception of flicker was negligible at 100 Hz or higher, but stroboscopic effects could be perceived at 300 Hz. Reducing flicker modulation from 100% to 33% decreased perception of stroboscopic effects. A higher duty cycle was associated with slightly lower discomfort. The implications for solid-state lighting systems producing high-modulation flicker are discussed.

Previous studies have demonstrated that the perception of stroboscopic effects from flickering light is strongly influenced by both the frequency and the amount of modulation (e.g. percent flicker). The relationship, if any, between these factors for the detection and acceptability of stroboscopic effects has not been elucidated under conditions corresponding to illuminating engineering practice. In a laboratory study, participants reported whether they could detect stroboscopic effects from flickering light with a range of frequencies and percent flicker values, and if detected, whether it was acceptable. The resulting data can provide functional relationships between frequency and percent flicker in terms of detection and acceptability of stroboscopic effects under conditions corresponding to those tested.

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Recently, there has been increased interest in energy-efficient lighting as energy resources become higher in demand. Anecdotal evidence suggests that certain populations believe light-emitting diodes (LED) produce more glare than traditional technologies. This may be due to a number of factors such as spectral power distribution (SPD), source luminance, or beam intensity distribution. A study was conducted to assess the effect of different SPDs on the perception of discomfort glare from an LED source. For the range of conditions evaluated, the presence of any luminous surround significantly reduced the perception of discomfort glare from the LED array. The blue luminous surround reduced discomfort glare perception significantly less than the white or the yellow luminous surrounds. The implications for solid-state lighting systems are discussed.