Visual performance in the mesopic range of outdoor lighting V Kulbokaite1, R Stanikunas1, A Svegzda1, A Zukauskas1, A Tuzikas1, R Vaicekauskas2, P Vitta1, A Petrulis1, P Eidikas1, A Zabiliute3 |
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1Vilnius University, Lithuania |
| The search for cost-efficient outdoor lighting has brought light-emitting diode (LED) lamps as a replacement for older type high-pressure sodium lamps (HPS). Various LED lamps have been introduced in the market and there is little data about visual performance in the mesopic range under those LED illuminations. The aim of this research was to evaluate visual performance in the mesopic range under two illumination conditions: HPS lamp and LED lamp optimized for minimal disruption of circadian rhythm [Zukauskas et al, 2012, Applied Optics, 51(35), 8423-8432]. During the experiment the subject was fully adapted to LED or HPS illuminance. Four luminance levels 0.1, 0.3, 1 and 3 cd/m2 were used. Visual performance was evaluated by reaction time (RT) to low contrast stimulus displayed at 18 deg eccentricity from the fixation point and colour discrimination with the Farnsworth-Munsell Test (FMT). Results showed that RTs and FMT scores for colour discrimination were better under all luminance levels of LED lamp in comparison to HPS. For both illuminants RT degradation had logarithmic dependency from increasing luminance, while colour discrimination was reducing linearly with diminishing luminance. [Supported by the Research Council of Lithuania ATE-01/2012] |
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