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Table 1 Radiometric and photometric comparisons of the light devices used in the three treatment groups

From: Transcranial bright light treatment via the ear canals in seasonal affective disorder: a randomized, double-blind dose-response study

Group Spectral characteristics Luminous flux (lumen) Illuminance (lux) Irradiance (μW/cm2) Photon density (photons/cm2/s)
1 λmax ≈ 448 Nm 1 2386 720 2.00 × 1015
2 λmax ≈ 448 Nm 4 9542 2881 7.98 × 1015
3 λmax ≈ 448 Nm 9 21470 6482 1.80 × 1016
  1. Values are measured and calculated from one randomly selected light source. Illuminance and photon density are measured at a distance of 1 cm from the light source. There were minor differences in the spectral compositions between light sources.