Figure 1.
x and y chromaticity coordinates [52] for each lamp listed in Table 2.
On that figure, the spectral locus, which is the line for monochromatic light, is shown by the thick black line. Thin black lines indicate color zones. Black squares show monochromatic values, while small black circles are lamps.
Figure 2.
Various spectral sensitivities: human eye photopic [44] and scotopic [41] spectral sensitivity; MSAS: human melatonin suppression action spectrum; PAS: photosynthesis action spectrum.
Figure 3.
Constant lumen spectral power distributions.
A subset of the spectrum used in this paper is shown here. Pane (a) shows HID lamps, pane (b) illustrates white LEDs, (c) shows low blue content broadband LEDs and (d) shows thermalized spectra such as for halogen and incandescent lamps and our reference D65 illuminant from the Commission Internationale de l’Éclairage (CIE). D65 illuminant corresponds to a midday Sun in Western/Northern Europe with CCT∼6500 K. LED filtering was performed using the Equilib optical filter commercialized by Ledtech International.
Table 1.
Parameters of the lognormal components of the MSAS fit.
Table 2.
Photometric characteristics of lamps under direct lighting.
Figure 4.
Spectral impact of the atmospheric transfer function as a function of the distance for the CIE D65 illuminant without cloud cover in (a) and with cloud cover in (b).
Direct SPD relates to the original SPD before any atmospheric transformation. Compared to direct SPD, scattered SPD is bluer at short distances and redder at long distances.
Table 3.
Photometric characteristics of lamps after scattering into the atmosphere.
Figure 5.
Atmospheric scattered Melatonin Suppression Index dependency, with distance between lamp and observer, (a) and (c) for usual street lamps and (b) and (d) for new technologies that reduce light pollution.
The two upper plots (a) and (b) are for clear sky conditions, while (c) and (d) are for cloudy sky conditions.
Figure 6.
Same as Figure 5 but for Induced Photosynthesis Index.
Figure 7.
Same as Figure 5 but for Star Light Index.