VS - Lighting Systems - Lighting - 998542

5. The lighting system: what is light?

5.2.1. The luminous spectrum The visible spectrum depends on the type of light source. The following figures illustrate main light source spectrums. l Daylight is the most homogeneous light. l Light from Tungsten lamps is more into the red light spectrum (so called a hot colour). l Low pressure Sodium lamps are almost monochromatic light sources (a small wavelength range is emitted).

The diversity of light sources is linked to the variety of illumination needs as well as technologies constant evolution, some are better known than others to the public. The domestic market and regulations are pushing for low consumption and CO 2 friendly lighting technologies, compact fluorescent lamps and Halogen lamps are very common today. This trend to decrease power consumption is also true for automotive light sources but it is a partial reason for this change. Security features like night vision quality and day time visibility are major vectors too.

Tungsten

Low pressure Sodium (SOX)

100

100

80

80

60

60

40

40

Relative power

Relative power

20

20

0

0

400

500

600

700

800

400

500

600

700

800

450

550

650

750

450

550

650

750

Color wavelength (nm)

Color wavelength (nm)

Metal halide 3000 K (MBI)

High pressure Sodium (SON)

100

100

80

80

60

60

40

40

Relative power

Relative power

20

20

0

0

400

500

600

700

800

400

500

600

700

800

450

550

650

750

450

550

650

750

Color wavelength (nm)

Color wavelength (nm)

10