Rods
Photoreceptors of the retina in which pigments are sensitive to scotopic vision. Rods
are considered not to play any role in the discrimination of colour stimuli.
S
Saturation
Attribute of a visual sensation that allows you to judge the proportion of pure chro-
matic colour in the total sensation.
Screen
Part of a lighting device consisting of translucent or opaque elements, geometrically
arranged in such a way as to hide the lights from the observer at certain angles.
Scotopic vision
Vision that occurs when the eye adapts to luminance levels less than a few hundredths
of a candela per square metre; the rods are considered the main active components of
the eye in this condition. The spectrum appears not coloured.
Secondary optics
In an optical system, these are elements that are intercepted by light in the second
place.
Security lighting
Part of the emergency lighting system designed to ensure the safety of persons.
Sensitivity
Quotient between the response Y of a detector and its excitation X.
Solid angle
Solid angle subtended at the centre of a sphere by a cap with an area that is numeri-
cally equal to the square of the radius. Measured in steradian, sr.
Source
Any element able to product an electromagnetic radiation.
Spectrum
Distribution of a radiometric magnitude (radiance, radiation intensity, radiating flux),
as a function of radiations frequency or wave length.
Standard EN60598-1
Standard regarding electrical safety of lighting devices.
