Collimation lens
A lens directing the light rays incident on itself to the parallel optical axis of the
lens itself.
Colour temperature
It is the temperature of the black body producing a spectral emission with chromatic
features similar to the source itself. The colours emitted by heating the black body are,
starting from the lowest temperatures, red (up to 1,800K), orange (between 1,800
and 2,200K), warm white (between 2,200 and 3,500K), neutral white (between 3,500
and 5,000K), cold white (from 5,000K to infinity)
Colour tolerance
Colour difference inside a chromatic section of a lighting source (e.g. LED), usually
produced by the manufacturer and identified with an acronym.
Colourimetry
Measurement of colours, based on a set of conventions.
Cones
Photoreceptors of the retina containing pigments that are flexible in light which are
the basis of the photopic vision process.
Connector
Connecting element between two components of a system. It can be mechanical,
electrical or electronic.
Constant current
See also definition of ‘current’. Current supplied by an electrical device that is kept at
a constant level. Constant current power supplies distribute a specific current within
certain tension limits. These can vary from zero to a maximum value, or from a mini-
mum to a maximum value.
Constant tension
See also definition of ‘tension’. Tension supplied by an electrical device, kept at a
constant level until its maximum power level is reached.
Contrast
Subjective adjustment of the difference in appearance of two parts of a visual field
(observed simultaneously or in succession).
Cool white
White light with cold colour temperature (5,000-10,000K)
