|
|
|
|
|
|
|
Glossary
of the most important Lighting
Term
|
|
|
As with any technical or scientific discipline, light technology has its own
terminology.Special term and concepts are used to define the characteristics of
lamps and luminaries and to standardize the units of measurement. |
|
|
Light is taken to mean the electromagnetic radiation that the human eye
perceives as brightness, in other words that part of the spectrum that can be
seen. This is the radiation between 380nm and 760nm,a tiny fraction of the
spectrum of electromagnetic radiation
|
|
|
Unit of measurement: lumen [lm]
All the radiated power emitted by a light
source and perceived by the eye is called luminous flux F
|
|
|
Unit of measurement: candela [cd]
Generally speaking, a light source emits
its luminous flux F in different direction and different and at different
intensities.The visible radiant intensity in particular direction is called
luminous intensity I
|
|
|
Unit of measurement: lux [lx]
Illuminance E is the ratio between the
luminous flux and the area to be illuminated.An illuminance of 1 lx occurs when
a luminous flux of 1 lm is evenly distributed over an area of 1 square meter
|
|
|
Unit of measurement: candelas per square meter
The luminance L of a light
source or an illuminated area is a measure of how great an impression of
brightness is created in the brain
|
|
|
Unit of measurement: lumens per watt [lm/W]
Luminous efficacy Indicates
the efficiency with which the electrical power consumed is converted into
light
|
|
|
Unit of measurement: Kelvin [K]
The color temperature of light source is
defined in comparison with a "black body radiator" and plotted on what is knows
as the "Plankian curve" the higher the temperature of this "black body radiator"
the greater the blue component in the spectrum and smaller the red component.An
incandescent lamp with a warm white lights, for example. Has a color temperature
of 2700K, whereas a daylight fluorescent lamp has a color temperature of 6000K
|
|
|
The light color of a lamp can be neatly defined in term of color temperature.
There are three main categories hereWarm < 3300K Intermediate 330 to
500kDaylight > 5000KDespite having the same light color, lamps may have very
different color rendering properties owing to the spectral composition of their
light.
|
|
|
|
|